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If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Lathe & Its Uses - Or, Instruction in the Art of Turning Wood and Metal. - Including a Description of the Most Modern Appliances For - the Ornamentation of Plane and Curved Surfaces. With an - Appendix, In Which Is Described an Entirely Novel Form of - Lathe For Eccentric and Rose Engine Turning; a Lathe and - Planing Machine Combined; and Other Valuable Matter Relating - to the Art. - -Author: Anonymous - -Release Date: November 30, 2019 [EBook #60819] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK THE LATHE & ITS USES *** - - - - -Produced by Karin Spence, Curtis Weyant and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from scans of public domain works at the -University of Michigan's Making of America collection.) - - - - - - - - - - [Illustration: FIRST-CLASS 5-IN. CENTRE LATHE, WITH TRAVERSING MANDREL - AND OVERHEAD APPARATUS, BY JAMES MUNRO, LAMBETH.] - - - - - THE LATHE & ITS USES; - - OR, - - INSTRUCTION IN THE ART OF TURNING - WOOD AND METAL. - - - INCLUDING - A DESCRIPTION OF THE MOST MODERN APPLIANCES FOR THE - ORNAMENTATION OF PLANE AND CURVED SURFACES. - - - With an Appendix, - - IN WHICH IS DESCRIBED AN - - ENTIRELY NOVEL FORM OF LATHE FOR ECCENTRIC AND ROSE - ENGINE TURNING; A LATHE AND PLANING - MACHINE COMBINED; - - _And other Valuable Matter relating to the Art_. - - - COPIOUSLY ILLUSTRATED. - - - NEW YORK: - JOHN WILEY & SON, PUBLISHERS, - NO. 2, CLINTON PLACE. - 1868. - - - - - PREFACE - - -Although the title of this work is sufficient to declare its contents, -a few prefatory remarks may not be superfluous as to its design and -the manner in which that design has been carried out. - -It has ever been to the writer a matter of surprise and regret, that -although the art of turning has been so long and so successfully -pursued in this country, both by artisans and amateurs, no work has -appeared in the English language treating upon the subject, except one -or two sketches and imperfect treatises. - -Some years since Mr. Holtzapffel advertised a forthcoming series of -seven volumes, intended to supply this manifest deficiency in our -scientific and mechanical literature, and the subject would have been -handled by him in a thoroughly exhaustive and masterly manner. - -The untimely death of that gentleman occurred after the publication -of the first three volumes, which are indeed complete in themselves, -and of immeasurable value to the mechanic and amateur; but which -are unfortunately only introductory, "simple turning by hand-tools" -being the special subject of the proposed fourth volume. The present -proprietors of the firm of Holtzapffel & Co. having, in their -catalogue even up to the time of the most recent edition, continued -to advertise the seven volumes, amateurs especially have anxiously -hoped for the publication of some part at least of the remainder of -the series. That expectation is, it is to be feared, little likely -to be rewarded; and, not until that fact had been ascertained with -something bordering upon certainty, did the author of the present -work venture to take up the pen and endeavour to set forth the -principles and practice of an art which, like so many others, he has -found so absorbing and attractive, and withal so delightful a source -of recreation to mind and body. Several things, however, contributed -to make the writer hesitate to undertake such a work. In the first -place he was aware that a number of _possible_ readers would probably -be more competent than himself for such a task, especially those whose -means might have enabled them to procure a large amount of the most -modern and approved apparatus connected with the Lathe, and whose -occupations might allow of more leisure for their extensive use than -falls to the lot of the writer. - -In the next place the risk of publication was such as he felt himself -hardly justified in encountering. Just at this time, however, chance -placed in his hand two or three numbers of the "English Mechanic," -in which some one else had begun, but speedily resigned, a series of -papers "On the Lathe and its Uses," compiled from American journals. - -The author of the present work at once put himself in communication -with the editor and proprietor of the above periodical with a result -now well known to the readers. - -The following pages are not, strictly speaking, a mere reprint -from the "English Mechanic." The papers have been carefully -revised and re-arranged; some statements, the correctness of which -appeared doubtful, modified or wholly withdrawn; while, in one -or two instances, whole chapters have been re-written, and the -suggestions and inventions relating to the Lathe, furnished by other -correspondents, embodied (when they appeared of real value) in the -work. - -But, in addition, a valuable Appendix is now published, containing -matter of great importance, contributed by one or two gentlemen, who -most kindly placed their papers at the service of the author. Foremost -among them stands a paper on the angles of tools, by Dodsworth Haydon, -Esq., of Guildford. A clever arrangement of Lathe for Rose Engine -Work, by the aid of the Eccentric Chuck without Rosettes, is also -added from the pen of Mr. Elias Taylor, of Brighton; and one or two -matters, which did not appear so fully treated as they deserved in the -body of the work, have been resumed and more fully discussed in the -Appendix. - -The author gratefully acknowledges the suggestions of various -correspondents, amateurs and working men, from whom, as a rule, he has -not failed to obtain any required assistance. - -That the work, in its present form, is entirely satisfactory or -complete, the writer cannot pretend; that many errors have crept in is -highly probable; but, if it is acknowledged to be the best work _yet_ -produced on the Lathe, and should prove in any degree serviceable to -amateur or artisan in the pursuit of this most delightful art--aye, if -it should stir up some abler pen to write a better and more complete -series, it will afford real pleasure and lasting gratification to - - THE AUTHOR. - - - - - CONTENTS - - - PREFACE. - - Introduction. - - Chucks. - - Hand Turning of Wood. - - Hollowed Work. - - Cutting Screws. - - Hollowing Out Soft Wood. - - American Scroll Chuck. - - Metal Turning by Hand Tools. - - Overhead Apparatus. - - Self-acting and Screw-cutting Lathes. - - Wheel Cutting in the Lathe. - - Fret Saws to Mount upon the Lathe Bed. - - Turning Spheres. - - Hoblyn's Compound Slide-Rest. - - Chucks with Slides and Compound Movements. - - Turning Ovals, etc., by Means of a Template. - - Eccentric Chuck. - - Curiosities. - - Grooving and Mortising Small Work. - - Ornamental Turning. - - The Eccentric Cutter Frame. - - Segment Engine. - - Holtzapffel's Rose Cutter Frame. - - Universal Cutter Frame. - - Rose Engine. - - Rectilineal Chuck. - - Epicycloidal Chuck. - - The Spiral Chuck. - - - APPENDIX. - - Professor Willis's Tool Holder for the Slide Rest. - - Munro's Planing Machine to be attached to the Lathe, and - worked with the foot. - - Hicks' Expanding Mandrel. - - Turning Spheres by means of Templates. - - Plant's Geometric Chuck. - - A Paper on the Principles which Govern the Formation and - Application of Acute Edges, with special reference to Fixed - Turning-tools, contributed by Mr. Dodsworth Haydon. - - Detached-cutter Holders. - - New form of Rose Engine by E. Taylor. - - Oval Turning and Rose Cutting with Templates with my - Apparatus. - - - - - THE LATHE AND ITS USES. - - -The Lathe has now for many years been steadily making its way from -the workshops of our leading artisans to those of the amateur and -lesser stars of the mechanical world. This is but the natural result -of the various additions and improvements which have been introduced -into its construction from time to time. The unworkmanlike and -clumsy tool of olden days has long since been superseded by one of -admirable finish and perfect aptitude for its designed uses; and -now that its construction is no longer dependent upon the skill of -the workman alone, but upon machinery moving with the precision of -clockwork, the fitting of the various parts is accomplished with -the greatest ease and certainty. The sale being thus extended, the -price has considerably diminished--the monopoly enjoyed by one or two -makers no longer exists; and there are few of a mechanical turn of -mind who cannot now provide themselves with a lathe suited to their -requirements. - -Nevertheless, the adepts in the art of turning are by no means so -numerous as might be expected, and, among amateurs especially, it is -rare to find work executed in first-rate style by simple hand tools -requiring skill and practice in their use, so that it not unfrequently -happens that a workman who can turn out exquisite specimens of ivory -carving and ornamental lathe work, is but a fourth-rate hand with the -gouge and chisel. - -But however beautifully executed such ornamental work may be, the -_credit_ is rather due to the tool than the workman, and a -well turned box with accurately fitting cover may bespeak more skill -in handiwork than the above elaborately designed specimen. - -Moreover the one requires lathe fittings, which are not always to be -had unless the purse is well filled, whereas the general mechanic -(amateur or professional) can provide the tools needed for the other; -hence we propose first of all to give some practical hints on plain -hand turning of wood and metal. The ordinary form of foot lathe is -well known and requires no special description, it is represented in -the frontispiece of this volume. There are, however, certain points -of detail in its construction, to which it is necessary to direct the -reader's attention. - -First and foremost comes the mandrel, of which there are several -patterns, according to the special purpose for which the lathe may be -intended. - -Now of whatever form it may be made this is the essential part of -the lathe, and must run with the utmost truth in its bearings. -Imperfection here will be imparted to all work executed upon it, and -accuracy in this part alone will make up for any slight defects that -may occur in less important parts of the machine. - -For ordinary work in wood alone or in brass the best form is -represented in Fig. 1. - - [Illustration: FIG. 1.] - - [Illustration: FIG. 3.] - - [Illustration: FIG. 2.] - -The part _a, b_, should be cylindrical, with a feather let in to fit -a slot in the pulley shown in Fig. 2. This pulley, whether of hard -wood or metal, is thus slipped on the mandrel as far as the collar -_d, d_, and a nut _e_, screwed up tightly at the back of it, fixes -it securely in its place, from which it may be moved if requisite -and replaced without fear of being out of truth. This cannot be done -if the mandrel is squared at _a, b_, and the pulley driven on with a -hammer, as commonly done by inferior workmen. The part _c_, is made -conical, to fit a hardened steel collar of similar shape. The angle -of this conical part is of some importance, as if it is too small the -mandrel is apt to jam and stick tight in its bearings. 35° will be -found to work well. With regard to the length of this conical part, -opinions differ considerably, but it must be remembered that friction -is independent of the _extent_ of the bearing surfaces and depends -on the force with which they are pressed together (in the present -case it depends on the tension of the lathe cord and the weight of -the material to be turned), so that a tolerably wide margin may be -allowed in this matter. Practically the question is decided by the -thickness of the casting of the poppet head, _which_ is regulated by -the required strength and size of the lathe. The collar is sometimes -of hardened steel, sometimes of brass. The latter would theoretically -cause less friction than the former, but practically nothing can beat -a well finished collar of hard steel. Collars of this material made by -the original Holtzapffel two generations back are now as good as ever, -perhaps even better. The centre, which screws up against the left-hand -end of the mandrel, should be of the form shown in Fig. 3--a plain -cylinder with a screw cut at each end to receive clamping nuts. The -central part is rather larger than the screwed parts, and passes truly -through the poppet head. This form is much better than a simple screw -with points, as the latter is not likely to keep the line of centres -in being screwed up into its place. - -It will be found of great convenience to have the screw on the nose -of the mandrel (and indeed _all_ screws about the lathe) of standard -Whit worth pitch, as taps for the chucks are thus readily obtained, -and nuts and screws of the various sizes may be also procured to -remedy breakages and losses. Upon this subject, however, we shall have -occasion to treat more fully when we pass from the description of the -lathe itself to the work that is to be accomplished by its aid. - -The only form of back poppet that need be particularised is that made -with cylinder and leading screw. The simple pointed screw passing -through the lathe head tapped to receive it, not only requires -no special description, but it is only calculated for lathes of -the commonest design, as it is seldom that the line of centres is -accurately maintained by the point at every part of the revolution -of the screw. Moreover, the latter soon works loose in the poppet, -and for anything like accurate work becomes speedily useless. The -cylinder and _pushing_ screw is indeed far superior to the form just -alluded to, and where cheapness is an object it has its advantages -over the first-named and best form. It is represented in Fig. 4. The -cylindrical part is shown at B, and may have at one end the usual -point, and at the other a small conical hole or hollow centre. It may -then be reversed in its bearings at pleasure, or other cylinders with -different shaped ends can be substituted, as may be found convenient. -Of course the pushing screw A is for the purpose of advancing the -cylinder, which is clamped by the small screw at C. The cylinder and -leading screw are shown in detail in Fig. 5, which is the poppet -head bored throughout to receive the spindle or cylinder A. At the -right hand this bore is enlarged to form a recess, B, to receive -the head of the leading screw, C. This screw is generally made with -a left-handed thread, so as to withdraw the back centre when turned -from right to left. The spindle A, A is bored, and a left-handed female -thread is cut from end to end--this however is turned off at the place -destined to receive the movable point or centre, and a hole slightly -tapering is cut, or if preferred a cylindrical hole is made and tapped -for the same purpose. The spindle has also a slot cut from end to end, -into which a screw enters from the poppet, preventing the spindle from -turning round while the internal screw is revolving by means of the -small wheel and handle fixed to its right hand end. The spindle is -now put in its place, the screw inserted and turned till the head or -flange, C, rests in the recess before mentioned--a flat plate, F, is -then attached to the back of the poppet by three or four screws, the -head of the leading screw passing through its centre; the small wheel -is then attached and the whole is complete. - - [Illustration: FIG. 4.] - - [Illustration: FIG. 5.] - -It is evident that by turning the wheel the internal screw is put -in revolution, and as it is prevented by its flange from assuming -any motion in the direction of its length, the movable cylinder will -instead be withdrawn or thrust forward. - -This form of poppet is the best that can be adopted and is of general -use in all first-class lathes. In addition to the movable point _g_, a -flange similar to H should be fitted. This will be found of great use -when the lathe is used for drilling, the piece of work resting against -it, while the pressure is regulated by the leading screw. - -There are, in addition to the flange and pointed centre, other pieces -of apparatus that can be substituted, as occasion may require, and -these will be hereafter described in this series. With regard to the -common rest for hand turning a lengthened description is unnecessary. -The T or tee should for wood turning be of the form shown in Fig. 6 at -A. It is often made as B, which is a very inconvenient pattern, as the -cross piece on which the tool rests cannot be advanced sufficiently -close to the work if the latter exceeds a diameter of two or three -inches. For metal turning the top of the rest should be flat, and -about one inch broad, as the heel of the hook tools used for turning -iron must be able to take a firm bearing upon its surface. Sometimes -a plate of brass is riveted on the flat top, as the tool takes a -firmer hold on this metal, and when the latter becomes defaced and -channelled it can be renewed without the cost of a new casting in -iron. The turner should be provided with two or three tees for metal -and for wood,--one may be long enough to have two legs and require -two sockets, as shown at C. This is convenient in turning long pieces -of wood,--a very short tee, not more than an inch in length, should -also be provided, and if one tee is specially kept with a very level -and smooth edge, it will be found of great advantage in chasing -screws--indeed the latter work can hardly be managed at all if the top -of the rest is damaged and uneven. The next part requiring description -is the boring collar, without which even a hand turning lathe can -hardly be considered complete. This boring collar is intended so to -support one end of the work, instead of its being held by the back -centre, as to enable the workman to get at the end of it for the -purpose of drilling it. Suppose for instance the work in hand is a -tool handle, and that it is so far finished as only to require the -hole for the reception of the tang of the tool. If this is bored by -hand with a gimlet, it is seldom that the hole will be truly in the -axis of the piece, but when this is done in the lathe by the help -of the boring collar the bore will be truly central, and the tool -when in place will fall in the same line with the handle. This will -conduce to the correctness of the work in hand more than the amateur -or other workman might suppose, and a row of tools thus truly handled -and in good condition generally bespeaks an efficient and careful -artisan. There are several plans for boring collar of nearly equal -efficiency, and we shall describe one or two of the most common, and -also one invented by the author, and which, if carefully made, is of -great service. Fig. 7 represents a poppet head, B, which is but half -the height of the other poppets of the lathe--a side view of this is -shown at B, Fig. 8. Near the top of this poppet is a hole through -which passes a bolt C, by which and its nut the circular plate A can -be securely clamped in any desired position, as it revolves freely on -the bolt as a centre pin. This plate is bored with a series of conical -holes, which are so arranged that their respective centres will be in -a line with the centres of the mandrel when any one of them is brought -into a position corresponding with the line _c, c_. The hole thus -brought into position for use (having been selected according to the -size of the work to be bored), takes the place of the back centre; -the end of the work rests in the cone, which is greased or soaped to -reduce friction, and the rest being fixed at the other side of the -boring collar, the drill can be readily used, and the bore afterwards -enlarged if necessary with any convenient tool. This boring collar is -generally made of iron, but a substitute of hard wood will frequently -serve the purpose, and can be made by the amateur, who may be unable -to obtain one of more durable material. If made of wood the best -unguent will be soap or black lead, such as is used for grates, or a -mixture of the two. This black lead or plumbago (it has no lead in its -composition) will always be found serviceable where wood works upon -wood, and also to give a smooth surface to wooden patterns for casting. - - [Illustration: FIG. 6.] - - [Illustration: FIG. 7.] - - [Illustration: FIG. 8.] - -Where cost is an object, a simple substitute for the boring collar -is frequently made by the ordinary workman by a piece of board one -inch thick, shaped like Fig. 9, with a single hole of the size most -generally required; and the work is then fitted to the boring collar, -instead of the latter to the work. In turning tool handles, for -instance, where a few dozen are required all of the same size, or -nearly so, a device of this kind, which can be made in a few minutes, -is sufficiently effective. This form has been modified in two ways, -and either will be found convenient. In the first, the conical hole -is made of the largest size likely to be required, a set of boxwood -plugs are then turned to fit this hole and are themselves bored in a -similar way to suit various sizes of work. The form of these plugs is -shown in Fig. 10, which is a side sectional view, and at B, where the -same is shown in perspective. Two small screws or pins _b, c_, Fig. -10, fitting into the holes _a, a_, Fig. 9, prevent these flange-shaped -plugs from turning round in the board as the work revolves. The -pattern of A, Fig. 9, may be varied, and is better made of hard wood, -and of a form which will afford a good bearing upon the lathe bed. - - [Illustration: FIG. 9.] - - [Illustration: FIG. 10.] - -The second modification is more difficult to make, but equally -effective. It is shown complete in Fig. 11. This form, arranged by -the writer, has many advantages over the two last-named, and is very -serviceable. A is the poppet, of the full height of the ordinary -lathe heads, or a couple of inches higher. B, the slide forming the -support of the piece to be bored. The form of the poppet without this -attachment is shown in Fig. 12. If for nice work it should be made -of metal and the face of it planed, but for general purposes hard -wood will suffice. _b, b_, Fig. 11, are two pieces of brass forming a -groove or guide in which a slide B, with dovetailed edges is fitted -to work. This slide is bored, like the ordinary collar, with conical -holes of different sizes, and should be made of metal and planed on -back and edges. Over each hole is a mark, and this is to be brought to -a similar mark on the face of the poppet. The plate is then clamped -in position by a screw at the back of the poppet. One or more of such -slides may be fitted at pleasure, and in case of wear or damage these -are the only parts requiring to be renewed. - - [Illustration: FIG. 11.] - - [Illustration: FIG. 12.] - -It is a good plan to arrange a socket and tee of a rest as _b, c_, -Fig. 13, at the back of this boring collar, especially as the position -of the tool will be always the same, so that the rest may be a -permanent part of the poppet. There is sometimes a difficulty with the -ordinary form of boring collar in advancing the rest T sufficiently -near the work (the foot of the poppet, and that of the rest preventing -it, by coming in contact.) There is another modification of boring -collar, forming at the same time a guide for the drill, which in -slender work, where the tool is long and fine, becomes almost a matter -of necessity. - - [Illustration: FIG. 13.] - -This consists in making such a guide cone as mentioned and shown -in Fig. 10, B, but with a continuation containing a smaller hole -for the drill, as Fig. 14. Both this and the other shorter cones -above-mentioned may be made to screw into the poppet A, Fig. 9, -instead of being kept in place by the pins at _a, a_, of that figure. -In that case however the hole in the poppet must be cylindrical and -only used as a support for the cones themselves. In addition to -the use of these boring collars already alluded to, they serve for -the purpose of turning up the points of screws like those of lathe -centres. These are first formed between centres with carrier chuck, -the back poppet is then removed and the extreme point fitted through -one of the holes of the boring collar and the marks of the centre -turned off. - - [Illustration: FIG. 14.] - -Another useful adjunct to the lathe is the back rest for supporting -long and slender articles, which would otherwise bend under the -pressure of the tool. The ordinary and simplest form is shown in Fig. -15, and this is of general use with brush handle makers and others -whose work is confined to a few sizes and shapes only. A better form -is shown in Fig. 16. A support of wood or metal shaped like A is -clamped to the lathe bed. Through the upper part the slide B passes -and is wedged up so as to support the work--or the socket of a lathe -rest may be arranged to take the upright part A, which must then be -rounded, as shown at C. - - [Illustration: FIG. 15.] - - [Illustration: FIG. 16.] - -A modification of the latter, communicated to the _English Mechanic_, -is shown in Fig. 16A. Its construction and mode of application is -sufficiently evident without a detailed description. Fig. 16B is -another form made in metal. It consists of two similar plates with a -triangular opening A, through which the work is passed, and which has -an oval slot D, by which the apparatus is secured to the short poppet -of the boring collar. Between the two plates slides a third, partly -visible at C, which can be clamped by a screw at B, this screw also -serving as a stud by which the plate may be moved. The work is allowed -to take up its own bearing in the triangular opening as it revolves in -the lathe. The clamping screw of the poppet is then secured, and the -centering thus made certain. The plate C is then made to descend so as -to touch the work, and clamped in that position. This is a very good -central support for long slender articles. - - [Illustration: FIG. 16A.] - - [Illustration: FIG. 16B.] - -There is a plan practised by German turners by which the back rest -is in a measure superseded, and which may be mentioned here. It is -simply the peculiar method of using the left hand. This is placed on -the piece to be turned so that the fingers partly encircle the work -while the thumb rests in the hollow of the gouge, or upon the end of -the tool. The fingers thus form a back rest and keep the work pressed -against the cutting edge, which is further steadied by the thumb. As -the tool traverses the work the left-hand accompanies it, and with -a little practice a ramrod or similar long and slender article may -be readily and accurately turned. This position is shown in Fig. 17, -and though the novice will find it difficult to work thus, it is well -worth the trouble of mastering, as the method once acquired will be -found of very great service. - - [Illustration: FIG. 17.] - -We have now described more or less in detail the principal parts of -the lathe as adapted for hand turning. Before we dismiss this part -of the subject, however, it will be necessary to say a few words -respecting the bed and lower fittings, the flywheel, treadle, and -their adjuncts. - -Beyond question the iron bed, planed as it now is at a moderate price, -by machinery, is the best that can be adopted, especially if it is -intended eventually to fit up the simple tool with slide rest and -superior apparatus. Nevertheless, the pocket must in this case also -frequently decide the question of material. If wood is preferred by -necessity or otherwise, it should be _hard_ wood, beech, or Spanish -mahogany, unless it is proposed to plate the surface with iron. This -latter plan costs little and, besides stiffening the bed, it prevents -the wear and tear caused by the constant shifting of the back poppet -and rest. A flat strip of iron one inch or an inch and a half wide -can be picked out from the stores of any village blacksmith straight -and level as it came from the rolls of the manufacturer. Selecting a -piece of the required length and breadth, the eighth of an inch thick -or rather more, the purchaser will have holes drilled and countersunk -at intervals of nine or ten inches, to receive 3/4-inch screws. -These strips will have to be laid upon the top of the bed, at its -inner edges; they need not be let in flush with the surface unless -appearance is studied. - -They must then be screwed down firmly, and by means of a file worked -by both hands up and down their length (not across them) a good -surface may be readily obtained. If the iron is let into the bed this -filing will abrade the wood work, which is the reason why we prefer -screwing it on the surface. This method produces a very excellent and -durable lathe bed, and it will be free from much of the tremor which -is so disagreeable while working upon a lathe entirely of cast iron -unless the bed of the latter and the standards are more substantial -than is usual with small lathes. - -The standards supporting the axle of the fly wheel and bed may in like -manner be of wood or iron. Even when the bed is of iron these may -be of hard wood, although it is customary to make them of the same -material as the bed. If of beech, oak, or mahogany, as in some of -Holtzapffel's best lathes with iron beds, the tremor before alluded to -will be considerably lessened. Iron is nevertheless very neat, and is -quite the fashion with the majority of makers, but is too often faulty -in respect of solidity. - -The standards as a rule are too slight, an elegant pattern being -studied to the sacrifice of substance and weight, The bed and stand of -a lathe cannot be too strong and stiff. - -Respecting this matter of stiffness and solidity we seldom find it -sufficiently considered, and, even with practical workmen, a defect in -this particular is more frequently acknowledged and put up with than -remedied, although the _comfort_ of a steady lathe is beyond question, -to say nothing of its superiority when good workmanship is studied -(as it always should be). The old French lathes made in the form of -a thick table with four stout legs, forming the bed and back-board, -are by no means to be despised as patterns; and instead of the usual -method of making but one standard at end of the bed, there can be no -question that two additional ones add considerably to the stability of -the machine. - -The fly wheel should be sufficiently heavy and have three speed -grooves on the rim and two additional ones to produce a slow motion, -which is required for turning metal. The latter may be worked with -ease in this way when the article to be turned is small, but if -heavy work is likely to be encountered the back geared lathe, to be -hereafter described, must be substituted, and the slide rest will then -also replace the hand tools. The crank axle is generally supported by -two centre screws, the points being hardened, and also the ends of -the axles, which are accordingly made of steel, and the holes for the -centre screws neatly drilled and countersunk. - -This is however not the most perfect method, and as we are speaking of -better class lathes, as well as those of more common and cheaper make, -we must by no means omit to speak of a very superior way of fitting -the crank axle. The latter must be turned at both ends, the wheel -bored and slipped on, and keyed in its place. - -Two wheels of brass about two inches diameter, must then take the -place of the centre screws. These are called friction wheels, and they -must be placed sufficiently near each other to support the end of the -axle between them, as shown in Fig. 17B, _a_ and _b_. A pair of these -must be thus fitted to each standard, and after the axle is placed in -position a third may be placed above it to prevent the lathe cord from -lifting the axle out of place by its tension. The axle and friction -wheels will thus work together with an exquisitely smooth rolling -motion--there will be no tendency to thrust the lathe standards apart -as must result from tightening the ordinary centre screws, and the -friction of the axle on its bearings will be reduced to a minimum. -Any person acquainted with the use of the lathe may readily fit up -these friction wheels, and the time and trouble so expended will be -amply repaid by the superior ease with which the lathe can be used. We -may say the same of the chain and eccentric, which can replace with -similar advantage the crank and hook in ordinary use. - - [Illustration: FIG. 17B.] - - [Illustration: FIG. 18.] - -For the latter the following arrangements are necessary. A is the -eccentric keyed to the crank axle, and may be either in the middle -of the same or, as in Muir's patent lathes, at one end outside the -standard. Around it passes the endless flat chain B (known as crank -chain). This also passes round a roller in the treadle shown at C. -This chain does not act as a mere link, but when the lathe is in -action it moves round and over the eccentric and treadle roller. The -motion of the whole is smooth and regular, and, what is almost as -important, _noiseless_. In Muir's and other lathes the crank chain -is used without the eccentric, being applied to the crank instead. -Perhaps there is not much to choose between the two, but no one who -has studied the eccentric and observed its exquisitely gentle and -smooth motion in an ordinary engine can have failed to be struck by -these valuable qualities. It must however be remembered that its throw -is half that of a crank of the same eccentricity and the latter will -have the advantage in power size for size. - -In whatever position the lathe may be set up let the rise of the -treadle be moderate. It is exceedingly disagreeable to work at a lathe -where the rise of the foot board is so great as to bring the knee into -contact with the lathe bed, a consummation not infrequent in country -made ones. - -This is only to be escaped by giving up a certain portion of power. -Let A, B, Fig. 19, be the line of the treadle when at rest; _c_, -the crank. To gain power we should let part A, E, be longer than E, B, -as in the sketch. But let this arrangement be made, and when the -crank is at its highest point, the line G, B, will show the position -of the treadle and foot board. Hence this kind of leverage is not -practicably available to any extent, and the length taken from foot -board to link may with advantage be even less than that from link to -the axle on which the treadle works. In lathes, of all machine tools, -it is essential that the workman should be able to stand easily, that -the movements of the leg and body should not be communicated to the -tool, the play of the treadle and such items of detail being of more -consequence than might at first sight appear, and any method tending -to diminish friction, vibration, and noise is well worth consideration -in planning this machine. - - [Illustration: FIG. 19.] - -We may now suppose the reader the happy possessor of a well made foot -lathe, long or short in bed, high or low in poppet, according to his -need, but, of whatever size, carefully made and firmly fixed in a -well-lighted place, and if possible on the basement floor--an upstairs -workshop is objectionable owing to the certain vibration of a boarded -floor. He will now require certain chucks and tools, many of the -former of which he will have to make for himself. - - - CHUCKS. - -No lathe can be considered well fitted until it is supplied with a -large number of chucks, by which strange term are signified the -various appliances for fixing to the mandrel the article to be -turned. When it is considered how varied are the forms which present -themselves to the turner, it may readily be conceived that much -ingenuity has to be exercised in contriving methods for mounting his -work in the lathe; and when in addition to variety of _form_, variety -of _size_ has to be taken into consideration, it is plain that a -large assortment of chucks is a necessary item in the workshop of the -turner. A vast number of these chucks are of necessity made of wood, -as required, and such wooden ones are altered from time to time to -suit different-sized work, till they eventually become so completely -used up as to be only fit for the fire. In addition, however, to -these, there are certain chucks of metal (chiefly brass or gun metal) -which should always be ordered with a lathe, or fitted to it before -any work (even the making of wooden chucks) can be satisfactorily -accomplished. The first of these, is represented in Fig. 20, the part -A, screws to the mandrel; while the work is attached to the taper -screw B. The use of this chuck is to hold short pieces or flat discs, -which allow of a hole in the centre and require to be turned on the -face. It is only used for wood-work. This is the chuck to be selected -when it is desired to make a wooden chuck. A piece of sound wood -being chosen of the requisite size, and roughly rounded by the axe or -chisel, a hole is made in one face by a gimlet rather smaller than -the tapering screw. The piece is then firmly screwed to the latter, -the opposite end dressed with gouge and chisel, and the rest being -placed across the end, a hand-drill for wood is brought to bear upon -the piece. The hole thus made in the centre is then enlarged by any -convenient tool until its diameter is only a little less than that of -the screw cut on the lathe mandrel. An inside screw tool is then made -use of to cut a thread of the same pitch as that of the mandrel, or a -tap of similar size and pitch screwed into it (the former is the best -but most difficult method to a novice), the piece detached from the -taper screw chuck, which is removed, and the wood attached to the nose -of the mandrel on which it may now be accurately fitted and finished -to the requisite form and hollowed out or otherwise, as may be -necessary. Numberless articles may be in a similar manner turned upon -the above chuck such as the bottoms of candlesticks, ring or other -stands, bread-platters, small wheels, and so forth; it may therefore -stand as number one of these adjuncts to the lathe. - - [Illustration: FIG 20.] - -Fig. 21 is the face plate, another most serviceable chuck of almost -universal application in such work as surface-turning and boring, and -where a hole in the centre is inadmissible. To this belong various -dogs or cramps, a few forms of which are shown at _a_, _b_, _c_, _d_. -These hold the work firmly down to the surface of the plate, being -tightened from behind by screw nuts. It will be seen that there are -four slots and numbers of holes in the face plate, some of the latter -being tapped for screws. These slots and holes may be increased in -number, and some of the latter may be square instead of round, and -the cramps may be of all shapes and sizes, because sometimes it may -be required to hold down a flat piece of brass the eighth of an inch -thick only, and the next job may be to hollow an irregular block of -wood of three or four inches in thickness, or it may be necessary to -bore out the boss of a wheel, or to turn the rim--all of which, and a -hundred others, are cases in which the aid of the face plate will be -in requisition. - - [Illustration: FIG. 21.] - -Fig. 22 is the chuck specially used for turning rods of metal. It -consists of two parts, the body A, which screws to the mandrel, and -the piece B, which passes through a slot and is clamped by a small -screw at one side _c_. To these must be added the carrier which is -of such forms as A1, B1, C1. Above is shown a rod of metal to be -turned with this chuck in position for use. Of this we shall have to -speak again when we arrive at the subject of metal-turning. There -should be several sizes of carriers kept in stock, from 1/4in. in the -largest part of the ring to 2in. or 3in., or even much larger for -heavy work. The amateur will, however, scarcely need these larger -ones. The usual method of making the wood-holding chuck for work that -is to be also supported by the back centre, is to have a socket cast -like Fig. 23, C, with a central hole to take the fork A, which is held -in place by a set screw. This socket is useful for other purposes as -it will hold short pieces of iron to be turned, but the fork is far -inferior for general work to the piece _b_; this is made of iron, and -the end of the cross (against which the wood to be turned comes) is -sharpened but must not be _too_ sharp. The end of the piece of wood -has then two saw-cuts made at right angles to each other into which -the sharpened edges of the cross fall, Fig. 23 D, and the whole will -turn together without any chance of slipping. It often happens, when -the ordinary fork is used, that if the tool chances to hitch in the -work, the latter is either thrown quite out of the lathe, or the -centre of the fork retains its place, while the other two points slip -and score the work. This can never happen with the form B, which is -the most reliable pattern that can be devised for work of this nature. - - [Illustration: FIG. 22.] - - [Illustration] - - [Illustration: FIG. 23.] - -Fig. 24 is to some extent self-centering. A piece of wood hollowed out -conically has three nails, or three-square saw-files so placed within -the cone as to present three sharp edges inwards. Any piece of wood, -if not too hard, will, if placed with one end in the chuck, while the -back centre is screwed against the other, centre itself in some part -of this cone, and, being at the same time held by the three sharp -edges, will necessarily revolve in the chuck. There are many cases in -which even in this rough form such a chuck will prove useful; but if -it were cast in metal and the three edges formed by slips of steel, -and the whole accurately turned, it would be a very efficient and -good self-centering chuck. In its more common form it is largely used -by the turners of mop and broom handles, who work rapidly and cannot -afford to waste time in chucking their work. With the above, the -lathe, if worked by steam or water power, is not even stopped,--the -screw of the back centre has a quick thread, so that a single turn -to or fro fixes or releases the work; and thus, one handle being -finished, another piece takes its place in the chuck, is fixed by a -half-turn of the back screw, and being set in rapid motion is turned -and completed by a practised hand in a couple of minutes or less. - - [Illustration: FIG. 24.] - -Fig. 25 represents another useful chuck, generally of boxwood, called -the barrel stave chuck. It is turned conical, the largest part being -towards the mandrel; it is then wholly or partially drilled through, -after which saw-cuts are made longitudinally, as in the drawing. These -allow a certain degree of expansion when a piece of work is fitted -into it, and it is tightened round the latter by driving on a ring of -iron or brass. This ring is sometimes cut with a coarse thread inside, -and a similar thread being chased on the outside of the chuck, it -is screwed upon the cone instead of requiring to be driven by blows -of a hammer. One important use of this chuck is to re-mount in the -lathe, for ornamentation by the eccentric cutter or other apparatus, -any finished work that could not be readily chucked in any other -manner, or to hold rings requiring (like curtain rings) to be turned -on the inside. Such articles will, from the nature of this chuck, be -truly centred at once; and their exterior parts will not be liable -to injury, as they would be by being driven into an ordinary chuck -hollowed out to receive them. - - [Illustration: FIG. 25.] - -Another useful chuck for turning short pieces of metal such as bolts -and binding screws, and which is in a great measure self centering -is made of cast iron, and is usually called the dog-nose chuck, -represented in Fig. 26. This is made with movable jaw hinged, as more -plainly seen in B. The screw clamps these jaws firmly together, and -any small piece of work is thus securely held. The centering, however, -is not accurate, though sufficiently so for many purposes. The die -chuck (Fig. 27) is accurately self-centering, and although somewhat -expensive, is a valuable addition to the lathe. This chuck consists, -first of all, of a socket for screw to fit the mandrel, and round -flat plate of brass cast in one piece, as in Fig. 28. This must be -carefully turned and faced in the lathe. Two pieces of iron or brass -are then screwed to the face, as B, B, 28A, leaving a space between, -the sides of which are to be truly parallel. These pieces may either -be chamfered to form V-pieces, or may be rectangular on their inner -edges; at C, C, a part of each is cut away, and the outer or back -plate is also filed down to receive the small plates D, D. E shows a -groove in which a screw lies, half of which has a right and half a -left handed thread; this is shown in Fig. 29. It will be evident that -if this screw is placed in the groove of the bottom plate, and its -ends pass through the pieces D, D, which are screwed to the plates, -it can revolve in its bearings, but will have no endwise motion; -the collar F resting in a recess under the top plate D. This screw -passes through a projection in the back of the pair of dies, which -projection also goes into the same slot in the back plate in which -the screw works when turned by the key (Fig. 27, B). The above being -nicely fitted, the dies moving evenly but stiffly in their places, the -plain top is screwed on, keeping all firmly together. This plate has -a long opening or slot (Fig. 27), through which the jaws of the dies -and part of the screw are visible. The ends of the screw should not -project, as any such projection is calculated to bring to grief the -knuckles of the turner--a consideration worth attention in every form -of chuck--the squared ends of the screw lie in a recess in the small -plates, as shown in the section of one of these plates (Fig. 28X). -Into this recess the key fits over the screw end; and by turning this -the dies are simultaneously moved asunder, or closer together so as to -grasp centrally as in the jaws of a vice, any small article, such as a -screw or short rod of metal placed between them, A similarly contrived -chuck is often used under the name of a universal chuck, for holding -pieces of large diameter, and is very useful for taking pieces of -ivory which have to be hollowed or otherwise worked, as will hereafter -be detailed. In this case the jaws may be semicircular in form, as -Fig. 30. - - [Illustration: FIG. 26.] - - [Illustration: FIG. 27.] - - [Illustration: FIG. 28.] - - [Illustration: FIG. 28A.] - - [Illustration: FIG. 29.] - - [Illustration: FIG. 30.] - -It is however, evident that these two chucks have a rather limited -range. The first can only be used for small work, and the only case -in which the latter can take firm hold all round the work is when -the jaws are just so far apart as that they form portions of the -circumference of one and the same circle. Practically they will hold -the work tightly under an extended range of sizes, and they are thus -of great use to the turner. The following is however more perfect in -operation, from the fact that it has four jaws instead of two which -meet concentrically. This may be made either with two long screws at -right angles to each other, with right and left-handed threads to -each, as in the die chucks, or more simply and, in some respects more -satisfactorily, with four distinct screws, all of the same pitch, and -all with squared ends of equal size, to allow of the same key being -used to turn them. It is possible to use such a chuck as an eccentric -chuck if desired, which is certainly a recommendation in its favour -over those which work always concentrically. The face of this chuck is -shown in Fig. 31. The ends of the four screws have a bearing in the -small centre plate _b_, whilst the collars or flanges rest in a recess -under the several plates _c, c_. The face of this chuck is graduated -by each die, so that it is easy to set the jaws concentrically or to -place one or more eccentrically to take in work of other shape than -round or square. The jaws of this form of chuck are used for two -purposes, either to hold work inside them like a vice, or externally. -A ring, for instance, requiring to be chased on the outside is slipped -over the jaws, which are then caused to recede from the centre so as -to hold the work securely. If the latter does not run truly, one or -more of the screws can be slackened, and the opposite ones tightened, -or if the eccentricity appears to be in an intermediate part, two -adjacent screws will have to be thus slackened and the others -tightened. On the whole this is a most useful pattern of chuck. - - [Illustration: FIG. 31.] - -The following is a very excellent self-centering chuck now coming -into extensive use. It has been noticed in more than one periodical. -The description annexed is extracted from the pages of the _English -Mechanic_. "The chuck hereby illustrated seems to be a very convenient -form, easily adjusted and holding the drill securely. It is also -well adapted for holding wire to be threaded. Every piece of which -it is composed is of cast steel well hardened. It can be furnished -with a shank to fit the hole for the centre, screwed on the spindle, -or slipped on the centre. No wrench is necessary, the gripe of the -fingers being sufficient to secure the shank of any drill. The -inventor claims that he has used a one-inch drill, in tenacious -wrought iron in one of them, receiving a shank of only three-eighths -of an inch diameter without using a wrench." - -Fig. 31A represents the shell of the chuck with milled bosses for the -fingers. The core, B, is threaded and receives a steel wire spring -which is inserted into the rear of each jaw, so that when relieved -from pressure, the jaws open automatically. - - [Illustration: FIG. 31A.] - -With this brief explanation, the operation of the chuck can be easily -comprehended. These chucks are made of two sizes, one with an opening -of three-eighths of an inch, and the other of three-sixteenths of an -inch, and they can be made of larger sizes. Patented by L. H. Olmsted, -Stamford, Connecticut, United States America. - -Another chuck of self centering design, has likewise appeared in the -periodical above named, into which it appears to have been copied from -an American paper. - -The accompanying engravings illustrate some improvements in the -arrangement of chucks which have been recently patented in this -country, the inventors being Messrs. Smith and Haight, both of New -York, U.S. The first part of the invention refers to an arrangement -of adjustable chuck, by means of which tools and other articles of -different diameters may be held firmly in the jaws of the chuck. Fig. -31B is a longitudinal view of the chuck, partly in section. The -spindle, _a_, is fitted so that it may be inserted tightly in the -mandrel of the lathe. On the front end of the spindle is a conical -screw on which is fitted the cap, _b_; this part is formed with an -opening at the front end, having three longitudinal slots in it. In -each of these slots an adjustable jaw, _c_, is fitted, the inner part -of which is threaded with a female screw, to fit the conical screw on -the spindle, _a_. An outer casing _d_, encloses the front part of the -chuck, and behind this is fitted a loose collar, which is screwed into -the casing _d_, so as to connect the parts firmly together. By turning -the cap, _b_, with the casing, _d_, and collar, in one direction, the -jaws, _c_, are moved forward and project out through the openings, and -they may thus be adjusted to grip a tool or other article of small -diameter. The opposite motion of the cap causes the jaws to recede, -and in this way they may be adjusted to grasp articles of different -diameters. - - [Illustration: FIG. 31B.] - -Another arrangement of the adjustable chuck is shown in Fig. 31C, -which is a front view, and Fig. 31D, a longitudinal section of the -same. A, is the body of the chuck, the front part of which is formed -with a rim or flange, in which are three radial recesses having -fitted therein the sliding jaws, B. In the rear of each jaw is a -bearing, in which is fitted a pin carrying a small lever, C, the -front end of which is rounded, as shown in the section, and enters a -slot made in the jaw, B; so that when the levers are moved outwards -they cause the jaws to contract or move towards the centre. The -back part of the body, A, of the chuck is threaded, and on this part -is fitted a collar, D, and in front of this is a sliding collar, E, -which is connected to the collar, D, by means of a pin which enters -a groove formed in the latter. The sliding collar is prevented from -turning round on the body, A, by means of a feather, which works in a -longitudinal groove formed in the inner circumference of the collar. -Three inclined planes, F, are formed on the periphery of the collar, -E, which extend to the backward ends of the levers, C, so that by -moving the collar to and fro, the jaws, B, are caused to contract or -expand, according to the size of the article to be grasped. A short -cylindrical block, G, made of a conical figure internally is fitted -loosely within the chuck, A, and serves to centre the end of a drill -or other short article, but may be removed when it is desired to pass -a rod or other article through the body of the chuck. To provide for -the easy turning of the collar, D, it is shown as fitted with a hand -wheel, H. With this arrangement of the several parts, the jaws of the -chuck readily adapt themselves to drill or bit shanks as well as to -articles of parallel form, or of a tapered or irregular figure. - - [Illustration: FIG. 31C.] - - [Illustration: FIG. 31D.] - -The chucks last named belong to the class of compound or mechanical -tools; and though their usefulness is beyond question, they need -not be considered absolutely necessary, as the work which they are -designed to facilitate can be and often is done without their aid. -Indeed, success in the art of turning by no means depends absolutely -upon the possession of expensive apparatus, and the amateur or -mechanic will find the advantage of ransacking his own brain for the -devising of divers makeshifts and off-hand contrivances--especially -in this chuck-making department. - -Among the simple expedients the following will be found well worthy of -adoption. - -A, Fig. 32, is a simple flange or flat brass plate with a boss behind, -similar to a small face plate, and is to be turned up, drilled, and -tapped to fit the mandrel. If the latter has a diameter of 3/4 of an -inch, a few of these brass pieces should be cast from a set of wooden -patterns ranging from two to three or four inches across the diameter -of the plate, and, after having been fitted to the mandrel and turned, -four holes, countersunk for wood screws, should be made, as shown in -the sketch. These are intended to do away with the necessity of boring -out and tapping each individual wooden chuck. They can be readily -attached to any piece of wood by four screws, and a few minutes will -be sufficient to adapt the same to any required purpose. A flat piece -of board, for instance, itself too thin, or of too soft substance to -permit of its being attached to the mandrel in the ordinary way, can -thus be made into a temporary face plate, or a ring cut out of it, or -any desired operation performed upon it. Indeed, these socket pieces -will be found serviceable on many occasions, and will do away with the -necessity of a large set of cup chucks. - - [Illustration: FIG. 32.] - -A few of the latter, however, are very useful and will cost but -little. The castings are sold by weight, and the turner will -experience no difficulty in fitting and finishing them for himself. -Fig. 33 is the form of these, and needs no description. The substance -may be from 1/8 to 1/4 of an inch, and need not be more, as that -thickness will stand any reasonable shock caused by driving a piece -of wood into the chuck, and it is always well not to overweight the -mandrel with chucks of undue size or substance. The addition of -three to six screws to one or two sizes of the cup chuck extends its -usefulness. This form is represented in Fig. 34, A and B. In this -case, the casting may be rather more substantial (1/4 to “3/8 of an -inch in thickness). The screws _must be strictly radial_, pointing to -the centre of the circle, and their ends must be turned off or filed -flat. Their heads may be squared to enable a key or pair of pincers to -be applied, or round with a hole through them. It is better to make -this kind of chuck with six screws--three in one plane, and three -again _between_ these in another plane behind them. In fitting a piece -of work into the chuck, it will not at first be found an easy matter -to make it run truly. The best way is to centre it as nearly as can -be guessed, by means of the three screws nearest to the open end of -the chuck, and then, placing the latter on the mandrel, set the lathe -in slow motion and correct the eccentricity of the piece by means of -the three inner screws. Even after this it is probable that a little -alternate slackening and tightening of the different screws may be -necessary; but a little practice will quickly enable the turner to set -a piece of work in the true axial line of the mandrel without much -difficulty, and the work will then be held very securely. Any short -piece, such as the ring of an eccentric to be bored truly inside, may -be held by the outer set of screws alone; but if such a piece of work -as a small cylinder is to be bored, the six screws must be brought -into action. Here let the hint given when speaking of projecting -screws, be repeated, _Beware of the knuckles_, which are peculiarly -liable to be damaged in making use of these chucks. The shirt sleeve -or coat, moreover, does not always enjoy perfect immunity from similar -danger, and both should be kept out of harm's way, not for their own -sake only, but because the arm may be brought into violent contact -with the rest if the sleeve should get entangled (the momentum of the -flywheel being great, and therefore not to be checked entirely at any -given moment). A single rap of the above nature is not a _delightful_ -even if _salutary_ lesson to the novice. - - [Illustration: FIG. 33.] - - [Illustration: FIG. 34.] - -To hold rings and washers a tapering mandrel, Fig. 35, is used; -and of these it is necessary to keep a few different sizes to suit -different diameters. These may be made of iron or brass if for -permanent use, but box or other hard wood is a ready substitute, and -may be turned down for smaller work when the surface gets spoiled by -use. The expanding mandrel, "Hicks' patent," which will be treated of -hereafter, is a convenient substitute for the simple conical form here -spoken of; and in manufactories where large numbers of mandrels have -to be kept of various sizes, a great saving of time, money, and labour -is effected by their use. For amateurs and artisans in a smaller -way of business the simpler form is generally sufficient. A slight -modification is here appended, by which the common form may sometimes -be made more efficient in the holding a ring tightly while undergoing -the operation of turning, and this can be made applicable to metal -mandrels, though specially intended for wooden ones. Fig. 36. - - [Illustration: FIG. 35.] - - [Illustration: FIG. 36.] - -The mandrel having been turned conical (N.B., the angle of the cone -must be small, so that the size will diminish very gradually from the -largest end), the wood is divided by a fine saw, just as the chuck -already described with the outside rings was sawn into segments, a -conical hole having been first made at the smallest end, as shown -in the section _b, b_. Into this a short cone of larger angle is to -be fitted, against the end of which the point of the back centre -will press, tending to drive it into the mandrel, which will thus be -made to expand. The ring to be turned will prevent the mandrel from -splitting by the wedge-like action of the plug, unless the said ring -is of light substance, in which case this form must not be used. The -work will, by the above method, be securely and centrally held and not -liable to slip towards the small end of the chuck. - -In the Fig. 36, a groove, _c, c_, is shown at the bottom of the -saw-cuts. This should also be made round the boxwood spring chucks -with rings, as it gives more freedom of expansion to the segments. -With such a groove and the chuck itself completely hollowed out, -the pressure of a _strong_ india-rubber ring will be sufficient to -hold work whilst being polished: and this will, when the latter is -delicate, be even superior to the screwed rings, as the pressure -will be more gentle and equable. India-rubber rings for this purpose -must not be thin and flat, like those used for bundles of papers or -letters, but made of round material, the thickness of a quill or even -larger. They may be had of all sizes at an india-rubber warehouse -in Holborn, at the bottom of the hill on the left hand side going -eastward, and not far from Negretti and Zambra's shop. The writer is -not acquainted with the name of the proprietor. - -Having had occasion to speak of tapping chucks of metal to fit the -mandrel, it will be as well to speak here of the requisite tools for -effecting this. - -In the case of iron chucks it is not likely, as a general rule, that -the amateur or workman will obtain access to a screw-cutting lathe, -and to cut an internal thread by hand with the chasing tool is hardly -feasible, though readily accomplished in the case of brass chucks. -When, therefore, a lathe is purchased, a set of taps of the diameter -and pitch of the screw on the mandrel should be provided. Of these -there must be three--an entering taper tap, an intermediate one -rather less tapering, and a plug tap, which is cylindrical. And here -we must enter a caution. Do not let the tapering taps be too long. -For instance, let it be required to tap the boss of a face plate in -which the hole cannot be drilled through the plate. It is first bored -out to the size of the _bottom_ of the mandrel threads, or rather -less. Tap number one must then be screwed into it; but if this is too -long, so that it cannot enter to the end of the threads cut upon it, -the second tap will be too large and will not enter properly, but -will most likely start a new thread for itself and spoil the first. -Fig. 37, _a_, _b_, _c_, shows the form required; _d_, the form to be -avoided, except in cases where, as in the cup chucks, a hole can be -made quite through the article, so that the tapering tap can be worked -to the line _x, y_, or nearly so. The long tap, _gradually_ tapering -as it does from end to end, is of course the easiest to use, and for -nuts and such like is far the best; the conical tap of larger angle -requires more power, but in the case named it is a matter of necessity -to use it; and, if preferred, a set of four taps instead of three will -remedy any difficulty. The novice must take great care to place the -tap perpendicular to the face of the chuck, or the shoulder will not -fit close to that on the mandrel. If much difficulty is experienced, -such an arrangement as Fig. 38 may be of service. A represents the -standard of an upright drill-post, of which B is the bench, C the -screw by which to depress the drill and keep it to the cut. For the -latter, and brace by which it is worked, substitute the tap, and place -a spanner or wrench round the head of it. In the centre mark, which -is generally left from the turning, place screw point _c_. By means -of a plumb line or square, D, test the perpendicularity of the tap; -and as the latter penetrates, keep it to its work by the screw C; oil -the tap freely, and the chuck will be easily and accurately cut with -the required thread. Some kind of clamp will of course be required to -secure the chuck to B, while it is being tapped. - - [Illustration: FIG. 37.] - - [Illustration: FIG. 38.] - -The upright drill should always have a place in the workshop. It is -much easier to drill with it than in the lathe, and the mandrel will -thus be saved considerably. The latter should never be used except -for light work. A variety of drilling apparatus will hereafter be -described in this series, so that we need not now write more upon this -part of our subject. - -Somewhat akin to the chuck described as the cup chuck with six screws, -is a chuck mentioned in an old French work,[1] the purpose of which -is to turn up a cylinder, with a point at the end, so as to insure -the axial line being kept. In the ordinary course, the cylinder would -be turned up with the point and carrier, or driver, chuck already -described; the conical point would be then turned down as far as -possible, and the mark of the back centre afterwards turned off by -means of the boring collar. It is by help of a miniature lathe and -boring collar in one piece that the pivots of the balance of a watch -are finished. In both cases the work may be well done by the same -process. The chuck now to be described requires no boring collar, -but at the same time it does not seem to be well suited for any but -light work; in which latter case however it would be advantageous, -and must therefore have a place in our present paper. The body of -the chuck is shown in section, in Fig. 39. A is the socket with -screw to fit on the mandrel of the lathe. It will be seen that the -chuck itself is hollowed out cylindrically, and in this cylindrical -cavity slides a plug, _c_, bored conically, which can be fixed by a -thumb-screw, _h_, traversing a slot in the body of the chuck. This -cone is destined to receive one end of the cylinder to be pointed, -which will, according to its diameter, centre itself in some part of -the conical hole in the plug. The latter is made movable, so as to be -adapted to the length of the article to be turned. At the outer end -of the chuck is a groove dovetailed to receive a slide, shown clearly -in the cross section B. The slide must be of sufficient substance to -allow a clamping screw, _f_, to be tapped into it at one end, which -screw must be long enough to reach when fully advanced nearly to the -apex of the triangular opening seen in the slide. The action of the -whole contrivance is as follows:--The cylinder to be pointed is placed -in the conical cavity of the plug--the latter slid to or fro till -the point to be turned projects a short distance beyond the mouth of -the chuck through the triangular opening in the front slide; when it -is fixed by a turn of the screw, _f_, which forms the third point of -resistance, the sides of the triangular opening forming the other -two. As the point or apex of the triangle is always in the diameter -of the cylindrical chuck, it will only be necessary to move the slide -itself in order to bring the axis of the cylinder to be turned in a -line with that of the mandrel. As soon as this is accomplished so that -the piece runs truly, the screw, _g_, is turned, and the slide fixed -in position. A good deal of ingenuity is displayed by the inventor of -this chuck, a description of which was published twenty years ago, and -there are very many cases in which it will be called into requisition -by the mechanic. With a little care, moreover, the amateur might make -one for himself--the body of brass or gun metal, the plug and sliding -part of iron or steel. - - [1] Manuel de Tourneur par H. Bergeron. - - [Illustration: FIG. 39.] - -Amongst the various devices connected with the lathe, many of which, -even as makeshifts, are valuable to the turner, is one not generally -known for keeping up the tension of the lathe cord in whatever groove -of the fly wheel or pulley it may be placed. The plan is not more -ingenious than practical, and the writer is acquainted with one -workman, a gasfitter by trade, who has had it in constant use for -many years. Directly over the mandrel pulley is another of larger -diameter, in which are two grooves of equal depth, fig. 40. This -upper pulley is suspended on a movable arm, D, which is pivoted at -E, and kept up by an india-rubber spring, F, or, as in the original -plan (before these rubber cumulators were known), by a cord passing -over a pulley, and having a heavy weight attached, as shown by the -dotted lines. In the fig. A represents the fly wheel, B the mandrel, -C the upper pulley. The lathe cord is very long, and passes upwards -from A, over the upper pulley in groove 1, down again and round the -mandrel, a second time over groove 2 of the upper pulley and down to -the fly wheel. The tension of the cord is thus always the same, and is -regulated by the spring or weight. If the cord is slipped to a smaller -part of the lathe pulley, the slack is instantaneously taken up by the -descent of the weight, and rising of the arm D, which in like manner -yields to allow the cord to be slipped to the larger groove of the -mandrel pulley. - - [Illustration: FIG. 40.] - -There are many other useful contrivances for chucking work in the -lathe, a few of which will be noticed on a future page. The main -thing to be attended to is the holding securely as well as centrally -the object to be turned. If this is attained, the precise form of -chuck is of little importance, and it matters not whether it be -made of metal or wood. The latter has indeed, in some respects, an -advantage resulting from its elasticity and the ease with which its -form is modified. - - - HAND TURNING OF WOOD. - -We have now described the simple foot-lathe and chucks adapted for -hand turning, but of the latter a great number may be provided, -and will, in fact, accumulate as the turner proceeds to work upon -objects of varied form and size. No chuck once made should be thrown -away until it has become so reduced, from repeated alterations, as -to be no longer serviceable. And now, before we commence actual -turning, it will be well to offer a few concluding remarks upon the -selection of a lathe. It will be evident from our previous remarks -and illustrations that there is room for great diversity in the size -and quality of this machine, and it is astonishing what excellent -work is often turned out by an experienced hand from a lathe of the -worst description. The simple pole-lathe, which is so out of date -that we did not deem it worthy of notice in this series, with its -reciprocating motion, like the little tool of the watchmaker, has, -before now, supplied the cabinet maker with first-class work, and not -many years since we ourselves stood before just such a clumsy tool, -taking first lessons in the art. Our next step was to a lathe with -wooden poppets, and flywheel of the same material, a mandrel made by -a country blacksmith, which scarcely did even _him_ credit; the value -of the whole, with stand and beechen bed complete, was £2 sterling, -and sufficiently dear at that price. Now, we do not recommend such a -tool, and in the present day a much better may be had at that price, -but, notwithstanding its evident defects, very tolerable work may -be produced from it. We state this to deter the reader from a very -common fault--namely, the purchase of an expensive tool and elaborate -fittings when the purse is shallow, and the skill shallower still. In -fact, any amount may be spent in lathes, and in fitting up a workshop, -but to gain real pleasure and satisfaction from the pursuit of the -mechanical arts, the outlay should not be more than the probable -result in work fairly warrants. A hundred pounds is often expended -in the purchase of a lathe, and a hundred shillings would more than -purchase the work done by it. We speak from our own experience in this -matter, and believe our advice proportionately valuable; and we well -know the satisfaction that ensues when good work has been produced in -spite of the defects in the appliances at command. If the means do -not admit of the purchase of a good lathe necessity must decide the -question, and an inferior one must take its place in the workshop. -Nevertheless, we would rather counsel a certain amount of delay, and -economy and hoarding, that a good foundation may be laid and a lathe -purchased of such average excellence that future additions may convert -it into a really serviceable tool. - -It would be invidious and perhaps rather unfair in this little work to -send the reader to any particular lathe-maker. There are several good -and two or three first-class ones in London, and if prices range high, -the work is at any rate of undeniable excellence. - -There are also many cheaper firms than those alluded to, where the -work is rather of rough-and-ready style; all depends on what _class_ -of work the would-be purchaser proposes to engage in, whether he -intends to confine himself to plain hand-turning in wood, to the -construction of steam engine, and other models of machinery in metal, -or to the more beautiful finished work in hard wood and ivory, which -develop the full power of the machine itself, and the skill of the -accomplished turner. In the former cases, a very plain and inexpensive -lathe will suffice. In the latter, it is absolutely necessary to -purchase one of the best construction, at a tolerably high figure. - -The best advice to those of slender means, and who, therefore, vastly -predominate, is to sacrifice all else to the mandrel and collar. The -latter may be bought at from twenty to thirty shillings, ready for -mounting in detached wooden headstocks, and will be far superior to -any that an ordinary smith can produce. In this case, the two poppets -that carry the mandrel and centre screw should be connected together -by a block of wood between them, which latter may be rounded off and -shaped to something near the form of a cast-iron headstock. - -The only care necessary in mounting such a mandrel, will be to keep -the axial line parallel to the lathe-bed, and directly over the centre -of the latter. Whether the mandrel is thus a separate purchase, as may -happen from necessity, or obtained as part of the lathe, and fitted in -a cast-iron headstock, it should certainly be hardened, and also the -collar, if of steel. Both will take a higher polish for this process, -and will run easier in consequence. The cost of such a mandrel is -rather greater, because many warp or split in the process, and have -to be thrown aside; and the labour of grinding mandrel and collar -to an exact fit, is considerably increased. The gain, however, is -greater than the loss to the purchaser, and the extra outlay must not, -therefore, be grudged. It is very annoying to find a conical mandrel -worn down by the collar after a twelvemonths' work; for a collar is -thus formed on the conical part, so that it cannot be tightened up by -the back screw. - -The first tool to be noticed is the gouge, the form of which is a -longitudinal section of a tube, and is shown in Fig. 41. Of this -tool not less than three sizes should be selected, of the respective -diameters of one inch, half-inch, and a quarter or three-eighths. -When purchased, they require grinding, the bevel being too short. It -is essential that this tool and the turning chisel have a long bevel, -so that the cutting edge should be a very acute angle. (Fig. 41, not -like 42.) It is impossible to do good work with the latter form of -tool which is, nevertheless, of frequent occurrence in the workshops -of amateurs. Both gouge and chisel must be sharpened on an oilstone -(Arkansas or Turkey will be found the best) to a keen edge, _and no -pains must be spared in preserving the tools in this condition_. Three -sizes of chisel to match the gouges should be selected. The latter -tool is not made like that intended for carpenter's use, with the edge -at right angles to the sides, but is sloped like Fig. 43, so as to -present an obtuse angle A, and an acute one B, and the cutting edge -is central, the bevel being alike on both sides, so that the tool may -be turned over, and used with either of the flat sides upwards. The -handles of gouges and chisels should be much longer than those used -by carpenters, and nicely rounded and shaped in the lathe. The most -difficult thing to turn being a cylinder of soft wood; a description -of the method of effecting this will be the best means of initiating -the novice in the art of turning. In all the most perfect work by -practised hands, there is a sharpness of edges and roundness of -mouldings, that are exceedingly agreeable to the eye, and bespeak -at once keenness in the tool with which the work has been done, -and steadiness in the hand of the operator. The novice must aim at -similar perfection, and to this end he must determine to avoid the -use of sand-paper, and trust to his management of exceedingly keen -tools to put a workmanlike finish to his work. To commence with the -proposed cylinder. Let a piece of sound beech be selected for the -first essay, as being less difficult to manage than deal, the grain -of the latter tearing up in long shreds under the action of the tool. -The first thing to be done, after sawing off the necessary quantity -of sufficient diameter for the proposed work, is to round it off -roughly by means of the hatchet and draw-knife, or spoke-shave. The -next thing is to mount it in the lathe. For this purpose the prong -chuck, or, better still, that represented as an improvement on the -latter, and shown in Fig. 23B, must be screwed on the mandrel, and -the work made secure by the aid of the back poppet centre. Care should -be taken that the piece runs truly between the points of support, and -that it revolves steadily without shake. There is no real necessity -for using the compasses, or other contrivance for finding the exact -centre at each end, as sometimes recommended, neither, indeed, is it -always possible thus to find the axial line. It is easy to fix it at -first lightly in its place, and ascertain by a turn or two of the -mandrel, how nearly it runs as it ought to do. If it seems tolerably -true, a turn of the back centre fixes it securely, if not, it can be -shifted in any direction at pleasure. The tyro ought, however, to -be warned that he is likely to be deceived in the size of the rough -piece, and that he may very probably think it of sufficient diameter -for the proposed work when in reality it is too small. Practice, or -the use of the callipers, which are bow-legged compasses for measuring -the diameters of work, will soon settle the question. The piece being -properly fixed in the lathe, the latter is to be set in motion by -means of the treadle, the rest having been first fixed as near as -possible without touching the piece, and the T clamped parallel to it. -If the tyro wishes to become a proficient, no pains must be spared -to acquire the knack of working the treadle without moving the body -to-and-fro. He must learn, therefore, to stand firmly on one leg, and -after the wheel has been put in motion, he must let it and the treadle -have its own way. He will thus soon _feel_ when the crank has passed -the dead point at the highest point of revolution, and the proper -moment to bear down with the foot. It is not necessary to describe the -precise movement, as a few trials will teach the method much better -than any written description. At first it is hard work, and constant -change of leg from the right to the left, and back again, will have to -be resorted to to diminish the fatigue. Practice will, however, remove -all difficulties, and allow the whole undivided attention to be given -to the management of the tool. - - [Illustration: FIG. 41.] - - [Illustration: FIG. 42.] - - [Illustration: FIG. 43.] - -The gouge must be held down firmly on the rest with the hollow side -upwards, and the bevel of the edge forming a tangent to the work, Fig. -44. In this position it will cut freely and smoothly, and the edge -will be preserved. If held horizontally, as in Fig. 45, it is evident -that the fine edge of the tool will be immediately destroyed by the -rapid blows it will receive as the rough wood revolves in contact with -it. Its tendency in the latter position will be to scrape, instead of -cutting, and the fibres of the wood will thus be torn out in threads, -and the surface of the work be roughened. The gouge, then, being -placed in the former tangential position, the right hand grasping the -handle, the left the blade, as in Fig. 46, the tool is to be slowly -slid along the rest, and a series of light shavings, more or less -continuous, will be removed from end to end of the piece. Let the -workman bear in mind that the tool is to take a firm bearing on the -rest, and that it must not move to-and-fro with the inequalities of -the piece to be turned. It is not necessary to remove large chips -unless the turner has acquired from practice perfect command over the -tools, and for the adept this chapter is not written. After the most -prominent inequalities have been removed, the _side_ of the gouge will -come into use instead of the extreme end, and with this the work may -be rapidly reduced to its intended size, always allowing, however, -for the final cut with the chisel. Before the latter is taken up, -the piece of work is to be rendered as level and true as can be done -by the aid of the gouge alone; indeed, if the latter is of tolerable -size, and skilfully used, a finish can be put upon the work by it -almost equal to that which the chisel can produce and if the work -in hand were a moulded pattern, with hollows and raised work, great -part would have to depend on the gouge alone. In the present case the -chisel must be used, and the method is as follows: Take a hold with -both hands, as directed for the management of the gouge, but instead -of the flat part lying evenly on the rest, the tool must be partly -raised from it, so that only the lower edge takes a firm bearing. -By this means the upper angle of the cutting edge (_generally_ the -most acute) is kept clear of the wood, and the latter is cut away -only by means of the middle and lower part of the edge, as shown in -Fig. 47. If placed as in Fig. 48, the acute angle, _a_, is sure to -catch and stick into the work, spoiling in two seconds all that has -been done. The chisel can be used with either of its flat sides -upwards, and moved along the rest from right to left, or from left to -right, or turned upside down, as Fig. 49, so that the acute angle is -downwards. These positions are shown in the Figs. 47 to 51. The only -care necessary is to keep the upper point clear, allow the chisel to -rest as flatly on the wood as the above precaution will permit, and to -take as _fine_ and _continuous_ shavings as possible. The chisel will -be found to draw itself along in some degree as the cut proceeds, and -when this action is felt, it is doing its work properly--still, it is -a difficult thing to use a chisel well, and the tyro will fail many -times and oft before he will succeed. - - [Illustration: FIG. 44.] - - [Illustration: FIG. 45.] - - [Illustration: FIG. 46.] - - [Illustration: FIG. 47.] - - [Illustration: FIG. 48.] - - [Illustration: FIG. 49.] - - [Illustration: FIG. 50.] - - [Illustration: FIG. 51.] - -The chances are that this initiatory lesson will result in anything -but a correct cylinder--the surface will not be true like a ruler, -but if tried by a straight edge it will be seen to be wavy. Tested by -the callipers, Fig. 52, one part will be larger than another, even if -the extreme portions be tolerably true to the proposed gauge. Now, -the best turner on earth found just these difficulties, and nothing -but perseverance and resolute determination will overcome them. -Never mind spoiling the first piece of work, give up making it of a -determined size, but do not give up making it a true cylinder. Keep -the callipers at work, and gently level the prominent parts (you must -work down to the size of the deepest hollow, for you cannot fill up -such valleys like a railway engineer; you must throw down the adjacent -hills instead), proceed gently, little by little; make the tool obey -you, show it (as Ruskin speaks of pencil and brush) that you will -not yield to its caprices and "henceforward it will be your most -obedient servant." Having done the best you can with the surface of -your cylinder, proceed to square up the ends, and mind the angle at -this part is a right angle, _square_ and _sharp_, not rounded off. Now -this again requires care and a knowledge of the proper method. You -will work chiefly with the lower corner of the chisel, and we shall -best describe the management of the tool by supposing the cylinder -an inch too long, and that the extra piece is to be removed. Now -there are three positions in which the chisel can be placed to bring -its lower corner in contact with the cylinder. First, with the blade -perpendicular to the work; secondly, with the blade inclined to the -left, Fig. 53, as if to round off the end of the piece; thirdly, -inclined to the right, Fig. 54. Held perpendicularly it will cut a -fine line, but penetrate slightly; alternately in the other positions -it will remove a V-shaped piece, and thus the cutting off is to be -begun. One side of the cutting, however, has to be perpendicular, the -other may be as sloping as convenient. Now, it is to be remembered in -cutting the upright side, which is the end of the roller, the chisel -is to incline _rather to the right_, for this reason,--if it incline -to the left a momentary inattention will cause it to take the path -_a, b_, Fig. 55, the tendency being to cut a spiral track towards -the left. The experiment may be made by gently resting the edge thus -inclined on any part of the roller, when it will describe a spiral -at once. To the right, then, the chisel must _slightly_ incline, and -it will cut off a thin curling shaving like Fig. 56, leaving the end -of the piece quite smooth and shining. When the piece is nearly cut -off, great care and lightness of hand must be used, as the central -portion will have become weak and ready to break off before the work -is finished. When it will no longer bear the chisel, take it out of -the lathe, break it off, and neatly finish with the sharp chisel the -central portion, and your first lesson is learnt. There is certainly -very little of interest in turning an imperfect cylinder, for it is -useless when done, but the alphabet of the art, though not amusing, -must be first thoroughly mastered, and the rest will follow in due -course. If, however, the work seem unreasonably dull and stupid, -the cylinder may be converted into a tool handle, which will be at -any rate a useful article, besides affording practice. No special -directions are needed in addition to the above, except in respect to -the ferrule. This is to be cut off a piece of brass tubing or an old -gun barrel, or it may be had at the tool shops ready cut to any size. -Begin by turning down the place for this ferrule, taking care not to -cut it too small or the ferrule will drop off. Take the piece out of -the lathe, and with a mallet hammer on the ferrule. Return it again, -taking care to centre it in the old marks, and finish the handle. The -brass or iron may be polished with a file for this first attempt. - - [Illustration: FIG. 52.] - - [Illustration: FIG. 53.] - - [Illustration: FIG. 54.] - - [Illustration: FIG. 55.] - - [Illustration: FIG. 56.] - - - HOLLOWED WORK. - -It is now necessary to speak of hollowing out wood for the purpose -of making boxes, cup chucks, &c., and the latter, which may be made -in any quantity, and of all sizes, will afford excellent practice in -this part of the turner's art. The majority of work of this kind is -done rather by scraping or fretting out than by cutting; side tools -of the forms of Figs. 51 and 56 being used for the purpose. These -however, are specially adapted for ivory and hard woods, the grain of -which, being very compact and close, is not torn out in shreds by the -action of such tools, as would be the case with softer woods. Where -the latter material is used in quantity, as in the manufacture of -wooden bowls, hook tools, like Fig. 57, are made use of, which cut on -their upper edges. These are exceedingly difficult to use, though the -practised hands of those brought up to the art, make them cut with -a surprising ease and rapidity--fairly surrounding the lathe with a -ceaseless cloud of fine shavings removed in the progress of the work. -The difficulty experienced in the use of these tools is not confined -to the novice, for the majority of turners accustomed to hard wood -often cut a sorry figure in the manipulation of softer material with -the aid of the tools in question. The hard and soft wood turners form, -in point of fact, two distinct branches of the trade. We have in part -anticipated this section, by speaking of the making a wooden chuck -when describing the use of the metal chuck with taper screw. We shall, -therefore, proceed to describe the best method of turning a plain -wooden box with cover, but not screwed; the latter being reserved for -more extended notice hereafter. The best material to work upon is -sound Turkey boxwood, and care must be taken that it is quite dry -and well seasoned, or, after it is worked up with, it may be, great -care and trouble, the box will split, or the cover become so loose -as to fall off, either fatality being sufficiently vexatious. We may -mention, in passing, that hard woods of all descriptions may be had -in large or small quantities of Messrs. Fauntleroy[2] and Co., 110, -Bunhill-row, Finsbury, or of Jacques and Sons, Covent-garden. Most of -the lathe-makers also supply it, especially Holtzapffel and Co., of -Charing-cross, but the first-named is a large dealer, wholesale and -retail, and his charges are moderate. - - [2] Now Messrs. Mundy and Berrie. - - [Illustration: FIG. 51, 52, 53, 54, 55, 56, 57.] - -Supposing a selection made of size proportionate to that of the -intended box, including cover and a tolerable margin for waste and -accidents, proceed as before to rough it down between two centres -and thus to reduce it to a cylindrical form--there is, however, -no occasion to use the chisel at present, as we only need a rough -cylinder. Remove this from the lathe, and if you have no brass cup -chuck into which you can fit it, proceed to make one out of a piece -of beech, ash or, if you have plenty, boxwood. Do not hurry the -work, but cut the chuck out neatly, screw and fit it, as previously -directed, on the nose of the mandrel. We shall suppose it as yet -merely a short neat cylindrical block, quite solid. Place the rest -with the tee across the end of the piece of wood, the top edge a -little below the centre (by the thickness of the blade of the tool). -For the latter select one of the three following--either will answer -well--58, 59, 60. With one or the other drill a hole in the centre, -keeping the tool quite horizontal across the rest. Enlarge this hole -by a left side tool, working from the centre of the piece towards the -outside, not taking the whole depth at once, but a quarter or half an -inch at a time. You must hollow it out about one inch, and see how -nicely you can fit the hollow to the size of the piece you are going -to turn. You will, of course, have squared up one or both ends of the -latter, which must now be driven tightly into the hollow chuck. If you -squared the ends of the cylinder correctly and left also the bottom of -your chuck level and true, you will be gratified by seeing the piece -run evenly at once. - - [Illustration: FIG. 58, 59, 60.] - -Fig. 61 shows a section of the chuck with the piece to be turned -fitted inside it. Now take the gouge and chisel and reduce the piece -to a plain cylinder, and take special care to square up the outer -end. This may be done by the aid of a carpenter's chisel held across -the rest, like the side-tool. If the end is much out of truth you had -better use first the round-ended tool, Fig. 60, but if you have worked -carefully from the commencement this will be unnecessary. - -To ascertain the correctness of this part, apply a small steel square -like Fig. 62, the blade of which slides through the brass part and is -clamped by a small screw at the side. We show the method of applying -this tool to gauge depth, test right angles, &c., in Figs. 63 and 64. -It is a most convenient and necessary instrument, and should be at -once provided. Having thus ascertained that the end of your cylinder -is at right angles with the side, take the point tool, Fig. 58, or the -acute corner of your chisel, and, setting the lathe in motion, mark -off the intended depth of the _cover_, as D, C, Fig. 61. (Observe, -it is the cover and not the box that first demands attention.) Now -proceed to hollow out the cover as you hollowed out the chuck, but -with greater care. You must allow in the thickness of the top rather -more material than you will eventually require, the thickness of the -sides, also, may be a trifle in excess, but take the utmost care to -make the inside rectangular, that is, the line _f, g_, perpendicular -to g, D. Upon the correctness of this the fit of the cover will -depend. This being done and tested as to truth with the square, as -before, you may cut off the cover with a parting tool, Fig. 65. This -tool is thin, with a cutting edge at the end, and is held edgewise -upon the rest. The blade is made rather thicker near the end, so that -as the tool penetrates the work it may not bind, but allow the small -chips made by it to escape freely. The rest must be removed from -its former position and placed parallel to the side of the piece, -and the tee at such a height that the latter may, when the tool is -held horizontally, point to the axis of the work. The tool should be -occasionally withdrawn, and the point, instead of being kept precisely -in one position, may be slightly raised and lowered from time to -time, describing a small arc. It will soon be ascertained in what -position it cuts most easily. There are different sizes of parting -tool, some very thin in the blade, for ivory and precious woods, some -thicker, for box and less valuable stuff, some with a notched end, -forming two points, for soft woods, the action of all being similar -to a saw tooth, or, in the last, to two adjacent saw teeth set out to -clear themselves in working. Care must be taken that the thin blades -do not bend and twist while cutting, especially after the cut has -become deep. To avoid this do not hurry the work, but take a little at -a time, and be careful to keep the tool with its sides perpendicular -to the rest. With these precautions the cover will soon be cut off -neatly. If care is not taken to allow for the necessary thickness of -the cover, the turner will be mortified by finding that instead of -the latter, he has merely cut off a ring, and he will have to expiate -his want of judgment by beginning a new cover and making a shallower -box. We name this to put him on his guard. Supposing the above work -satisfactorily accomplished--the top of the cover, however, being -(as will probably be the case) either convex or concave, requiring a -little touching up and finishing, it will be necessary to turn down -on the solid bit of wood left in the chuck the part A, B (Fig. 66), -on which the cover will eventually rest. On no account, however, must -this be now turned small enough, it must be left so large as not quite -to enter the cover, because if it is now nicely fitted, and the box -subsequently hollowed out, the cover is sure to be too slack, the -wood shrinking in the process of hollowing out. This shrinking may be -accounted for by supposing the rings of woody fibre, the result of -yearly growth, naturally elastic, with a tendency to contract, each -one, like a series of india-rubber bands, embracing that within it. -The central ones being removed by the tool, permit the outer ones -to contract, their particles approaching nearer to each other and -the structure becoming more dense. This tendency causes those radial -cracks so often seen in the ends of pieces of wood sawn from the trunk -or limbs of the tree. The outer parts becoming drier than the inner, -and prevented by the latter from shrinking, necessarily split, hence, -when it can be done, the centre of such pieces is bored out, while the -wood is yet full of sap, and the rest is thereby preserved. Where this -cannot be done the ends may be covered with glue or resin; or paper -may be glued on, to prevent access of air, and thus the drying of the -outer portion may be so retarded as only to keep pace with that nearer -the centre. The concentric rings thus shrink equally, and no radial -splitting takes place. - - [Illustration: FIG. 61, 62, 63, 64.] - - [Illustration: FIG. 65, 68, 66.] - -We will now return from this explanatory digression to the work in -hand. Having cut down the flange for the cover to nearly the required -size, proceed to hollow out the box. Work carefully, so that the -sides shall be smooth and perpendicular to the bottom, and the latter -plane and neat. Take care, as with the cover, to leave the necessary -thickness of bottom, allowing for the cut of the parting tool, and, -if possible, half an inch or more beyond it. Now finish that part on -which the cover is to rest. Take great care, as before, to secure -right angles, and cut away the wood little by little, trying on the -cover from time to time, until at last it will just go smoothly and -stiffly into its place. It must fit rather tightly, but take especial -care not to force it on, or you will split and spoil it. We shall here -introduce to the notice of the reader another form of callipers useful -in such work as the above, and in many cases absolutely necessary. -They are called in-and-out callipers, and are made as shown in Fig. -67. These are so arranged that whatever interval exists between _a_ -and _b_, exists also between _c_ and _d_. If, therefore, the inside of -a box cover (or similar article) is measured by the latter, the other -end of the instrument will show the exact size to be given to the part -A, B, Fig. 66. The convenience of such an arrangement for an infinity -of cases will be apparent on an inspection of the figure. - - [Illustration: FIG. 67.] - - [Illustration: FIG. 69, 70.] - -The cover of the box must now be put on, the lathe set in motion, -and the outside, and also the top of the cover, carefully turned and -finished. If the box is to be cylindrical, care should be taken that -it is truly so, and that the angle formed by the junction of the top -and sides is sharp. If sand-paper is used to finish the work, the -edges will be rounded and the workmanlike appearance spoiled. If, -therefore, the article is made of box or other hard close-grained -wood, this finishing-off may be done with a carpenter's chisel held -so as to act as a scraper. The turning chisel will answer the same -purpose, but it is a pity to spoil the edge, which should be always -preserved keen and fit for use. If the box is made of soft wood, -scraping will not answer; the turning chisel must then be made use -of, held as previously, described. If the cylindrical form is not -proposed, the sides of the box must be left thicker, and after the -cover is fitted on the outside may be moulded by the gouge and chisel, -and tools like 60 and 68 to 70, to any desired pattern. The only thing -remaining to be done is to cut off the box with the parting tool, the -same precautions being observed which we spoke of in separating the -cover. If there should be any defect in the bottom after the work is -detached, the box must be placed in a cup chuck turned to receive it, -and the above defects removed. - -In hollowing out a piece of solid ivory or similar costly material, it -would be exceedingly wasteful if the central part were removed as in a -common box, by being reduced to small chips. It is possible to remove -the whole interior in a solid block, and with exceedingly trifling -loss of material. This is effected by means of side parting tools, -71, 72, 73. A common parting tool is first used and a groove cut -therewith in the face of the block to be turned. Fig. 74 represents -this face 75; the section after the groove is cut the depth of the -box required. The shaded part in the centre represents the part to be -removed. The smallest parting tool, Fig. 73, is now introduced, the -back of the tool being laid across the rest, so that the crook takes -a perpendicular position, A, B, Fig. 74. When at the bottom of the -groove the hook is turned to the left, so that it may cut a groove -underneath the block, until stopped by its shank. It is then withdrawn -and Fig. 72, and subsequently Fig. 71 introduced, and used in a -similar way. In Fig. 76 the black line shows the tool in position, -with the under cutting done by it. The sizes are thus increased until -the last tool removes the block entire.[3] - - [3] The side parting tools are sometimes inserted in the centre - of the work, a hole being made for their introduction, they then - cut from within outwards. In this case, however, instead of a - solid piece a thick ring of the material is detached. - - [Illustration: FIG. 71, 72, 73.] - - [Illustration: FIG. 74, 75, 76, 77.] - -We now propose to describe the method of turning a round ball or -globe, and, to make the work more interesting, it shall contain a -small box. The first thing necessary is to decide upon the diameter. -In the present case let it be an inch and a half. Turn a cylinder of -boxwood a little exceeding this, and cut off from it rather more -than an inch and a half in length. The excess is merely to allow for -waste. You will thus have a cylinder whose diameter equals its length. -Before removing it from the lathe, mark its centre by a groove with a -point tool--subdivide the outer spaces with five lines, and from the -latter remove the corners of the piece, thus reducing it to the form -77. Test the length and breadth by the callipers and take care that -the ends of the cylinder are at right angles to the sides. Now place -the piece in the chuck in the position shown in the figure, that is, -at right angles to its original position in the lathe. It must be -tested as to truth by holding a point tool on the central line E, F. -If correctly placed this will only make a dot when the lathe is put in -motion. If the piece does not lie evenly the point of the tool will -make a small circle--it must then be corrected with a light tap or -two, until it runs evenly. - -If the inside of the chuck is rubbed with chalk the work will be less -liable to slip. The following operation, however, must be conducted -very gently and with exceeding care, or a satisfactory result will not -be produced. It will be observed that the central line having been -marked or cut upon the side of the cylinder is necessarily a circle, -and its revolution on its axis forms a sphere. - -We have therefore only to cut away the piece truly down to this line -to finish what _ought_ to be a perfect globe. Bergeron, however, -justly remarks that although the theory is correct it is next to -impossible to manage the tools with sufficient skill to complete in -this way a true sphere. One great cause of this difficulty, is that -as the work revolves in its new position the central line is not -visible as a line, but simply becomes the boundary of the sphere. This -may be in part done away by making a _red_ line or black one (red is -the best) instead of a mark with the tool. The work will then appear -red as it revolves, and the gouge and chisel must be used to cut -away this red part, great care being taken only just to remove what -appears coloured. Thus you will in the end have cut the work away so -as _barely_ to remove the line. Work from the central part outwards, -and always with exceeding care, and you will eventually succeed to -your satisfaction. It is, nevertheless, a very difficult bit of work -to finish even fairly well--mainly on account of the great obscurity -of your landmark, the red line. For the more perfect finishing of the -above a template of steel may be made like Fig. 78, with which to -test the work--its diameter is equal to that of the sphere, and it -will serve as a gauge or scraper. It should be made of saw plate if -intended for the latter purpose, otherwise sheet brass will answer as -well. After the semi-globe has been turned in the first chuck, it will -be necessary to turn another to receive the finished part, and for -the more perfect formation of the same a semicircular template of the -same gauge as the concave one first made may be provided, as the more -nicely the ball fits the chuck, the less chance there will be of the -work shifting during the turning of the latter half of the sphere. - - [Illustration: FIG. 78.] - -In order to obviate the difficulty of following the diametrical line -with the cutting tool, the following contrivance has been suggested -to the author by one who has followed lathe work as a profession -for many years, and is an adept at the art. The lathe band is to be -slightly slackened by partial untwisting (a turn or two will suffice), -if of catgut, so that it will carry round the pulley, if desired, but -will slip if the hand is placed on the latter. Thus, the tool may be -applied, and a light cut taken, and the work instantly stopped for -examination without stopping the lathe, as the flywheel continues to -revolve all the time. This examination can be repeated, if necessary, -every few seconds, by merely placing the hand on the pulley, and in -this way the work being carried on little by little, a good result is -attainable with comparatively little difficulty. - -The best position for the rest during the above operations will be -across the face of the work, as in hollowing out boxes, working -carefully, little by little, from centre to circumference. Towards the -finish a scraper should be used, the common carpenter's chisel being -as good a tool as any. Now to proceed with the box. Before removing -the finished ball from the chuck, bore it through with tool Fig. 59, -enlarge with Fig. 51, and make the hole conical, unscrew the chuck, -with the ball remaining in it, and put on another with a piece of -boxwood large enough to make a plug to fit this hole. This plug, when -fitted, is to be hollowed out, and converted into a box, like Fig. 79. -The latter, when put in place, must fit so neatly that only a light -circle shows its position. To conceal it still more completely, a -series of circles are to be set at each of the six sides of the ball, -as shown at Fig. 80. To remove the box, the thumb is placed at the -small end, and pressure made. This forms a neat pocket needle-case, -and may be made of ivory as a present to your lady-love. - - [Illustration: FIG. 79.] - - [Illustration: FIG. 80.] - -There is no practical difficulty likely to be met with in the above -after the round ball is itself made, unless it may arise in respect -of the conical hole. Let this be turned out as directed, until at the -furthest (smallest) end it will just allow a gauge, like the annexed -figure, 80A, to pass through it. - - [Illustration: Fig. 80A.] - -Having also gauged the large end of the hole to the desired size, -take care to finish the side evenly from one to the other. The gauge -may be a disc of tin on a wire, or, still better, a short cylinder of -box wood, on a similar handle, as there will be a little difficulty -in feeling whether the disc is placed at right angles to the axis -of the hole. Unless, however, you desire to work to a pre-arranged -exact measurement, the above precautions will scarcely be necessary, -inasmuch as the hole is first bored, and the conical plug afterwards -fitted to it. The ball may, therefore, be taken from the chuck, each -end of the bore measured, and the plug gauged at each end by the -callipers, and turned to an exact fit. - -In the above account the unmathematical phrase of "_six sides_ of the -_ball_" is used for want of a better; the _meaning_ of the author -will, however, be evident. - - - CUTTING SCREWS. - -The ambition of amateurs, especially, is very commonly centered in -a desire to cut screws in the lathe, and there is good reason for -this, because in the first place there is a difficulty presented -which it is pleasant to overcome, and in the next place, a screw is -of absolute necessity in the greater number of turned works. There -is an apparatus of simple but ingenious construction called a screw -box, which is commonly used by carpenters and others who have not -attained the skill necessary for chasing screws in the lathe, and -which is very convenient even for those who have obtained this power. -A sketch of this is given in Fig. 81. A, shows the tool complete, B -is a view after the top plate has been removed, showing the knife or -cutting tool, the latter being delineated alone at D on a large scale, -C is a section. To make this tool, which is within the power of any -person of average skill, a block of hard wood is first selected, and -drilled with a hole corresponding to the proposed size of the screw -to be cut. If no tap is at hand of the desired diameter and pitch, -this block must be mounted in the lathe, and the thread chased as we -shall presently describe. It is absolutely necessary that the block be -nicely squared up and level on the face. A small place must then be -cut to receive the knife, the edge of which is so constructed as to -form part of the thread cut away to make room for it. It is V shaped -like Fig. D, and very keenly sharpened. The method used to clamp the -knife in position, which is shown in Fig. D, permits the cutter to be -advanced or withdrawn until its position is accurately determined as -above. The top plate of wood is now fitted, and adjusted--the central -hole, _which is not tapped_, but as large as the _outside_ of the -screw-thread to be cut, forming a continuation of that which is tapped -in the lower block. A slot _b_, Fig. A, forms a passage from the -knife, to allow of the escape of the chips. The piece to be cut into a -screw should be shaped like Fig. 82. The part _a_, will be left plain, -_b_, is that on which the thread is to be cut, and must be truly -cylindrical, and of such size as to just enter the hole in the top -plate of the screw box. The part _c_ must pass through the threaded -part of the screw box, not loosely, but just so as not to damage the -threads in the least. The lower part of the central division is sloped -off as seen in the sketch. To cut the thread the screw blank is fixed -in the vice by its head, which, after being turned, should be planed -off at each side. The screw box being then placed upon it the lowest -and smallest part of the blank should just project, as in Fig. 83. -This part is intended to insure the perpendicular position of the -blank in respect of the screw box. The latter is then turned from left -to right until the screw is cut, which ought to come from the tool -clean and smooth. Box wood is especially suitable for this purpose. -This method is, of course, wholly inapplicable to anything but wooden -screw bolts, and for practice the tyro may set to work and make three -or four of the following screw clamps, which are useful to hold pieces -of wood that have been glued together. The tap for screwing nuts and -the jaws of these clamps, is similar to that used for metal, but, the -teeth, or cutting threads, are deeper and more pointed. The jaws of -the clamps shown in Figs. 84, 85, are usually made of beech, which -will take a very fair thread; or of birch, which is still better; and -the screws may be made of the same material, box being too costly and -scarce for such purposes. In making these clamps, there is to be no -thread cut on that part at which the handle of the screws project, -nor is there any thread on this part of the bolts, which pass through -a smooth hole in one jaw and lay hold of the other only. Other forms -will suggest themselves, but the two given will be found serviceable -patterns. - - [Illustration: FIG. 81.] - - [Illustration: FIG. 83.] - - [Illustration: FIG. 82.] - - [Illustration: FIG. 84.] - - [Illustration: FIG. 85.] - -The above method of cutting screws is not of anything like universal -application, nor specially the work of the turner; we shall now, -therefore, speak of cutting them by the chasing tool in the lathe. To -effect this with certainty requires much care and long practice, and -at first the attempt should never be made on a box or ornamental piece -of work, otherwise finished, but on a plain cylindrical bolt, such as -those of the clamps just described. For the inside, or female screw, -the making of chucks will afford endless practice, and a failure in -either of these will be of little importance. The screw tool for male -and female threads is represented in Figs. 86 and 87. It is of steel, -and as each tooth inclines in the direction and with the pitch of the -screw, it cannot be made with a file, but is cut by being held against -a revolving tap (or screw hob, which is of similar form.) There is -certainly a defect in the above common form of screw chaser, and a -slight modification, to be presently described, will be found easier -to use, and, in many respects, easier to make. To cut a thread with -the chasing tool, the top of the rest must be quite level and smooth, -so that the tool may readily slip along it. Suppose an outside thread -to be required on a cylinder of box or other close grained wood. The -rest being firmly fixed so that the upper edge is level with the axis -of the piece, and about half an inch from it, as Fig. 88, the tool is -advanced to touch the work, not in a line with the axis, but so as -to bring the part, _a_, in contact with it first, and the moment the -tool is felt to run along, which it will do as soon as this part of it -indents the wood, the handle is raised a little so that the points of -the teeth come into work. The tool in fact must describe the segment -of a circle, as shown by the dotted line. If this is done cleverly -the tool will not hitch, nor produce a drunken thread, but the latter -will come out clean and sharp. It is, nevertheless, necessary to -practise till the knack of thus chasing a thread is attained, and, -considering that once acquired, the necessity of traversing mandrel or -other expensive (and yet more or less defective) apparatus, no longer -exists, it is evident that the young aspirant should spare neither -time nor patience in becoming an adept in this useful art. - - [Illustration: FIG. 86.] - - [Illustration: FIG. 87.] - - [Illustration: FIG. 88.] - -One great difficulty in cutting the screw-threads to the top of a box, -or the inside of its cover, arises from the necessity for stopping -short, and removing the tool instantly as soon as it touches the -shoulder, or the top of the cover. The latter should be made rather -deeper than is necessary, so that there may be a turn or two of screw -to spare. This will give more room for the play and removal of the -inside chasing tool. - -The ordinary form of the latter is as shown in Fig. 87, the part under -the plane upper surface (_a_) being either slightly hollowed or flat, -generally the former, from having been cut by a revolving cylindrical -hub. - -Now, although this form may be suitable for outside screw tools, -which have to work on cylindrical pieces, it does not appear equally -suitable for inside tools, which are to act on concave work. The -writer of this article has experimented upon many patterns of chasing -tool, and has found it perfectly easy to chase an inside thread with -an ordinary grooved tap, which seldom makes a false cut, or crosses -the threads. From this the idea naturally arose of a convex edged tool -for inside chasing, and a concave one for outside work, as Fig. 89. - - [Illustration: FIG. 89.] - - [Illustration: FIG. 90.] - -Practically, however, the convex edge, Fig. 90, will answer -satisfactorily for an outside cylinder. In order to obtain an -efficient cutting edge from this form, the rounding must be very -slight. The out or inside tool is used with a rolling movement on -the rest as it advances. If for hard wood, a notch cut across in the -line _e, f_, Fig. 90, with a saw-file, will, by making a partially -cutting edge on the convex part, cause the tool to enter more readily -at starting. Tools like the above must be necessarily the work of -the amateur himself. The regular makers have a great objection to -make any tool or machine out of the ordinary routine. Hence the same -patterns are constantly reproduced year after year, until some one -connected with the manufacture invents an improved form, or some one -else of mechanical genius, and possessed of means, registers a new -design. Amateurs are apt to cavil at this system, and in some cases -it no doubt interferes with, and checks improvement in tools and -machines, but the evil is almost a matter of necessity. Tools are made -not singly, one of each pattern, but so many score or hundreds of one -form are forged out, and handed over to the grinding and finishing -department, and it would sadly interfere with the system and order -of the manufacturer to make a single tool or two for individual -purchasers of different pattern to those ordinarily used. If a design -is sent in by a retail dealer who can order a hundred or so at his -own risk, the above objection is obviated, and the new pattern of -tool or machine is at once introduced. If, however, any new design by -an amateur, being submitted to such men as Holtzapffel, Buck, Fenn, -or Whitworth, appears to _them_ good and saleable, they will not -only not object to introduce it, but may possibly give a premium to -the inventor. We have thought it necessary to make these remarks to -obviate the possible disappointment of amateurs in this respect. It -is but natural to suppose that some ingenious device must have long -since arisen to obviate the difficulty of thus cutting screws by hand. -Every turner finds the difficulty, and few perhaps have failed to try -some plan or other to counteract it. There are two methods whereby -this can be done: one by causing the tool to traverse at a given rate -according to the proposed pitch of the screw, the other by giving -similar movement to the mandrel, while the tool remains still. For -such work as screwing the lids of boxes, the traversing mandrel is -commonly used, but for cutting long screws in metal, the tool is fixed -in a slide rest, and the latter is made to traverse, if necessary, the -whole length of the lathe bed, by means of a guide screw driven by -suitable gearing put in motion by the mandrel itself, the speed being -adjusted by a series of cog wheels which can be interchanged to cause -various rates of motion. The latter method belongs to machine lathes, -and will be treated of hereafter in this series. - -The author has great pleasure in here introducing a device, not -exactly for _cutting_, but for starting the threads of a single, or -double screw, or, indeed, a quadruple one. It is the invention of a -gentleman whose _nom de plume_ is East Norfolk Amateur, and was by him -kindly communicated to the _English Mechanic_, of June 21, 1867. The -description is here given in his own words:-- - -"I think the plan to be described will produce to a certainty any -required number of screws and turns to the inch. The screws are -entirely cut with a common comb tool, but started by a revolving -cutter set to the required angle, and applied firmly to the work, on -the T-rest. I call it 'the universal screw guide tool,' contrived -and made by myself, and I believe will prove as useful to others as -it has to me: the drawing will almost explain the tool. The cutter, -A, is 9/16ths of an inch in diameter, turned to a cutting edge, and -finely tempered. The stem, B, in which it revolves, is round, and fits -into the shoe, C, having a graduated collar, D, in front of C, to set -the cutter to the required pitch or angle, the set screw, E, makes it -fast; having turned a piece of rod, of brass, iron, or steel, a little -above the size necessary, and supposing a quadruple screw is to be -cut having ten turns to the inch, there would, of course, be forty -threads when complete; if one of these four can be truly traced, the -comb tool will easily follow by inserting the outside tooth, either -right or left hand, as found convenient, in the line traced, when the -other three will soon appear with perfect accuracy, provided the first -one exactly corresponded to five points of the comb, which is easily -accomplished after a few trials, and if not successful at first,[4] -can be removed by a dead flat file several times, without reducing the -rod too much. When found to exactly fit the five points, the cutter -may be applied with more force to leave a good chase for the comb. The -T-rest requires a smooth surface for the shoe, C, to slide freely on, -and to be set parallel with the work, and the tool held at a right -angle as it proceeds along the rest, or the lines formed would be -of unequal distance. After a little experience it will be found to -work with beautiful accuracy, and for those who have not screw-guide -mandrels, and are not practised hands at flying common screws, it -will be found a great assistance, as it sets to anything. I described -only the quadruple, but the same rule applies to all quick screws; -for a double the chase must correspond to three points, and so on for -any number, that is, one more point of the comb than the number of -screws to be cut, and for a common one the chase must fit the comb -altogether." - - [4] This doubt seems to mar the invention. It is, however, on the - whole a good design. - - [Illustration FIG. 90 and 91.] - -The above simple apparatus will, it is believed, be of great service -to those who find difficulty in hand chasing of screws; it is, -however, necessary to speak of other methods, and especially of that -so universally used by the turners of "Tunbridge ware"--viz., the -traversing mandrel. This is represented in Fig. 91. A is the poppet; -B, the mandrel, no longer conical at the place where it traverses -the collar, but cylindrical, and passing through _two_ cylindrical -collars. It is prevented from advancing towards the left in its -bearings by the shoulder, K, and in the other direction by a plain -cylindrical collar, or ferrule, C, which slips over the end, and is -secured by a nut, D. The whole is thus ready for use, as an ordinary -mandrel. To cause it to traverse from left to right, as it revolves, -the nut and collar, C, D, are removed, and a ferrule, or guide, F, -which has a screw of the desired pitch cut on its edge, is slipped -on the mandrel over a short feather against a shoulder, where it -is retained by a nut or pin. There are several such guide-ferrules -supplied with the mandrel of different pitches of screws. The nut G -is then removed and the piece E, which is of brass or gun metal 3/8 -or 1/2 inch in thickness, with similar screw threads in each of the -hollows is attached. This guide is slipped on at H, and secured by -replacing the nut. The pin, which carries the guide, is frequently -made to slide up and down the face of the poppet, by the action of a -screw, M, working through a brass piece attached to that which carries -the pin. It is thus readily lowered out of gear or drawn up again -to touch the screw ferule. This is better than a pin screwed to the -head of the poppet, and is always adopted in the best lathes. In the -frontispiece is a photograph of this arrangement. This guidepiece acts -like a half nut, and as the mandrel revolves it gears into the ferule -and causes the required traverse. A single point tool, therefore, -held against the work will trace a screw of the same pitch as that of -the guides, and of a length equal to that of the ferule. The above -is not intended for cutting long screws, which would have to be done -in successive short lengths, but for screws of box lids, chucks, -and similar work it is a most excellent contrivance, and peculiarly -adapted for the use of the amateur. The guide threads in the commoner -patterns of these lathes are cut on the mandrel itself, which is -made of greater length than usual, and these several guides are cut -upon the part within the poppet heads, as Fig. 92, which represents -such a lathe as is sometimes used by gasfitters and brass workers in -general.[5] In the latter it will be noticed that there is added a -sustaining screw at the back of the mandrel. This is a good addition, -and indeed almost a necessary one if the lathe is to be used for -ordinary rough work, especially drilling, as it takes off the pressure -which must otherwise come against the shoulder, K, Fig. 91, and it -must be remembered that these lathes are expensive, and, therefore, -ought to be taken care of. The amateur may also be warned against -bad work; none but the first-class makers can turn out a reliable -lathe of this description. The collars and mandrel require _perfect_ -fitting, and they must be quite hard, because there is no possibility -of tightening them when worn. They must be kept well oiled, therefore, -when in use, and the oil holes in the top of the poppet should be -fitted with brass covers, to prevent any particles of metal, and -especially emery dust, from working in between collars and mandrel. -Be sure to have one guide screw of the same pitch as that on the nose -of the mandrel, for the purpose of tapping chucks to fit thereon. In -using the traversing mandrel, either the cord should be slackened so -that the pressure of the hand on the pulley may stop the revolution -of the work in a moment, or the flywheel should not be brought into -use, the cord being instead grasped by the left hand, because it -is generally necessary to cut to a shoulder or given point. It is, -however, possible sometimes so to arrange the guides by insertion of -a washer or other expedient as to cause the action to cease of itself -at the required point. In a future chapter, the cutting of long metal -screws will be treated in detail, but before concluding the present -chapter, it may be useful to say a few words concerning the nature of -the screw itself as a mechanical expedient. A screw may be defined -as a continuous inclined plane--or an inclined plane wound round a -cylinder--the pitch being the inclination of the plane, that is, the -ratio of its height to the length of its base. From the mechanical -principle of the inclined plane it follows that the greater number -of threads in a given space the greater is the power of the screw -when used as in a press, or to draw along its nut, as in the slide -rest, in which endlong motion in the screw itself is prevented. It -seems, at first sight, easy to devise a method for cutting screws of -any desired pitch, but this is far from being the case, and when it -becomes necessary to increase the number of threads to fifty, sixty, -eighty, or even more to the inch, with such accuracy that one turn of -the screw shall always produce an _equal_ longitudinal movement of the -nut, the most delicate machinery scarcely suffices for the purpose. -The microscope detects and shows errors even in the best work, and it -is questionable whether a perfect screw of any length _can_ be cut by -machinery, as every imperfection in the latter is communicated to -the work done by it. If the amateur, therefore, requires a screw for -a slide rest, eccentric chuck, microscope, or other delicate piece -of machinery, or philosophical instrument, he had better get it cut -by some practical mechanician, in the possession of the necessary -apparatus. - - [5] There should be a collar or shoulder to this mandrel, the same as - at K in the other figure. - - [Illustration: FIG. 91.] - - [Illustration: FIG. 92.] - -In the "Manual Bergeron" is an ingenious contrivance, by an amateur, -which is worth notice, although unsuited for any work where extreme -accuracy of pitch is required in the screw. The following, Fig. 93, -is a description:--The mandrel is made to traverse in its bearings, -as before detailed in this series, but instead of its motion being -governed by guide hubs, it is dependent on the action of a pair of -differential pulleys, B. A bent lever, C, is pivoted at E to the -face of the poppet, having a bit of hardened steel fitted to work in -a semicircular groove in the mandrel itself, and so arranged that -on raising the tail or long arm of the lever the mandrel is thrust -forward from left to right, while a reverse action of this lever -causes a similar movement in the opposite direction. The movement of -the lever is thus regulated:--At the extreme end of the long arm is a -pulley and hook, as shown in the drawing; the double, or differential -pulley, is fixed to the end of the mandrel, and from the smaller -part depends a cord which passes thence through the pulley on the -lever, and is wound round the larger one on the mandrel when its end -is secured. On the hook is hung a weight. It will be evident, on an -inspection of the drawing, that on putting the lathe in motion the -cord on the differential pulley will coil itself round the largest -part of the same, and will draw up the end of the lever with a speed -proportionate to the difference of diameter between the larger and -smaller parts of the double pulley. The short end of the lever will -at the same time with similar proportionate motion move the mandrel -and work, and cause the fixed tool to cut a spiral or screw thread on -the latter--a good deal of ingenuity is displayed in the above, and it -has the advantage of being easily fitted up, but it is evident that -some alterations and additions would be required to adapt it to any -other use but that specified. A contrivance similar to Fig. 94, may -in some cases be a sufficient makeshift, when a more perfect one is -not at hand. A screw is here cut on the outside of the chuck, and a -kind of double tool is used, the tracer which is in contact with the -guide thread being adjustable as to its length, and the cutting tool -having a sidelong adjustment as well. The rest being placed between -the connecting bar of the tool and the work, the former will be held -with sufficient steadiness to enable the workman to traverse the -whole easily by hand. The use of this tool is of course limited, but -the plan is simple and fairly effective. The only really serviceable -plan is the slide rest, to be hereafter described. But one other plan -is here added, which is called "Healey's chuck." The description and -sketch are from Holtzapffel's work, in which it was however copied -from an older treatise. The author, it must be understood, has never -seen the contrivance himself, and there is a fault in its principle -of construction which must militate against its use except in a very -limited degree. Since, however, Holtzapffel has considered it worthy -of a place in his work, it is at any rate well to introduce it to the -reader, especially as its defects will not be of great importance -in tracing screws of half a dozen threads or so. The apparatus is -represented in Fig. 95. in plan. C is the chuck which carries the work -to be screwed, and T is the tool which lies upon R, R, the lathe rest, -that is placed at right angles to the bearers and is always free to -move in its socket S, as on a centre, because the binding screw is -either loosened or removed. On the outside of the chuck C is cut a -coarse guide screw which we will suppose to be right handed. The nut -N, N, which fits the screw of the chuck is extended into a long arm, -and the latter communicates with the lathe rest by the connecting rod -C, C. As the lathe revolves backwards and forwards, the arm, N (which -is retained horizontally by a guide pin, G), traverses to and fro, -as regards the chuck and work, and causes the lathe rest R, R, to -oscillate in its socket S. The distance S, T being half S, R, a right -hand screw of half the coarseness of the guide will be cut, or the -tool being nearer to and on the other side of the centre, S, as in the -dotted position T, a finer and left hand screw will be cut. The rod C, -C, may be attached indifferently to any part of N, N, but the smallest -change of the relation of S, T to S, R would mar the correspondence -of screws cut at different periods, and therefore T and R should be -united by a swiveljoint capable of being fixed at any part of the -lathe rest R, R, which is omitted in Mr. Healey's perspective drawing -of the apparatus. - - [Illustration: FIG. 93.] - - [Illustration: FIG. 94.] - - [Illustration: FIG. 95.] - -This is one of the least perfect modes of originating screws, it -should, therefore, be only applied to such as are very short, as, -owing to the variation in the angular relation of the parts the motion -given to the tool is not strictly constant nor equable. When in the -midway position the several parts should lie exactly at right angles -to each other in order as far as possible to avoid the error. The -inequality of the threads is imperceptible in a short screw. A little -modification of the screw-chuck of Healey would result in a more -correct and serviceable arrangement. - -The disadvantage, for instance, of being obliged to set the T of -the rest across the face of the work is apparent at once, and it is -difficult to understand how such an arrangement could be made to -answer when the work might be of a length to require the support of -the back poppet. The following plan, Fig. 96, would obviate this and -the other disadvantages, and make a more efficient apparatus. B is the -chuck with screw chased on the outside, A the nut travelling upon the -same. To this is attached a bar H, which passes through the bar K, -to which it is clamped by the binding screw visible at H. Two short -pillars, F, F, are screwed into the bed of the lathe, in which there -might be more than one hole for each to permit the pillars to be fixed -at different distances from the line of centre. Through slots in these -passes the square bar of polished iron or steel E, supporting the -traversing rest socket, D, of which two other views are given at Figs. -97 and 98. It will be evident on inspecting the drawing that as the -nut A travels to and fro, it carries with it in a line parallel to -the lathe bed the rest socket and T. To enable the workman to steady -the tool, the latter should rest against two short pins fixed in the -top surface of the rest in holes made for the purpose; with the aid -of these the tool will be made to traverse the work with great ease -and regularity. In chasing a right-handed screw, the tool would have -to lie on the left side of the pins, and the latter would insure its -traversing with the rest. A longer T (or half T) being turned in its -socket to stand across the face of the work will enable an inside -thread to be cut with the ordinary tool either of one or more points. -Of course, in this modification of Healey's chuck, the screw cut will -be of the same pitch as that of the chuck itself; but as the latter -may be of boxwood, there would be no difficulty in having from three -to six with the most generally useful pitches of screws, as the arm -may be screwed into the near side of the nut, and, therefore, it, -and all the other parts of the apparatus, would answer for the whole -set of chucks. If the work to be screwed is merely a box cover, or -some such work where great length of screw is not required, it is -evident that to rig up this kind of contrivance, or Healey's, or -indeed anything of similar elaboration, would appear like summoning -a gang of navvies to remove a mole-hill. Hence, if a traversing -mandrel cannot be obtained, by far the simplest plan is the chasing -tool used by hand; it is therefore well worth while to get into the -knack of using this tool. To give confidence (which is essential to -success, the least nervousness generally proving fatal to such work) -the part on which the screw is to be cut may be left larger than will -finally be necessary. The screw is then commenced, and if a failure -takes place it is again levelled, but if, as is more probable, the -attempt is successful, the chisel and chase are alternately used, the -cuts of the latter not being obliterated by the former but always -left sufficiently deep to form a guide until the desired object is -satisfactorily accomplished. - - [Illustration: FIG. 96.] - - [Illustration: FIG. 97.] - - [Illustration: FIG. 98.] - -Having treated of screw cutting so far as we are able without -trespassing on that section of the present series which is to be -devoted to machine work with slide rest and change wheels, we shall -enter on the matter of spirals, or Elizabethan twists, the method of -making which was long kept a secret by the trade. These twists are -essentially screws of very extended pitch, and generally rounded -threads. The latter sometimes embrace the central cylinder or core, -and sometimes are detached so as to assume a more open form like a -corkscrew, and in the latter case two, three, or more threads can be -cut, so that the spirals appear to intertwine. These spirals, too, -are frequently ornamented with the aid of the eccentric chuck, and -thus the work becomes fit for the adornment of the drawing-rooms -of the highest in the land. No turned work can in short exceed in -beauty these delicate and elaborate specimens of the turner's art. -To commence with a single twist of one thread. A cylinder of the -requisite length must first be turned. The number of turns the -thread or cord of the spiral is to make in a given space must next -be determined. We will suppose the cylinder one foot long, exclusive -of any mouldings or tenons at the ends, and that the spiral is to -make three turns round it, that is, one turn in four inches of its -length. Divide the cylinder into three equal parts by the lines B, C, -Fig. 99. Next rule equidistant lines D, E, F, along the cylinder in -the direction of its length; in the present case let there be _four_ -such lines. The three divisions first made must be subdivided each -into four (always the number of the longitudinal lines). The angles -of the parallelograms thus formed must then be connected diagonally -as shown in the figure, which diagonals being continued, will be -found to describe a spiral line. A second similarly constructed -spiral determines the thickness of the thread or cord of the twist. -These spirals may now be cut with a tenon saw, and all the material -outside the cord carefully removed with the gouge, so as to form -a semicircular hollow between the threads. This cannot be done by -putting the treadle and flywheel in motion, but the work itself must -be grasped with the left hand, while the right holds the gouge upon -the rest and guides its edge. After the work has thus been roughed -out, it must be finished by rasps and files, or by a kind of plane -with a semicircular cutting edge. While the latter is being used, the -flywheel must be brought into action, so that the work may be made to -revolve with sufficient rapidity to ensure a clean and smooth cut. A -hollow plane may be used to round the cord of the twist, and the whole -finished with glass paper and polished. - - [Illustration FIG. 99.] - -The "kind of plane" named was designed by a regular workman for his -own use, and was made thus and grasped in the fist, or rather hollow -of the hand. The iron was like _c_, sharp at one edge, the block of -wood being slightly bevelled off in front of the cutting edge. The -workman, who made scores of these twisted works for the trade, of all -dimensions, would run this along the hollows, while the lathe was -in motion, with great speed and accuracy. He marked the spirals as -described, and then grasping the work in the left hand, and the gouge -in the right, turning the work round with the former (the cord thrown -off the wheel), he cut out the wood boldly in large pieces with little -apparent care, and perfect ease. Then came the plane described above. - -Fig. 100 shows a simple spiral thus made. If the piece to be turned -is dark it is not easy thus to mark out the divisions. In that case -the following method will answer equally well. It is the plan used -and contrived by the writer,[6] and specially handy when a number of -similar twists are to be cut, as in ornamented pieces of furniture. -A, Fig. 101, is a straight edge of hard wood, through which, at any -given angle (regulated by the number of turns the cord is desired to -make in a given length of cylinder), a knife edge is fixed. If this is -held as in the figure, and the blade is pressed down upon the cylinder -to be cut, the lathe being put in motion, a very correct spiral will -be traced, which can be at once deepened by a tenon saw as before. -The thickness of the cord being determined it only remains to place -this tool again upon the work so that the second line shall be traced -at the required distance from the first. A second, or any number of -cords, may be thus traced in succession parallel to each other by this -simple method. By a slight modification of this instrument, which -allows the knife to be clamped at any desired angle with the straight -edge, the inclination of the cords, and, consequently, the pitch of -the spiral can be varied at pleasure, and a second blade can be added -to trace the second line, determining the thickness of the cord with -one movement of the tool along the cylinder. The edge of the knife may -be across the rest, the piece of wood just overlapping the T on the -side next the workman, if the blade is long enough to reach across the -work when thus held. The tool will be steadier and perhaps more easy -of management in this position. One hand should then lightly press the -back of the knife, while the other retains the wood against the rest -as a straight edge. East Norfolk Amateur's design of a screw guide is -on the same principle, the only difference being the substitution of a -revolving instead of a fixed knife edge. In using either it requires -some care to allow the tool free traverse, as the least check would -spoil the thread. - - [6] A similar plan is noticed in Holtzapffel's mechanical - manipulation, which the writer had not seen. It is satisfactory to - him to find the method thus authorised. - - [Illustration: FIG. 100.] - - [Illustration: FIG. 101.] - -The next class of spirals is that in which no central core exists, -but the coils stand separate and distinct, two or more rising from -the same base. The coils are sometimes flat, sometimes rounded, and -still more frequently, in the best work, exquisitely, and (as a -casual spectator would say) _impossibly_ carved. The process is as -follows:--Turn a cylinder of ivory or hard wood, forming at the end -any required mouldings as a base and capital. Determine the number of -coils and the pitch, and by one of the previous methods mark out the -same. The cylinder is now to be bored out from end to end, leaving -sufficient for the thickness of the required cords. This bore may -with advantage be slightly larger at one end than at the other, so -that a mandrel of wood may be fitted into it, to be afterwards easily -withdrawn. This will certainly be necessary if the ivory cords are -to be of light substance, as they require support to enable them to -bear the action of the tool. After the cylinder has been bored as -above directed, let a mandrel of common wood be inserted, and the -lines, marked as shown, be cut quite through. The intermediate parts -between the intended threads must then be removed carefully (with a -round rasp, if of ivory) with any convenient tool if of wood. The -cords must then in a similar way be rounded or otherwise moulded, and -afterwards the common and now damaged mandrel removed. In the case of -ivory the piece of work will not only be strengthened by the insertion -of a polished mandrel of ebony, but its appearance will be improved. -Sometimes, however, it may be preferable to line it with red velvet or -silk, or it may be left entirely open. The further ornamentation of -the cords, depending on the eccentric chuck or eccentric cutters, will -not be described in the present paper. These open spirals are worth a -vast amount of patience and trouble, which their elegant appearance -when finished will amply repay. - -The reader is not to suppose that this method of cutting spirals by -rasp and file is the only or best method, especially when ivory is -the substance operated upon. Further on will be described various -modes of accomplishing the same ends by self-acting machinery, and -by the spiral apparatus designed for use with the ordinary lathe, -but all these need the slide rest, whereas it is quite possible in -the foregoing manner to make spirals by hand tools alone, which for -correctness and finish may vie with those which may have been worked -with more elaborate and costly apparatus. - -Before quitting the subject of plain hand turning in wood, a few -more words may be necessary in respect of certain details of lathe -manipulation, foremost among which comes Chucking work. This is often -carelessly done, especially by amateurs, who, in consequence, are -frequently annoyed by the shifting of the material under the influence -of the cutting tool. If this is hard and valuable--as are many of -the best woods for ornamental turning--the fork or prong chuck will -not enter sufficiently to sustain the piece, and at the same time -the stuff is too valuable to allow of the waste incurred in screwing -it direct to the mandrel, or inserting it sufficiently far into a -brass cup chuck. In such cases the best plan is to screw a piece of -common wood upon the mandrel, face it truly, and cut a few shallow -concentric circles upon the end thus levelled, both for the purpose of -a guide to centrality, and also to give a hold to the glue by which -the more precious material is to be attached to it. For this purpose, -both chuck and work are to be well warmed, and the glue--boiling -hot--brushed upon the parts to be united. The latter are then to be -rubbed together a few seconds, and when the piece to be turned runs -truly, the back poppet with boring flange attached--if the right hand -end of the piece is level, otherwise, the point allowed to remain--is -to be brought up and screwed as a clamp against it till dry. This -process requires time, but is well worth the trouble, as the material -will be securely held, and can be safely operated on. None but those -who have had to contend personally with a tyro's difficulties, and -have, in consequence, seen the work shift in the chuck when nearly -completed, can truly appreciate the advantages of efficient chucking. -In the case detailed, there is absolutely no waste of material, no -possibility of the work becoming loose or out of truth; and the -ornamentation by eccentric cutters, drills, and so forth, can be -proceeded with, and carried out with that confidence which never fails -to promote good workmanship. Even with the above arrangement the back -poppet should be used while the excrescences are turned down, and -retained as long as the gouge has to be used in bringing the design -into an approximation to its intended form. This should be removed, -however, before taking the final cut, as the work will generally seem -to drop a little when the support is taken away, in consequence of -the mandrel, which has been forced against the back centre, returning -to its place in the collar. - -Pieces of six or seven inches in length, and of one or two inches -diameter, requiring to be hollowed out, may frequently be turned by -reversing the usual method and boring out the interior, previous to -shaping the outside. A case for pencils, for instance, or a bodkin -case, may be thus worked:--Mount in the square hole chuck, an American -screw auger, sets of which are now to be had beautifully finished and -polished. The kind meant has a scooping kind of edge above the screw, -Fig. 102, and cuts cleanly and rapidly. The piece of wood--soft wood -alone is meant--is brought against the tool, being grasped by the -left hand, while the back centre, with flange, is steadily advanced -with the right hand against the opposite end. This auger will run -straight through several inches without requiring to be withdrawn, as -the borings pass freely along the polished threads of the instrument -and escape. If necessary, however, it can be readily withdrawn by -reversing the action of the lathe, and replaced without difficulty. -The piece thus bored may then be mounted in the lathe and finished on -the outside. To do this satisfactorily, an arrangement is requisite -by which the centrality of bore is insured, else in the process of -cutting the external surface, the material will, in all probability, -be cut through in one part, while in another it will remain of -considerable thickness. If the piece is bored quite through, so as to -become a tube, Fig. 103 will be satisfactory, as the cones preserve -centrality, whilst the use of the carrier will prevent the necessity -of screwing the cones up so tightly as to endanger splitting the wood. -This is the best way to chuck small cylinders and brass tubes. The -more obtuse the angle of the cones the better. - - [Illustration: FIG. 102.] - - [Illustration: FIG. 103.] - - [Illustration: FIG. 104.] - -In this method the bottom of the case must be turned as a plug and -glued into its place. If the bottom of the case is left solid, an -arrangement like Fig. 104 will answer well. The plug chuck, A, must -not be at all conical, and the part that enters the work must be at -least an inch long. If this is attended to, and the face of the work -and of the chuck is square, the tube will be truly centred, only -requiring the back poppet to take off the strain upon A, when the -tool is applied. If A is chalked, there will be no slipping, provided -it has been accurately fitted. Observe, nevertheless, that as a -general rule, hollow work should be placed _inside_ and not _upon_ a -chuck, unless you have to work upon the _whole_ exterior surface. By -this plan, there will be no likelihood of splitting the object, an -undesirable consummation which not unfrequently takes place when the -contrary method is pursued. - -Thin discs of wood or brass are most conveniently turned upon a -face-plate, to which they can be attached by turners' cement, already -described. If, however, one surface only has to be worked, and the -plate is not of less thickness than 1/8th of an inch, it may be -mounted on a flat chuck with small projecting points, the back poppet -being used to keep it firmly against the face of the chuck. Even a -plate of brass may be thus turned if placed first of all against the -chuck and gently tapped so as to mark the position of the points, and -then drilled to suit them. Bread-platters are thus easily chucked, -first of all _face downwards_, and then reversed with the bottom -against the points, so that in the latter position, the chisel or -broad may be applied to the face and the marks removed. The larger -designs on these platters are carved by hand after their removal from -the lathe, and the small figures forming the ground, which often -appear round the main design, are made by figured punches. - -_Chucking Egg Shells_:--The method of doing this so as to enable the -turner to cut the shell evenly in two parts, is given by Holtzapffel, -in his "Mechanical Manipulation," and has been copied elsewhere. It -is ingenious and effective. The object is simply to obtain a pair of -delicate vases, to be edged with ivory, and mounted on a pedestal, as -a curiosity. The following account is from the pen of the inventor, -Mr. G. D. Kittoe, as communicated to Mr. Holtzapffel:--"In the -accompanying figure--Fig. 105--is represented the nose of a lathe, -with an egg chucked ready for cutting." Fig. 106 is the chuck used -first "to prepare the egg, to be mounted in the above way. The latter -is generally termed a spring chuck, and is made by rolling stout paper -with glue upon a metal or hardwood cylinder, the surface of which -has been greased to prevent the paper sticking to it, and upon which -it must remain until perfectly dry, when it may be removed and cut or -turned in the lathe as occasion may require." [N.B. Nothing is said -in the above account of the evident necessity of fixing the paper -cylinder to a wooden block, in which a screw must be cut to mount it -on the nose of the lathe.] "This sort of chuck is very light--easily -made and well adapted for the brittle material it is intended to hold. -Before fixing the egg in it, the inner surface should be rubbed with -some adhesive substance (common diachylon answers exceedingly well); -when this is done the egg should be carefully placed in the chuck, -the lathe being slowly kept in motion by one hand whilst with the -other the operator must adjust its position until he observes that -it runs perfectly true, then, with a sharp pointed tool he must mark -the centre and drill a hole sufficiently large for the wire in the -chuck, Fig. 105, to pass freely through. When this is done the egg -must be reversed, and the same operation repeated on the opposite end, -its contents must then be removed by blowing carefully through it. -It is now ready for cutting, for which purpose it must be fixed in -the chuck, Fig. 105. A is a chuck of box or hard wood having a recess -turned in it at _a, b_, into which is fitted a piece of cork as a soft -substance for the egg to rest against. B is a small cup of wood with -a piece of cork fitted into it serving the same purpose as that in -A. A piece of brass, _d_, is to be firmly screwed into the chuck A, -and into this a steel wire screwed on the outer end, on which a small -brass nut _e_ is fitted to work freely in a recess in the piece B. -When the egg is threaded on the wire through the holes previously made -in it, this nut is to be gradually tightened up until it presses the -cup B against the egg sufficiently to hold it steady and firm enough -to resist the action of a finely-pointed graver used to cut it. The -tool requires to be held very lightly, as a little undue violence -would crush the shell. Neither should the latter be pinched unduly -tight in the chuck, as otherwise when the point of the tool divides -the shell the two parts might spring together, and be destroyed by -the pressure. It requires some delicacy of hand to attach the rings -to the edges of the shell to constitute the fitting. The foot and top -ornaments are fixed by very fine ivory screws, the heads of which are -inserted within the shell." - - [Illustration: FIG. 105.] - - [Illustration: FIG. 106.] - -Box wood is decidedly the best material for ordinary chucks, as it -takes a screw almost as well as brass, is pleasant to work, holds -the material firmly, and is of good appearance, which last is not -unimportant to those who possess good lathes, and like to see -everything in decent order about the workshop, and it is certain -that a disorderly workman will commonly produce slovenly work. This -wood, however, though tolerably plentiful, is sufficiently costly to -be worth preserving, and by a little management chucks may be made -to answer for a longer period than might be at first supposed. A -chuck, for instance, too large to hold the work, may be plugged with -a worn-out chuck of smaller bore, or with wood of inferior character, -to save the necessity for hollowing out a new piece of box wood. The -latter material, moreover, excellent as it is, may be replaced by -other kinds of wood, provided the latter will bear a good screw. - -_Beech_, if dry, will answer very well for the purpose. - -_Pear_ is tough and screws well. - -_Apple_ is little inferior. - -_Ilex_ or _evergreen oak_ is sufficiently hard and tough and will be -found quite satisfactory. Elder of large size is good, and screws well. - -_Sycamore_ screws well, but is not always equally tough. - -All hollow or cup chucks should be furnished with rings of iron or -brass to prevent splitting. About six sizes of rings will suffice -for a great number of chucks. Bergeron, speaking of the barrel stave -chucks already alluded to, prefers the encircling rings plain and not -screwed. He gives the following reason:--"If a piece of work entered -in such a chuck does not run quite truly, a tap on the ring in the -proper place will, by closing the sawgates more in that part, rectify -the error, whereas with a screwed ring this is impossible." There is -reason in this, but at the same time it would be easy to unscrew the -ring a turn or so, give a light tap to the work, test its position -by putting the lathe in motion, and when true fix it securely by -screwing up the ring. There is, however, one precaution to be taken -in making these useful chucks--namely, to cut the staves of equal -width, else they will not yield equally to pressure, and the work -will not be so readily centred truly. A grip chuck of inexpensive -make (one additional pattern of which is introduced from a design by -contributors to the _English Mechanic_) should always be provided. A -rough block of ivory for instance may be seized in its jaws, and the -exterior useless part cut off by a parting tool as a ring, leaving the -nicely rounded material ready for chucking. Ivory nuts or _corosos_ -which are peculiarly awkwardly shaped for mounting in the lathe, may -also be thus seized, and one portion faced up and rounded so as to -allow of being fixed on a face chuck by glue or cement, or fitted into -a cup chuck. Rough pieces, too, thus mounted may be faced up, bored -and tapped to fit the mandrel as chucks, and a thousand similar works -may thus be handled. The simple grip chuck in question is important -as having the very useful addition of a centre point which the writer -would, if he did not abominate and eschew puns, direct attention to, -as the chief "point" of interest--"I call it," says the inventor, -a "Universal Self-Centering Grip Chuck." The drawings 1, 2, and 3, -almost speak for themselves, to practical turners. - - [Illustration: FIG.(drawing) 2.] - - [Illustration: FIG.(drawing) 1.] - - [Illustration: FIG.(drawing) 3.] - -1, is an elevation of one of the grips. 2, a section through centre -of chuck. 3, a side section of ditto. The body of the chuck is made -of cast iron, to screw on to the mandrel; and the grips, 1, are moved -simultaneously by a right and left-handed screw acting in a circular -groove. The jaws of the grip are serrated and tempered, the same -as in ordinary vices. In the centre of the grips, when closed, a -three-sixteenth hole is bored true to the centre of the lathe. Behind -this there is a true centre point screwed into the body of the chuck, -as marked at _a_. The above hole and this centre point are to be -particularly attended to, as on their truism depends the correctness -of your work. - -If I want to turn a solid cylinder I make the usual centre at each -end; put one on the above centre point and the other on the back -centre of lathe, and then screw up the grips tight; but if the work is -short you need not apply the above centre point or the back centre, -as the grips are alone sufficient. The hole in the jaws of the grips -admit of any kind of drill or other tool being put into them without -using any centres, and the grips will admit anything up to two inches. -In fact, I do almost every sort of thing with this chuck, and I think -amateurs, if not others, will find it a most valuable and handy -contrivance. - -Fig. 108, A and B, represents a modified form--a chuck already spoken -of and recommended for ordinary plain turning, in which the work -is supported at both ends. The present form is to a great extent -self-centering and will hold the work also without the saw-cuts -otherwise needed, the sharp edges of the double fork entering the work -with the pressure caused by the back centre. The chuck is useful not -only for ordinary work, but for re-mounting pieces centrally, which -it may have been necessary to remove when partly finished, and to -return to the lathe for completion. A still further addition to this -chuck of a steel point sliding through the centre, as in the section, -Fig. 109, makes it a very complete and serviceable apparatus, as by -this means it is easy to reverse the work without destroying its -centrality. The point is intended, as in the chuck of Wilcox, to slide -back stiffly (being if necessary kept up by a spiral spring as shown), -as it is only intended as a guide to assist in mounting the piece. If -the mandrel is not bored the chuck must be long enough to receive the -pointed wire within its substance. This will be found in every way a -most serviceable chuck. It may be of iron or brass, or even of wood, -if a round plate of brass is mounted on its face, to which the holding -pieces can be soldered or brazed. - - [Illustration: FIG. 108.] - - [Illustration: FIG. 109.] - - - HOLLOWING OUT SOFT WOOD. - -This is done, as already described, by the regular soft wood turners -in Tunbridge and elsewhere, by means of hook tools. A great number -of workmen, however, use only the gouge, and for boring out chucks, -hollowing boxes, small bowls, and similar work, the latter tool will -be found effectual if rightly held and carefully managed. It must not, -however, be applied to the inner surface of the work at the point -usual with scraping tools, but beyond the centre, Fig. 109A. The -rest, B, does not require to be turned across the face of the work, -but remains parallel to the bed of the lathe. The blade of the gouge -is to press against the near side of the hollow as the work proceeds, -which considerably aids in securing the position of the tool. The back -of the gouge is to face the bottom of the hollow (next the mandrel), -but the tool is generally rolled on the rest a little, so that its -hollow side is often more or less below, towards the lathe bed, and -the point is also lightly raised as it approaches the finish of the -cut. Begin with the tool almost horizontal, and at the centre of the -piece, the back against the wood, and, depressing the handle as the -shaving is removed, finish at the top _outer_ edge of the hollow, -rolling over the tool, so that it shall leave the work with its back -upwards and hollow downwards. Thus used it will not stick in its -course, and, after a few trials, will be found to cut out the wood -cleanly and rapidly. - - [Illustration: FIG. 109A.] - -Another grip chuck, or self-centering scroll chuck may here be -introduced, from the source of information previously alluded to. The -writer thus describes it-- - - - AMERICAN SCROLL CHUCK. - -This chuck is made upon the same principle as the Warwick Drill -Chuck--namely, a flat spiral so acting on three jaws sliding in radial -grooves as to make them recede from the centre to admit any object -between certain sizes, and then to be tightened upon it. Fig. 1 is -a plan of a 4-inch chuck. Fig. 2 is a vertical section of the same. -Fig. 3 is a view of the outside of the chuck, and Fig. 4 is a separate -section of the principal part _a, a_, taken through the line _z, z_ -(Fig. 1). - -In Fig. 2, _a, a_ is this piece, _b, b_, has the spiral cut on it -which actuates the jaws 1, 2, 3 (Fig. 1), _c, c_ screws on the piece -_a, a_ to keep _b, b_ in its place and _d, d_ is the plate which -screws on the mandrel, and which is fixed to _c, c_, by three -countersunk screws, one of which is shown in section. - - [Illustration: FIG. 1.] - - [Illustration: FIG. 2.] - - [Illustration: FIG. 3.] - - [Illustration: FIG. 4.] - -If the foregoing observations are carefully studied the further -practice of plain hand-turning in wood will not be difficult, and -we shall proceed to speak of metal turning, before passing to a -description of the Slide Rest and other apparatus usually added to -the lathe. We may, however, observe here, that, for ivory and hard -wood--especially the former, the first roughing down cannot be done -with the gouge. A point or small round-ended tool must in these cases -take its place, to be succeeded by one or more of those tools which -rather scrape than cut, as described in detailing the process of -hollowing out boxes and similar work. - - - METAL TURNING BY HAND TOOLS. - -The first requisite for the above work is a well made and sharp tool, -for, strange as it may appear, a keen edge is as necessary for making -good work in metal as in turning wood. The principle of this cutting -edge must be well understood, and this has been well explained by -Nasmyth and others. - -The remarks of the above eminent mechanic upon this subject, as also -those of Professor Willis and Mr. Babbage have been embodied in a -very excellent paper by Dodsworth Haydon, Esq., an amateur, and will -be found in the Appendix to this work. The whole principle of the -formation and application of cutting tools is explained in that paper, -so that it only remains to treat briefly of a few special _forms_ of -tools which are required for metal-turning in the lathe, whether by -hand or by the aid of the slide-rest. In the first place, however, -a word or two may be necessary as to the kind or quality of steel -required for such tools. What is called Blister steel may be at once -passed over as unfit for the formation of tools--it is, however, the -raw material (so to speak) from which, by the process of reheating -and welding, the next quality, called Shear steel, is made. When bars -of this are similarly heated and again welded into a homogeneous mass -under the tilt-hammer or between rollers, double shear-steel is made, -which is of extensive use for cutting tools, and must, moreover, of -necessity be used in almost every case where there is to be an iron -shank, for economy's sake, the steel being then welded to the iron, -and forming that part of the tool intended for the edge. The third -and best kind of all is Cast-steel, formed of blister steel, melted -at an intense heat and run into iron moulds. This, however, can be -welded only with great difficulty, and hence the whole tool, whatever -its length, must be of the same material. This can be purchased in -bars of a convenient size of round, triangular, square, or other -section, and needs only the careful use of the hammer, file, and -grindstone to become a tool of any required pattern. It would be very -advantageous to an amateur to master the art of forging in a small -way to enable him to make his own tools, for he may sometimes require -them of unusual form, and if he lives far from a manufacturing town -he will find it very difficult to get them fashioned to his liking. -Cast-steel will not allow of the welding heat applied to iron--it will -burn, and cannot then be made to recover its proper consistency, and -is for ever useless for the purpose in question. Double shear will -take a moderate white heat, while cast-steel must not be brought to -a higher temperature than that indicated by bright red--a point never -to be forgotten when shaping a tool at the forge. There are in every -workshop a number of files laid aside as worn out. These being made of -the best cast-steel, are invaluable to the turner in metal, as they -supply the best material for his tools at no cost whatever. To begin -with the saw files (called, by a horrible perversion of mathematical -definition, "three square"). Here you possess a tool at once for the -mere trouble of grinding off the teeth and reducing the sides to a -smooth surface. Each angle is equally useful--each 60°, which, as the -paper above alluded to demonstrates, is the best angle for cutting -iron. On brass, however, its use is by no means to be recommended, -being, as Holtzapffel remarks, "too penetrative and disposed to dig -into the work." It is to be used upon iron in the position shown in -Fig. 110, where A is the rest, B the cross section of the tool, C the -diametrical line. The side, of which D is a continuation, is to form -very nearly a tangent to the circumference of the work, being, as -explained in the Appendix, only 3° from that position. Worn out square -files being of rectangular section, are exactly suited for brass -turning, for which metal a cutting edge is required of 80° to 90°, the -former for the first or roughing down cut, the latter for finishing. -The position of such tool is shown in Fig. 111. - - [Illustration: FIG. 110.] - - [Illustration: FIG. 111.] - -The flat files are not altogether so useful for making turning tools -as those alluded to; they are too thin in proportion to their breadth. -Their sides, moreover, generally speaking, are not rectilineal, but -curved, so that they are more fit for grinding off at the ends to -form brass-turning tools with rectangular edges. They may, however, -by careful forging, be made to assume a square section, and thence -be formed as desired; but a rectangular bar of steel, ready-made, is -then to be preferred. A round or rat's tail file is of far greater -service than the last-named--not, indeed, in its own shape, for the -reasons stated by Mr. Haydon, but as being capable, with very little -labour at the forge, of being converted into a bar of square section. -The first tool to be made from such a bar is the graver, _the_ tool -of the watchmaker, and not less useful to the general mechanician. -This is formed by grinding the end of a square bar diagonally, so as -to produce a lozenge-shaped face. The angle to be preferred in this -operation is 45°, which will give two cutting edges of 60°. The latter -may be varied at pleasure by varying the angle at which this face is -ground, as explained in the chapter which treats upon this question. -The graver will do all kinds of outside work, light or heavy, as it -may be made of any size. It is represented in Fig. 112. Fig. 113 is -the heel-tool shown in position for work; 114 and 115, two forms of -nail-head tool very commonly used, but both requiring great attention -to the angles of the cutting edge to become effective. All the above -are for outside work, and are to be so held that the side next to -the work--the _sole_ of the tool in Fig. 113--forms very nearly a -tangent to the work--a position, as Holtzapffel remarks, strangely -similar to that required by the soft wood chisel and similar tools. -The heel-tool, indeed, if more keenly sharpened, will cut soft wood -(on the face) with great rapidity, and is in principle similar to the -broads used for that purpose. It is, however, an unsafe tool, owing -to its great tendency to dig into the work. It is a good plan to make -extensive use of various shapes of hand-tool before passing to the -slide-rest, because the hand feels exactly the _resistance_ which the -tool meets with, and the best form and position is thus _practically -tested_, and will be found to bear out to the utmost the theory -advanced in this work, and founded on mathematical truths worked out -and applied by Willis, Babbage, and others. - - [Illustration: FIG. 112.] - - [Illustration: FIG. 113.] - - [Illustration: FIG. 114.] - - [Illustration: FIG. 115.] - -Inside tools must of course be made upon the same principles as the -last, the particular form alone being modified to enable the cutting -edges to penetrate into the various nooks and corners that may occur -in such work. The inside tool for iron (Fig. 116), with cutting angles -of 60°, is of a general and useful pattern. It must be so curved and -so placed that _both_ cutting edges come into action, one on the -face and one on the side of the cut, a condition explained in the -Appendix as _essential_ to all good work. It being quite impossible -to cut metal like wood, and necessary to allow sufficient time for -such work, a pointed tool is in most cases preferable to one of a -semicircular or rectangular form of edge, and the greater part of -the heavy work done in large factories is thus executed. Inasmuch, -however, as such a tool, well formed on correct principles, may be -made to take a tolerably deep cut, the shaving detached will be of -sufficient _thickness_, and consequently sufficient width to reduce -work a satisfactory quantity at each cut. The cut, too, must be -continuous wherever possible, the tool being slowly and steadily -advanced the whole of the acquired distance without being removed, -and then re-entered for a second cut. The result should be a smooth, -even surface, and that great exertion is not required when thus -working with hand-tools is sufficiently evidenced by a remark of Mr. -Haydon to the writer, "I have often detached, with a graver alone, a -tolerably thick shaving of iron, two feet and more in length." From -what has been said, it will be understood that in hollowing out a -piece of metal such as a chuck, the tool should not be made with a -_long_ cutting edge, such as would be used if it were intended to -scrape the whole depth of the side. A _broad_ shaving is not to be -thus aimed at, nor is the _inside only_ to be thus attacked, but -the tool advanced gradually inwards from the face of the work till -it reaches the bottom, thus (to repeat the important point again) -cutting at the same time the front and side of the shaving. The -half-round or cylinder-boring bit already described is, of course, an -inside turning tool, but is used with the aid of the back centre. In -principle it follows other inside tools, the end being bevelled or -sloped off 3°, and the side being 90°. The latter is to be regarded -as a blunt cutting tool, being the largest angle that can be used; -but, nevertheless, this bit must be regarded as cutting in the two -required directions--forward and sideways. If a regular Goniometer for -measuring angles is not to be obtained, nor any apparatus for grinding -a tool to the required bevel, an addition to Nasmyth's tool-gauge, -described in the Appendix, may be made by constructing in tin a set -of templates, with the angles marked upon them. The easiest way is to -mount on the lathe a few round sheets of tin, and mark the degrees -by the division-plate, the outer circle of which contains 360°. -The tin may then have pieces cut out, as shown in Fig. 117, to be -applied as gauges over the ends of the tool, or _solid_ pieces of the -required sections (those which are removed in forming the above) may -be retained. It will, perhaps, be as well to finish up both neatly, -taking care to mark the angles on each. The degrees most required are, -as explained, 90°, 60°, 80°, and 3°; but intermediate numbers may be -prepared, and will often be found convenient. An inside tool for brass -must retain the angles 80° to 90°, the latter acting as a scraping -tool to put a finish to the interior of work roughed out by a tool -of the lesser angle. There are not many forms in general vogue, for -brass work, whether internal or external. The round, the flat, and the -point tools (Figs. 118 to 121) are more or less capable of hollowing -out work, as well as surfacing. With the first ground to an angle -of 80°, brass chucks can be hollowed, and, with the second at 90°, -finished; and if there chance to be any internal angles out of reach -by the point-tool, it is only necessary to use a similar one bent -round at the end towards the left. Much of the turner's success in -brass work depends upon the quality of the metal, which is often very -hard and unequal in texture and perhaps blown and honey-combed. It is -always the best plan to send patterns of any work of importance to -some well-known firm, instead of trusting to a country foundry, whose -business, if worthy the name, is generally iron work, and who only run -brass once in a way, and make a terrible mess of it, too. The same may -be said respecting iron castings. It is worth while, as an experiment, -to test with turning tools the quality of a country casting, pulley, -or what not, by the side of a similar work really made of malleable -iron, such as is now so extensively used by the sewing-machine makers. -Tools that will stand the first and make good work deserve a place in -the British Museum, with a portrait of the turner! - - [Illustration: FIG. 116.] - - [Illustration: FIG. 117.] - - [Illustration: FIG. 118, 119, 120, 121.] - -For light brass work, such as small model engines now so generally -sold, a description of lathe may be used of which no mention has yet -been made--namely, a bar lathe Fig. 122. Such a tool may be made for -£3 or £4, and will be found sufficient for such work as specified. - - [Illustration: FIG. 122.] - -In place of the double bed a triangular bar of cast iron is used, on -which the poppets slide, and are clamped. D shows one of two sockets -with feet which hold the ends of the bar, and by which the lathe can -be mounted on any stout plank or on the window sill. The pulley A is -made for a strap, because this allows of a plain flywheel, which is -much cheaper than those which are bevelled and turned. The rest is -shown at E and F. The part E slides upon the bar like the poppet--at -the top is a dovetailed groove to receive the slide F, which carries -the socket for the tee, and is fixed by a turn of the screw seen on -the top of it. There is much to be said in favour of triangle bar -lathes, they are very stiff, and can be fixed anywhere. The flywheel -can be supported on a separate frame, which is an excellent plan, for -the jerk of the treadle and crank is not communicated to the poppets -and mandrel. In Maudslay's triangle bar lathe, which was made for -amateurs, a slide rest was attached, and the whole work was first -class--of late they have gone out of fashion, but are nevertheless -good tools. - -Fig. 123 represents another very simple form of lathe for turning -small articles of brass. It may be said to be one remove from the -watchmaker's bow lathe, as it has no true mandrel or treadle; the -small flywheel being attached to an arm at the back and worked by -hand. The left hand is used for the latter purpose while the tool -is held in the right. Through a tapped hole in the left hand poppet -passes a steel pin shown at E, on a larger scale; this screws into -the poppet after passing through a brass pulley B; this bolt ends -in a point, and an arm fixed into the pulley becomes a dog to act -against a carrier screwed on to the work as in turning iron. Thus -the mandrel and point are fixtures, and the pulley only turns when -motion is communicated to it by a catgut from the flywheel behind -it. The back poppet and rest, which last is shown separately, slide -on the rectangular bar; the latter is about two inches wide, and -three eighths thick, and is made with feet to screw to any convenient -support. This lathe is especially adapted for work of small size which -can be centred at both ends, and on which a carrier can be fixed -to bear against the pin, E, of the pulley; nevertheless it is even -possible to use chucks, if cast in metal with a pulley to each like G. -A spindle must in this case be made like H, on which the chuck must -be slipped, and fixed by the nut in the hollow of the chuck. Although -however this form of lathe is sometimes met with, and may be used as a -makeshift, a small triangle bar or 3in. lathe of the usual form is far -preferable. - - [Illustration: FIG. 123.] - -In centering a bar of iron in the lathe too much care cannot be -exercised in causing it to run evenly. The ends should be drilled, -first with a small, and afterwards with a larger drill, so that a -countersunk hole may be obtained in order _to keep the point of the -lathe-centre from touching the bottom of the hole_. If this is not -done the friction of the work upon its bearing will soon spoil the -lathe-centre, and the work itself will speedily get out of truth, and -it will not be possible to screw up the spindle of the back poppet -so as to correct this. Of course in turning up very small work this -drilling cannot be done. A simple hole must then be made, sufficient -for the safe support of the work while being turned, but even in this -case the angle of the drill point should be less than that of the -conical centre of the lathe, the point of which will then run free. -To mark the true centres of a round bar of metal a punch has been -devised like Fig. 124. This is figured in Bergeron's work, and is -very serviceable. To insure its working truly be careful that the bar -of metal is filed flat on the ends, and that the surface of the latter -is at right angles to the length of the bar. It is then only necessary -to place the end of the piece in the conical part of the cup (which -will be best effected by fixing the bar in a vice) and by raising the -spring and letting it go sudden by a sufficient mark will be made to -guide the point of the drill. - - [Illustration: FIG. 124] - -The proper place at which to commence turning an iron bar is at one -end, the rest being placed so as to bring the tool just upon the line -of centres; if applied lower the tool would take too deep a hold, and -would either be broken or lift the bar out of the lathe, damaging the -centre points. The ends of the bar should be squared up before the -circumference is turned, and on no account must a file be used after -the turning tool has done its work. It is only at the commencement -before a cutting tool has been applied, that an old file may be made -use of to take off the scale and roughness left from the forging or -casting. - -Brass may be attacked upon or just below the line of centres, because -the form of tool is such as cannot penetrate deeply. This metal is -perhaps easier in some respects to turn, but the tool is apt to form -undulations on its surface (is apt to chatter). This is due, partly -to the impossibility of obtaining continuous shavings, and partly to -the vibration of the tool, and when once this has taken place there -is a tendency to deepen these channels, which makes it difficult to -produce a plane and even surface. If a rectangular tool is used in -the position already shown and described under the head of tools for -metal turning, this chattering will be avoided. If it takes place, the -undulations should be worked off by gentle usage of the angle of the -tool, the rest being placed close to the work, and only a light cut -taken. - -With regard to the method of mounting a piece of brass in the lathe, -any convenient chuck may be used, but sometimes the piece is short -or irregular and requires to be bored out. In this case use solder -and firmly attach the piece to a face plate of brass. The easiest way -is to smear the two faces to be joined with sal-ammoniac made into a -paste with water, and laying a piece of tin-foil between the surfaces, -which must be quite clean and bright, apply heat. The tin will melt -and a perfect union will be effected. When the piece is finished it -is re-heated and detached. This may be considered a wrinkle worth -knowing. The flat flanges of brass spoken of under the head of chucks -are just suited for this method of working, and they are not damaged -by the process, as the solder can be wiped off quite clean when -the chuck is made hot. This is a good way to mount small cylinders -of brass for model engines, as they can be bored and turned on the -outside at one operation with great ease and certainty. If a piece is -to be drilled or bored in the lathe, the following is the arrangement -to be adopted. Fig. 125, A is the face plate, B, the piece to be -drilled, C the drill, which is advanced by screwing up the point, E, -of the back centre; D is a hand vice or similar article to prevent the -drill from revolving with the work. If it is more convenient to fix -the drill itself in a chuck, the point of the back centre is to be -removed, and a flange of brass or iron substituted, as A, Fig. 126. If -the drill is to penetrate quite through the work a piece of wood must -be interposed between the latter and the flange to receive the point -of the drill and protect it from injury. The pressure should be so -regulated as to be constant and equal without being excessive, or the -drill will be bent or broken. Boring is simply drilling on a larger -scale, and is of such general use as to require detailed notice. -In the first place there are several tools used for the purpose, -according to the size of the work. The first is the cylinder bit, -Fig. 127. This is a most excellent tool, as it will work very truly, -and can hardly get out of place if properly directed at starting. The -cutting part A is half a cylinder, the centre being just left visible, -the end is not quite at right angles with the length of the tool, -but is sloped off a little and bevelled also slightly below.[7] This -forms the cutting edge. The other end of the tool has a central hole, -drilled to receive the point of the back centre by which it is kept to -its work. To use this tool, let the piece to be drilled be placed in a -chuck, and a recess turned in it of the same diameter as the cylinder -bit, the latter is then placed in this recess B, and when screwed up -it cannot possibly rise or shift its position; a hand-vice or spanner -is then fixed as shown in Fig. 125, and the lathe put in slow motion, -oil or soap and water being freely used to lubricate the tool. Either -a solid piece of metal, or a hollow casting can be thus bored. - - [7] To an angle of 3°. See Appendix. - - [Illustration: FIG. 125.] - - [Illustration: FIG. 126.] - - [Illustration: FIG. 127.] - -These cylinder bits can be had of all sizes, from one-eighth of an -inch upwards. - -Pipe stems are bored with the smallest of these tools. For this -purpose they are made of round steel wire, which is sometimes merely -flattened with a hammer at one end to spread and enlarge it, this -part being afterwards rounded on the underside with a file, and with -the same tool finished on the upper flat face. These slender drills -require to be delicately used, and are conveniently held in a pin vice -or pair of pin pliers, the handle of which being hollow, allows the -greater part of the drill shank to lie within it, a small part only -being drawn out at a time for use; thus the drill will be kept from -bending, and will work quickly and well. - -Of recent inventions in the matter of drills, the most important is -the Morse American twist drills sold, in sets, at 30s. on a neat stand -with a self-centering chuck, complete. The form is that of a cylinder -with spiral grooves cut round it of extended pitch. The cutting edge -is as difficult to draw as it is to describe, and must be seen to be -understood. It is chiefly formed by the meeting of the spiral grooves -and the solid end, the latter forming a blunt angular point rendered -cutting by the edge of the grooves. They should have a place in every -workshop. - -The next tool to be described is also much used, especially in -agricultural implement manufactories, for boring out the brasses, -or bearings. It is called a rose bit, or grinder, and is shown in -Fig. 128 A and B. In this case also a recess is cut in the work as a -guide, and as the tool fills up the whole interior as it proceeds, no -change of position can occur. The rose bit is used as shown in 125. A -bit of this pattern is very useful for brass work of all kinds, such -as the cylinders of small engines, bosses of wheels, bearings and -collars, and one of these tools of the exact size for hollowing out -the sockets of brass chucks, previously to their being tapped, will be -found serviceable. The third kind of boring tool is made with movable -cutters, which can be removed at pleasure, to be sharpened or replaced -by more convenient ones. The simplest consists of a cutter bar, A, -Fig. 129, with a slot in it to hold the tool, which is fixed by -driving a wedge at the back of it. The tool here shown has two cutting -edges, _b_ and _c_ which should be shaped according to the principles -already enunciated respecting hand tools for iron and brass. The -cutter bar is usually fixed between the lathe centres, and turned by -a driver chuck and carrier, while the cylinder to be bored is clamped -to the slide rest, and thereby advanced against the cutting edge. This -form is chiefly used upon work that has been cast hollow, or drilled. - - [Illustration: FIG. 128.] - - [Illustration: FIG. 129.] - -Fig. 130 is another form of boring tool for large and heavy work. A -boss, A, is fixed to the cutter bar, having a series of dovetailed -grooves, or slots, on its surface, in which cutters are fixed by -wedges. In this and every similar form, it is expedient always to -complete the circle, or, at any rate, two-thirds or three-quarters -of it, by driving in blocks of wood in the slots not occupied by the -cutters. This preserves the concentricity of the tool. One edge of -these movable cutters should be radial to the centre of the bar, or -boss, the other rather less than a right angle, which will ensure a -good cutting edge. The best lubricant is oil for the first cut, and -soap and water, or pure water, for the finishing cut. The surface will -thus be left bright. It is not well to finish with emery any collar -in which an axle is to work (as the collar in which the mandrel of -the lathe runs). This substance imbeds itself in the pores of the -metal, and by forming a grinding surface, considerably increases -the friction and wear and tear of the parts.[8] Although boring and -drilling are capable of being done in the lathe, a far superior plan -is to employ an upright boring apparatus, as is now generally used in -making steam cylinders. The work is not then suspended between two -points, or carried on the slide rest, but takes up a firm bearing on -a fixed support, and the boring tool descends by a pressure screw, or -self-adjusting contrivance, as the work proceeds. - - [8] Oilstone powder may be substituted, especially for the best brass - work. - - [Illustration: FIG. 130.] - -We have spoken of the slow motion as necessary for turning metal work. -This is represented in Fig. 131 A B C D. The first is a plan seen from -above. The poppet is cast double like F, so as to afford a bearing -for the mandrel, and a second for the back spindle seen at A. This -back spindle, it will be observed, passes through its two collars or -bearings, and can slide freely in them from side to side. This can, -however, be prevented by dropping a pin through a hole in the top of -the poppet, which falls into a semicircular groove in the spindle. The -pulley is securely attached to a small cog wheel, and can be firmly -united to a larger one, as seen at A2, and separately at C and D. -This pulley and small cog wheel run loosely on the mandrel, and do -not revolve with it until clamped to the wheel, C, which is itself -keyed to the mandrel. Suppose them to be thus free to revolve, and the -wheels in position shown in the plan, A. On putting the fly wheel in -motion, the pulley will revolve on the mandrel, carrying with it the -small cog wheel, which in turn will act on the large wheel on the back -spindle. The small cog wheel on the latter will thus put in motion the -large one geared with it, the which being keyed to the mandrel, will -put the latter in motion. There are many ways of clamping the pulley -to the large cog wheel, perhaps the following is as good as any. It -must be so clamped for wood turning when the back spindle is to be -slipped on one side out of gear. - - [Illustration: FIG. 131.] - -In the face of the pulley, which is concave, is a piece of brass flush -with the rim, and which forms a dovetailed groove, into which the head -of a clamping screw, E, fits. This screw projects through a slot in -the wheel D. When it is required to fix the pulley, this screw is slid -up towards the rim till the head rests in the dovetailed projection, -and it is clamped in that position by a nut. When it is desired to -put the back action into gear, this nut is loosened, the screw-bolt -dropped towards the axle (thus freeing the head from the dovetail), -and again fixed by the nut. The wheel and pulley are thus independent -of each other, the back spindle is slipped sideways into gear, and -held by the pin, and the slow motion will be obtained. - -There is one fault in the arrangement of the back geared lathe that -with amateurs in a private house is especially disagreeable, and it is -questionable whether in large machinery establishments it might not -with great advantage be corrected. In the action of toothed wheels, -nuts and screws, and similar gearing, there occurs what is called -_back lash_. If, for instance, the tool holder of a slide rest is -advanced, and then the action is to be reversed, the movement of the -nut and tool holder does not commence simultaneously with the movement -of the screw. This is due to the play, or necessary looseness of the -working parts, the pressure coming on one side of the thread when the -screw is turned in one direction, and on the contrary side when the -motion is reversed. In toothed wheels a similar defect exists, and -gives rise to that disagreeable and ceaseless noise which assails the -ear on entering a building where machinery is in motion. This may -be avoided by the use of frictional gearing, a simple but excellent -mechanical contrivance which deserves far more extensive notice than -it has yet received. It is the invention of a Mr. Robertson, and -is patented. A lathe fitted with it would be almost noiseless, and -would work with a delicious smoothness, very conducive to the comfort -of the workman. This gearing, represented in Fig. 132, is merely -the substitution of V shaped or semicircular grooves for cogs, the -former running round the periphery of the wheel like the grooves in -an ordinary lathe pulley. In this method of gearing, it would be -necessary to move the back spindle to-and-fro, the usual horizontal -movement not being possible. This is easily effected by a screw or a -cam, either of which might be made to act on the frame which carries -the back spindle, and which may then work on a centre, as Fig. 133, -where A is the poppet, B, the support of the spindle, D, a cam; when -the handle of the latter is raised, the standard, B, is allowed to -fall back out of gear into the position shown by the dotted line, C. -A screw movement would have the advantage of enabling the workman to -regulate with greater precision the pressure of the friction pulleys -against each other. The drawing shows the grooves of these pulleys -larger and deeper than usually made. They are generally rather shallow -and numerous, and it is astonishing with what firm hold they grip each -other without that violent pressure which it might be imagined would -be necessary to prevent slipping when in use. - - [Illustration: FIG. 132.] - - [Illustration: FIG. 133.] - -The ordinary slide rest for hand lathes is made as follows:--That for -ornamental turning will have a separate notice. Fig. 134, shows the -slide rest viewed from above, and it is evident if the tool is clamped -to the holder F on the top plate, it can be advanced from end to end -of the top slide B, and also (with the upper frame itself) along the -lower frame A, A, these movements being at right angles the one to the -other. For parallel work this is sufficient. In this compound rest a -third motion is arranged for turning cones or taper plugs like those -of stop cocks, taps for screw plates and such like articles. For this -purpose the upper frame is cast like Fig. 135, with a flat surface, -but with two ribs underneath, uniting the frame to a circular plate -with two concentric slots in it. This plate revolves on the plate G -G, turning on a central pin, and it can be clamped by the two screws -which pass through the slots into the plate in any desired position; -once clamped at the required angle a piece of metal can be bored -with a conical hole and a plug turned to fit it without possibility -of failure. The details of construction allow of considerable -variety, and different makers keep to their respective patterns; the -main desideratum is strength and solidity, combined with accurate -adjustment of the moving parts. The =V='s, underneath the frames, -and the edges of the latter, must fit, so as not to be tighter in one -place than another, and the upper and lower frames must cross each -other accurately at right angles. It is likewise essential that the -tool traverse the work in a perfectly horizontal line. Every part -must, therefore, be accurately made by means of the lathe and planing -machine, and the whole carefully put together. Notwithstanding the -above desiderata, a slide rest is not necessarily beyond the skill of -the amateur. We have, indeed, seen one thus made quite equal to the -work of a professed mechanic, though the file and scraper had to take -the place of the planing machine. The rough castings can be bought -for about half-a-crown, suitable for a five-inch centre lathe, and it -would be much better to try and fit up a set of these castings than -to attempt such a substitute as a wooden slide rest. The latter has -nevertheless been made, and we remember seeing one of mahogany edged -with brass, the work of a cabinet maker, which did good service in -turning and ornamenting wood.[9] This, however, was upwards of twenty -years ago, since which time the facilities for obtaining slide rests -of metal, properly constructed, have materially increased. As the -dovetailed edges of the slides wear away by use, it is necessary to -provide means for tightening up the =V=-pieces. This is shown -in Fig. 136. The holes in the =V=-pieces through which the -top screws pass are not round, but oval, so as to admit of lateral -movement. - - [9] In the Paris Exhibition of this year (1867) are some slide-rests - made of hardwood and metal. - - [Illustration: FIG. 134.] - - [Illustration: FIG. 135.] - - [Illustration: FIG. 136] - -Two large headed screws, E E, are tapped into the place on which -the =V=-pieces rest, and when these are screwed up, their -heads (which are sunk for the purpose in two recesses in the lower -plate) press against the =V=-pieces, driving them closer to the -dovetailed slide. When thus adjusted the top screws are made use of -to fix the strips _c_, _c_. By this method the slides can be adjusted -to work with the utmost ease and accuracy, without shake or side -play. The edge of the circular plate and the heads of the leading -screws are very frequently marked in graduated divisions, so that -the advance of the tool or the angle to be made with the work by the -tool can be accurately measured and preserved. There should at any -rate be a mark on the circular plate to show when the rest is set for -parallel work. There are several patterns of tool holder, of which -the forms shewn are convenient for light work. The one shown in 138 -& 139 on the rest is somewhat different. The plate F, Fig. 134, is -cast with a boss and socket, like that of an ordinary rest. In this -socket the tool holder fits, and can be not only turned round so as -to set the tool at any angle, but also slightly adjusted in height, -which is a great advantage. The tool is clamped by a single screw -as shown in the sketch. The drawback to this form, and that on the -rest, is this single screw, which will indeed hold the tool when the -work is easy, but will not always retain it with sufficient firmness -when the work is rough, or of tolerable size. In large workshops one -usually meets with the holder represented in Fig. 140. A plate, A, -with central block B, and slide C, are in one casting. Through A pass -eight screws. The tool lies on either side of the central square block -and is clamped with three screws, it has thus a fair bearing on two -sides, and the screws form a third above, so that accidental shifting -of the tool during the progress of the work is hardly possible. The -tool holder of Professor Willis, which is described in the Appendix, -is perhaps the best of all at present in use. It holds the tool firmly -at any desired angle. - - [Illustration: FIG. 140.] - - [Illustration: FIG. 138.] - - [Illustration: FIG. 139.] - -It is quite possible that the novice who has seen mere boys working -with slide rests at manufactories will be disappointed at his own -first attempts to use this piece of machinery. All the difficulty lies -in the shape and set of the tool. When turning metal with hand-tools -it is easy to feel one's way. If the cut is not satisfactory, the hand -at once modifies the angle of the tool, and regulates its direction -to a nicety, but the slide rest cannot thus adapt itself to its -work. It must be set with its slides in position, and the tool once -fixed must pursue its own course. Hence it requires a very accurate -knowledge of the nature of cutting tools, such as we have given in the -Appendix to this work. If the tool is well placed upon the axis of -the work for iron, a little below it for brass--it will cut cleanly -and easily, without rubbing or jarring, both of which are proofs of -either a wrong angle of edge, or a wrong form of tool. The work should -proceed with as much apparent ease as if the metal were an apple, and -the shaving should curl off like its peel. Moreover, this case is not -merely apparent, it is perfectly easy to cut iron, and the strain on -the tool, whether held by the hand or by slide rest, is comparatively -slight, if the tool is properly made and held. Fig. 141 is quite the -best form of tool for surfacing cylinders with the slide rest. It -is to be so placed that both edges are made to cut near the point; -hence the crank should slightly curve away to the left. It is not -possible to cut metal quickly, be content with fine clean shavings -curling off freely. You will soon see whether you can take a deeper -cut with safety. The tool here sketched is not at all likely to dig -in and hitch in the work; if it is not properly placed it will spring -and jump, or its side will rub against it, and no cut will be made. -To describe the exact position is very difficult, but the principle -once grasped, little difficulty should be experienced in making and -setting to work any tool, whether for inside or outside work. The -_rule of thumb_ was all well enough in olden days and in the infancy -of the art of metal working, but it is time to discard it; to master -and man it is equally advantageous to do so. Indeed, in some of our -leading firms, the old system of follow-my-leader, when the leader -was as ignorant of his work as the follower, is waning, and the "how" -is now, as it ought to be, coupled with the "reason why." One of the -best papers ever written on this subject is to be found in Weale's -series, "Mechanism and Construction of Machines," by T. Baker, and -"Tools and Machines," by J. Nasmyth, 2s. 6d. The latter part is that -specially referred to, and is well worth the whole price of the work. -The remarks, however, of that eminent mechanic are embodied in the -paper in the Appendix, and therefore, after the reader has studied the -latter, he should make trial for himself of the principles laid down. -Expend a quarter or a half an hour experimenting thus, with keen and -obtuse tools, held at divers angles, and you will see and understand -what is meant by setting a slide rest, or hand tool to cut metal as it -ought to do. - - [Illustration: Fig. 141 is too much cranked; half the length of the - hanging part would amply suffice.] - -Supposing the tool fixed in the tool holder in the position indicated, -and just overlapping the circumference at one end (the right). Take -hold of the handles, one in each hand, and with that which advances -the tool from end to end of the bar try very carefully whether the -tool will cut cleanly by making a turn or two while the lathe is in -slow motion. If the tool bites too deeply, turn the other handle -and ease it. If you still find the tool sticking into or scraping -the work, instead of bringing off a fine shaving, look well to its -position, and observe whether the edge is well placed on the axis of -the piece. If it has been hitching in the work it is probably too low, -if rubbing it, too high, and touches at some point below its edge. -It is presupposed, of course, that the tool is made correctly as to -angle of cutting edge. Do not lower the point by packing the end of -the shank; _pack the whole length_ or none. It is astonishing what -a great difference is made to the cutting power of a tool by slight -adjustments of this kind, and how smoothly a tool will work with -proper attention to these details, which would otherwise be probably -cast aside as unfit for the work. Hence the greater ease in managing -a hand-tool. The hand _feels_ the error, and at once, if experienced, -corrects it by an almost imperceptible movement--slightly raising or -depressing the handle or gently varying the angle sideways on the -rest. When once the tool is found to cut as it ought to do, nothing -remains but to turn the handle in the right hand, and thus cause the -tool to progress steadily along the work from end to end. Then free -it by a half turn of the other handle, reverse the movement until the -tool has arrived at its old place, and having slightly advanced it to -take a fresh bite, repeat the process until the whole bar is reduced -to the required size. If the piece is slender and bends away from the -tool, add to the slide rest a support; let it be fixed opposite to -the tool, and it will keep the work steadily up against the cutting -edge. It can be fixed (if a hole is made for the purpose) anywhere -about the slide which traverses in the direction of the length of -the work. It is well to drill and tap a few holes about the slide -rest, and some along the side of the bed of the lathe. These will be -found very useful at various times for fixing apparatus. For, be it -observed, (and we shall recur to this with some practical hints by and -by) the lathe may and ought to do many kinds of work beyond ordinary -turning. It may become a machine for planing, slotting, drilling, -wheel cutting, &c., and is to be pressed into the service of the -jack-of-all-trades, without compunction. - -When ordering a slide rest let steel screws and nuts be specified, and -gun metal V-pieces, and let the parts be strongly made (too strong -for the supposed work); for the latter may unexpectedly turn out to -be sometimes rather heavy. We have found the top plate of a 3in. -slide-rest so weak that when the tool was clamped on the top of it, -by the screw of the tool holder, the slide itself became jammed; a -defect quite beyond remedy, except by the substitution of a new and -stiffer plate. The same advice may be given respecting the tools. Let -these also be strong; neat and pretty tools are all very well, but -you seldom see them in a workshop; you don't require pretty tools, -but good and serviceable ones. Nevertheless, let the material be of -the best quality possible; and that you may not be ever at a loss, -you should learn to make tools yourself. Procure some small square -and round steel bars; save up as directed your old files, and you -need but heat them red hot (not on any account white hot), and with -hammer and file shape them to your mind. Then temper to a deep straw -colour, and after being accurately ground and finished on the stone, -they will be fit to use upon any metal. The form of tool given as the -best for slide rest work may be exchanged, when the bar is nearly -turned, to the required size, for a fresh one, keen, sharp, and of -an almost flat edge instead of point. A tool, of which the edge is a -segment of a very large circle, will serve the best as a finishing -tool, just to take off the lines left by the pointed tool. With -regard to lubricating the work, we may observe that the chief object -is to prevent the point or edge of the tool from heating and losing -temper; oil, water, or soap and water will therefore answer, but it -is a curious fact that oil will not produce so polished a surface as -water will. We should advise in all cases soap and water. Soft soap -is best, boiled in water, and allowed to cool. The drills with which -the huge armour plates of ships six inches thick are drilled are thus -lubricated, and instead of throwing out dust in a wet state as usual, -these large drills fairly turn out curled shavings similar to those -produced by the planing tool. It is by no means a bad plan to lay the -shank of the tool which falls upon the top plate of the rest, upon a -piece of leather, wood, or sheet lead. The surface of the iron, when -planed and finished, is often too smooth, and the tool will sometimes -slip from this cause, unless screwed unduly tight, to the detriment of -the rest. By the above plan this annoyance will cease at once. - -We will now say a word about hollowed work. Finishing a chuck will -serve our purpose, and here be it advised not to go to much expense -about chucks--get those which must be of brass in the rough, and -practice metal turning by finishing them yourself. If no slide rest -is available do it by hand. However, we are supposing the slide rest -to have been procured, and may therefore proceed to use it. First -you must drill the back part of your chuck as directed in a previous -chapter. The drill is to be the size of the diameter of the hollows -in the mandrel screw, that is, smaller by the depth of a thread, than -the full size of the nose. Having drilled it, proceed with the most -tapering of your taps, which we suppose to be provided to form the -internal thread (external if your mandrel has female screw, in which -case, instead of a drilled hole, the chuck will have a projection to -be turned truly cylindrical, and a screw cut outside with stock and -dies or chasing tool). - -Follow up with the intermediate and finish with the plug tap. If you -were careful to square up the shoulder, the drill having been likewise -placed perpendicularly to the face of the chuck, the latter will fit -truly up to the collar or shoulder on the mandrel. If not, you must go -to work again, and square up the back of the chuck till a good fit is -produced. - -Now, if you have a compound slide rest--that is, one in which the -slides turn on a centre pin--you can loosen the screws and turn it -a quarter of a circle. If not, you simply put the tool into the -holder, at right angles to its former position, so that the movement -of that slide which is parallel to the lathe bed will become that -requisite to advance the tool into the hollow of the chuck. Whichever -way you set to work put in a side tool, like Fig. 142, and, as it -is a brass chuck, remember that the bevel underneath is to be very -slight. Introduce the tool so as to take a light cut at first, until -the roughness is taken off, after which you may cause it to bite more -freely. Repeat this until the chuck is sufficiently hollowed out, when -you may substitute a similar shaped tool, but with a flat or slightly -rounded edge, to take off the marks left by the point tool. To finish -the bottom of the inside you will require a tool which cuts on the -end, but it should not have a perfectly flat end--at any rate, not -until, by means of a pointed or small round-ended tool, you have cut -away the roughness left from the process of casting. This has always -in its interstices a number of grains of sand fused, and very hard and -detrimental to cutting edges of all kinds. The point tools dig these -out very effectually, and should always precede those of other forms. - - [Illustration: FIG. 142.] - -The outside must be turned in a similar manner, and a hole drilled -to receive a pointed bar or wrench, for the purpose of unscrewing it -when screwed up tightly. To turn up a face plate of iron or brass -proceed in a similar way, but commence from the centre with a point -tool. This tool is the best for taking off the rough outside of hard -wood, instead of the gouge, as well as for removing the roughness of a -fresh casting. It is absolutely necessary that the faces of these flat -chucks, or surface chucks, be truly at right angles with the mandrel; -hence it is very difficult to turn and finish them by hand. We may -here also state the necessity of knowing when the slides of the rest -are at right angles to each other, without which no work can be turned -correctly. It is necessary to ascertain this by help of a small steel -square. Once fixed truly, it is only necessary to make a mark on the -quadrant (which should be marked in true degrees), by which the same -position can be found again at any time. We have spoken here of the -quadrant--we mean the arc, or arcs with slot--allowing the circular -movement of the compound slide rest. The chief use of these is to -enable the workman to turn true cones instead of cylinders, which -latter will only be produced when one slide is parallel to the lathe -bed. Such is the common use of the slide rest; and it will be evident -from these few remarks that there is an infinity of work, not only -produced with ease by its aid, but which cannot, even with expenditure -of time and labour, be produced without it; hence we advise this to be -the chief ambition of the tyro after he has mastered the difficulties -of ordinary hand turning (and not before). The cost of a fair one -for 5-in. lathe will be £5, or thereabout. At Munro's, £7 or £8; at -Holtzapffel's, £10 or £12. Both the latter are of course perfect. - -We have directed to tap the chuck where it is to be screwed to -the mandrel with a set of three taps, or to cut it with stock and -dies if an outside thread is required. In both cases more true and -satisfactory work may be produced by the chasing tool. We speak of -the latter as used by hand; an account of cutting the threads by -help of the slide rest we reserve for the present. Mount the work -in any convenient way, either driving it into a wooden chuck, or by -clamping it to the face plate if you have one. Now in this way you -have advantages. In the first place you need not have a drill the -exact size, though it is convenient to have such a one, and also a -cylinder bit. You can drill and enlarge the hole by the slide rest -tools, and you can also with the slide rest ensure the perpendicular -position of the hole with respect to the end. Thus it is sure to fit -up close and snug to the shoulder of the mandrel. When bored thus -it will be in position for chasing. It is not difficult to chase a -thread in brass, as it does not chip away like wood, but cuts clean -and sharp. Follow the directions already given and you will succeed in -a few turns in getting the tool to run. Then let it have its own way; -hold it lightly, but steadily, and do not force it either to cut too -deeply, or to advance too quickly; it will run along of itself after -the faintest thread is cut or scratched, and the lathe can be worked -by means of the treadle all the time as soon as you have attained the -knack of dropping the chaser into its place at the commencement of its -cut, and suddenly withdrawing it when it has reached the bottom of the -hole. A chuck thus turned and screwed entirely in the lathe is sure -to prove a good fit, and there can be no better practice than to cut -screws in all your brass and boxwood chucks in this way. A very good -chuck to hold flat plates of brass was invented by a Mr. Wilcox, of -Bishop's Stortford, some years ago--an amateur of rare ingenuity and -mechanical knowledge, and who made all his own apparatus for plain and -eccentric turning. The chuck, Fig. 143, as described by him in some -unpublished manuscript, is made of boxwood, or may be of metal. It -is a plain disc or surface chuck with three slots A B C. and a steel -centre. This last must penetrate rather deeply into the wood of the -chuck, but is only kept up so as to project from the surface by a -spiral spring below it. Hence, when pressure is made upon its point by -the application of the object to be turned, the pin recedes into the -body of the chuck, suffering the work to lie flat on its surface. In -the three slots are three screws, with nuts at the back of the chuck -the screws pass through two pieces of brass, forming a pair of jaws, -one of which is shown separately. - - [Illustration: FIG: 143.] - -Fig. 143 shows the chuck complete. Suppose we have to face up a round -disc in its central part, or to perform any surface work in which the -jaws will not be in the way of the tool, the centre of the plate is -marked at the back of it, and this mark laid on the central pin. The -work can be clamped down by the three jaws, and the necessary work may -be done. Now so far the chuck is but a simple affair, and the receding -pin does not show itself to such great advantage; we will therefore -suppose a plate is to be drilled at several spots; let these be marked -at the back by a centre punch. It is now only necessary to bring these -marks in turn upon the central point, and clamp the plate in position. -Bring the point of the drill against the work and keep it up to cut by -the back poppet screw. In the same way eccentric work or any operation -may be done to such a plate, with the certainty that the point to be -thus worked upon is precisely central with the axis of the pulley, -or mandrel. Many similar applications of this chuck will present -themselves to the reader upon due consideration. We present the chuck -in this place because we have had occasion to speak of drilling as -connected with the slide rest, and there are many pieces of work that -could not otherwise be conveniently held in the desired position.[10] - - [10] The MS. book containing the above was kindly lent to the author - of the present work by Mr. Hoblyn, of Bishop's Stortford, who is the - inventor of a new form of slide rest, which will be introduced in a - later page. The chuck in question is, however, commonly attached to - the watchmakers' lathes of the present day, and therefore may not, as - the writer supposed, be actually the invention of the late Mr. Wilcox. - - - OVERHEAD APPARATUS. - -It now becomes necessary to speak of another addition to the lathe, -by means of which the use of the slide rest is considerably extended. -We mean the overhead motion. Of this there are several patterns, and -we have sketched three of these. As to their respective merits we can -hardly venture to speak. They all answer equally well the purpose for -which they have been designed, and the turner must select according to -his fancy, or, if he please, design a better for himself. A, Fig. 144, -represents the lathe bed. From the left-hand standard rises a round -iron rod, not less than one inch in diameter. This is not generally -fixed, but is attached to the standard by two staples, _a, b_, which -hold it securely in an upright position, but allow it to turn with -its projecting bar F, F, after the manner of a crane. It may thus be -turned back, out of the way, or brought into any desired position. The -part F, F is made to slide up and down on the part B, and is fixed by -a clamping screw D. Thus, if the cord should break and require to be -shortened, the arm can be brought nearer to the bed of the lathe. Upon -F, F slide two rings, or rather short pieces of tube, from which depend -two India rubber springs (door springs), E, E, now procurable at any -ironmonger's at one shilling each. From these hang double pulleys, or -better still two single ones. These pulleys, with their attachments, -are adjustable at any position on the arm F, F, which may be round or -square. If considered desirable, a second standard can be added, so as -to uphold both ends of this bar; but it is hardly necessary, as the -latter is seldom required of greater length than half that of this -lathe-bed. It is evident that the above addition to the lathe can be -made complete for a few shillings. The following are more expensive, -but more general, the writer having devised the above to suit his own -fancy, and for his own use. In Fig. 145 A represents the standard as -before, the top of which is forked, as shown at E, and sustains the -ring, free to revolve in its arms, as seen in the sketch. Through -this passes a bar, B, B, with a heavy ball C cast on its end to act -as a counterbalance to the longer arm and its connections, and to -keep the cord stretched. By sliding this bar either way through the -ring which supports it, the tension of the cord can be increased or -lessened.[11] When in position it must be very securely fixed by the -screw T, which should not simply press against it, but enter one of a -row of depressions made for the purpose. The pulleys C, D are double, -as in the previous plan of overhead, and are likewise adjustable at -any position on the bar B, B. The only drawback to this pattern is the -danger of the heavy ball slipping out and falling. We prefer to hang -a weight from the end of the lever, as shown by the dotted line. This -may be within a few inches of the floor, and if it should fall no -harm can ensue. The third pattern, Fig. 146, is the most expensive, -but although it is of a more finished appearance, and wears an aspect -more stiff and stable, it is not practically any better than the last. -From a standard A, with overhanging bar F, F, is suspended a frame H, -by means of two coiled springs in brass boxes B, B, which keeps up the -necessary tension on the cord, or rather cords, for in this case two -are needed--one from the flywheel to the small pulley, and a second -from the roller to the slide rest. - - [11] Sometimes the bar is merely hung on pivots, and the weight is - made to slide upon it. - - [Illustration: FIG. 144.] - - [Illustration: FIG. 145.] - - [Illustration: FIG. 146.] - - [Illustration: FIG. 145.] - - [Illustration: FIG. 143] - -This roller, which may be grooved or plain, may be replaced by a -second small pulley, which is capable of being slid along the round -bar which forms its axle and turns with it between the centre screws. -In this case the bar is made with a groove or channel along its -length, Fig. 147, and a pin projecting from the central hole in the -pulley enters this groove. Thus the two will turn together, and at -the same time the position of the pulley is adjustable at pleasure. -The tension of the springs B, B, is increased or lessened by a turn -or two of the nuts C, C, just in the same manner as the spring of -the safety valve is adjusted on the boiler of a locomotive.[12] The -application of the overhead motion is plainly shown in Figs. 143 and -144. The work is fixed in the lathe, and the mandrel kept stationary. -The cord passes to the overhead directly from the fly wheel, and -thence to a pulley on the screw of the slide rest, as in 143, to a -drill, as in 144, or to any other apparatus at pleasure. To fit the -work in the lathe in such a manner as to enable any point in the face -or side to be operated upon, a division plate and index are required. -The first is a round plate of brass or gun metal, 1-16th of an inch -thick, drilled with holes in concentric circles. The index is a steel -spring with a projecting point, which, entering any one of the holes, -retains the plate, and with it the pulley, on the face of which it is -fixed immovable. There are generally four circles of holes, the number -in each selected with reference to its divisibility by the greatest -possible number of divisions--thus 360, which is usually on the -outside or largest circle, can be divided without a remainder by 2, 3, -4, 5, 6, 8, or 9--144 is a good number for the second circle, being -divisible by 2, 3, 4, 6, 8, 9. The other two may be 112 and 96. The -uses of the division plate are many. Eccentric cutting and drilling -could not be done without its aid, and wheel cutting for clocks, or -for making cycloidal and other chucks, is entirely dependent on this -contrivance. - - [12] The frontispiece shows another superior form of overhead, with - balance-weights hanging close to the ground behind the lathe. - - [Illustration: FIG. 147.] - -The division plate and index are shown in Figs. 147, A, B, C. The part -B is a knob with a round hole through it, to take the tail of the -spring C. This is shown again at C on a larger scale, to bring to view -a slot which allows of some slight adjustment of the point, to suit -the different-sized circles. The milled-headed screw clamps the point -at any desired part of this slot. When not in use, the spring is drawn -back so as to release it from the division plate, and turned down in -the position shown by the dotted line. - -The overhead apparatus is applicable not only to revolving cutters in -the slide rest, but to other contrivances available where the latter -is not possessed. There are many cases in which the back poppet may be -brought into use to hold revolving drills, or stationary tools, if the -resistance to their action is not too great. The only damage that can -well happen in this method is to the pin working in the slot on the -outside of the spindle. If this is of steel and tolerably stout and -strong (being very short it cannot be subject to any very injurious -strain), no harm is likely to result. With this it is possible to -drill very neatly, and also to do a little eccentric cutter work, -under certain conditions to be described. Screwing, or rather chasing, -may likewise be done very passably. We do not, of course, advise this -course when the more perfect slide rest is at hand, but there are many -who are obliged to put up with all sorts of homemade contrivances, and -to press into service for divers operations apparatus and tools not -precisely meant to be thus used, and it is as well to learn how to act -under an emergency, even if the practice is not intended to be carried -out generally. The drill stock is shown in Fig. 148, in which the -screw A fits into the spindle of the back poppet. If the hole in the -latter is conical instead of cut with a screw thread, the drill must -be made accordingly. - - [Illustration: FIG. 148.] - -The pulley of brass has a hole drilled through it, and the screw is -also drilled, the hole in the latter being rather larger than that -in the pulley (which is tapped). The steel pin H, shown white in -the sectional drawing, passes truly through the centre of the screw -in which it revolves, and is screwed into the pulley. The socket -of steel to hold the drill is then screwed or soldered into the -opposite face of the pulley. The black part shows a flange on the -screw which abuts against the cylinder of the poppet into which it is -screwed. Thus the pulley, being attached to the cord from the overhead -apparatus, is free to revolve upon the steel pin with great rapidity, -and will carry round any drills or cutters placed in the socket B. The -simple straight drill being thus worked and advanced by the leading -screw of the poppet, will suffice for holes in any work held on the -mandrel. On page 335, vol. ii., of the _English Mechanic_, this method -is mentioned, and also a similar pattern of slide tool to be used for -boring, being, in fact, the head and spindle of the back poppet, but -instead of the standard and sole, a pin, like that of a =T=, to -fit the socket of the rest. This has the advantage of the back poppet, -but must be made on purpose, and if any special slide tool is added, -a proper slide rest is by far the best. Our present purpose is to -describe the use of the back poppet as a substitute for a better tool. - -With the following modification of the eccentric cutter, a fair amount -of good ornamental work may be done. Fig. 149 represents the back -poppet with the apparatus in position. The various parts are shown -separately in A, B, C, D. A is a small frame, two or three inches -long, and 3/4 to 1 inch wide, cast in iron, with a circular piece -at the back, 1-1/2 or 2 inches diameter. This circular piece is to -be accurately divided on the edge with any even number, which is -divisible as above explained. This is turned and drilled through the -centre. B is a flange-shaped piece to screw to the poppet as before, -and this is also accurately drilled, and the two are attached by a -central steel pin, so that the two flanges can turn face to face, the -outer one with frame revolving against the other. The pin must be -put in its place in B, and turned at the same time as the face of B, -that it may be truly central. The divisions on the edge of the outer -flange are to be drilled like the division plate of the lathe, or cut -into cogs, and in either case can be held at any point by a spring -detent or index attached. C shows the front of the frame, with a screw -down its centre and traversing slide _f_. The head of this screw is -divided, and a small brass index marks its position; one side of the -frame may likewise be divided. The small brass pulley and drill socket -are fixed to revolve in the traversing nut or slide _f_, as shown in a -side view at D. Drills of all shapes, as E 1, 2, 3, 4, may be fixed in -the socket at pleasure. - - [Illustration: E] - - [Illustration: FIG. 149.] - - [Illustration: Fig. 150.] - - [Illustration: Fig. 151.] - - [Illustration: Fig. 152.] - - [Illustration: Fig. 153.] - -It is evident that the cutter frame last described having a division -plate of its own dispenses with the necessity of one on the pulley of -the mandrel. Indeed it was the impossibility of supplying the latter -on the face of the cogwheel of the author's back-geared lathe that -necessitated the substitution of that alluded to. The latter may -consequently be omitted if applied to a lathe already fitted with -division plate and index. With crank-form drills the cutting edges -of which may be as E 1, 2, 3, 4, or other form, such patterns can be -cut, as shown in Figs. 149, 150, 151, 152, which are merely samples -of the simplest combinations of circles intersecting in straight, -spiral, or other lines. Although not now treating of eccentric work, -we may state in passing that to produce the pattern round the edge -of 150 the division plate of the instrument only is required. Select -a crank-form drill which by its revolution will produce the required -size of circle. Turn the divided screw head until you find upon trial -that the circle will come at the required distance from the edge, -and putting the lathe in motion cut the first circle. The work on -the mandrel is understood to be stationary, the mandrel being fixed -so as not to turn. The cutter frame is now turned on its axis, one, -two, or more of its divisions, and fixed by its detent, and a second -circle cut intersecting the first. This is repeated till the whole -circle is completed. The straight line of circles in Fig. 151 is cut -as follows:--The first circle is made as before, but the cutter-frame -should be placed so as to stand either horizontally or vertically. -Between each cut the divided screw-head is moved so many points -according to the proposed fineness of the pattern, and no movement -of the cutter frame on its axis is to be made. The spiral, 152, is -simply the result of a combination of the two movements. Start from -the centre by turning the screw head until the shank of the crank-form -drill is coincident with the axis of the mandrel. Cut the central -circle. Thence for each successive circle turn the screw head and the -frame an equal number of points, and the pattern will be formed. If -the divided screw head is made to take off and a handle substituted, -stars formed of channelled lines, or radial flutes can be made as Fig -153, but in this case the crank form drill is replaced by a plain -straight tool with a rounded end like 149 E 4. Set the tool as for -pattern 150 straight across the face of the work, put the drill in -rapid motion, let it be advanced by the leading screw of the poppet so -as to penetrate slightly, and with the handle that has been attached -to the screw of the cutter frame cause it to traverse the face of the -work as it revolves. When one flute is thus cut, turn the frame on its -axis as many points as required, and proceed with number two, and so -on to the completion of the star. It is not necessary at present to -describe other patterns. Fig. 153 is therefore merely given without -special details of the method of producing it. - -We must now return from this digression to speak of other applications -of the slide rest. It is evident that when connection is made between -the overhead and a pulley on the screw of the slide rest, the latter -becomes self-acting. The speed is, however, far too great, and in -addition, the mandrel is stationary. The above connection, therefore, -is not practically possible, and the overhead is only connected with -the pulleys of revolving drills and cutters fixed in the tool-holders -of the rest. It is, however, very important to be able to form some -such connection between the lathe mandrel and the screw of the rest, -for the purpose of cutting screws or spirals. A little consideration -will show the principle of this arrangement, from which some practical -plan is not difficult to design. If, for instance, the tool simply -remains in contact with a cylinder while the latter revolves with the -mandrel, a simple line will be cut round its circumference; but if, -while the mandrel revolves once, motion is given to the screw of the -rest by which the tool is made to traverse a distance of one-eighth -of an inch, the commencement of a spiral having that pitch will be -made. A perfectly smooth surface, as it leaves the lathe, in which a -slide rest has been used with a point tool, is in reality cut with a -very fine screw thread readily discernable under the microscope. We -have, therefore, only to devise some method of giving regular motion -to the screw of the rest while the work revolves as usual, in order -to turn plain surfaces, screws, or spirals. For the purpose of plain -turning a plan is sketched by Nasmyth in the last chapter of "Baker's -Mechanics," in Weale's series. A spur wheel is represented fixed to -the slide rest screw, the teeth of which are alternately caught at -every turn of the work, by an arm fixed to the latter, after the -manner of a lathe carrier. This plan is simple, and might be to some -extent used, but for one defect, due to the fact that the slides -of ordinary rests are the reverse of what is required to make this -plan available. The screw which advances the tool towards the work -is generally underneath that which moves the tool along the surface -of the work. The result is that, when the tool-holder is advanced -to take the deeper cut the spur wheel is brought nearer to the arm -which acts upon it, and greater traverse is thus given to the screw. -This is shown in Fig. 154. A is the spur wheel, B the cylinder to be -turned, C the arm or carrier. The arrow shows the direction of the -movement. Now, if the lathe is put in motion, the arm will remain -in contact with one tooth of the wheel until both arrive at _b_, -giving a certain amount of motion to the screw, and thence to the -tool-holder. After one cut is thus taken, the lower screw of the rest -is turned to advance the tool nearer to the work, the effect of which -is to cause the arm to extend further over the wheel. Suppose its -position represented by the dotted line, it will remain in contact -with the tooth till both arrive at _c_, having thus traversed a -larger arc, and given more movement to the tool. Now if the frames -of the slide rest were made to cross in the contrary direction so -that the screw to advance the tool towards the work was above that -which gave the traverse in the direction of the bed, this objection -would no longer hold, and the above gearing would answer very well, -since the necessary advance of the tool would not affect the relative -position of the spur-wheel and carrier. In Fig. 5 of the same book, -in which the gearing is effected by two cogwheels, this alteration -in the rest appears in the drawing. In this case the work and rest -are connected for screw cutting, and the arrangement is satisfactory -and simple, and for the amateur especially is the simplest and best -that can be devised. The range of screw pitches is however limited, -and the rest must have a left-handed screw, or the result will be a -left-hand thread to that which is cut. Hence another device has been -arranged, represented in Fig. 155, A, B, C. A shows the apparatus -complete. B is an arm of iron or brass which is about 1/4 inch thick -or rather more. This is first slipped over the mandrel screw in front -of the poppet and fixed in any desired position by a screw passing -through the slot _a_, into the face of the poppet. This slot allows -the arm to be raised or lowered at pleasure and adjusted, as will be -presently described. In the slot formed in the long arm B, pins D with -nuts, fit, on the rounded part of which cogwheels, _b_, _c_, _d_, -are made to revolve and to gear with each other, and with a similar -wheel attached to the back of the chuck, C. The centre of the outside -wheel, whether one, two, or three are used, is connected to the screw -of the slide-rest. For the production of a right-handed screw, the -intermediate wheel comes into play, simply to reverse the direction -of the motion imparted to the screw of the slide rest. The number of -teeth which it may contain is of no importance, the calculation of -the change wheel teeth being only necessary with the first and last. -The central one is called an idle wheel, though its work is equal to -that of the rest. Thus, suppose the wheel on the chuck to contain 40 -teeth, and the third wheel 20, while the former revolves once, the -third will, if in immediate contact with it, revolve twice, introduce -an idle wheel with 10 teeth between these two. The wheel, with 40 -teeth, revolving once, the idle wheel will revolve 4 times--the third -wheel twice, just as if the idle wheel was not in use. In any train of -wheels, if we regard relative speed, any number between the first and -last become similarly idle wheels, and the ultimate result is the same -as if the first and last were in immediate contact. - - [Illustration: FIG. 154.] - - [Illustration: FIG. 155.] - -Take, for example, the following train of five wheels, even -numbers being given for the sake of clearness, to represent the -circumferences or number of cogs in each, Fig. 156. We have here, as -the first and last, 6 in. and 120 in., and, if in contact, the first -must revolve 20 times, while the latter revolves once. Interpose the -three idle wheels of 10, 30, and 60 in. respectively. During one -revolution of the largest wheel, the second will revolve twice, the -third four times, the fourth twelve times, the fifth twenty times, the -same precisely as if the first and last had been in immediate contact. -The range of a slide rest-screw is quite long enough for many purposes -of the amateur, and a connection thus made between the mandrel and -such screw is what may be termed a miniature of the arrangement -adopted in the large self-acting lathes. In the latter, however, a -leading screw is added the full length of the bed along which the -slide rest travels bodily. We may, therefore, consider the screw of -the slide-rest a leading screw, and make use of the rules applied in -the case of large lathes to decide the proportions of wheels required -to cut a given screw. It is plain that when the pitch of the required -screw is greater than that of the leading screw, the revolution of the -latter must be at a quicker rate than the former. If, for instance, -a spiral is to be cut, like the Elizabethan twist, containing but -one perfect thread in two inches, while the leading screw contains -twenty threads in the inch, or forty in the 2 in., the latter must be -arranged to make forty revolutions while the former makes one, because -it takes 40 revolutions to carry the tool along 2 in., which is the -pitch of the required spiral. The two outside wheels must therefore -bear that proportion to one another. Forty to one, however, would be -a practically difficult ratio, to place as described, even a pinion -of ten teeth on the leading screw requiring 400 teeth on the chuck. -Hence a different arrangement would be necessary if such very great -difference exist between the pitch of the leading or rest screw and -that to be cut. The same obvious difficulty would occur where a very -fine screw is required, and the pitch of the leading screw is coarse. -This will have to be referred to again. One example, therefore, of the -method of overcoming this difficulty will suffice. A train of wheels -is shown in Fig. 157, of which A has 60 teeth, B 10 teeth, C, _on the -same axle and united to_ C, 30 teeth, D 20 teeth. While A turns once, -B will turn six times, C necessarily six times also, D nine times. In -this case, if the first and last had geared together D would have made -but three turns, while A made one. - - [Illustration: FIG. 156.] - - [Illustration: FIG. 157.] - -The following is an easy method of calculating a series of such change -wheels:-- - -Write down the number of threads in the screw to be cut, and also -the number of threads in the leading screw; multiply both by any -convenient number likely to give such results as to tally with the -cogs in the set of change wheels. Suppose it is desired to cut eight -threads to the inch, and that the leading screw has two threads in -that length. Then: - - 8 80 8 120 8 160 - - × 10 -- or - × 15 --- or - × 20 = --- &c. - 2 20 2 30 2 40 - -If you have either couple of these wheels, you can put one on -the leading screw, and another on the mandrel, and fill up the -intermediate space with dummies. - -If the above is inconvenient, or the wheels are not to hand exactly -as required, proceed thus. If you have the wheel for the mandrel, and -the one you wish to use for the leading screw has only half the proper -amount of teeth, it is evident that the leading screw would revolve -twice as fast as required, for they are proportioned as two to one--or -if I have the proper wheel for the leading screw, and the wheel I -wish to use for the mandrel has twice the proper number of teeth, it -amounts to the same thing. You can get over the difficulty by using -any two wheels which are in the proportion of two to one (say 20 and -40, 30 and 60, 40 and 80, &c.), and coupling the two firmly together, -so that the larger wheel of the two works into the mandrel wheel (or -dummy working into the mandrel wheel) and the smallest into the screw -wheel (or its dummy); if the speed is wrong in the contrary way, so -that the case is reversed, the coupled wheels are made to gear in a -reversed direction; and whatever may be the amount of error, whether -such as to cause either mandrel or screw to revolve 1/8, 1/4, or -3/4 too slow or too fast, the same arrangement may be pursued, the -coupled wheels bearing that proportion to each other. The above method -was communicated to the _English Mechanic_ by a working man, James -Connor, and is perhaps as easy as any; but tables are published of -change wheels for any pitch, with any thread of leading screw. Where -it is not possible or inconvenient to apply the above arrangement, -and where only a few pitches are likely to be needed, another method -can be arranged by connecting the lathe pulley to the overhead motion -and thence to the screw of the rest. Such an arrangement is shown -in Fig. 158. A is the fly wheel, B mandrel pulley, C, D, pulleys on -the overhead, E pulley and screw of the slide rest. To facilitate -calculation, let diameter of C equal that of the part of the mandrel -pulley that drives it, by which it will revolve in the same time. The -calculation of the sizes of pulleys, D and E, will be the same as for -the cogwheels of the screw-cutting lathe, circumference and number -of cogs being, so far as calculation is concerned, the same thing. -Let the leading screw have eight threads to the inch, and let it be -required to cut a spiral of two threads to the inch. Proceed as before -by dividing the required number of threads to be cut by the number -on the leading screw 2-8 =·25. The pulley on the leading screw will -be therefore one quarter the size of that on the overhead (which is -virtually that on the mandrel as it revolves at an equal speed with -the latter). The overhead pulley may be conveniently twelve inches -diameter, and that on the screw three inches. While the mandrel makes -one revolution the screw will make four, advancing the tool half an -inch, and cutting one thread of a spiral in that distance. The next -revolution will advance the cutter a second half inch, cutting a -second complete thread of spiral. Two threads will, therefore, have -been cut in the space of one inch as desired. By the above method -short screws and spirals of divers pitches may be cut at pleasure. -_The practical difficulty in this plan is due regulation of the -various speeds._ - - [Illustration: FIG. 158.] - -We here introduce a modification of self-acting lathe for cutting -Elizabethan twist described by Mr. Wilcox in his MS. before alluded -to. The work is here done by a leading screw and toothed gearing, the -principle being that of the ordinary machine lathe. A chuck, A, with -cogwheel attached holds the work as usual, the back centre being also -required. The cogwheel gears with one of less diameter attached to the -end of the guide-screw B. On the latter works the rest C, in which -is a nut of the same thread as that on the guide screw, and which -holds the tool in a notch or hollow upon its upper part. The tool is -then used by hand, but is guided in its course along the surface of -the work to be turned. This guide screw, with the rest and cogwheel, -is mounted on a board as a separate piece of apparatus, and is, when -used, clamped on the lathe bed. As the rest is after all little else -than a large nut, it must be prevented from turning round, and must be -arranged to bear the pressure of the tool, relieving the long screw -from the strain that would be thus caused. This is effected by a long -flat bar--like the rest of a chair maker's lathe--extending the full -length of the bed shown here at E, and supported by standards F, F. A -projecting part of the rest bears upon this, and slides along it with -the tool. The work is begun with the rest on the right hand, and some -care is necessary as it nears the cogwheel on the left, when the work -must be stopped and the whole run back by hand to its starting-place. -This is one chief defect in this apparatus, for the rest very quickly -traverses the length of the screw, and great delay is caused by having -thus constantly to stop the lathe and reverse the motion. The closest -attention is also necessary to prevent the rest from overrunning its -mark and striking the cogwheel. It is evident that by using different -pitches of cogwheels, many screws of varied threads can be cut in the -above lathe. There is, however, another defect in the above tool not -noticed by the writer of the MS. from which the description is taken, -namely, the difficulty (common to all such contrivances for turning -wood), of obtaining the requisite speed. If the work is put in rapid -motion, without which wood will not be cut clean, the movement of the -rest will be so rapid also, from the effect of the multiplying wheel, -that the tool will be carried from end to end in a few seconds. We -will therefore proceed to describe a modification of this and similar -apparatus, which allows the tool a slow traverse lengthwise of the -work, but gives it immense rapidity in the necessary direction. The -following is applicable to the lathe described above, to the ordinary -slide rest worked by hand, or to the large self-acting screw-cutting -lathes used in manufactories, and is specially adapted for cutting -spirals or other patterns in wood. In the Fig. 160, A represents a -shank, which may be made of any shape to fit particular patterns of -tool holder. This shank is turned up and becomes a cylinder at B, like -that of the ordinary revolving cutter. This part is bored, and fitted -with a steel spindle, which should be of strength proportionate to -the size of stuff likely to be operated on. One end of the spindle is -fitted with a brass pulley, from which a cord is to be attached to the -overhead apparatus, the other end terminates in a round or hexagonal -boss, D, round the margin of which are securely held, by means of -bridles B1 or other simple contrivance, a pair or more of small sharp -gouges. This apparatus is put in the tool holder of the slide rest, -set to the angle that corresponds with that of the screw or twist, -and put in rapid revolution by means of the overhead apparatus. The -whole rest, or merely the upper part, is then put in motion by one of -the before-named means, and the tool advanced to make a cut. However -slow the movement of the rest may be, the cutters move with such -velocity as to make clean and beautiful work.[13] This may be applied -to the slide-rest of the twist lathe, just described, or any similar -apparatus. In the overhead, a roller, supplying the place of the -second pulley, as described in a previous page, will allow the second -cord sufficient power of traverse to keep up a proper position in -reference to the pulley C. Revolving cutters on the same principle as -the above, have of late years come into extensive use in wood-cutting -and carving machinery. The steam planes now used in the preparation -of flooring boards, the spoke turning lathe, moulding and shaping -machines for wood are all thus fitted. The gouges or other cutters -used must not be placed radially, but as tangents to the circumference -of the boss in which they are fixed. An improvement upon the simple -bridle to hold the cutters would be the substitution of Babbage's -tool holder, four radial arms being substituted for the metal boss -above alluded to. This tool is described and figured in Holtzapffel's -"Mechanical Manipulation," to which the reader is referred for an -accurate description. It chiefly consists of a shank turned up at the -end like Fig. 161, the outside, at B, being rounded to fit hollow -gouges such as Fig. 161H; against this the hollow of the gouge is laid, -and opposite to it, at C, a small piece like D. A band or hoop, E, is -now placed over both the above, and between the two a wedge-shaped -piece, F, which is intended to bring a strain upon the hoop and -tighten it round the gouge. This last piece is attached to the shank -or holder by a screw passing through it into the shank. The tighter -this screw is worked the lower the central wedge is drawn down, and -the tighter the hoop is made to embrace the tool. This holder is also -modified to suit flat chisels. The tool cannot possibly slip, but -can be released in a few seconds if desired. Such a termination of -two, three, or four arms revolving on a spindle in place of the boss -would form the best possible circular cutter for shaping lathes. The -above lathe for producing Elizabethan twist introduces the reader -to self-acting, screw-cutting, and machine lathes, such as are used -in all large manufactories. Hand-turning, indeed, except in such -light work as turning up the heads of small bolts, and finishing up -work which, from peculiarities of form, cannot easily be done by -self-acting tools, has become a thing of the past in factories of any -pretensions; hand labour, in fact, not only no longer pays, but is -quite insufficient to meet the requirements of the present age. Take, -for example, a piston-rod requiring to be as "true as a hair," to use -a common expression, from end to end. The traverse of an ordinary -slide-rest would only enable us to turn a short length at a time, -and the result, when accomplished, would not be satisfactory. With a -self-acting lathe the tool traverses in a perfectly straight line from -end to end, is returned to its starting-point by a quick traverse, and -the movement repeated until the proper dimensions are attained. The -process is not absolutely rapid, because time is requisite in cutting -iron and steel, but the work is executed as speedily as the nature of -the metal to be cut will allow, and the execution is perfect. Of late, -however, even the above has been improved upon, for two cutters are -used at once--one on each side of the bar, so that by one traverse -of the rest a cut of double depth is taken, and the tendency of the -work to spring away from one tool is counteracted by the operation of -the other. But we require something more than speed in the present -day. We must have work of absolute truth of measurement. What would -our ancestors, or the immortal Watt himself, think of measuring work -to the hundredth part of an inch, yet it can be and is done to the -thousandth part. I believe I am correct in saying that Whitworth -constantly gauges work to that or even a higher degree of nicety. It -is not too much to assert that the best engines of the present day -really work with the precision of clockwork, and even the bore of -an Armstrong or Whitworth gun is executed with no less accuracy and -precision. Look again at that ponderous affair, the steam hammer, -so ponderous as to require a depth of solid masonry and timbers to -sustain the force of its terrific blows. In a few minutes a solid -mass of metal is reduced to a flat plate such as would have taken the -united strength of a dozen men wielding the heaviest sledge-hammers -for an hour at least. The ground beneath the feet of the spectator -trembles at every blow of the machine. The work is done, and behold! -with a touch the same ponderous concern becomes a nutcracker, not even -injuring the kernel when it breaks the shell. Such is one of a hundred -specimens of accurate workmanship carrying out in practice the clever -designs of the mechanical engineer. Sweep away self-acting machinery, -and such work would become a simple impossibility. Again, so long as -turning, boring, planing, and such work was performed by hand alone -(even after the introduction of the slide principle), an attendant was -required at each machine. Now that the latter is contrived to regulate -its own movements, one man at two or three lathes is sufficient. Thus -the same article that was once imperfect and costly, owing to the -demand on skilled labour, which was difficult to procure and at best -inefficient when procured, has now become cheap, and to all intents -and purposes perfect; and although the demand for such work increases -year by year, self-acting machinery being constantly improved and -simplified, enables the manufacturer to keep pace with the demand. - - [13] The spiral chuck for fine work in ivory and costly woods is - described in a later page. - - [Illustration: FIG. 159.] - - [Illustration: FIG. 160.] - - [Illustration: FIG. 161.] - -The advantages of self-acting machinery are of course chiefly confined -to the trade, and it is not often that the mere amateur requires such -aid. Indeed, the expense necessarily attendant on the fabrication of -these machines deters the great majority from making such a purchase. - - - SELF-ACTING AND SCREW-CUTTING LATHES. - -The first requisite for fitting up a lathe for screw-cutting and -plain turning is the fitting a guide-screw, and adding a saddle to -the slide-rest. But it must be observed that the ordinary mandrel of -small foot-lathes, which works in a collar and back centre, is not -convertible, and must be replaced by one working through two collars, -so that a part may project at the opposite end to that intended for -the chucks. On this projection various cogwheels have to be fitted. -Now there are divers patterns of mandrel suitable for the above -purpose; some are perfectly cylindrical, some have one conical part, -some are fitted with a second cone, independent of the mandrel, and -which slides upon it, and can be adjusted by means of regulating -nuts. This latter being a good pattern, when well constructed, we -shall first describe in detail. In Fig. 162 is shown A, the mandrel -complete, with fittings in section, but without any of the change -wheels. The cone _a_ is forged on the mandrel, which then becomes -cylindrical. The cone is figured too large in proportion to size of -mandrel; the latter should be represented as much more substantial. -At _b_ the second cone slides on, the latter shown again at B. It is -bored truly, and a slot cut to fit a feather on the mandrel. Thus it -will slide along it, but must necessarily turn with it. Beyond D on -the left are two screwed parts, one slightly larger than the other, -one being made with a left-handed, the other with a right-handed -thread. On these screw the two nuts, _d, e_, which drive the movable -cone towards the right, causing it to fit more tightly into its -collar, and also by the same movement tightening the fixed cone in -its bearings. The mandrel is thus readily adjustable in the collars, -and can be made to run very truly and easily without shake or endlong -movement. Any pressure, however, against the front, such as would -be caused by drilling, would jam the front cone in its collar, and -tend to loosen the other. This is counteracted by the part _f, g_, -with its screw, _h_, against which the end of the mandrel bears. That -this form requires good workmanship is evident, for there are three -points, or bearing surfaces, to be brought into a correct line, and -the slightest deviation will cause the mandrel to jam in some part of -its revolution. The nuts screw up in opposite directions to counteract -the tendency in either to screw up more tightly, or to become looser -by the revolution of the mandrel. On the whole the above is a good -form of mandrel; if it has a fault, it is a slight tendency to work -heavily. The next form is that of the ordinary mandrel, with single -cone, but a second collar is added, which is cylindrical, through -which the mandrel passes, and it then abuts on the sustaining screw -as before. This is shown in Fig. 163, with the addition of the wheel, -which is to be connected by intermediate wheels and pinions with the -leading screw. If the conical collar is replaced by a cylindrical -one, so that two similar bearings are made use of, a shoulder becomes -necessary to prevent the mandrel from slipping endwise. The collars -must also be split as in Fig. 164, so that they can be tightened up as -they become worn. Either of the above forms of mandrel can be used; -each has its advocates, and not unfrequently all may be found in -different machines in the same manufactory. The bed of a self-acting -lathe requires to be accurately surfaced, and formed by the planing -machine with two V's or edges bevelled underneath, as 165 _b, b_. The -saddle of which we have spoken is a flat plate of cast iron fitted -with V pieces to match the bevelled edges of the lathe bed, along -which it slides truly, its under-edge being planed. To this plate the -slide rest is attached securely, either turning when required on a -central pin, and being clamped at any desired angle, as before stated -when treating of the compound slide rest, or, when this movement -is preferred to be given to the upper slide, fixed permanently by -nuts and screws. The saddle is represented detached in Fig. 166. The -principle of the self-acting lathe is very simple. Motion is given -to the screw by means of cog wheels geared with the mandrel, a nut -fitting the screw is attached to a hanging bracket of the saddle, and -this with the rest is thereby carried along the bed. It is necessary, -however, to add some contrivance for instantly throwing the screw out -of gear, without the necessity of stopping the lathe itself. There -are many ways of effecting this, the most common being the use of a -split nut, which embraces the leading screw when the two halves are -brought together upon it, but which is instantly freed by separating -them through the action of levers and cams, or other simple mechanical -contrivance. In Fig. 167, _a_ is the bottom of the saddle from which -depend the brackets E, E. The nut B, B, which is divided across the -middle, slides up and down between these brackets, D being the leading -screw which they embrace when closed. The movement of the halves of -the nut is effected by the lever _c_, in the form of the letter T -moving on a centre pin at K, and having two links, D, D, attached to -the halves of the nut at one end, and to the ends of the cross lever -at the other. A connecting bar pivoted to the part, L, is attached -to a lever and handle, by which motion is communicated to the lever. -When this rod is moved in the direction of the arrow the links will -cause the nut to close and _vice versa_. The next form, 168 and 169, -represents the split nut attached to two arms, A, A, hinged together -at E. B, B, are slots in which work the pins attached to the cross -head of the levers C, C. A heavy knob of iron keeps the latter in -the position to which it may be moved. In 168 the pins keep the arms -and nuts apart. When the lever is thrown over, as in 169, the nut -is securely closed and held in gear. This form requires to be fixed -to the lower part of a bracket attached to the saddle of the slide -rest, such as is shown at B, C, Fig. 170. In this figure, A is the -bottom of the saddle E, E, the V piece, that on the left, having an -adjusting screw to tighten it on the lathe bed when necessary. At F -is a projecting piece of the saddle fitting accurately between the -lathe bed, and kept down by a screw with bed plate underneath. This -serves to steady the movement of the saddle and relieve the pressure -and strain upon the V pieces. The bed-plate may be cut out to fit the -lower part of the bed on which it slides, both being planed for the -purpose, as shown at H. - - [Illustration: FIG. 162.] - - [Illustration: FIG. 163.] - - [Illustration: FIG. 164.] - - [Illustration: FIG. 165.] - - [Illustration: FIG. 166.] - - [Illustration: FIG. 167.] - - [Illustration: FIG. 168.] - - [Illustration: FIG. 169.] - - [Illustration: FIG. 170.] - - [Illustration: FIG. 171.] - -In Fig. 171 the half nuts slide up and down on the front of the -saddle, and are moved by a circular plate on the outside. The action -is very similar to that of Fig. 167, intervening links, attached to -the plate and to the halves of the nuts, giving motion to the latter -as required. Cams and eccentrics of varied forms are also made use -of for the same purpose, every lathe maker devising new and improved -movements from time to time. There is indeed little difficulty in -arranging a satisfactory method, the best being that which is under -easy control, of adequate strength, and not likely to be easily -disarranged by the rough treatment it is liable to receive at the -hands of the workman. The leading screw may either be placed on the -outside, in front of the bed next to the workman, or inside between -the bearers. The former is preferable as being more accessible, but -it is rather more exposed to injury. When between the bearers the -large saddle of the slide rest serves to protect it from the falling -chips and shavings of metal which, mixing with the oil, are apt -to clog the threads and add to the friction of the parts, besides -increasing considerably the wear and tear, and no accidental blow is -likely to reach the screw thus protected on both sides by the lathe -bed. Nevertheless, all the various parts of a machine should be made -as accessible as possible, and, with the exercise of ordinary care in -its preservation, the position outside is on the whole the best. If -the lathe bed is very long, it may be desirable to support the screw -by allowing it to rest on friction wheels fixed to the saddle at both -ends, or by allowing it to pass through a pair of brasses. Thus, as -the saddle is often two feet in length, such bearings at each end, -with the split nut between the two, form points of support which go -far to prevent the screw from jagging or bending in the middle from -its own weight. - -The general arrangement of self-acting tools is similar with all the -makers. Fig. 172 is a drawing of such a tool from a sketch of Eades & -Son, an old firm in Lichfield-street, Birmingham, the screw being here -placed in front. Whitworth, the eminent mechanician of Manchester, -makes many lathes with the screw between the beds. He also uses a -double slide rest, with a tool working at each side of the piece to -be turned, which cannot thus spring away from the cut. This is called -a duplex slide rest. By this method double the cut is taken, and the -strain upon the work lessened. In addition to the screw there is -usually a rack attached to the lathe bed, on the furthest side, and a -cog wheel working upon this, attached to the back of the slide rest -saddle, is turned by a handle in front of the rest, Fig. 173. This -enables the workman, after having, by means of the screw, completed -the cut to the end of the work, to run the rest back again very -quickly, having first released the split nut from the screw. The tool -is thus brought into position for the next cut far more rapidly than -could be managed by reversing the motion of the screw. This is called, -therefore, the quick return motion, and is almost always attached to -the larger class of machine-lathes. Before entering upon the details -of other forms of gearing, and the arrangement of change-wheels for -cutting screws or for plain turning, we shall introduce a few remarks -upon the often-repeated question as to the advisability of self-acting -lathes for the purposes of the amateur. It must be remembered that -the chief object of such a lathe is the manufacture of large screws, -long shafts, and such work as the piston rods of engines, requiring -perfect accuracy from one end to the other. Boring cylinders and -similar work is now generally done in an upright or vertical boring -machine, which is for many reasons more convenient. This class of -work, of course, the amateur has nothing to do with. The traverse of -an ordinary slide rest is generally adequate for surfacing or boring -to a length of six inches, which is sufficient for most purposes, and -can readily be done by turning the leading screw of the rest by -hand. Then, as regards screw cutting in the lathe, it is questionable -whether it is not easier to turn up the blank and cut with stock and -dies. The thread thus formed is a copy of that of the tool, and the -latter, as made by Whitworth and other first-class makers, is as -perfect as machinery directed by talented workmen can produce. If -it is really desirable, however, to make use of the lathe for this -purpose, the plan already suggested is generally applicable, namely, -gearing the leading screw of the slide rest to the mandrel, either -by means of change-wheels attached to an arm, or by connection with -the overhead pulleys. There is, in addition, a plan of attaching a -pair of dies to the tool holder of the rest, after detachment of -the screw from its nut, which may be available in some cases. There -are also screw plates made in two halves, the plates being divided -lengthwise and clamped together at pleasure, admitting of application -to any screw-blank while revolving in the lathe; and, lastly, pairs -of dies, fitted like pliers, can be similarly used by hand without -any slide rest. On the whole, then, it will hardly pay to give £50, -or £60, for a screw-cutting lathe that is merely destined for small -work; that can be done sufficiently well in a common lathe with -hand motion to the rest. For cutting short screws, such as those of -boxes, a convenient and practically useful contrivance is still a -desideratum. The traversing mandrel is, no doubt, the best, but it is -an expensive pattern, if well made, and it is necessary to sacrifice, -in a measure, general utility to questionable and certainly partial -advantage. Turning is, moreover, an art, and to attain skill in it, -perseverance and practice are necessary--hence the zest experienced -in its pursuit by the real lover of it. This perseverance pays, and -to attain the skill required to trace a short screw with the chasing -tool is within the reach of any one who desires to accomplish it. The -art once acquired, the desire for a traversing mandrel ceases; for -no good workman would accept a contrivance of the kind when he can -more easily and quickly accomplish his end without it. Writing this -for the special benefit of amateurs, we would strongly advise them -not to throw away money to purchase the means of doing what after -all they will probably never, and certainly only seldom, carry into -practice. The pleasure afforded by all the mechanical arts is greatly -enhanced by meeting with and triumphantly surmounting all sorts of -difficulties. Let it be a standing rule of our readers to make use -of the appliances at hand instead of seeking others which only save -trouble and render skill unnecessary. What can be more aggravating -than for an amateur, with his hundred guinea lathe and chests of -tools, to be obliged to take his work to a mechanic, and to see him, -whose whole stock might be bought with perhaps a tenth part of the -money, take in hand and finish with ease what has baffled the skill -of his more wealthy patron? The common fault of the amateur is undue -hurry. To him time is seldom an object, yet the mechanic, to whom it -is so precious, readily spends more upon his work. He never hurries, -never compromises, but with lathe and file fits the several parts of -his work with the most patient care and practised skill. The result is -at once seen when his productions are placed side by side with those -of the zealous but too hasty amateur. - -It remains, as previously described, to arrange certain cogwheels -gearing with each other upon the spindle of the mandrel and upon the -end of the screw, to enable the workman at pleasure to vary their -ratio of speed, in order to give him the means of regulating the -pitch of thread to be cut. For this purpose a set of change wheels is -supplied with the screw-cutting lathe, the number of cogs in which -usually commencing at fifteen, increase by five, until the number -one hundred and twenty is reached, then increasing by ten up to the -complete set. Duplicates of some numbers are also convenient. The -method of finding the proper sized wheels is, of course, based upon -the proportion borne by the required pitch to that of the leading -screw and one form of calculation for the purpose has already been -given. Thus, supposing the leading screw to have two threads to the -inch, it must revolve twice to move the tool that distance, and if -we wish to cut a screw of ten threads to the inch, the work on the -mandrel must revolve ten times while the leading screw revolves twice, -or, which is the same thing, the mandrel must revolve five times while -the screw revolves once. The cogs in the wheels must therefore be in -the proportion of five to one, say fifty on the screw and ten on the -mandrel, with an idle wheel on the stud to cause the motion of the -tool to be such as will cut a right-handed thread, or to cause the -mandrel and screw to take the same direction. Now, it seldom happens -that two wheels and an idle one will give the requisite speed to the -tool, and the number of cogs required soon mounts to inconvenient -numbers. In this case, therefore, according to a principle already -laid down, a stud-wheel with a pinion attached to the same, is -placed in the train of wheels, and the object readily attained. A -modification of the rule of calculation may make the system of change -wheels still clearer. Let the pitch of guide screw be as before, -namely, two threads to the inch, and let five be required. Place the -numbers thus, 2-5, and divide both into their factors, twice one, or 2 -× 1, and twice two and a half, or 2-1/2 × 2. - - 2 1 - -------- - 2-1/2..2 - -Now, it is certain you can have no wheels containing half notches, nor -of such small numbers of cogs, therefore multiply by any convenient -numbers--ten, for instance, which give - - 20..10 - ------. - 25..20 - -This is all that is needed. Put a wheel of twenty cogs on the -mandrel, and let it work into one of twenty-five on the stud, the -latter carrying a pinion of ten cogs, driving one of twenty cogs -on the screw. To prove this, as before, the screw must make two -revolutions to carry the tool one inch, and during that time the -mandrel (carrying screws to be cut) must make five revolutions. Let -the screw wheel revolve twice, the pinion of ten teeth will revolve -four times (twice 20 = 40 and four times 10 = 40); but as the stud -wheel and pinion are as one, and revolve together, the stud wheel -must also revolve four times (4 × 25 = 100). Thus the mandrel wheel -will revolve five times as required (20 × 5 = 100). No other method -is so easy to understand and work as the above. To give full details -and provide working drawings of the various screw cutting lathes -by different makers would be to extend the present series to an -unnecessary limit, but we shall nevertheless describe another method -by which these lathes with traversing rests are made self-acting when -screw cutting is not required. Instead of a leading screw extending -from one end of the lathe to the other, there extends a bar of steel -about the diameter of the screw with a key groove or slot from end -to end. This bar is supported in bearings at each end, and carries -upon its surface a ferrule of steel with a screw cut upon its outside -similar to Fig. 174, where A is the bar and B the ferrule. The pitch -of screw is coarse, being similar in its object to the guide screw -previously described. A pin fixed into this ferrule falling into the -slot permits it to travel along the bar but causes both to revolve -together when the bar is put in motion by means of a cog wheel or -strap pulley at one end. Along the same side of the lathe bed, and -level with the surface, is a rack, C, upon the face of which works a -pinion, D, carrying on the same axis a cog or rather worm wheel, E, -to gear with the screw ferrule. The bearings of this axis are secured -to the saddle of the slide rest. Consequently, when the bar revolves, -the screw is also put in motion, the wheel, A, Fig. 175, and pinion, -B, partake of the movement, and the latter traverses the face of the -rack, carrying the saddle with its rest and tool holder along the bed -of the lathe. By this movement the screw ferrule traverses the bar as -it revolves, thereby virtually becoming a long leading screw. In Fig. -176, which is a view from above, looking down upon the lathe bed, A -is the rack, B, B, the saddle cut away to show the rack and pinion C; -E is the worm wheel, D the long bar, the screw ferrule, being under -the worm wheel, is not visible. As above arranged it is evident that -the ferrule might escape from the worm wheel instead of proceeding on -its proper course. This is prevented by its lying in the hollow of -a bracket attached to the rest, as Fig. 177, A and B. This retains -it in contact with the worm wheel, and also becomes a support to -the long bar. Fig. 174 shows the side of the lathe that is furthest -from the operator. The axle of the worm wheel and pinion carries a -handle on the near side to give the workman power to use the rack by -hand as a quick return movement. The above is frequently attached to -those lathes provided with a long screw, the latter being on the near -side and the bar on the other. Thus, the same lathe can be used for -ordinary or screwed work. Whitworth, however, commonly uses the long -screw placed between the beds or bearers of the lathe for screwing -and surfacing, instead of adding the apparatus just described. A long -screw being, however, an expensive affair, ought to be carefully -cherished, and when the work is such as the bar will suffice to -accomplish, it may be well made use of to preserve the screw. There is -an arrangement for forward or cross-feed in the above apparatus, the -principle of which is the connection of the cross screw of the rest -by means of a pinion, either with the worm wheel or with a cogwheel -on the same axle. When this is put into gear the rack and pinion are -disconnected. It is also necessary to provide a method of reversing -the motion of the long screw bar, especially when the cross feed is -used in surfacing. There are several modes of accomplishing this, -the best being the following, Fig. 178, which is a simple expedient -applicable to lathes or other machines. A is the end of the screw rod, -with bevel wheel attached, B, C, are similar wheels on the axle, D, -the latter being movable endwise in its bearings by means of the lever -handle; E, D, is the driving axle. By moving the lever to the right -B is geared to A. A movement to the left brings C into connection. -Between the two, both wheels are thrown out of gear, and though they -may continue to revolve, the screw bar will remain still. By this -contrivance the motion of the leading screw is reversed or stopped -in a second, with the advantage of its being unnecessary at the same -time to stop the working of the lathe altogether. It has probably -struck the reader that as the size of the change wheels are various, -there would be in some cases an impossibility of their touching so -as to gear together. This is partly remedied by the interposition of -dummies, or idle wheels, and partly by the following arrangement. The -stud wheel, or dummies, as the case may be, are not upon axles fixed -to the lathe-head or end standard, but upon such an arm as Fig. 179, -which turns upon a pin at A, and carries in the slot the pins upon -which the different wheels centre. These pins being made similar to B, -C, can be placed at any position in this slot, and are fixed by a nut -underneath. This arrangement gives considerable power of adjustment, -and enables the workman to place together wheels of various sizes -according to his need. It would not be by any means difficult to -arrange the above lathe for screw-cutting, especially if the pitch -of the required screw is not of great importance. An amateur's lathe -might be thus fitted to serve a good many purposes, although a leading -screw is to be preferred as the more complete and perfect arrangement. -It cannot, however, be denied that there is great friction produced -by the worm wheel and endless screw, which soon tells its own tale by -the wear and tear produced, and the power is not so economically used -as it is when the screw works in a nut. Expediency, however, in this, -as in many similar cases, must decide for or against the arrangement -in any particular case. It is, at any rate, a good addition to a -lathe provided with an ordinary leading screw, more especially in the -facility with which it can be arranged as a self-acting cross-feed to -the rest when used for surfacing. - - [Illustration: FIG. 172.] - - [Illustration: FIG. 173.] - - [Illustration: FIG. 174.] - - [Illustration: FIG. 175.] - - [Illustration: FIG. 177.] - - [Illustration: FIG. 176.] - - [Illustration: FIG. 178.] - - [Illustration: FIG. 179.] - - - WHEEL CUTTING IN THE LATHE. - -Among the various uses to which a lathe may be put, wheel-cutting -is one of the most important, so many pieces of mechanism requiring -cogged wheels of various pitches and forms of tooth. By the aid of -the slide rest such an apparatus as figured may be readily arranged, -and the work rapidly and accurately performed. The guide by which the -cogs and spaces are determined is the division plate already alluded -to, and which is not visible in the present drawing, but the index of -which is shown at G. C is the cutter frame with a side pulley (one on -each side) to conduct the catgut band from the revolving spindle to -the overhead motion on to the flywheel. The spindle carries a pulley -for the cord and a cutter wheel, I, to which an exceedingly rapid -evolution is given. There are many patterns of these wheels, the edges -of which, cut into teeth like a fine saw or file, are the exact form -of the spaces required between the cogs; hence, some are rectangular, -some have a triangular section. The thicker the wheel to be cut the -larger should be the cutter, so that the bottom of the cut may be -virtually level. In Fig. 181 another form of cutter is shown, which -if put into sufficiently rapid motion answers as well, if not better, -than the wheel-shaped cutters. It is a simple short bar of hard steel, -with the edges bevelled in alternate directions, fitted into a slot -in the spindle and held by a wedge or screw. The shape of the end is -as before, a cross section of the space between two teeth. The cutter -frame is here arranged to fit into the ordinary tool-holder of the -slide rest, but the form may, of course, be varied at pleasure. It -will be noticed that the slide rest, as delineated here, is different -to that of which details have been given. It is made without the sole, -and fits into the socket of an ordinary rest. Thus it can be turned -on a centre, and becomes, to all intents and purposes, a compound -slide rest. It is on this plan the small ornamental turning rest of -lighter construction is made. The spindle fitting the socket projects -from the centre of the lowest frame, and is cast in one piece with it. -If the apparatus is compactly and strongly made, it becomes a very -serviceable form, and is much used for the small lathes in sea-going -steamers. The sides are made very short, so that the extent of -traverse is small. We may here mention an addition to the rest socket, -enabling the workman to raise this kind, or that used with drills and -cutters, which is simple and convenient. Inside the iron socket a few -turns of a screw are cut, and a second socket of brass with an outside -thread is made to fit into it Figs. 182 A and B, the latter being a -section. The edge of the inside socket is sometimes milled round, to -facilitate holding it by the thumb and finger. In this way the height -of the slide rest, or tee of the common rest, is adjustable to a great -nicety. - - [Illustration: FIG. 180.] - - [Illustration: FIG. 181.] - - [Illustration: FIG. 182.] - -When a wheel is to be cut of large size, or of substance exceeding -that of clock-wheel work, the above method is not suitable. The wheel -is then generally laid flat, and the cogs are shaped by a slotting -machine, the chisel of which has a vertical motion. The lathe is -then no longer used; as a separate machine is more convenient and -economical. - -A most serviceable addition to a lathe, especially an amateur's foot -lathe, is the circular saw, with guides for cutting parallel, taper, -or mitred work. Great rapidity of work is thus combined with perfect -accuracy. A five-inch lathe will of course take a saw nearly ten -inches diameter, but it is not advisable to attach one of quite this -size, for the larger the saw the greater is the leverage against which -the turner has to contend, and the friction caused by a deep cut in -stuff of two inches diameter is quite sufficient to make the labour -considerable. When such work is necessary, it must be very gently -brought to bear upon the saw, and the flywheel of the lathe should -be heavy. The cord should also pass from the latter to the slowest -division of the pulley. If the workman, amateur or professional, -desires a lesson in practical mechanics, he has nothing to do but turn -a piece of ash six inches in diameter, with the lathe-cord extending -from the flywheel to the smallest part of the pulley, the diameter of -which is about half that of the object to be turned. This will teach -him what hard work is. Then let him try the job with the cord, from -the smallest part of the flywheel rim, to the largest diameter of -pulley. The change to a slower motion and greater power will not be -disagreeable. It must be remembered that a circular saw of six inches -diameter will not penetrate three-inch stuff, owing to the boss or -nut by which it is attached to its spindle. The above size will not -make good work of stuff exceeding two inches in thickness, and even -less thickness would be preferable. As to the size of saw, indeed, -that is most suitable to a five or six-inch foot lathe, much depends -upon the proposed work, and still more upon the weight and size of -the flywheel. As a general rule it is better to err upon the size -of smallness. The service to which this tool is commonly put is but -light; sawing narrow strips of mahogany, such as used at the angles -of bird-cages, cutting strips or segments of ivory (for which let the -saw be kept wet) sawing out mitred or dovetailed joints, and similar -work is within the compass of a five or six inch saw, and it is better -not to exceed this. The teeth should be tolerably fine for hardwood -and ivory, and coarser for deal and soft woods. Smaller saws of hard -steel, and made of thick plate, are used for metal. - -The method of mounting saws of small size, such as are suited to be -worked by the treadle of a foot-lathe, is shown in Fig. 183. E is -a steel spindle, of which the diameter equals that of the central -hole in the saw B. At F, about the middle of the spindle, is a fixed -flange, at the base of which is a short feather or inlaid key, X 184, -which fits the small slot seen in the centre of the saw and reaches -also within a similar slot in the movable flange, G, but it must not -be so long as to come through to the back of the latter. This flange -and nut H having been removed, the saw is slid upon the spindle till -it rests against the fixed flange; the movable one is now to be -brought against it and clamped by the nut. The spindle is sometimes -made with a square end to fit the square hole chuck, and centred at -the other, or it is drilled at both ends, so as to be driven by the -carrier or driver chuck, C, D. It must be so placed as to run towards -the operator. The above arrangement must now be made complete by -the addition of a platform, B, on which to lay the work that is to -be sawn, and on which some contrivance can be adjusted to guide the -passage of the saw through the same, so as to cut the work in parallel -pieces, or at any desired angle, such as would be necessary for mitred -joints. For the general uses of the amateur a mahogany or hardwood -platform is as good as any, and such as is delineated in vol. ii. -of Holtzapffel's valuable work is perhaps the best arrangement. The -saw table rests on the opposite ends of a kind of open box, which -is represented without the two sides, although they may be added if -desired, and the whole when removed from the lathe would then form a -case for the saws, or serve other similar purpose. The platform is -hinged, so as to overlap, as seen in the Fig. 184A, and there -is in the middle of it a slit cut by the saw itself, which, when it -is mounted on its centres will be in the position shown. If sides are -added a notch must be made in the upper edge of both for the passage -of the spindle. The fillet B fits between the bearers of the lathe, -securing the parallelism of the whole. When made with four sides the -box must first be placed on the lathe bed and loosely held by the bolt -beneath. The saw is then mounted, and the box adjusted to its place -and fixed. The cover is then (if for the first time) brought carefully -down upon the saw, and the lathe being put in motion the slit is made, -and its position will be truly at right angles with the spindle and -the lathe bed. Of course, in future operations the platform is lowered -over the saw before the holding down bolt is permanently screwed -up. The sides of the saw-kerf may be edged with brass if preferred, -but on the whole the plan is not to be recommended, for if, as will -occasionally happen, the saw should get slightly out of truth, or -vibrate a little when in use, the teeth will come into contact with -the metal and be blunted or broken. If the saw-kerf by constant wear -should widen too much, the whole platform is renewable at little -cost, or a new piece can be let in, and a fresh saw-kerf made. There -are several guides for parallel work. The one shown in Fig. 185 is -precisely such as is to be seen in the ordinary parallel ruler--A is -the back bar screwed to the platform at the right-hand edge; B the -guide or fence which, when the connecting links C, C are perpendicular -to A, should touch the saw; D, D are arcs of circles of which E, E -are the centres. They may be arcs of brass pivoted to the links and -passing through a slot in the bar, A, A, or may themselves be cut as -mortises in the platform, in which fit a pair of bolts with thumb-nuts -passing through the links, by which to clamp the fence in any desired -position. This form of parallel guide is not very substantial, and is -not correct in practice unless the pins are very nicely fitted, and -the links precisely of a length. The second figure shows the sectional -form of the fence G, the links being represented at H, and the fixed -bar at K. The following is a more solid and unyielding guide, and -much to be preferred. Holtzapffel attributes it to Professor Willis. -It is merely a modification of the T-square as used with the ordinary -drawing board with an arrangement for fixing it in the required -position. The present arrangement differs from that in Holtzapffel's -work in the manner of fixing it and the addition of a second T-piece -on the side next the workman. In Fig. 186 A is the upright part of -the fence, B the bottom or sole, to which is attached at each end -the T or cross pieces, E, E, which slide along the straight edges of -the platform and secure the constant parallelism of the fence to the -surface of the saw; C is the groove or slot, in which a screw, D, -traverses, and the fence is thus fixed by a turn of the thumb-nut, -D. This fence can by no possibility get out of truth; it is easily -removed by taking out the single screw, and it is far more simple and -more easily made than the one previously described. The nearest edge -of the platform may be marked in inches and eighths, and the fence -can then be instantaneously adjusted for sawing pieces of any desired -width. It is not always, however, that straight, rectangular, or -parallel strips are required, and an additional arrangement is needed -to form a guide for sawing angular pieces. Now it is not sufficient to -lay the guide fence at a given angle, for if the latter were arranged -for that adjustment by taking off the tees and causing it to turn -upon the screw which secures it in place, and a piece of board were -placed against it to be sawn, the latter would press against the saw -sideways as seen in Fig. 187. The guide fence for angles must itself -therefore travel in a line parallel to the saw and carry with it the -piece to be cut. The simplest and usual arrangement is that given -in Holtzapffel's work. A dovetailed groove in the platform running -in a direction parallel with the saw carries a sector attached to a -bar which fits the groove, and this bar is free to move forward or -backward without lateral movement. The piece to be sawn is thus rested -against the fence forming the straight face of the sector, and the -whole is moved forward together against the edge of the saw. Fig. 188 -explains this. It will be seen that several grooves are made side -by side, all of which fit the slide alike, and by moving the latter -into either of these a lateral adjustment is effected to suit pieces -of different widths. The sliding strip should be made of hard wood -and nicely fitted, and may be lubricated with soap, or polished with -black lead, either of which will cause it to slide with diminished -friction. Fig. 189 shows a somewhat different arrangement, by which -more lateral adjustment may be given. The sector is replaced by a -T-square, the blade of which has a slot through which a screw passes -into the sliding bar. A second jointed rod is added, passing through -a staple in the slide, and by a screw in the latter the T is fixed as -required. The staple must turn on a centre to accommodate itself to -all positions of the T-square, and a second eye may be placed on the -opposite arm to allow the guide rod to be removed to that side, which -is sometimes more convenient. The sector also may be made adjustable -as in Fig. 190, and clamped by a simple screw in the slot. Either of -the above methods will allow sufficient range for small work, such as -is likely to be the object of amateurs or those who add small saws to -the foot lathe. The guide for angular pieces may indeed be in many -cases dispensed with by making use of patterns of wood chiefly in -the form of triangles; these sliding against the parallel guide, and -carrying the work with them, will answer well in a number of cases -where other provision for such work has not been made in arranging -the saw table. It must be remembered, however, that in this case the -length of the piece (supposing it to be the side of a picture frame -to be mitred) is limited to the space between the fence and the saw, -which in the more perfect arrangement is an evil plainly avoided. -It may sometimes be necessary to cut pieces with various angles not -in the same plane. By using the hinged platform, and adding a screw -attached to the front of the box, and standing perpendicularly, the -front of the table can be raised to a given angle, but those who are -likely to enter extensively into the cutting mathematical figures -are referred to vol. ii. of Holtzapffel's work, where the subject is -fully explained and illustrated. The following remarks upon the proper -speed of saws and sizes of teeth are copied from that work, and may -therefore be relied on:-- - - "The harder the wood the smaller and more upright should be the - teeth, and the less the velocity of the saw. - - "In cutting with the grain the teeth should be coarse and - inclined, so as rather to remove shreds than sawdust. - - "In cutting across the grain the teeth should be finer and more - upright, and the velocity greater, so that each fibre may be cut - by the passage of some few of the consecutive teeth rather than - be torn asunder by the passage of one tooth only. - - "For gummy or resinous woods and ivory, the saw teeth must - be keen, and the speed comparatively slow, to avoid the - dust becoming adhesive (by reason of the heat engendered by - friction), and thus sticking to, and impeding the action of the - saw." - - [Illustration: FIG. 183.] - - [Illustration: FIG. 184.] - - [Illustration: FIG. 184.] - - [Illustration: FIG. 185.] - - [Illustration: FIG. 184A.] - - [Illustration: FIG. 186.] - - [Illustration: FIG. 187.] - - [Illustration: FIG. 188.] - - [Illustration: FIG. 189.] - - [Illustration: FIG. 190.] - -By raising the platform so as only to expose a small portion of the -saw, it is easy to cut rebates, grooves for tongueing, and other work -of a similar kind. The above arrangement of hinged table facilitates -this application of the saw. - - - FRET SAWS TO MOUNT UPON THE LATHE BED. - -Convenient as the circular saw is when fitted as an adjunct to the -lathe, its use is confined to pieces which are rectilineal. Curved -lines cannot be cut by its means, and as it must frequently happen -that portions of the proposed work are composed of arcs of various -dimensions, it becomes necessary to provide the means of cutting them -out. We may remark here, that although the circular saw, and that of -which we are about to speak may be fitted to mount on the ordinary -lathe bed; it is better for many reasons to have a separate stand, -made like that of the lathe, but smaller, and fitted with crank, -treadle, and flywheel, to serve for the various purposes of sawing, -grinding, or polishing; the latter operations especially soiling and -tending to damage the lathe. The above description of the methods of -mounting circular saws will answer for a separate stand, as will the -following details of saws for curvilinear work. In respect of the -latter we have to provide for the perpendicular motion of the blade, -which is necessarily thin and narrow, and also for stretching the -blade so as effectually to prevent it from bending or buckling--guides -are not required in general, as the work is moved about by hand in all -directions according to the intricacies of pattern to be traced. For -plain circular pieces, however, a very simple expedient is sometimes -used, which will be described in its proper place, when treating -of Bergeron's _scie mecanique_. The guides for parallel motion are -various, and a selection may be made from the following Fig. 191. -No. 1 is the arrangement used by Professor Willis, and detailed in -Holtzapffel's work. A, A are wooden springs, one above, the other -below the platform B. C is a guide pulley, D an eccentric. The catgut -band which gives motion to the saw may be passed round this, or -affixed to a metal ring as in the eccentric of a steam engine--or -may be attached to a ring slipped over the pin of a crank disc, as -shown at E. This pin being adjustable, permits the traverse of the -saw to be regulated, which gives it perhaps an advantage over the -first method. In the above the motion of the saw is not truly in a -right line, but the deviation in so short a traverse is unimportant. -The reader may, perhaps, imagine wooden springs a somewhat primitive -expedient, but this is by no means the case, as they will retain their -elasticity longer than metal ones when they are subjected to the -rapid vibration which they are called upon to undergo. No. 2 is the -parallel guide, used by Mr. Lund, and also described by Holtzapffel; -the metal springs, however, shown by the latter being here replaced -by india-rubber, which is now formed into springs of various sizes and -powers suitable for our present and many similar purposes. A, A, and -D, here form guide pulleys, the saw, E, being suspended from the first -by the two catgut bands, on the ends of which are the india-rubber -springs, F, F. The lower end of the saw is attached to another catgut -band which passes over the pulley, D, and thence to the eccentric -or crank disc as before. The platform is at B, B. Number 3 is an -arrangement similar to the beam of Newcomen's engines. The arc at -the end of the oscillating rod, and from the furthest point of which -the saw is suspended, forms the guide for parallelism. Underneath -the platform the pulley and eccentric may be used as before, and the -saw is raised by the spring attached to the arc as shown. It will be -evident on inspection that this arrangement is similar in principal to -the last, as the arc forms part of a large wheel of which the centre -is the point of oscillation. Watt's parallel motion, represented -in the next diagram, is also suitable, the saw being attached to -the centre of the short link--the springs being so contrived as to -act upon the ends of the longer bars. With regard to the means of -producing the necessary rapidity of movement, the above-described -eccentric or crank disc can hardly be surpassed. In the saw patented -lately by Mr. Cunningham, the disc is attached to the mandrel like a -chuck, and the crank pin is connected to the oscillating rods that -carry the saw by an intervening rod or link. - - [Illustration: FIG. 191. N^o 1.] - - [Illustration: No. 2.] - - [Illustration: No. 3.] - - [Illustration: No. 4.] - - [Illustration: FIG. 192.] - -The whole is represented in Fig. 192, which is copied from the -inventor's circular. There is a satisfactory parallel motion, and -an india-rubber ball with a small tube attached is pressed at every -stroke to blow away the sawdust. The whole plan and details are as -good probably as can be devised, and as an addition to the lathe this -saw is invaluable. Another form of mechanical saw to work with the -foot, but without any flywheel, is figured by Bergeron, and is thence -copied into Holtzapffel's book, and would therefore have been omitted -here were it not that the price of Holtzapffel's work places it beyond -the reach of many whom it is specially qualified to instruct; and that -the former is in French and has not been translated. Therefore, as the -arrangement of saw is exceedingly good, the writer has determined to -introduce it here. Its construction is simple enough to be within the -reach of any amateur in carpentry, and the only metal work required -consists of a few iron rods screwed at the ends, such as the village -blacksmith can readily supply. The saws are precisely those sold as -turn or web-saw blades. It must be understood that the use of this -tool is not the same as that to which fret or buhl saws are applied, -but merely the cutting of boards in strips or curved pieces, such as -the felloes of small wheels, circular plates to be finished in the -lathe, as bread platters, or such other curvilinear works as the chair -or pattern maker is accustomed to cut out with the several sizes of -frame saws. - -A, B, Fig. 193, is a stout bench with cross bar, C, underneath, cut -away to allow of the movement of the treadle and its rod. On the top -of the bench is a pillar, D, to support the spring bow E, by which -after depression the saw is raised to its original position. F, F, and -G, G, are guide rods (not continuous). The lower ones are fixed to the -cross bar, _c_, and under side of the bench. The upper form the sides -of a rectangular frame, H, H, of which the top and bottom bars of wood -are dovetailed at the back to slide up and down the chamfered bar -behind them, K. The frame thus allows of being raised or lowered, not -only to suit work of various thicknesses, but also to act as a stop to -prevent the saw from lifting the work as it ascends. The lower bar -is extended on one side as in the figure, and is divided into inches, -and on this graduated part is a slide with a point below, which can -be fixed by a screw. This is, as the drawing plainly shows, intended -for the guidance of the wood in cutting circular pieces. The saw is -similar to the ordinary framed saw used by chair makers, but has two -blades, and one central stretcher. The saw for curved work is narrow, -that for straight cutting is broader. Near the latter a parallel -guide is fixed, as described when treating of circular saws. This -simple contrivance, although planned so many years ago, is of great -value, and deserves to be far more generally known. To the joiner and -cabinet-maker it would form a most useful addition to the usual tools -of the workshop. - - [Illustration: FIG. 193.] - -Akin to the circular saw are the various revolving cutters used either -for the purpose of ornamentation or for grinding, such as circular -files for flat surfaces, in which the teeth are cut upon the face or -tool-cutters of particular sections for cutting the teeth of wheels, -in the manner already described, to which may perhaps be added milling -and embossing tools, although the action of the latter is rather that -of a revolving die by which the work is stamped or indented with the -pattern formed upon the edge of the cutter. The small grindstones and -emery laps belong also to this section, as their action results from -the abrasion of the material by means of the combined cutting power of -innumerable small points or miniature teeth formed by the particles of -emery or other material attached to the surface of the laps. - -Most of the steel cutters may be made by the amateur, the metal -being turned to the required shape and the teeth cut by small files -or punches while the material is in a soft state. The little discs -are then hardened and mounted, by a central hole previously made, on -suitable spindles, the latter being either attached at one end to -the mandrel as arbor chucks, or centred at both ends and driven like -miniature circular saws. The ornamental cutters for embossing, Fig. -193B, A and B, are turned to the form of short cylinders, -and the patterns cut by punches. These and the milling tools are -mounted alike, Fig. 194. The rest is placed a short distance from the -work, and the tool revolves against it. Some pressure is necessary to -imprint the design, and this is easily obtained if the cutter wheel -is placed so as to attack the work below the axis; the rest then -becomes a fulcrum, and the shank and handle of the tool acting as the -long arm of a lever supply the required force with little exertion -on the part of the operator. In this way the milling is done on the -edges of screw heads, and the embossed patterns on soft wood boxes. -It is not easy to understand how the patterns in these cases are -produced clearly without one part cutting into and effacing another, -unless the size of the work is exactly a multiple of that of the -tool. The error is plain if the work is stopped exactly at the end -of the first turn, but in successive revolutions this error becomes -gradually obliterated, and the pattern is eventually impressed clear -and well defined. The same shank is arranged for different patterns -of wheel-cutters, as the pin which forms the central axis is readily -withdrawn and is made to suit the holes in several sets of discs. - - [Illustration: Fig. 193B.] - - [Illustration: Fig. 194.] - - [Illustration: Fig. 195.] - -By the aid of the above simple tool a neat finish is readily given -to many small works in wood and metal. A modification of the beading -tools is here shown very similar to the screwing guide already -given, but made with figured instead of sharp-cutting edge. This was -communicated to the _English Mechanic_, Nov. 2, 1866. E, 195, is the -guide which is placed on the handle A, B, C, D, and fixed by screw F. -The mark _i_, on the guide, is placed against the rim, A, B, which is -graduated and numbered. Each figure, as it is brought up and placed -opposite _i_, will cut a different pattern when the guide is fixed. -The tool must be held very firmly on the rest (the bottom of the guide -G, H, being flat, is carried on the rest), the tool is advanced to -the wood. The tool must be worked very steadily; but with a little -practice, any amateur will soon use it perfectly, and produce many -very pretty patterns. It is evident that provision is here made for -placing the cutter at different angles to the work, by which means -the circles of patterns may be traced spirally and in other positions -varying from the ordinary one at right angles to the axis of the work. - -The laps alluded to, which are to be mounted on spindles like the -circular saw, are composed of wood and metal of determinate forms. -First, there is the thin sheet-iron slitting wheel used by lapidaries, -and which, when charged with emery, or sand and water, forms the -nearest approach to the circular saw. It _is_, in fact, the circular -saw of the stone worker, the ordinary saw used in their trade being a -flat blade without teeth, stretched in a wooden frame and similarly -fed with sharp sand and water in lieu of being made with teeth, the -latter being replaced by the grittiness of the material. The circular -plate of iron, brass, or lead alloyed with antimony, mounted on a -spindle vertically, is used in a similar manner for grinding flat -surfaces with the aid of emery, crocus, oilstone powder, and other -substances, and the same is used edgewise for other work, as grinding -and polishing tools, the section of the lap being such as will form -the article required by reproduction of the revised plan of its own -edge. Thus a lap running horizontally with a convex edge will produce -the concave form required in beading tools, the latter, however, are -more conveniently ground on brass cones mounted like the arbor chucks -used for turning washers, rings, &c. The face of the tool or flat side -is held towards the small end of the cone, and the latter is armed -with flour emery. See Fig. 196. - - [Illustration: Fig. 196.] - -Before describing the eccentric and other compound chucks, a few -examples will be given of the method of turning some of those forms -in which the circle does not appear, where, in short, the boundaries -of the figures are straight lines. It seems at first sight impossible -to produce in the lathe by any simple means such solids as are formed -from squares or triangles, of which the cube or die is the most common -and most generally understood. This can, however, be accomplished, -and a number of mathematical problems may be clearly demonstrated to -the eye by such works skilfully made in the lathe. In this kind of -work it is absolutely necessary to strive after perfection. In short, -as Bergeron rightly says, the work imperfectly done is simply worth -nothing at all; but when accomplished with exactness, nothing can be -more worthy of a place in a cabinet of curiosities. The usual method -of turning a cube is by shaping it out of a perfect sphere, but as the -latter can hardly be made without a special slide rest made for the -purpose, a method of turning the cube by hand alone will be given, -the foundation of it being that which the lathe so readily produces, -namely, a cylinder. By far the most proper material for the work in -question is sound boxwood, and special care is to be taken to keep all -angles as sharp as possible, and therefore to cut clean with sharp -tools, and to avoid as far as possible the use of sand or glass paper. -Fig. 197 shows a square described in a circle. The non-mathematical -reader may be told to draw through the centre two diameters at right -angles to each other, and to complete the square, as in the figure, -by joining the extremities. The largest square that is possible to -be drawn in the circle is thus described. This square will form one -face of the cube, and the diameter of the piece of wood must be -regulated according to the proposed size of the finished work. It is -evident that this diameter is equal to the line drawn from corner -to corner called the diagonal of the square. Now, in turning a ball -or sphere, a cylinder would be turned of the exact length of A, C, -because every measurement taken on a diameter of the sphere would -be of that length. In the present case, however, the cylinder must -be of the same length as the line A, B. Turn, therefore, with great -care a cylinder of any desired size, gauging it carefully with the -callipers and squaring off the ends truly. On one end, in which the -centre point just remains visible, draw diameters and construct the -figure 197. Turn out a chuck to fit it exactly, and let the bottom -of this chuck be truly square. Take the precise length of the line -A, B, with finely pointed compasses that can be fixed with a screw, -and measure off the same, and mark it on the side of the cylinder. -When the figure is placed on the chuck, a mark must be traced round -it at this point, A, B, Fig. 198, _and this must remain to the end_. -It may be made with a hard pencil or steel scriber, and, though -distinct, must be very fine. It is at this line the wood will have -to be cut off, but in this operation keep beyond it so as not to -erase it. While the piece is in the chuck, rule lines, as E, G, from -the points C, D, E, F, 198. Bisect also the length of the cylinder -by the line, H, K, also finely drawn. Draw two more diameters, as -shown by the dotted lines bisecting the sides of the cylinder, which -is now divided round its circumference into eight equal parts. The -lines, E, G, &c., can be ruled along the edge of the rest, or, if the -latter is untrue, the cylinder may be laid on a plane surface, and -a scribing block, or gauge, Fig. 199, may be drawn across it, or, -lastly, a small steel square may be used; one part being carefully -placed on the lines at the end of the piece in succession, the other -part will lie evenly along the side, and will form a ruler by which -to work. A division plate on the lathe pulley will facilitate the -above measurements, but they can be readily made without it, and once -carefully marked, all the guides required for cutting out the cube -will be complete, and the work can be proceeded with, with confidence -and decision. Proceed, therefore, to cut off the piece at A, B, with -a parting tool, but with the precaution already named of not erasing -the line by so doing. Now prepare a chuck which will take the piece -lengthwise, Fig. 199-2, and insert it in that position to the depth -of the diameter so as to hold it securely, and the central line will -show whether it lies evenly (which is, in fact, the use of this -line). If even, a point-tool held on this line will form a mere dot -upon it; if uneven, it will make a circle as it revolves. Place the -rest across the face of the work, and, beginning at the centre, cut -carefully towards the outside until you have cut away the wood as far -as the line, A, B. You will thus complete one face of the cube, and -an inspection of the end of the piece, shown black in the sketch to -show the quantity removed, will prove that you thus produce a right -line, C, D. Take out the work, and reverse it, and operate similarly -on the opposite face; but in every case do not quite obliterate the -lines first marked as guides. You have now a piece shaped like Fig. -200, A and B, and must make a smaller chuck to hold it; you have then -to cut away in a similar manner the remaining parts of the cylindrical -portion, and the cube will be complete. To finish the sides more -neatly, lay upon the table the finest sand paper, and tack it at the -corners, and with gentle movements work down precisely to the guide -lines. This requires extreme care, for if once the piece is but in -the slightest degree tilted up, an angle will lose its sharpness, and -the beauty of the work will be marred. Hence we recommend to cut with -sharp tools, instead of trusting to the finishing process. To cut, -however, _exactly_ to the line is very delicate work, and to the less -practised hand the use of the sand paper on the faces in succession -may be the _necessary_ expedient. The main secret of sharp edges in -works of wood and metal is to finish with hard substances, as emery -stick or glass paper glued to a piece of wood, or the same nailed on -the bench, and to try always to work on the centre, leaving the edges -or angles to take care of themselves. When the reader has made a cube, -as above, that will bear delicate measurement, he will be more than -usually gratified, and will be qualified for still more difficult -work. A chuck figured by Bergeron, Fig. 201, is very convenient, as -it holds the work truly central; the jaws work simultaneously by a -right and left-handed screw as in the die chuck. It is, however, -perfectly easy to do good work without it, but the chucks should -be carefully made, turned very flat at the bottom, with side truly -perpendicular. A little extra care bestowed upon chucks will save -many disappointments, and conduce to good work. The formation of a -four-sided solid, consisting of triangles solely, in the lathe is a -work of difficulty, owing to the impossibility of fixing the work -satisfactorily in an ordinary chuck. The natural way to form such a -solid is to turn a cone A, B, Fig. 202, and on its base to mark a -triangle of the required size. It is then necessary to place the cone -in a chuck, so that the ends of one of the lines thus marked and the -apex of the cone are precisely level with the surface of the chuck, as -shown in Fig. 203. But it is evident that adequate support is not thus -obtainable. The apex of the cone cannot, in point of fact, be inside -the chuck at all, as it is necessary to cut clean to its extremity, -and even the base of the cone is imperfectly held at two points. -Hence it becomes necessary to make use of "turner's cement," and to -imbed the work fairly in it, while both are warm, to such a depth as -will hold it securely and still allow the guide lines to be seen. -The latter should be carried from the three angles of the triangle -marked on the base to the apex. On the whole, this is the easiest -method of fixing such work in the lathe; and if the piece is itself -warmed before being placed, there will be time to adjust it precisely -before the cement is cold. To do this, place the rest parallel to the -lathe bed, hold a pointed tool steadily upon it, and note whether, -as the work slowly revolves, the three points in question, viz., -the two angles of the triangle and the top of the cone, are in one -plane. When they are so placed, the rest is turned to face the work, -and the material is carefully cut away till the gauge lines are just -reached.[14] A pyramidical solid with a square base may be similarly -turned. The following is the method of preparing the above turner's -cement:--Burgundy pitch, 2 lb.; yellow wax, 2 oz. Melt together in a -pipkin, and stir in 2 lb. of Spanish white. When the whole is well -mixed, pour it out on a marble slab and roll it into sticks. Fine -brickdust, whiteing, or any similar substance finely pulverised, will -answer equally well to add to the pitch and beeswax. This cement is -very useful, as it will hold the work firm enough to turn carefully, -and nevertheless a slight blow will loosen it. To clean it off, warm -or dip the work in hot water and wipe quickly with a piece of cloth. -The above is from the "Handbook of Turning," the author of which has -copied from Bergeron both the recipes given in his work; the one here -described is stated to be specially serviceable in cold weather. It -is perhaps rather less brittle than the first of Bergeron's, and for -this cause is the best for general use. Holtzapffel sells this at -one shilling the stick, which is of convenient size and generally of -excellent quality. Bergeron gives a method of turning pilasters or -balustrades, which is of great ingenuity, and applicable to work of -various sections. The rectangular and triangular sections illustrated -are not, indeed, strictly rectilineal figures, as the sides of the -balustrades thus formed are not flat but rounded surfaces; they are, -however, sufficiently curious, and when well turned are interesting -specimens of lathe work. Bergeron's description relates to the pole -lathe, or to work mounted between two centres with a pulley cut on -the work itself to receive the lathe cord. The ordinary method of -mounting on a foot-lathe will, of course, be much better and the whole -operation of more easy performance. Let it be required to turn a -moulded pillar or balustrade of the section Fig. 204, viz., a triangle -with slightly curved sides. A piece of wood of the requisite length -is planed up accurately to a triangular form, or, as it generally -happens that a set of such pilasters are required, a number of such -pieces are prepared which must be accurately planed to the same size, -for which purpose a gauge or template, Fig. 205, should be made -use of. Six or eight of these, if not too large, may be operated -upon at the same time; but as six pieces of two inches across each -face require a cylinder of about eight inches diameter, the number -must depend on height of centres. The larger the cylinder, however -(which, in fact, forms a chuck), the more nearly will the sides of -the finished work approach to plane surfaces, as they will form arcs -of a larger circle. Let a cylinder, then, be turned of sound wood -with a reduced part at one end so as to form a shoulder. Divide the -circumference into twice as many equal parts as there are pieces to -be turned, the divisions being equal to one of the sides of these -pieces as measured in a cross section. These divisions are to mark the -positions of the grooves or channels in which the triangular strips -are destined to lie. Half the circumference will be so cut out, the -alternate divisions being left. Thus, to turn four pieces, each two -inches wide, a cylinder of sixteen inches will be required, affording -four grooves two inches wide, and four intermediate pieces forming the -partitions between the grooves. The latter must, by means of the saw -and chisel or other tools, be made to receive the strips exactly, and -the ends of the latter being carefully squared off, are to be made -to rest against the plate C, Fig. 206, which is cut out and screwed -against the shoulder, after the above-mentioned grooves have been cut. -The whole are then secured by two rings, with screws. Probably the -stoutest india-rubber rings now made would answer as well as the iron -clamps in Bergeron's description. Lay the strips in their places, but -as they are flat they will not form part of the cylindrical surface, -but will lie lower, as Fig. 207, or higher, Fig. 208; the latter is -the best, and the pieces may, for this cause, be cut out a trifle -deeper than ultimately required and they may be planed down a little -to remove the angles and assimilate them to the cylindrical surface. -The whole may then be turned together so as to form a plain cylinder, -the clamping rings, Fig. 209, being shifted when requisite. The whole -is now to be formed into a balustrade, but as the proportions of the -mouldings of such a large cylinder would not suit the small pieces, -the hollows must be less deep, and the raised parts less prominent -than they would ordinarily be made. The clamps are now to be loosened, -and the pieces reinserted with another face upwards, the flange or -plate against which their ends rest forming a gauge or stop to ensure -their position, without which precaution the mouldings would not -eventually meet at the angles. In cutting a fresh side the utmost -care is requisite, for if the work on the original cylinder is cut by -the tool, it will be impossible to restore it, and the work will be -spoiled. In replacing the strips, let the finished part lie below, so -as to come first in contact with the tool, by which the angle will be -clean. Extra care is for this purpose required in cutting the last -side. It appears to the writer that another precaution should be taken -which Bergeron omits, namely, to arrange the mouldings so that certain -parts are left of the original size of the wood, in order to retain -a certain number of points of contact with the sides of the grooves, -so that the strips shall not fall deeper into them than at first. The -extremities of the strips should certainly not be left smaller than -the central portion, or the pieces will rock on the latter while in -process of being turned. The two ends, therefore, should be allowed -to retain their original triangular form, forming base and capital -of the pillar, or the pattern may be so planned that, after the -extremities have been left as supports they may be cut off when the -work is complete. Care must be taken, in working as above, to have -the cylinders so large above the estimated size that the inner apices -of the triangles do not nearly meet at the centre, else the whole -chuck would be very weak and split into triangular strips. The lathe -called a spoke-turning lathe would accomplish this kind of work in -a far more easy and speedy manner. The balustrade would have to be -made by hand as a pattern, and cast in metal, and any number could be -produced precisely similar. The lathe in question is on the following -principle:--The frame carrying the tool (a set of revolving gauges) -is made to oscillate backwards and forwards to and from the piece to -be operated on. This is accomplished by its having attached to it a -roller or rubber working against the cast-iron pattern placed parallel -to the work, and below or one side of it. The rubber and frame are -kept against the pattern by a strong steel spring. The cutters also -travel in a direction parallel to the axis of the piece. Hence any -elevated part of the pattern causes the tool to recede from the work -in a corresponding degree, and a hollow allows a nearer approach -of the tool. Thus, as the tool is carried by a screw slowly from -end to end of the work, it is made to advance and recede in exact -correspondence with the form of the pattern. An immense deal of work -is done in this way, such as balustrades, spokes of wheels, the long -handles of the American felling axes, and similar irregular forms. - - [14] With the universal cutting frame this kind of work is much more - readily accomplished. - - [Illustration: FIG. 198.] - - [Illustration: FIG. 197.] - - [Illustration: FIG. 199^2.] - - [Illustration: FIG. 199.] - - [Illustration: FIG. 200.] - - [Illustration: FIG. 201.] - - [Illustration: Fig. 203.] - - [Illustration: Fig. 202.] - - [Illustration: Fig. 205.] - - [Illustration: Fig. 206.] - - [Illustration: Fig. 209.] - - [Illustration: Fig. 208.] - - [Illustration: Fig. 207.] - -The _principle_, indeed, is not new, as the rose engine is a similar -tool, and, so long back as Bergeron's time, pattern plates were used -giving any desired motion, endlong or otherwise, to the tool, or, -which in effect is the same, to the work to be operated on. - - - TURNING SPHERES. - -We must now recur to the sphere of which we have already spoken. The -method previously given for producing it is not sufficiently accurate, -although a very close approximation can thus be made to the perfect -figure. It is probably impossible without special apparatus, rendering -the tool independent of the hand, to turn out an absolutely correct -sphere--indeed, it is a sufficiently delicate operation, even with the -following or similar apparatus. For ordinary purposes, indeed, where -the object is simply to produce a croquet ball, a spherical box, or a -globe to be afterwards covered with paper, or any such work, the plan -already given will generally suffice, and, indeed, is very extensively -used. Some practised workmen, too, will, without even the aid of ruled -lines, turn out spheres of average excellence by the eye alone, aided -by a template. When, however, it is proposed to hollow out a sphere -so as to leave a mere shell of 1/8 in. or less, and perhaps include a -number of such shells one within the other, and a star in the centre -of all, it evidently becomes necessary to work with greater accuracy, -and still more so with respect to billiard balls, in which even the -slight variation caused by increased temperature will seriously affect -the result of the most skilful play, and cause the very best players -to fail. The principle of the spherical rest is displayed by the -diagram, Fig. 210. - - [Illustration: FIG. 210.] - - [Illustration: FIG. 211.] - -A is the chuck carrying the ball to be turned, of which C is the -centre. In a right line with the latter, and below it, is a pin fixed -to a block between the bearers of the lathe, and on this the arm, D, -turns. The latter carries a tool-holder in which a pointed tool, E, is -fixed. The point of this tool will evidently move in a circle, when -the arm is moved by means of the handle, D; and, as the centre of the -circle is exactly under that of the proposed sphere, the latter will -be correctly shaped when the lathe is put in motion. Fig. 211 gives -another view of the tool-holder. It is essential that the point of the -tool should be in a line with the centre of the lathe mandrel, so that -it shall act on a diametrical plane as it is carried round the work. -Such is the principle upon which a practically useful tool for turning -spheres has to be arranged. - -The faults in the above simple machine are many. In the first place -no provision is here made for the advance of the tool towards the -work. In the second place the requisite firmness and stability cannot -be obtained by merely causing the bar to revolve upon a centre-pin; -and thirdly, as the tool post is fixed to the horizontal bar, the -diameter of the ball must be limited. In point of fact, therefore, the -above arrangement would not answer, and it is only described in order -to illustrate the principle of all inventions for the production of -spheres in the lathe. To give steadiness of action the pin forming -the centre of motion is connected with a circular metal plate truly -turned, upon which a second similar plate works, and to the latter is -attached the tool-holding apparatus. It is difficult to make choice -of a circular or spherical rest so as to give it precedence, since -most of the patterns ordinarily made are good. To obtain the requisite -movement is, indeed, by no means a matter of difficulty; and one or -two adjustments in respect of the height and radius of the tool being -provided, a very simple apparatus will answer the purpose. To commence -with Bergeron's, which, though venerable, is by no means inefficient. -This is represented in Figs. 212 and 213. A, B, is the base, the -tenon, B, accurately fitted to slide between the bearers of the lathe, -the whole being held down as usual by the bolt and nut, _c_. The top -part of the base is surmounted by the accurately faced plate 214, on -which a side sectional view is given in Fig. 215. This is fastened -to the base plate (which, in Bergeron's description, is of wood) by -four countersunk screws. It is turned with a recess, so that the -outer part stands up in the form of a rim, and from its centre rises -a conical pin, _b_, the upper part of which is first octagonal, and -then rounded and tapped. It is this strong pin which forms the centre -of motion, and it must stand with its axial line precisely in the -centre of the lathe bed, so that if the plate were slipped close to -the poppet head this line would bisect the nose of the mandrel. This -is essential in all patterns of spherical slide rest. Upon the lower -circular plate rests that represented in Fig. 216, A and B, the latter -being the sectional representation. This plate is drilled in the lathe -with a central hole, the lower part conical to fit the pin in the -base plate, the upper part countersunk as in the figure, to receive -the octagonal part of the pin and the nut. The projections _a_, and -_b_, in B, represent the projecting rim, _a_, in the Fig. 216, A, and -this is made to fit very nicely within the rim of the lower plate, -while the adjacent part, _c_, rests upon the rim itself. The accuracy -of these bearing surfaces is of the utmost importance, It is evident -that this arrangement is calculated to give great stability during -the revolution of the upper part of the rest, which is fixed securely -to the plate last named. This plate has a hollowed edge cut with a set -of fine teeth to be acted on by the tangent, screw D, Figs. 212, 213, -and shown in Fig. 217 on a larger scale. The bearings of this screw -are attached to the base plate, and the screw is prevented from moving -endwise by collars as usual. - - [Illustration: FIG. 212.] - - [Illustration: FIG. 213.] - - [Illustration: FIG. 214.] - - [Illustration: FIG. 215.] - - [Illustration: FIG. 216.] - - [Illustration: FIG. 217.] - - [Illustration: FIG. 218.] - - [Illustration: FIG. 219.] - - [Illustration: FIG. 220.] - -On the upper surface of the top plate are fixed parallel bars -chamfered beneath like those of a slide rest, and between these the -tool holder slides, the advance of the latter being effected by a -screw precisely as in the slide rest already described. In the plan of -this instrument, as seen from above, Fig. 218, A, B, are the bars. The -tool is seen in position at C, the tangent at D. A scale is attached -to the sliding part of the tool holder for determining the size of -the sphere. The tool is again seen in position in 219, and detached -in 220. In Bergeron's description of the above spherical slide rest -the method of using the apparatus is thus described:--"Commence by -placing in a chuck a cylinder of some sound wood, and reduce it to -a convenient diameter, which should be a little greater than that -of the proposed ball. With the gouge work down this, and give it -roughly the form of a ball attached to a cylindrical base." This base -serves to sustain the ball during the operation, and the form of -an inclined plane is to be given to it where it is attached to the -ball, as seen in the drawing, to facilitate the passage of the tool. -After this preliminary work, place the instrument on the lathe bed, -and cause the tool holder to advance by means of a screw (the one -attached to the lower slide, not the tangent screw) until, reckoning -from 0in., the starting point, the index attached to the sliding -part has travelled over the graduated divisions of the scale, so as -to denote the size of the ball in its present rough state. Then -slide the instrument along the lathe bed, until the tool, accurately -adjusted as to height, just touches the ball at the quarter circle. -This will be better understood by the diagram Fig. 221, in which A, -B, are the lathe bearers; C, the tool in position; D, the ball; E, -the chuck or the base of the cylinder. Having previously determined -the size of the finished ball, the work may now be carefully begun by -clamping the rest underneath the bed, and making use of the tangent -screw. Little by little the work is to be reduced, taking care not -to cut too near the base on which the ball is yet carried. This -base is to be cut away little by little as the tool comes round, -and at the last cut the ball will drop off finished, and it is not -to be further touched with sand paper or other material. Hence, as -it approaches the finish, the tool must be delicately and steadily -made to traverse, so as to leave a finished surface as it advances. -Bergeron adds certain precautions as follows:--"If the material is -very rough from the gouge, so that at any point the tool is likely to -meet with such resistance as would endanger the work, such part may be -pared down again by using the machine as a common rest for gouge or -chisel; for the apparatus once arranged should not be altered nor the -fixed tool shifted until the work is done. The tool throughout is to -be advanced very gently forward at each turn by means of the screw, -which causes the parallel movement, and the tool is to be accurately -adjusted so as to be exactly in a line with the centre of the mandrel; -it is also to be very keenly sharpened, and even polished." The first -impression given by an inspection of the above figures is that the -ball would be liable to drop off before it could be fairly severed by -the tool. The writer determined to test this objection personally. -He selected a piece of sycamore, which is very fit for the purpose, -and useful as a kind of medium between hard and soft woods. A ball -was turned by hand from this material having a diameter of about two -inches. The neck by which it was held was retained of the size of a -cedar pencil during the final shaping of the rest of the ball. It -was of course not thus reduced until the ball was nearly spherical. -Gradually the neck was cut away until it was perhaps as small as -the lead of a pencil, yet still the ball retained its position, and -the final stroke cut it off truly and tolerably cleanly, E, 212 and -213. It is really astonishing how small a portion of sound wood will -retain a ball so turned, but the lathe should not be allowed to stop, -else the tendency to hang down or sag would overcome the sustaining -power of the fibres. Bergeron states, indeed, plainly, that the -process answers satisfactorily, and as a man of large experience his -opinion is certainly reliable. Nevertheless, since sand papering or -after process is to be eschewed, it does appear to the writer that -the final cut would leave a minute portion untouched requiring to -be afterwards removed. Not having one of the rests in question the -writer's opinion is to be taken _quantum valeat_. The spherical rest -more commonly used is that represented in the "Handbook of Turning," -since it is necessary not only that the machine should be efficient -for turning a sphere, but likewise applicable to the ornamentation -of the same by the revolving cutter and other apparatus used in such -processes. This and some other forms will presently be described, and -also an ingenious adaptation of the ordinary slide rest by means of -guide pieces or templets to work of this character. A very good form -of chuck for holding spheres during the operation of hollowing them -out or forming stars or cubes within them will, however, be first -introduced here as described by Bergeron. It will be at once seen how -simply and efficiently a ball can be thus held during such processes. - - [Illustration: FIG. 221.] - -Fig. 222 represents a chuck for holding balls, A being a sectional -view, B an elevation. In the first, _b, b_, represents the body of the -chuck, made as usual to screw on the mandrel. At _a_, the chuck is -formed with a shoulder like an ordinary box. This part of the chuck is -to be hollowed out to fit the ball on which it is intended to operate. -On the side of the chuck at _b_, is to be cut a screw of medium pitch. -Mounting another piece of wood in the lathe a kind of cover, _c, c_, -is now to be made to fit over the body of the chuck like the cover of -a box, but hollowed out to the curvature of the ball. A ring of brass -or wood of section D being screwed on the inside to the pitch of the -male screw on the outside of the chuck will hold the three separate -parts of the apparatus firmly together. Let them be thus arranged and -finished as one piece on the mandrel. Afterwards drill a hole in the -centre of the part which forms the cover, and enlarge it so that its -diameter shall slightly exceed that of the openings necessary to be -made in the ball for the purpose of hollowing out and forming within -it stars, or lesser spheres, box, cube, or other design, at pleasure. -In this chuck the ball will be held not only centrally but securely. -It is of course necessary to have a chuck specially made for each -different sized ball, but when it is considered that such things as -these are merely turned as curiosities and to prove the capabilities -of the workman, it is not probable that more than two or three sizes -of chuck will be needed, and the difficulty of making them is not -great nor the necessary expenditure of time, either. They should be -made entirely of sound boxwood, and so arranged as to the size of the -respective parts that when the ball is inserted and the cover placed -on, the latter shall not quite reach the shoulder on the base of the -chuck. In the spherical rest of more modern times the principle of -that already described is almost necessarily retained. It is figured -in 223. The sole A is formed like that of an ordinary hand rest, so -that it can be advanced across the lathe bed, and secured by the nut -and screw underneath as usual. From this rises a central circular -plate, which need not be more than a quarter of an inch thick, but -turned truly flat, that it may be parallel with the surface of the -lathe bed. From this rises the conical central pin upon which works -the plate B, the edge of which is racked to be moved by the tangent -screw C. Across this circular plate is securely fixed the chamfered -frame D surmounted by the part E which carries the socket and tool -receptacle, the details of which will be entered into when describing -the rest for ornamental work.[15] - - [15] The drawing shows a band at X encompassing the screw. This is - an error, as the whole upper part, including this screw, is made to - revolve by means of the tangent screw. - - [Illustration: FIG. 222.] - - [Illustration: FIG. 223.] - -The method of turning from a pattern acting on the tool has been -alluded to. In some cases a similar method is pursued, in which the -hand supplies the place of automatic machinery, an instance of this -is the application of pattern plates or templets to the small slide -rest now to be described, by which not only parallel or spherical -work may be done, but the elevations and hollows in moulded work may -be followed without difficulty. The pattern plates can be made by -the amateur or workman so that not only is no extra cost incurred, -but any desired form can be given to the work and as many duplicates -made as may be requisite. The simple slide rest itself is represented -in Fig. 224. The lower iron or steel frame is rectangular, chamfered -underneath, and is cast with a projecting part B underneath to the -socket of the hand rest. There is, therefore, no sole or saddle -required, and the height is adjustable at pleasure to suit 3, 4 or -5-inch centres. C is a plate of brass, cast with one V-piece similar -to D, the second E being removable at pleasure, or both V-pieces or -guide bars may be attached by screws. They are attached by two or -three screws passing through oval holes in the plate and tapped into -the bar, so that a little play to or fro is allowed, by which they -can be adjusted to grasp with more or less friction the iron bevelled -frame. They are kept up to their places by a pair of large headed -screws tapped into the edge of the brass plate and marked _e, e_, in -the drawing of the rest. On the top of the brass plate is fixed in -a like manner another pair of chamfered bars similar to those of a -slide rest for metal, but in the ornamental turning slide rests, where -lightness and accuracy are more needed than strength, the parts are -proportionally smaller. The frame, for example, may be six inches -or six and a half inches in length by two in width, the brass plate -two inches square, or perhaps two and a half by two, the longest -measurement in the direction of the upper guide bars, between which -the tool receptacle will slide. This will be quite large enough for -a five-inch lathe, although the measurement may be more or less if -desired. If taken as above, the iron frame may be half an inch deep -and the face of each side of similar size, leaving one inch between, -in which the screw will lie. 224 B shows the under side of the frame -with a cross piece to which the part, B 224, is attached. The guide -bars for the tool receptacle may be similarly small and light. If -the plate is 1/4 in. thick and two in width the bars may be 3/8 in. -stuff before being bevelled, the attaching screws can then be 1/3 in. -or 3/16 in. in the shank, the heads being large and flat, and not -countersunk. It is probable that many amateurs would like to attempt -such a rest themselves, hence we have given the above details. We -must however, warn them that as the above is for ornamental turning, -where accuracy is of the utmost importance, great care must be -exercised in the work, and the various parts must be fitted to the -utmost perfection. The upper face of the lower frame must be quite -level, and the sides quite parallel, and the upper or cross slide must -be fitted precisely at right angles to it. Above all, the screw by -which the upper part is advanced in either direction requires great -precision. It should be made with a fine thread deeply cut, and must -fit its nut under the brass plate, D, without shake. The nut itself -should be long, and must be carefully bored and tapped; it should -be also sawn through its length underneath, to give it a spring, so -that it may grasp the screw tightly yet easily, and this will also -compensate for wear. This will be understood when it is stated that -the milled head by which the screw can be turned is graduated round -its circumference, as is also the face of the bed or lower frame of -the rest. Hence to give the head a turn, or half, or a quarter turn, -must draw the sliding plate exactly the same distance to or fro, at -whatever part of the frame it may be at the time. This necessitates -all the threads being precisely alike. [We say precisely with a -certain mental reservation, for, strictly speaking, perfection is -hardly possible, and the skill and science brought to bear upon screw -cutting when perfect work has been necessary, as for astronomical -instruments, would hardly be credited, so extremely difficult is this -part of the mechanical art.] It would be better for the amateur to -get the screw and nut cut by Holtzapffel, Munro, or other first-class -maker, who has the requisite means and can command the highest skill. -Between the upper guide bars are fitted various tool receptacles. The -only one which need as yet be spoken of is that which holds the little -inch-long tools for ordinary work or for use with the eccentric chuck. -This consists of a brass plate bevelled to fit the chamfered bars, on -the end of which is a small piece of steel with a rectangular hole and -set screw, as seen in the drawing marked X. This plate has a tailpiece -of rather thicker metal, through which pass two set screws, which -regulate the depth of the cut to be made, their points bearing against -the end of the brass plate on which this tool receptacle works. No -screw is attached to move this upper slide, but a wooden handle -projects from it at right angles to be moved by hand, or a lever Y is -made use of. This has two projecting pins, the front one taking one -of the holes, 1, 2, 3 of the slide, the other one of a set of similar -holes in the top of the chamfered bars. By this the slide can be -advanced with ease and great steadiness. We now come to the pattern -plates or templets F, alluded to. These are formed of sheet iron about -1-20 in. to 1-16 in. thick, and must be long enough to reach from one -end to the other of the iron frame A, underneath which at each end are -two holes _a, a_., Fig. 224 B, to receive screws by which the templets -are attached by means of the slots, _b, b_. The outer edge, _a_, of -templet is the pattern to be copied. The dotted lines in Fig. 224 show -a plate in position. The tailpiece of the tool holder to be used has -a projecting stud, or is made with a screw with or without the roller -seen at H, and this is kept in contact with the templet by the hand -or by a spring, so that when the slide traverses the lower frame the -tool-holder necessarily follows all the curves of the pattern plate. -An inspection of K will make it evident that the projecting screw must -be so regulated as to length as to allow the tool-holder to go to the -extremes of the projections and hollows. It must therefore in the -pattern shown be at least as long as the line _a, b_, Fig. K, and a -tool-holder of sufficient length must for similar reasons be selected, -or the tailpiece might touch the fixed plate on which it works before -the guide pin had penetrated the deepest hollow of the pattern. With -these precautions nothing can exceed the ease with which this clever -adaptation of the slide rest is made and used, the greatest advantage -being that the workman can make his own templets to any curve or -series of curves that may be desired. - - [Illustration: FIG. 224.] - - [Illustration: FIG. 224B.] - -At a later page is described a slide rest with the arrangements of -the tool-holder somewhat improved, and calculated for the reception -of larger tools and apparatus. The little rest here described is, -however, very light and useful. - - - HOBLYN'S COMPOUND SLIDE-REST. - -A compound spherical slide-rest, for ornamental turning lathes, which -has been patented by Mr. Hoblyn, Rickling-green, Essex, is capable -of turning and ornamenting accurately spheres and any segments of -circles convex or concave, either on the surface or cylinder; also, -it is stated that by the addition of templates any other curves, -not segments of circles, can be turned out, in addition to the work -performed by an ordinary compound slide-rest. In our illustrations, -Fig. 1 is a side view, and Fig. 2, an elevation of the rest. A is -the lower, and B the top plate, C the carriage, and the saddle as -usual. The lower plate, of iron, is planed on bottom and sides, -and has a longitudinal bevelled slot in the bottom to receive the -fastening bolt, so that the plate can be tightened up at any point -on the lathe bed. At one end of this bottom plate is a piece raised -the whole of its breadth, accurately turned and faced, with a stout -turned pin, _b_, for a pivot in the centre. A wheel, _c_, is placed -around this raised piece, having any specified number of cogs, and on -its top any specified number of small holes drilled to receive two -pins as segment stops. The top plate is slightly narrower than the -bottom one, and has on its underside a corresponding surface to that -raised on the plate A, turned and faced with countersunk hole in the -centre to fit on the pivot _b_, on which it is tightened by a screw -and washer. The top of B is placed to receive two parallel bars of -brass, bevelled on the inner edge, so as to form sliding bars for the -carriage C, one bar being a fixture, the other capable of adjustment -by tightening screws. The sides are also accurately planed, and on -one a tangent screw, _e_, is so fixed as to be put in and out of gear -with the brass wheel, _c_, for the purpose of driving the top plate -round the pivot _b_. In the raised surface of B, is a countersunk -slot forming a quarter circle, with screw passing through it into the -bottom plate; by this means the top plate can be firmly fixed at any -angle to the bottom plate for the purpose of slide-rest turning. A -small pointer, _f_, works clear of the brass wheel in the capacity -of segment stop--two small pins being placed in the specified number -of holes in _c_. On the opposite side of the screw, _e_, on the top -surface, a screw, _g_, works in two standards screwed into the plate -through slots in the bar, which works through a traveller, _h_, firmly -attached to the carriage, C, and therefore capable of driving the -carriage in a rectilinear direction--for slide-rest purposes. This -carriage, C, consists of an iron plate _i_, with standard _k_, top -plate _l_, with parallel brass bars to receive tool receptacle _m_, -the bottom plate and standard being in one piece with the plate, -planed side and bottom, so as to slide truly between the parallel bar -on B. The standard has its surface accurately turned with a pin in -centre to form pivot. The top plate is planed true, bottom, sides, -and top, and has a countersunk hole in the exact centre, so as to -work on the pin, and tightens up with a large nut. In the plate is a -countersunk slot forming a quarter-circle, with screw passing through -into the standard, to set the tool receptacle either parallel with -B for spherical turning, at right angles to B for slide turning, or -at any angle for thick and thin cuts, and similar patterns when used -either as a spherical or slide rest. The parallel bars are to be -similar to those on B, to enable the tool receptacle to be advanced or -retired by screw or lever. This part of the machine can be adjusted -for height of centre thus:--The standard _k_ to be a hollow cylinder -with fixing screw on one side; the plate _i_ to be made with turned -pin on bottom, to fit into standard; elevating screw; saddle as usual, -but with the addition of a small hole drilled in one of the sides, and -a corresponding one in the side of the lower plate A, so placed that -when a pin is fixed into these holes the pivot is exactly central to -the lathe centre. - - [Illustration: FIG. 1.] - - [Illustration: FIG. 2.] - -The way of using the spherical rest is thus described by Mr. -Hoblyn:--"When altogether, and the point of tool adjusted by means of -a square exactly over centre of pivot, it is evident, if the top plate -moves round, the point of the tool will still be in the same place; -but if we retire the point one half-inch, on moving the plate right -round it would describe an inch circle, so that if the centre of pivot -be exactly under the centre of the lathe, and we move the rest the -half-circle, it will cut a perfect ball (or any part of one, if the -cut be less than half a circle) of such size as the distance doubled -of point of tool from centre of pivot. Therefore, by adjustment of -the lower plate on the lathe bed according to the size of material -(this, of course, does not allude to the act of turning a ball, when -the centre of pivot must be exactly under centre of lathe), adjustment -of carriage from centre according to the size of circle required, and -adjustment of tool for depth of cut, we are enabled to turn any convex -curve. To turn the concaves, instead of retiring from centre of pivot, -it is only requisite to advance the point beyond the centre to the -distance required, when the same rules apply as to the convex curves. -In turning the concaves, however, it is necessary to turn the plates -half-round, so that A and B are in the same straight line, instead of -over each other. This enables you to work on any sized piece of wood, -the object of the longitudinal slot in the lower plate being to enable -you to adjust your previously arranged curve to any sized wood or -ivory that your lathe will take, less 2 in., the height of machine. -The desired curve having been turned, take out the chisel, and place -in the receptacle any ornamenting instrument, drill, eccentric, &c.; -advance the point till it touches the work, then set your screw for -depth of cut, and work according to fancy. Whatever it is it must be -mathematically correct on the curve, as you have not altered it in -any way. You then remove your rest to cut the next desired curve, and -proceed as before. The best way to execute a piece of work is first to -make a sectional pattern of your design, either by drawing or cutting -it out with scissors from a double piece of paper, when, of course, -both sides come the same, the line where the paper is doubled being -the line of centre of lathe. You can then, with a pair of compasses, -ascertain with accuracy the necessary size of circle, and the position -of centre of pivot to procure the desired curves. You may also produce -a very good effect by a combination of two different curves in this -way:--Let your ornamental instrument be the universal cutter; working -horizontally follow up your curve with it, but, instead of cutting -right out on your curve, let the instrument finish of itself in wood -previously turned so as to fit its curve, when you get the lesser and -greater curves following in unbroken succession. With the eccentric -chuck numberless effects of the most curious description may be -produced, even work supposed to be only possible with a rose engine. -We believe the tool is to be seen at the shop of Mr. Evans, 104, -Wardour-street. - -To turn a sphere by means of a template attached to the slide rest as -described, the following adjustment of the rest and mode of proceeding -should be followed. A, B, Fig. 225, is the chuck containing the -material, H, to be worked into a sphere. Upon this the length, or -diameter (equal to that of the template, as will be explained), is -to be marked at K, K, which being divided equally by the line L, L, -will give the dimensions of the ball as if it were about to be turned -by hand. The corners are to be turned off with the gouge, as far as -shown, K being equal to _e_ L, and K _f_ equal to K _e_. The outline -of the ball will with these measurements not be touched. The angles -left may also carefully be removed, but (as shown by the figure) this -operation must be conducted with great care. A template must now -be made containing a full semicircle, _every part_ of which can be -traversed by the stud or screw upon the under part of the slide, or -the ball will not be severed by the final cut. It is evident that the -traverse of the slide during the operation will be the full radius -of the ball, and in this, and indeed all cases of deep recesses, and -greatly projecting mouldings, the ordinary tool-holder with tailpiece -had better be removed, and replaced with a slide like M, having a pin -straight through it to rest in contact with the template. This will -preclude the necessity for the long stud or screw spoken of before -as necessary when the slide with the tailpiece is used, but the -tool cannot be advanced independently of the template as when the -other form is used. Fix the rest so that when the top slide is at its -central position the tool may stand as in the sketch exactly upon the -central line of the ball. Take care that thus placed the tangent-pin -of the slide is on the central mark of the template. The long frame -of the rest must likewise be parallel with the bed of the lathe, -keeping the top slide pressed against the template with the left hand, -while the top part traverses the frame under the action of the screw -moved by the right hand, the ball will be correctly cut.[16] One or -two cautions must, however, be given here, to ensure a satisfactory -result. In the first place the cylinder from which the ball is to -be made must be exactly of the diameter of the semicircle on the -template. H, H is the cylinder to be turned to a sphere, G, G, B shews -the position of the tool at starting, the dot on A, the templet, the -tangent pin of the slide, Fig. 226. As the work proceeds the tool will -take the several positions shown, the dotted lines, D, being equal and -parallel. The tool will thus repeat the form of the template. Let the -latter remain as before, but let a smaller cylinder be inserted in -the lathe, or, which is the same thing, let the tool be now lengthened -so as to start at C on the inner dotted line. When the pin, F, has -reached K, which should be the axis of the ball, the tool will be -at M, quite out of cut. Fig. 227 represents three forms of tool in -contact with the ball at two points. The first two will evidently be -out of cut at the axial line, as the side of these bevels will then -touch the piece to be turned. C is a form that will remain in contact -from the diameter to the axial line. The left side of the edge is -slightly overhanging the side line of the tool, D. - - [16] See Appendix. - - [Illustration: FIG. 225.] - - [Illustration: FIG. 226.] - - [Illustration: FIG. 227.] - -When the part shown has been cut this tool must be removed and a -similar tool bevelled in the reverse direction, adjusted by reference -to the central line of the ball as before.[17] It is recommended to -roughly shape the work with the gouge, and partially to cut it off -with the parting tool so as to relieve the tool as much as possible, -and when the last finishing cut is to be taken a freshly sharpened -tool is to be made use of. It is evident that in the above and -similar work the rest may be placed across the end of the cylinder if -preferred to turn the _right_ hand hemisphere, but it would have to -be moved for the second half, which should be avoided, if possible. -The advantage which the circular rest has over the above is due to -the fact that the tool and rest once in position, neither has to be -readjusted until the work is complete. The slide rest and semicircular -template forms, however, if judiciously used, a very serviceable -substitute and makes very satisfactory work. Whether or no the reader -has a complete rest for spherical work, he should decidedly provide -templates to use as above. They are not only useful for turning or -ornamenting spheres, but any forms whatever that may be desired, and -they possess this special advantage, that when a dome or other pattern -has been thus turned with a plain tool the same template used with -revolving cutters will enable the work to be ornamented with perfect -ease, doing away in a great measure with the need of a dome chuck. -Suppose, again, that a number of pieces are desired precisely similar, -as a set of pawns for a set of chessmen, a sectional drawing made and -transferred to a piece of sheet-iron, and the latter cut to form a -pattern plate, will enable the most unskilful to work satisfactorily. -Nothing more need be said of the uses of templates, and for the -present the subject will be dismissed, though it may possibly be -referred to again in a future page. - - [17] Holtzapffel uses a tool, the plan of which is semicircular, like - a small round tool, cutting on front and two side edges; the tool is - very narrow and bevelled below. - - - CHUCKS WITH SLIDES AND COMPOUND MOVEMENTS. - -The first of the chucks comprised under the above head is the oval or -elliptical chuck, and it is introduced first in order because it is -not essentially a machine for ornamental turning, as are the eccentric -and others of this class. There are many plain works required of -elliptical section, as bradawl and other tool handles, for which a -very simple arrangement is required. - -The principle of the oval chuck is as follows:--There is an -arrangement of slide, by which as the piece revolves it is drawn -gradually further from the tool during half a revolution, and in -a similar manner caused to approach it during the remaining half -revolution, each point in the circumference alternately partaking of -such movement; the whole of these points together, which, of course, -form the circumference, will become an ellipse. Let D, Fig. 228, be -the centre of the mandrel, A, B the direction of the slide moving -up and down in a right line, and carrying the work upon a screw -in the centre of it. C, E become centres, and may be taken as the -extremes, for as the work revolves a succession of centres are formed -and instantaneously changed. The figure produced will be the oval -shown. To render this, however, clearer, Fig. 229 may be taken, which -represents the chuck in its most simple form with separate details of -the parts which compose it. A is the chuck with central slider and -chamfered bars, as described in speaking of the slide and rest and -previous apparatus; B is the slide detached; D, front view of the -same. The short arms _a, b_, pass through slots in the back plate as -seen at C, which shows this plate with slide removed. Through these -short arms pass a pair of adjusting screws; or still better _a_ and -_b_ are themselves cross arms or pallets extending the width of the -plate as seen next drawing, and in the chuck of Muir which follows. -They are merely flat plates of steel embracing the guide ring, so that -some point in their inner surface may rest against it during every -part of the revolution of the chuck. - - [Illustration: FIG. 228.] - - [Illustration: FIG. 229.] - -The guide ring here alluded to is shown at E, and also at G, fixed in -its place upon the poppet. It is in the form of a raised ring with -arms, B, C., which are turned at right angles near their ends, and -through which pass adjusting screws with conical points. This plate -is flat at the back and bears against the face of the poppet, the -mandrel nose falling into the central opening E. It is kept in place -by the points of the screws falling into conical holes at the sides -of the poppet head. At F is a side sectional view of this plate, -with its raised and accurately turned ring, H, and at G is seen the -poppet with the plate attached, the left arm being dotted to show -the position of the adjusting screw. It is this ring and plate which -regulate the movement of the slider, and, with it, of the work, the -latter being attached to the screw in the centre of the sliding plate, -which screw is a counterpart of that upon the nose of the mandrel. -Suppose the chuck A screwed to the mandrel, and the ring accurately -concentric with the mandrel, in which position, the pallets must touch -at two opposite points. In the best chucks there is an adjusting screw -to each, by which the contact can be regulated. In this position -any object of a circular form can be turned, for the slider remains -in one position, and its screw, upon which the work is fixed, is a -continuation of the mandrel. But if now the adjusting screws of the -part E are turned, the one being loosened and the other tightened, -the guide ring will no longer be concentric with the mandrel, and, -as the screws of the slider bear upon it, the slider will during -its revolution be moved to and fro to a distance regulated by the -eccentricity of the guide ring. The combination of this circular -motion of the chuck and rectilineal movement of the slider will -produce an ellipse, and a stationary tool applied to the work will cut -it, into that form. - -The above simple arrangement of oval chuck suffices only for plain -work. The only figures that can be described by its means, upon the -cover of a box, for instance, being a series of ellipses of which -the longest diameters fall in the same right line, and of which the -centres are coincident with the axis of the mandrel, as Fig. 229. - - [Illustration: FIG. 229.] - -Even these, however, cannot be done without some compensating -arrangement, as the minor axis does not diminish in length at the same -rate as the major--hence the ellipses get narrower and narrower until -the central one becomes a mere right line. This is referred to again -in the ornamental section of this work. - - [Illustration: FIG. 231.] - - [Illustration: FIG. 232.] - - [Illustration: FIG. 233.] - - [Illustration: FIG. 234.] - - [Illustration] - -Combinations like 231, in which the ellipses intersect, cannot be -so obtained. Hence the oval chuck is provided with a wheel, either -racked to work by a tangent screw or fitted with a spring catch, by -which it becomes a dividing plate. This wheel revolves on a central -pin[18] fixed to the middle of the sliding plate, and carries a screw -of the same pitch as that upon the mandrel to which other chucks can -be attached. By this means the axial lines of the ellipse can be -varied in direction. This addition is shown in Fig. 232, which is -a section, and 233, which is a front view. In the former, A is the -wheel, which, as previously explained, should be so arranged as to -contain a number of cogs divisible by as many figures as possible; 96 -is such a number, being divisible by 2, 3, 4, 6, 8, 12; 72 is also -a good number, as it will divide by 2, 3, 4, 6, 8, 9. If the edge -is racked and moved by a tangent-screw with divided head a greater -range can be taken and finer work done. In this case the face of the -wheel can be marked with divisions, and a fine steel pointer, as -shown at F, added to count by. The pin B, which is firmly attached to -the centre of the slider plate, must be strong, and the lower part -at least should be conical. It is drilled and tapped at the smallest -end, and when the circular plate with its screw is slipped upon it, a -screw, E, the head of which is countersunk into the face of the large -screw, retains it in place. The slide, C, has a recess turned to fit -the wheel plate, and the latter is cut as shown at X, which ensures a -more accurate bearing than if it was left flat on the lower surface. -In making this chuck certain precautions are necessary. In the first -place, the guide ring fixed to the poppet must be exactly concentric -with the mandrel when in its central position; and when it is drawn by -the adjusting screws to the right or left the central line must remain -parallel with the surface of the lathe bed. To ensure this centrality -it is necessary to turn its outer surface when it is in position on -the lathe head. So at least says Bergeron; and it is perhaps the best -method whereby to ensure the accuracy that is required.[19] For this -purpose Bergeron directs the use of a cutter similar to Fig. 234 -attached to the mandrel as a chuck, the edge which is on the inside of -the bent part at _a_ acting on the exterior of the ring as the mandrel -revolves. The screws allow the tool to be advanced closer to the ring -as the work proceeds, while they secure it at any desired point. Such -a contrivance as this, used merely as a finishing tool to correct any -slight error, is no doubt sufficiently satisfactory. The various parts -of this and other compound chucks should be first turned separately -to near the required size, and accurately finished when in their -respective places upon the chuck. Any parts which present a difficulty -from the impossibility of retaining them in place while operated upon, -may be soldered with tinman's solder, and thus turned, after which -the application of moderate heat will detach them, and the fluid -solder can at the same time be wiped off with a pledget of tow or -cotton waste. As many of our readers may wish to make such apparatus -as the above, it may be desirable to add a few directions for the -preparation of chamfered edges such as those of the slide and guide -bars, the latter of which should be of iron or steel. Let the slide, -for instance, be cast as a rectangular plate and the two flat surfaces -be roughly levelled with a file. One of these must now be made -perfectly true, either by mounting it with solder upon the face plate -of the lathe, and levelling it with the aid of the slide rest, which -is perhaps the safest plan, or by careful working with the file, using -a straight-edge in all directions, and finishing by careful grinding -upon a flat stone slab with water, or on a wooden grinder charged -with emery and oil. After one side is finished, the opposite face may -be similarly treated; but for this the plate may be secured to the -finished surface of the lower plate of the chuck itself, and turned -with a tool fixed in the slide rest. The edges must now be filed truly -at right angles to the sides, care being taken to keep the long sides -of the plate parallel. (The short sides or ends will be rounded by -being turned true with the edge of the chuck.) The work must now be -tested with the straight-edge and small steel square, and any error -carefully corrected. Of course, if the reader is the happy possessor -of a planing machine, all these operations will be facilitated and -accuracy more likely to be ensured. It may here be mentioned that, -to supply the want of such planing machine (a want often felt by -amateurs who have not mastered the use of file and scraper), Monro, of -Gibson-street, has cleverly added a planing apparatus to the ordinary -foot lathe, rendering the latter tool complete for all purposes of -amateur engineering. - - [18] This pin should have been shown of a conical not cylindrical - form, and much stronger in proportion. - - [19] This part is always so turned by the best makers. - -This handy apparatus will be found on a later page fully described and -illustrated by a photograph of the machine. The writer has seen it and -used it, and can testify to its satisfactory working, as a lathe thus -fitted does not run heavier or require greater exertion than when used -for ordinary turning. - -The next step will be the chamfering of the edges of the plate. Let -235 represent the plate in its present condition, with rectangular -edges. To produce a chamfer of 45°, draw a line, _a, b_, at a distance -from the edge equal to the thickness of the piece. If a smaller angle -is desired, the line must be drawn further back. An angle of 30° to -35°, is, in the writer's opinion, better than one of 45°, as the -chamfered bars will then have a wider bearing on the upper surface of -the plate, tending to hold it more securely down upon the lower part -of the chuck. Nothing remains but to file carefully down from the -line thus drawn to the lower edge, by no means a difficult operation -if care is exercised not to obliterate the mark, or to trespass the -least beyond the assigned limit. A template, cut like Fig. 236, of the -desired angle, will be a gauge for the edges of the plate, as well as -for those of the chamfered bars, and will serve to make assurance -doubly sure. The arms which stand out at the back of the slider to -embrace the guide ring are not fastened to the plate immovably, but -with power of adjustment. A pair of short slots are made in the -slider, into which a square projection from the arms fits, and the -whole is clamped by a screw, as shown in 237, A, B, and C. - - [Illustration: FIG. 235.] - - [Illustration: FIG. 236.] - - [Illustration: FIG. 237.] - -A more accurate method is shown in the Ornamental Section -for finer adjustment than can be secured in this way, but for a home -made chuck the above will suffice and is the easiest plan to carry -into effect. To use this chuck, the guide is first arranged, so that -its ring is concentric with the mandrel. A mark is generally made -upon it, and also upon the lathe-head, by which this position can be -readily insured. The chuck is then screwed upon the mandrel, and the -arms adjusted, as just described, so as to embrace accurately, but -not too tightly, the guide ring. They are then, once for all, fixed -in that position by the screws alluded to. A few drops of oil are -necessary to lubricate their inner surface and the exterior of the -guide, and the latter being withdrawn by its adjusting screws to the -desired eccentricity, the work may be proceeded with. A rough piece -of wood, however, should always be first turned to a cylindrical -form, as an oval chuck being an expensive article is to be carefully -preserved, and not exposed to the shocks inseparable from the process -of roughing down the work. Moreover, there should always be one or -two screws passing through the slider into the back plate, to take -away the strain from the chamfered bars, which can be removed when -the slider is to be brought into action. Two precautions are here -laid down respecting oval turning, which, in all probability, a -tyro would not suspect to be necessary until taught by failure. In -the first place, at whatever point of the circumference the tool is -held, at that point it must remain, or rather, it must remain in the -same horizontal line, being neither raised nor depressed. Hence, for -all work where accuracy is needed, oval turning should be done with -the slide rest. In the second place, when it is desired to place a -succession of ellipses one within the other on the face of the work, -like Fig. 229, it will not be sufficient to place the tool nearer to -the centre for each ring, but the eccentricity of the guide ring must -be reduced at the same time; otherwise, when the middle is reached, a -straight line will be the result, instead of the proposed ellipse, as -already stated. The lathe should not be driven at a very high speed, -and the moving parts should be lubricated from time to time. There are -other ways of compensating the error produced by the oval chuck, or -elliptic cutting frame, which however are so entirely connected with -ornamental turning that they are reserved to be introduced into that -section. A contrivance for turning ovals invented, and communicated to -the _English Mechanic_ by a Suffolk amateur, deserves a place here. It -is thus described by the inventor:-- - - - TURNING OVALS, ETC., BY MEANS OF A TEMPLATE. - -Ovals are generally turned by causing the work to move in and under -guidance of an "oval chuck". - - [Illustration: FIG. 238.] - -There seems no reason why the same result should not be arrived at by -communicating a movement to the rest supporting the cutting tool in -the following manner:--Let A, A, be lathe bearers, B, pulley, C, screw -of mandrel, D, template fixed thereon, E, friction wheel on the end of -bar F, G rest (a board of any convenient width) moving on pivots at -H. The friction roller, E, is to be kept in contact with the template -by the cord running over the pulley T, stretched by the weight L. The -rest will thus oscillate under the guidance of the template, which may -be either oval or rose engine pattern, and the cutting tool form the -pattern of the template used. There might be other modes of causing -the rest to oscillate on the same principle. The lathe would require a -slow motion, the same as with an oscillating mandrel. - - - ECCENTRIC CHUCK. - - [Illustration: FIG. 239] - -Next in order of the compound chucks stands the eccentric, the use -of which is not entirely confined to mere ornamentation, as it is -often very convenient to the turner to have the power of shifting the -centre of his work. Thus, a _solitaire_ board may be drilled with -the necessary cup-shaped holes, or any work of a similar character -completed by the help of this chuck without the necessity for -constant re-centering. The _general_ work of the chuck in question -is nevertheless ornamentation, for which it is peculiarly adapted -either alone or in combination with other compound chucks, or overhead -apparatus. The sliding plate of this chuck works between chamfered -steel bars, the same as in the oval chuck. There is, however, no guide -ring on the lathe head to regulate the movement of the slide, and -therefore also no necessity for the projecting arms at the back. The -slide, in fact, is moved by a screw with a graduated head, similar -to those already described. Fig. 239 represents the common form of -this chuck, in which the wheel which forms a dividing plate is moved -by a tangent screw. The sliding plate is shown slightly drawn out by -its screw, the degree to which it is moved being that of its required -eccentricity. When the plate is drawn back to correspond with the -base plate, the centre will be in a line with that of the mandrel, -and any work turned upon the chuck in this position of the slide will -be cylindrical. The central screw of all these compound chucks being -alike and of the pitch of that on the mandrel, any of the ordinary cup -chucks can be used with them to hold the work; or the eccentric chuck -can be screwed to the elliptic, cycloidal, or any other in the set, by -which means an endless variety of curves can be described. The effect -produced by the simple eccentric chuck now described is as follows, -the slide rest being used with it as a matter of course. Let a piece -of box or other wood be fixed by means of a cup or other chuck upon -the screw of the eccentric chuck, and the slide rest with a single -point tool be brought in front of it. By means of this the work must -be carefully faced, and made uniformly level. A ring A, Fig. 240, may -now be cut, which will be concentric with the mandrel. The slide of -the chuck being now drawn down by a few turns of the leading screw -(the tool and rest being kept in its original position), the centre -of the work will thereby be shifted, and the tool being advanced to -touch the same, the circle B will be formed of the same size as the -first, but necessarily cutting it at two points. Another turn of the -screw will enable C, and similarly D, or any number of circles to be -successively formed. The centres of these circles will be in a line -across the face of the work. The ratchet wheel is added to enable -the turner to arrange his circles round a common centre, instead of -being thus obliged to keep them in a right line, and it will presently -be seen what a beautiful variety of interlaced circles can thus be -accomplished. The dividing wheel is, as previously explained, divided -on its edge into an equal number of teeth, or racked for a tangent -screw and divided on the face and edge. We shall suppose the number of -divisions to be 120. Face the work afresh, and, drawing back the slide -until the centre is concentric with the mandrel, as at first, cut a -boundary circle, A, Fig. 241. Move the slide of the chuck a few turns, -as before, and cut an eccentric circle. Now move the dividing wheel -thirty teeth, and cut a second, and, advancing by thirty each time, -cut a third and fourth, and Fig. 241 will be the result; the centres -of the eccentric circles falling upon four points of the inner dotted -circle, which is itself concentric with that first made. - - [Illustration: FIG. 240.] - - [Illustration: FIG. 241.] - - [Illustration: FIG. 242.] - - [Illustration: FIG. 243.] - -If the same process is followed, but the number of the circles -increased, a very neat snake-like ring will be formed, constituting -a border, in the inside of which other combinations may be made. In -Fig. 242, twelve interlacing circles are shown; in Fig. 243, twelve -circles, described upon centres, which lie upon the circumference of -a central circle of equal size. This last pattern, when more finely -executed, by doubling or trebling the number of eccentric circles, -forms the device generally cut upon watch cases, under the name of -engine-turned. The best way to _try_ patterns, is to cover the face -of a piece of boxwood with paper, using a pencil in the tool-holder -of a slide rest instead of a cutting tool. If a softer disc is used -instead of box, round pieces of paper or thin card can be fixed -upon it with ordinary drawing pins; and if the first pattern is -unsatisfactory, a second, and any successive number of pieces, can -be mounted, and fresh patterns traced by the same means. It would be -mere waste of time to multiply specimens of the patterns that may be -executed by the aid of the chuck just described; and, indeed, this -could only be done by cutting in the lathe itself the blocks from -which such specimens must be printed. For the present, at any rate, -the _principles_ only by which such devices may be executed will -be given (as above,) and the designs will be left to exercise the -ingenuity and taste of the reader. - -It happens, moreover, that few as are the works devoted to the -general principles and practice of plain turning, more than one has -been published on ornamentation by the eccentric and other compound -chucks, in which a variety of executed patterns appear, of more or -less beauty; and in the _English Mechanic_ has lately been printed a -selection of exquisite designs by Mr. G. Plant, whose chuck, indeed -(to be presently noticed), bids fair to supplant the most simple one -now described. The chief recommendation, perhaps, in the latter, is -its great simplicity, as it may be made by any amateur sufficiently -practised in the use of tools; whereas the geometric chuck is too -complicated to permit this. It will be observed, on inspecting the -drawing, Fig. 239, that the divisions on the face of the wheel are -continued on the side above the part that is racked; this permits them -to be seen when the piece of work overlaps the circle of the wheel. -The steel point shown at B, answers as an index, either to the surface -marks, or to those on the side. The tangent screw is now generally -fitted in a small frame, which is itself pinned at one end to the top -plate, and kept up to the dividing wheel by an eccentric cam. This is -not shown in the drawing; the plan is nevertheless good, as the screw -is instantaneously released from gear at pleasure, when the wheel -may be turned by hand to any desired position; after which a slight -movement of the cam brings up the screw, and all is made ready for -work. The eccentric chuck becomes available for such work as shown -in Fig. 244, representing the bottom of a candlestick, ringstand, -or similar article. In this case the centres of the eccentric work -(now cut quite through) are on the circumference of a circle larger -than, and outside, the work itself. Instead of cutting through the -whole thickness of the stuff the outer circle may remain such, and -the blackened part may represent an inner raised surface, when the -contrast formed by the sharp edges round the pattern with the smooth -circular part will be very agreeable to the eye. To improve still more -this design, the outer part may be ebony nicely moulded and edged with -ivory, and the raised part ivory; or the same may be alternations of -ebony and holly, which will form a contrast almost equally agreeable. -A small chisel-ended tool must be made for this work if the whole is -in one block, as it will be necessary to leave a level surface upon -the face of the lower part. There are an infinite number of designs -of similar nature, which will occur to the reader when the principles -of the chuck have been mastered, some of which would at first sight -appear to have been worked by other means. Fig. 245, for instance, -which is but a modification of the last, scarcely looks like lathe -work, but can be cut more rapidly this way than any other--of course -the fret saw will do similar work, but it would first have to be -marked out, and afterwards the marks of the saw teeth removed, whereas -the above is cut and polished at once. It may here be observed that -the eccentric chuck itself is used to fix the _position_ of the -various circles to be cut, whereas the _size_ of these circles is -determined by the slide rest. Thus in Fig. 246, while the centre of -the chuck is concentric with the mandrel, bring up the tool in the -rest and cut the circle F, G, H, of which B is the centre; draw down -the slide of the chuck until its centre is at C, leaving the slide -rest as it is, and the circle F, E, D, will be formed of _equal size -with the first_. Now move the screw of the slide rest so as to draw -in the tool towards the centre of the lathe bed without altering the -chuck, and the small circle will be the result, whose centre (being -dependent on the chuck alone) is the same as that of the larger -circle. Bearing in mind this principle, that the chuck determines the -various centres only, and the slide rest the radii, little difficulty -will be experienced in devising and executing designs. Such is the -simple eccentric chuck, of which the use is tolerably extensive; but -there are, nevertheless, certain positions in which the eccentric -designs are required, which cannot readily be obtained by its means. -Fig. 247 is one of these, in which a moment's inspection will show -the necessity of two distinct movements of the slide at right angles -to each other. Hence a second slide is attached to the first at right -angles, much the same in effect as a second chuck screwed upon the -first but standing across it. This is the compound eccentric chuck -to be subsequently described in detail. There is one drawback to the -use of these chucks, namely--their excessive weight, which causes -a great deal of vibration in the lathe itself, especially when the -eccentricity of the slide or slides is great. An accidental blow -moreover from the chuck under the above condition would be very -severe. Hence the various cutters eccentric and others, worked by -the overhead apparatus already in part described are infinitely more -pleasant to use and even more effective and more easily managed. -The eccentric chuck can be used in combination with these, and the -capabilities of the two will thus be vastly extended, but in this -case the chuck is kept stationary while motion is given to the tool, -and the defect just alluded to no longer exists. In cutting patterns -upon hard wood and ivory a common defect is shallowness of work, the -cuts should not be so light as to give merely an effect of a design -_scratched_ upon the surface. The cut should be deep and clean, and -the tool not only sharpened but polished so as to leave the device -boldly executed, the small triangular and other shaped pieces left -between the cuts standing up clear and solid. Some patterns, as the -shell, which will be presently spoken of, require to be deep at one -part and shallow at another. Some devices look best when cut with a -point tool with double and others with single bevel to the edge, and -the same design worked with different tools will appear almost like -two distinct patterns. - - [Illustration: FIG. 244.] - - [Illustration: FIG. 245.] - - [Illustration: FIG. 246.] - - [Illustration: FIG. 247.] - - [Illustration: FIG. 248.] - -The double eccentric is represented in Fig. 248. The part A is the -foundation plate, with a projection at the back, tapped to fit the -mandrel. B, B, the lower guide bars; K, K, the lower sliding plate. -All the above parts are precisely similar to those of the simple -eccentric chuck. Upon the face of this lower slide are attached two -chamfered guides, C, C, at right angles to the first. They are kept -in place by screws passing through oval holes on their faces, and -tightened when required by screws, tapped into four little square -blocks, D, D. Between these guides slides the upper plate, which -carries the screw for chucks, and the dividing wheel as before worked -by a tangent screw, G; to either end of which a key is fitted. The -leading screws, E and F, which move the two slides, have squared -ends projecting both ways, so that the plates can be made to work -eccentrically in either direction, which is sometimes an advantage. -The chucks do not screw down upon the face of the division plate, -on account of their projecting parts at the back; and very commonly -a round plate, O, somewhat smaller than the wheel and about 1/4 in. -thick is attached to the face of the latter to raise the work still -higher, so that the dividing plate can be readily seen. The more -compactly, however, the parts of this chuck are made, and the less -the work projects from its face the better; as there will be the less -strain upon the central pin, and upon the plates and their guide bars -when the tools are applied to the work. - -To be able thus to place in the centre of rotation any given point in -a piece of work, whatever may be the form of its boundary lines, is -of immeasurable advantage, even though the capabilities of this chuck -are confined to objects of plane superficies, it being impossible -to reach by its means the side of a cylinder, or the surface of a -sphere or spheroid. It is evident that any line upon the face of a -box, for instance, whether the latter be square, round, octagonal, or -of any other form, may be followed with two movements of the slides, -combined with the rotatory movement of the dividing wheel. Thus, a -border of interlacing circles may be carried round the edge of such -a box, Fig. 248; or, a series of such circles forming constantly -diminishing octagons, hexagons, squares, &c., may be thus readily -executed. Nevertheless, what was said of the simple eccentric chuck, -applies with even greater force to the compound eccentric. It is a -heavy piece of apparatus, requiring a lathe with substantial poppets -and bed; the whole well braced to the floor and wall, to withstand the -excessive vibration caused by the revolution of the apparatus. It was, -indeed, in view of this and similar appliances that we insisted in our -initiatory paper upon the great importance to the workman, of adequate -strength and solidity in the various parts of the lathe itself. - -In Fig. 249, we give a simple specimen of work to be executed by the -compound eccentric chuck. - - [Illustration: FIG. 249.] - - [Illustration: FIG. 250.] - -The compound geometric chuck of Ibbetson, manufactured by Holtzapffel -and Co., is a double eccentric considerably improved and of very -extensive application. A full description of it is published in a -book written by the inventor, in which an immense number of patterns -executed by its means is given with detailed directions for their -execution. As these patterns are almost essential to a description of -the apparatus as exemplifying the working of its several parts, the -reader is referred to the book in question, or to a translation of it -into French in the supplement to Bergeron's work. To enable the turner -to execute patterns on the side of cylindrical pieces a chuck is used -called a dome chuck, similar to Fig. 250. A rectangular frame of -brass, A, carries a sliding plate C, at right angles to it, the latter -having a tailpiece which fits accurately between the frame, and is -tapped to receive the finely cut leading screw with divided head, B. A -nut at the back of the frame clamps the slide in any desired position. -Upon the upper face of the latter is a wheel racked on the edge so as -to be moved by the tangent screw, E. This wheel, like that of the -oval and eccentric chucks, turns on a strong conical central pin, and -has a screw attached of the same pitch as that on the mandrel. The -chuck is screwed to the mandrel by the projecting flange, F. The work -is thus mounted at right angles to its ordinary position. - -By this arrangement any point in the side of a cylinder can be brought -in contact with a tool fixed in the slide rest, and by means of the -graduated screw heads of the latter and of the chuck various devices -can be accurately made. This chuck may be used alone or in combination -with the eccentric, and the quick revolution of such cumbrous pieces -that would be a great drawback to their use is less frequently -required, now that the following apparatus has been added to the -lathe, and eccentric revolving cutters, with drills and other tools, -have taken the place of heavier and more inconvenient apparatus. It is -indeed much more convenient in the majority of cases to keep the work -itself fixed, and to operate upon it by tools put in rapid motion, -because the latter, from their excessive velocity compared with that -which can be conveniently given to the material, make better work, and -at the same time from their lightness impart no tremor to the lathe -while in motion. The cuts thus made are in consequence very clean -and smooth, and free from those slight undulations apparent when any -vibration takes place in the lathe itself. The different varieties of -overhead apparatus have been already described and illustrated, and it -only remains to describe more in detail the revolving cutter frame, -drills, and other apparatus used therewith. - -The following pieces fit into the top of the slide rest in what is -called the tool receptacle, and are advanced to the work by means -of a lever as already described. Fig. 251 is the revolving cutter -frame, the spindle of which is put in rapid motion by a cord from -the flywheel passing to the small pulley through the medium of the -overhead apparatus, as shown in a previous page. For the purpose of -cutting _small_ intersecting circles, a forked drill, Fig. 252, or -a crank formed drill, 253, will suffice, and if these are made to -cut deeply the result will be a succession of hemispherical knobs or -beads (these must not intersect). A drill like Fig. 254 will give a -knob raised in steps, and it is plain that by cutting the end of the -drill to a section of the required moulding the latter may be rapidly -executed. The flat inch long cutters used with the geometrical chucks -(when the work revolves instead of the tool) are, of course, made of -a variety of forms upon the same principle. Cases of these drills -and cutters beautifully finished are sold by all the leading dealers -in turning lathes and apparatus. It is essential that these tools be -kept very sharp, and that their cutting edges should be _polished_ if -first-class work is to be done. The difference in the appearance of -execution is very evident when the cutter is thus perfect, as every -cut bears a high polish, which cannot otherwise be imparted. Nothing -can be applied to finish eccentric work except friction with a hard -brush, and even this is much better avoided, as rubbing of any kind -tends to round edges which should be kept sharp and to obliterate -the finer and more delicate lines. It is likewise the best plan to -finish with any particular tool all the work to be done by it without -removing it from the tool holder for the purpose of sharpening. If, -however, this is necessary the following contrivance must be used to -insure the precise form which the cutter had at the commencement of -the work. This being likewise necessary with respect to the fixed -tools for ornamentation, the apparatus requisite in either case will -be introduced here, the drawings and description being extracted from -Holtzapffel's valuable work already alluded to. - - [Illustration: FIG. 251.] - - [Illustration: FIG. 252.] - - [Illustration: FIG. 253.] - - [Illustration: FIG. 254.] - -Fig. 255 is arranged for flat tools of various angles, or drills with -single joints. A, is the stand of brass, with two turned and hardened -steel legs. To this is hinged at G, by a screw joint, the part K, the -upper part of which forms a semicircular arc, C. A second arc, B is -fixed at one end to the stand A, and passes stiffly through a mortise -at the top of K. The latter can be raised, therefore or lowered at -pleasure upon this second graduated arc, and clamped at any angle -by the screw H. To the lower part of K is pivotted the tool holder, -D, the upper part of which is pointed, and screws as an index upon -the arc C, showing the angle at which it is placed. This tool holder -is clamped by a nut at the back, which fits the end of a screw seen -near the point. The figure below shows a tool holder which fits into -the projecting parts of D, and serves to hold the small flat tools. -Below is a similar holder, used for round-shanked drills. F is one of -three flat slabs upon which the tools are to be ground, there being -one of iron, one of brass, and one of hard wood with a flat strip of -oilstone imbedded in it, flush with its upper surface. The tool and -its fittings are generally arranged in a box with three drawers; these -contain the slabs of oilstone and metal, with the powders necessary -for grinding and polishing. To use this instrument, the point of D -is adjusted to the required angle for one side of the point of the -tool. (It is shown at 40 deg. in the sketch.) The latter is then -placed in the holder, and made to project until, when the angle of the -chamfer is adjusted on the arc B, the part A is level, and therefore -parallel to the surface of the grinding plate. The whole thus forms -a tripod, the third leg of which is formed by the tool itself. The -latter is first rubbed on the oilstone with a little oil. It is then -finished more perfectly on the brass slab, dressed with oilstone -powder and oil. Previous to this the tool is moved one or two degrees -more upright by the arc B. A narrow facet is thus ground, having a -dull grey polish. The tool is now carefully wiped clean, and polished -with crocus and oil upon the slab of iron. If the point of the tool -is central, with a chamfer both ways, the point of the tool holder -is first adjusted on one limb of the arc and the tool ground, and -then the same adjustment made on the opposite limb, so that the other -side of the point can be operated upon. Thus tools of any angle and -any bevel may be sharpened to a nicety without fear of altering the -original form of the point, and this may be done, if necessary, during -the process of eccentric turning, although, as before stated, it is -better to fix the tools well sharpened at the commencement of the -work, and not remove them until at _least_ one complete set of circles -or other patterns have been cut. - - [Illustration: FIG. 255.] - - [Illustration: FIG. 246.] - - [Illustration: FIG. 247.] - -The instrument just described is evidently unsuited for the drills and -bead tools which present a concave edge like 246 A, B, C, enlarged -sketches of tools copied from Holtzapffel's work. For these the -latter directs to use large or small cones (247) of iron and brass, -to be dressed, the first (which is the polisher) with crocus, the -second with fine emery and oil, the flat side of the tool being held -towards the point of the cone, the bevel towards the thick end. Part -of the edge of C must be delicately sharpened by hand, as no guide -can be used for the step-like portion of the edge. The cones for -sharpening are either mounted in the usual manner, by one or both ends -in the mandrel of the lathe, or fitted into the spindle of a small -drilling lathe-head, the pulley of which is connected by a catgut -band with that of the mandrel of the small lathe-head, being fitted -with a tailpiece to fit the rest socket, or otherwise mounted on the -lathe-bed. The smaller cones especially require to be driven at a high -speed. When larger circles or mouldings are to be cut, these small -crank-form drills are no longer available, and are replaced by a very -simple, but most effective contrivance called the eccentric cutter, -by which any work that is within the scope of the eccentric chuck -and fixed tool may be executed with great precision and rapidity. -This is represented in Fig. 248[20]--a small oblong frame of brass, -about two or two-and-a-half inches in length, and half an inch or -so in breadth is traversed by a fine screw, prevented from moving -endwise by a collar, as in the slide rest (of which, indeed, this is -a miniature). A slide, C, with a little tool holder at the top of it, -is moved along the frame by the leading screw, the head of the latter -being graduated, and also the upper surface of one or both sides of -the frame. The projection A, fits into the end of the drill holder, -and is secured by a screw. Circles of a diameter equal to B, B" may -thus be cut, and their effect varied by placing tools of any form of -edge in the tool holder. Such a tool as A, will thus no longer cut a -minute circle forming a hemispherical raised knob, but will form a -circular moulding, such as that shown in part at Fig. 249, except when -the tool holder is on the middle of the frame and the tool concentric -with the mandrel. The single point tools, however, with single or -double bevel, are more commonly used, in this cutter, as mouldings -can be turned as efficiently with hand beading tools, with or without -the eccentric chuck, according to their required position. It may here -be mentioned that eccentric work should always be cut on wood of one -colour, or on ivory, as the veinings of the richer fancy woods, which -are so beautiful in other cases, only serve to confuse the tracery -made by the eccentric cutter. Of all woods for fancy work with the -eccentric chuck or cutter, nothing equals African black wood. It is, -however, costly, and only ranges to a diameter of five inches, as -great part is unsound. The rind is hard, thick, and white, similar to -boxwood. Next to this for such work stands, perhaps, cocus, or cocoa -wood, which is not the tree bearing the cocoa nut, the latter being a -palm, which is more like cane in texture. One of the most effective -patterns to be formed by the eccentric cutter is the shell, Fig. 250, -in which one side, or rather one portion of the circles composing it, -is very deeply cut, while the opposite part is shallow. This can be -simply effected by throwing the sole of the rest out of the level, -by placing a thin piece of wood or metal across the lathe bed, so as -to tilt up the rest and place it (with the cutter) in an inclined -position. The tool will thus begin to cut at one part before it -touches the surface elsewhere, and the desired effect will be readily -produced. In using the eccentric cutter great rapidity of motion -must be given to it, but the tool must be advanced very carefully, -or it will be broken. The lever handle is the best to use for the -purpose. Akin to the shell pattern are those in which part only of -the circles are cut, leaving an effect shown by the border round Fig. -250. This is produced in the same way as the last, being, in fact, a -ring of shells in their initiatory stages. This is a very effective -snake-like pattern, when fairly and cleanly cut. When the eccentric -cutter is used, it must be remembered that the principle of work is -not quite the same as with the eccentric chuck. With the latter it -was stated that the size of the circles depends on the slide rest and -the position of their centres on the chuck. In the present case the -eccentric cutter regulates the sizes, and the screw of the slide rest -itself the positions of the centres of the circles, since the part -A of the cutter will always be in the centres of the same, and this -part is attached to the rest. It will be understood that this remark -respecting position of centres only relates to circles lying on the -diameter of the work, such as Fig. 251, the distance between _a_ and -_b_ will be taken from the division plate on the pulley of the lathe. -The way to cut the above, for example, will be as follows:--Place -the slide rest so that when the cutter tool is in the centre of the -frame it shall be concentric with the mandrel. In this position it -will only make a dot in the centre of the work. Turn the screw of the -cutter frame until you have a radius sufficient for the centre circle. -Set the mandrel pulley with the index in No. 360, put in motion the -overhead apparatus and cut the circle, move the screw of the slide -rest a few turns (_thus fixing the centre of the second circle_), -until you find that the cutter will form the circle cutting the first, -and passing through its centre. (_Observe, this being the size of the -first, the screw of the cutter frame is not turned._) Cut the circle -in question, move the mandrel pulley a quarter round, so that the -index is in No. 90, and cut another; repeat the process twice more, -and 1, 2, 3, 4, will be cut. The _position of the centres_ of Nos. 5, -6, 7, 8, will now have to be determined as before, by working the main -screw of the slide rest; but, as their size is less than the preceding -set, the screw of the cutter frame must likewise be turned to diminish -them to the required degree. When by these combined movements their -position and size have been determined, they must be cut by the aid -of the division plate, in the same manner as the last, and so on, -till the whole have been cut. With respect to the ratio in which the -circles diminish, and the precise sizes of them, no rule can be given, -as this must depend on the taste of the operator. The sole object in -this place is to show the _principles_ whereby these patterns are to -be executed. A good deal of care is requisite in practice, and the -memory has to be often rather severely tasked. The best plan is always -to try a proposed pattern upon boxwood or paper, before risking it -upon more valuable material; and, where it can be done, it is well to -write down the numbers to be used on the various division plates. A -single false cut, it must be remembered, will spoil the whole work, -at a great waste of time, loss of material, and annoyance, only to -be appreciated by those to whom such an untoward accident may have -happened. The drilling apparatus, without the eccentric cutter, but -fitted with a round-headed drill, is used for the production of fluted -works, such as that shown in Fig. 252, A and B. The drill being -inserted in the end of the spindle, and its point or end (of any -desired form, either round, flat, or pointed) being brought opposite -one end of the flute, the lathe is to be put in motion as in ordinary -ornamental drilling, the mandrel being, of course, held fast by the -index and division plate. At the same time that the drill in rapid -motion is brought against the work by the lever handle, the screw -of the slide rest is slowly turned, and thus the groove or flute is -drilled out by the combination of longitudinal and vertical action. -The number of flutes in any given size of cylinder is determined, -first by a horizontal sectional plan on paper, and regulated -accordingly by help of the division plate and index. In making such -an article as Fig. 252, it will economise material, whether ivory or -blackwood, or a combination of the two, to form it of at least three -pieces, making the divisions at C, D. Care should be taken to leave -below the bowl, which should be as thin as paper if of ivory, the -part C on which the beads are to be drilled. The pedestal can then -be screwed into this, and will not penetrate the bottom of the bowl. -Ivory may be screwed in an ordinary set of stocks and dies if care is -taken not to screw up the latter too quickly. Lard may be used as a -lubricant in cutting this material, whether for sawing or drilling. -The part with raised mouldings between A and D is ornamented with -a vertical or universal cutter, and for greater ease and exactness -a template may be used in the slide rest by means of which all the -curves of the moulding may be accurately followed by drill or cutter. -The minute beads round the edges of the small mouldings are made with -two sizes of A, Fig. 246; a little knob is thus formed rising from a -hollow. The small knobs used as feet may be rapidly formed by a hand -beading tool of semicircular section, similar also to A, Fig. 246. A -pin may be left on each, or they may be drilled and attached by small -screws of brass wire made on purpose. The following cement will enable -the turner to make an ivory bowl for the above ornament so thin as to -be transparent; indeed it may be thus made so thin as to bend under -the fingers, although such extreme tenuity is not required in the -present case. - - [20] A newer pattern appears on a later page. - - [Illustration: FIG. 248.] - - [Illustration: FIG. 249.] - - [Illustration: FIG. 250.] - - [Illustration: FIG. 251.] - - [Illustration: FIG. 252.] - -Take the finest sifted lampblack and make it into a paste with glue, -about as thick in consistency as paint. After turning the ivory -tolerably thin, paint this on the inside; let it dry, and repeat the -process till sufficient is laid on to form a kind of hollow core, -of strength sufficient to support the ivory against the action of -the tool. The material may now be thinned and ornamented from the -outside. When finished, soak a few minutes in warm water, and then -agitate in cold; it will become quite clean as before. - -By altering the direction of the motion of the revolving cutter, the -several cuts made by it will assume a different character, and the -work will present a series of hollows scooped out, so to speak. The -cutter, 253, being fixed in the tool holder of the top slide, will -work vertically only, and produce patterns similar to Fig. 254, of -the nature of basket work. This is exceedingly effective, and, as it -may be cut so deeply as to penetrate the material of hollowed works, -the latter may be lined with red or other bright coloured silk or -velvet, and a variety of designs thus worked out. It is very necessary -in using the vertical cutters to move the tool holder forward very -gently, giving it at the same time great rapidity of revolution. -Without this it will at once stick fast in the work. The character -of the designs may, of course, be infinitely varied by using cutters -of different sections, as in the case of work done with fixed tools -with the aid of the eccentric chuck. The same cutters will, in fact, -serve both purposes. Fig. 255 represents a tool similar to the last, -but arranged to cut horizontally. With this, fluted work can be -done: but it is evident that the cord from the overhead apparatus -cannot here be directly applied, owing to the horizontal position -of the driving pulley. Additional guide pulleys, therefore, become -necessary, and, when these have to be arranged, the apparatus is -generally modified, and the universal cutter is used, of which one -form is shown in Fig. 256, and though it is not so good a pattern as -that which is described in a later page, it is nevertheless suited -for use with the old pattern of slide rest already delineated. With -this the direction of the cuts may be varied at pleasure--they may -be perpendicular, horizontal, or radial, and, when the templates -before mentioned are added to the slide rest, an infinite variety of -devices may be cut upon spherical and curved surfaces, so that the -cutter thus modified is fully entitled to its title of "universal." -The design, Fig. 258, is entirely the work of revolving cutters and -drills used with a template of the required section. It is intended -for a lady's workbox, opening with a hinge on the line, _a, b_, and -containing in separate compartments the various articles required. -It may be made entirely of ivory, lined with red or blue satin, and -the flutes round the body may be cut through to allow the lining to -appear. In the latter case, however, if the box is of ivory, black -velvet may be used to enhance the contrast, and, as the glossy pile -would be outwards, a second lining of any desired colour should be -added with the best side inwards. The rings for the handles, as for -all similar purposes, can be quickly made with the tool, Fig. 259. A -hollow piece of ivory being taken, and turned smooth inside and out, -one side of the tool is applied, as in the figure, so as to cut half -through the work. It is then removed, and the opposite edge applied -to the inside until the ring falls off completely finished. It is -then cut through with a thin saw or knife, and inserted in the tailed -ring or other projection intended to receive it. Handsome works in -ivory should always be kept under glass shades. The universal cutter -shown in Fig. 256 consists of a plate with chamfered edges to fit -the tool receptacle of the slide rest, having near each end small -poppets which support the round rod connecting the pulley bearing -piece, A, with the part, E, which carries the tool, F, the latter -being attached by a small slot and set screw to a cylinder revolving -in E, and having at its upper end the driving wheel, C. At G is a -circular piece or wheel racked on the edge, and turned by the tangent -screw, G. The hinder poppet is rectangular, and has divisions marked -upon it on each side of the angle numbered from the apex. The racked -wheel may with advantage be similarly graduated. When the part E is -vertical the cutter will be in a position to work horizontally, and -the pulley support will be vertical. By turning the tangent screw, -both the parts move together; but if desired the pulleys can move -independently by unscrewing D and L. The angular poppet may be made -semicircular if preferred, the degrees being numbered either way from -0" in the centre. When the tool holder is horizontal, or approaching -that position, the nut, D, must be loosened, and the pulleys placed -so that the cord will not slip off. They may be dispensed with if the -apparatus is to be used ONLY for vertical cuts (the _holder_, -E, will be horizontal); but if a radial pattern is to be cut, in -which the angle is to be constantly varied, the pulley piece must be -used and the pulleys re-arranged at D, as required from time to time. -There is a somewhat neat and serviceable little apparatus represented -in Fig. 259A, to take the place of the slide rest and its -revolving cutters, and although its powers are limited, much may be -done with it. The spindle A, works through brasses in the poppets, B, -B, and is put in motion by a cord from the overhead passing over the -pulley in the centre. This spindle, which holds the crank-formed and -other drills in a socket at one end, moves freely through the bearings -endwise, and is kept back from the work by a spiral spring working -against the end of the handle, C. This handle does not turn with the -spindle, but is mounted like the handle of a carpenter's brace, or -that of an Archimedean drill stock. The whole apparatus fits into the -socket of the ordinary rest. A screw should have been shown in the -drawing, passing through B towards the pulley, to regulate depth of -cut. - - [Illustration: FIG. 253.] - - [Illustration: FIG. 254.] - - [Illustration: FIG. 255.] - - [Illustration: FIG. 256.] - - [Illustration: FIG. 258.] - - [Illustration: FIG. 259.] - - [Illustration: FIG. 259A.] - - [Illustration: FIG. 260.] - -Once fixed by the screw of the latter in its intended position the -tool is advanced to the work in a straight line by pressing the handle -C, and is released from the cut as soon as this pressure is withdrawn. -With different sizes of cranked, forked, or round ended drills, a good -deal of ornamentation may be done with this simple tool, which is also -useful for ordinary light drilling. By putting in the socket a round -ended drill, and using the radial movement (turning the whole round in -its socket in the arc of a circle), short flutes can be drilled out -deep in the middle, forming basket work similar to Fig. 260, which is -exceedingly pretty when carefully executed. There is little difficulty -in making drills and cutters, as steel of all sizes in round and -square bars may be had at the chief tool shops, especially at Fenn's, -in Newgate-street. In making the revolving cutters, however, it is -necessary to observe the position of the axial line, which must -pass through the cutting edge. After the drill is roughly finished, -therefore, it should be mounted in the tool holder with which it is -to be used, and carefully tested upon a piece of unimportant work. -If in revolving against the latter it leaves a part of the material -untouched, the edge is not truly in the centre of rotation. The flat -side of the drills are to be diametrical, and hence, as Holtzapffel -remarks, these drills can only be sharpened on the end. The latter -authority also says most of the drills embrace (in contour of edge) -only about one-fourth of the circle, as when the drills are sharpened -with one bevel they can only cut on the one side of the centre, and -if the drills were made to embrace the half circle the chamfer of the -edge on the second side would be in the wrong direction for cutting, -and consequently it could only rub against the work and impede the -action of the drill. All ornamental cutters and drills should be kept -in a box with small separate divisions to fit the shanks, which are -all of one size. The points can then be seen and the selection made of -any required pattern. - - - CURIOSITIES. - -Many turners take special interest in the production of objects in the -lathe, that at first sight appear impossible to be produced solely -by its means. Inasmuch as such works manifest the skill and patience -of the artificer, they will always meet with appreciation; and, -although otherwise useless, they serve as elegant objects of vertu, -and are well worthy a place among the rare ornaments of the drawing -rooms. When first the Chinese balls, consisting of a set of hollow -spheres one within the other, all exquisitely carved, were brought -to England, it was believed they were made in hemispherical pieces, -united round the equatorial line with some kind of cement, the joint -being carefully concealed. I am not sure that they are made in a lathe -in China; but, at all events, they are so made in England, and our -home productions almost rival those of that strange yet clever nation. -I say almost, because the carving in ivory done by the Chinese is in -some respects unequalled, nor do I suppose that work requiring in many -instances years of patient industry could be made to repay the cost -of manufacture in England. No sooner were these curiosities in vogue -here than all kinds of similar impossibilities were manufactured. -Stars with from three to a dozen rays made their appearance, enclosed -sometimes in similar sets of hollow spheres--the rays projecting -beyond the limits of the outer shell--others were wondrously enclosed -in cases with flat sides, cubes, pyramids, six, eight, twelve-sided -hollow cases, all turned fairly in the lathe, were produced with -similar contents, so that the apple in King George's dumpling became a -very secondary wonder. The starry inmates were evidently too large for -the houses; yet there they were--legs and arms, of course, sticking -out through doors and windows, simply because there was no room for -them inside. We will penetrate the mystery, commencing with a single -hollow ball containing a star of six rays, the bases of the latter -standing on a central cube. - -In the first place a perfect sphere is required, and consequently the -slide rest and template, or spherical rest, must come into requisition -unless the turner can produce a ball by hand tools alone. Let this -sphere, or rather its boundary line, be drawn on paper of full size -with the compasses, Fig. 262, A, B, C, D. Draw the diameters A, D, -C, B, at right angles to each other. This will give you five points, -which on the sphere itself (on which these lines will have to be -drawn, including also another, answering to A, B, C, D) are centres of -six openings, here represented by the circles, through which the tools -have to be introduced to hollow out the sphere and form the star. The -points of the latter will be in the centres of these openings. Draw in -addition the plan of the central cube, and one ray of the proposed -star; next draw an inner circle, here dotted to mark the thickness of -the outer envelope. The object of this drawing is to enable you to -make a set of curved tools, one of which is shown black at E, and a -set are marked on a plate of steel, from which they must be cut out. -A close inspection of the figure will show that if ball, Fig. 262, -were turning on the point A, A D being its axis of revolution, tools -of the given section introduced at D would cut away the material -round the point or ray, leaving the latter standing;[21] and this -operation repeated at the five remaining openings would entirely free -the central cube with its rays according to the proposed design. The -tools have to be introduced in order, beginning with the smallest; and -although the above remarks will make clear the principle, there are -several points to be attended to in practice, and some few accessories -are required which will now be explained. It is evident that for -every different sized sphere fresh sets of tools will be requisite, -which will also vary in pattern according to the intended form of -the central base on which the rays stand; a cube or flat-sided solid -requiring one tool at least, with a rectilineal edge; spherical or -other solids demanding others whose ends are of different section. -Hence, in all cases, full-sized plans of the proposed work must be -drawn, and special tools designed therefrom. - - [21] There is an error in the position of this tool, which, thus - placed, would not leave the point of the star. Fig. 270 will explain - the method better. - - [Illustration: FIG. 262.] - - [Illustration: FIG. 269A.] - - [Illustration: FIG. 269B.] - -Fig. 269A is introduced to show more clearly the result of -the application of the first set of tools, or rather of the first -application of the set, as the latter are used throughout. - -The blackened part will be entirely cut away in this operation, the -shaded part meeting it will be removed when the tools are transferred -to the adjacent opening, the cuts meeting those first made. Hence -the tools need only reach from _a_ to _b_, and can be more easily -introduced than if the curved part were longer. Gauges, Fig. -269B, A, must likewise be made of thin brass or tin, that the -progress of the work may be examined, and each opening in the sphere -should likewise be measured with a gauge, or with compasses fixed to -one width by an adjusting screw. - -The proper chuck for this work is the capped ball chuck already -described, by loosening the cap of which any one of the six openings -may be brought under the action of the tool, these openings being, in -fact, bored out simultaneously with the formation of the star. After -the first point or ray of the star has been completed, the ball may -be reversed and the opposite ray formed. These are now to be secured -by plugs, which are to be turned conical, to fit the opening of the -ball at one end, and of a length to rest upon the central cube at the -other, being also bored out to fit over the rays, which they should -embrace closely at top and bottom, even if not at the other points -of its length. (Fig. 269C, A and B.) This is to be repeated -as each ray is formed, so that the central star may be held in place -until the work is finished, when the plugs are removed, and the star -will be entirely detached. The above-named tools being straight on the -right hand side of the shank will not form a finished _conical_ point -or ray. Hence it is recommended to file away that side, so that when -flat upon the rest, the back of the tool may be an exact counterpart -of a ray, Fig. 270, A. There is, however, no absolute necessity for -this, as the star point can be first made blunt, with perpendicular -sides, which can then be neatly finished by a separate tool made for -the purpose, and kept up to a very keen edge. The first and smallest -of the set of tools here shown, is the one with which the flat sides -of the cube are formed, and it must be bevelled from underneath, so as -to present a cutting edge on the end. The curved tools should cut on -the end and both sides of the crook. - - [Illustration: FIG. 269CC.] - - [Illustration: FIG. 270.] - - [Illustration: FIG. 270A.] - - [Illustration: FIG. 271.] - -It is quite possible to make the above in mahogany, but a closer -grained wood is much to be preferred, as the tools used--which are -held flat upon the rest--are rather scraping than cutting, and -mahogany, and fibrous woods in general, cannot be thus worked neatly. -Boxwood is, in every respect, the best material to begin upon, ivory -and blackwood being reserved until the eye and hand have become -accustomed to such work. The whole operation requires great care, and -is rather tedious, but the result ought to be a sufficient reward. -The external surface may, of course, be ornamented with the usual -apparatus, but the star should be left clear and sharp. The edges of -the openings should have a light beading, cut with a bead tool, Fig. -271, A and B. - - - GROOVING AND MORTISING SMALL WORK. - -Amongst the various purposes to which it is possible to apply the -lathe, may be noticed the drilling out grooves and mortises, a method -used in some of our Government arsenals, for cutting the recesses -for the reception of the Venetian lath work in cabin doors. The same -method is, of course, applicable to numberless similar cases, although -designed for the special object named. The apparatus is shown complete -in the drawing, Fig. 272, and the component parts in the succeeding -diagrams. A is a kind of compound slide rest, or vertical straight -line chuck, having a movement in a direction parallel with the lathe -bed at F; while the circular plate being pinned through its centre -to a slide, H, can be moved up and down by means of the handle G. -This circular plate can be set in any position, and has a projecting -shelf or rest to carry the work, which is steadied by guide pins, as -will presently be explained. The part F, has a bed similar to that -of an ordinary slide rest, which is clamped to the lathe bed by a -bolt and nut, as usual. This carries likewise chamfered bars, between -which slides the horizontal plate to which the vertical part of the -apparatus is attached. This is first a plate with chamfered edges, -Fig. 273 A, and a second similar but rather wider plate, Fig. 274 B, with -guide bars, likewise chamfered, to slide upon A. From the front of B -rises a stout pin, on which the circular plate, C, turns, which can -be clamped by a central nut, or otherwise, as in an ordinary compound -slide rest. This nut should not project above the general level of the -plate. On the face of the latter is, as previously stated, a rest, or -narrow metal shelf, D, and pins, _e_, _f_. The plate may be variously -arranged in this respect by substituting any kind of holdfast or -guide, according to the work desired to be done by its aid. The upper -slide is depressed by a hand lever acting on a pin fixed in the -sliding plate, Fig. 275; or, if preferred, by a similar lever, with a -quadrant and chain, or rack movement. The horizontal slide is worked -by means of a stirrup for the foot, with cord attached, acting on a -bell-cranked lever, seen in the first figure. To cut the grooves in -a bar, for Venetian blinds--as described--the lath to be drilled is -attached to a flat strip of thin iron, drilled with holes, Fig. 276 A, -as wide apart as the required distance between the grooves. It is then -laid against the shelf, and the guide pins are made to enter the holes -in the iron. The clamping nut of the round plate is loosened, until -the bar is set to such an angle that the grooves to be cut will form -vertical lines, Fig. 276. It is then clamped securely. - - [Illustration: FIG. 272.] - - [Illustration: FIG. 274.] - - [Illustration: FIG. 275.] - - [Illustration: FIG. 273.] - - [Illustration: FIG. 276.] - -It is necessary to be able to adjust the piece to be cut, as regards -its height, above the lathe bed. This is effected in part by the -position of the movable shelf--fixed by pins--and partly by guide or -set screws, which regulate the traverse of the slides. Suppose the bar -adjusted as in Fig. 276, the groove to be cut being brought opposite -to the drill. The set screws--two of which are seen at _x, x_, Fig. -275--acting on the handle, regulate the precise length of each groove. -A similar stop, connected with the horizontal part of the machine, -regulates the advance of the wood towards the drill, and thus the -depth of the cut. Hence it is only necessary to set these carefully -at starting--the pins on the guide plate insuring the proper width -between the grooves--and the lathe being put in motion, any number of -precisely similar grooves can be drilled with the utmost rapidity and -neatness. - -An inspection of the drawings will show what numberless purposes may -be served by this simple apparatus, which may be modified in its -details, while its principle of action is maintained. The drill should -have a chisel and be kept to a keen edge. The lathe should be put in -rapid motion, and if the required cut is to be deep, it should be cut -at twice. The lower slide should return to its place by means of a -spring when the foot is raised, the vertical slide being movable in -both directions by means of the slotted part of the handle. - - NOTE.--The above being taken from an apparatus for a - steam lathe, the stirrup action maybe used, as the foot is at - liberty. A foot lathe would require a slight modification. In - Fig. 275, the depressing handle is shown as if the chamfered - bars were fixed to the sole plate, and the plate A, were - movable, as is sometimes the case. When made according to the - above description, the handle would, of course, be pinned to - the fixed vertical plate, A, to which also the stops would be - attached, and the pin which passes through the slot of the - handle, must project from one of the chamfered bars. Either - plan may be followed, but the pattern described is calculated - for a stronger apparatus; inasmuch as the vertical plate can be - secured more firmly to the chamfered horizontal slide than the - mere pair of guide bars--the two might, in fact, be made in one - casting, if preferred. - - - ORNAMENTAL TURNING. - -The slide rest previously described, although applicable to the -purposes of ornamental turning, has one disadvantage. It is necessary -that the various pieces of apparatus to be used with it should have a -foundation plate with chamfered edges to fit accurately between the -guide bars. This is often inconvenient, and adds to the difficulty of -making, and consequently to the cost of such pieces. In addition to -this drawback, it may happen that one of these fittings by being more -frequently used becomes more worn than another, so that the guide bars -require constant re-adjustment, and their accuracy and parallelism -become impaired. To obviate these and similar inconveniences the -slide rest is now commonly made like Fig. 277, and a tool receptacle, -Fig. 278, is fitted to slide between M, M, and is so arranged as to -hold securely the universal cutters and other apparatus required -for ornamentation or for plain turning. These are all made with a -rectangular bar fitting the longitudinal channel in the middle of the -receptacle, and are secured by the following simple contrivance. It -will be seen by the drawing that the central channel is widened at - A, A, and that a groove or saw-cut B runs along the inside from end to -end. This groove is continued in a similar manner on the side next -to the reader. Fig. 280 represents an ordinary tool holder, with a -rectangular shank A, and clamping screw B, by which the tool _c_ is -secured. The part A is laid in the central channel, and a small piece -of metal shaped like Fig. 279 is inserted in one of the open spaces, -A, A of the receptacle and slid along with its lower flange in the -saw-cut until clear of the enlarged part of the channel. It is thus -retained, and the clamping screw which passes through its centre is -brought to bear upon the piece to be fixed, which is thereby securely -held in its required position. Two of these holdfasts are generally -used at the same time. If the main bar of the tool holder is not -quite thick enough to be clamped, then it is only necessary to lay a -small plate below it. By the above simple means, the necessity for -fitting each individual piece of apparatus to work upon the chamfered -guides is done away. In order to ensure the position of the sole of -the rest at right angles to the lathe bed a kind of saddle, A, Fig. -281, is used. This is of cast iron or brass, accurately planed on -the upper surface, and has a projection fitting between the bearers -of the lathe. The usual holding down-bolt passes through the hole in -the centre, securing the saddle and the rest at the same time. The -usual arrangement of a kind of double socket, the inner one rising at -pleasure by being tapped into the outer, has already been described, -and serves for accurate adjustment of the height of the rest. It is -convenient, in addition, to have a stop or set screw under the bed -of the rest, and a similar one on the top of the socket, so placed -that when the frame is swung round it shall stop precisely at right -angles to its former position. Thus, if the tool is first required -to be used upon the side, and then upon the face of the object to -be turned, these two positions are obtained at once, and can, if -necessary, be alternated without any re-adjustment of the moving -parts of the rest by the aid of the set square. The receptacle-holder -is generally advanced by the hand lever, Fig. 279, one pin of which -fits into the hole in the guide-bar as seen in the drawing, while -the other falls into a short slot _e_, made in the upper surface of -the receptacle, or of the piece of apparatus to be used in it. Of -course, this arrangement may be reversed, one or both pins being -fixed to the rest and its receptacle slide, and the holes made in -the lever. Sometimes, however, a slower and more regular movement is -required than it is possible to give in this way, and the lever is -replaced by the leading screw C, D, Fig. 278, the head of which is -removable, and can be replaced by a small winch handle. This screw -is tapped into the lug cast upon the receptacle, and its point is of -the form shown. The latter fits into a hole in the pillar A, 278, and -is retained by a pin, which falls into the groove, D, Fig. 278, and -prevents the screw from advancing or receding without carrying the -sliding plate with it. The pin being removed, the screw will no longer -act in this way, and the slide may be moved by the lever instead. -The other screw, E, F, of fine pitch, serves to regulate the advance -of the receptacle, and consequently the depth of cut of the tool--a -round head with divisions on its edge is attached to one end, which -abuts against the pillar B, Fig. 277, which latter has a mark on its -top to act as an index. Thus the advance of the tool can be regulated -to a great nicety, and successive predetermined and different depths -may be reached and repeated at pleasure, as is sometimes necessary. -C, C, Fig. 277, is one of a pair of stops which can be fixed by their -screws at any two points of the bed of the slide rest. These serve -to regulate the distance which the top slide and tool holder are -intended to traverse, as in drilling a number of flutes of equal -length, and many similar works. They are usually made of gun-metal, -the screws of iron or steel, or of a metal called homogeneous, which -may be described as between the two, and, being pleasant to work, is -worthy of notice. It is absolutely necessary that the slide rest for -ornamentation should be made with the greatest nicety. The slides must -work equally smoothly from end to end of their traverse. The pitch of -the screws must be not only fine, but even and regular, and the screw -itself of precisely the same diameter from end to end, else it will -work loosely through its nut in one place, and jamb in another. It is -extremely pleasant to feel the exquisite smoothness and oiliness, for -no other word will express it, of the movements of sliding parts in -the workmanship of Munro or Holtzapffel, especially if compared with -inferior work. _Good_ amateur's work indeed is often far superior to -that which is sometimes advertised, and perhaps a few hints may not -be out of place here, relative to the construction of this necessary -addition to the lathe. - - [Illustration: FIG. 277.] - - [Illustration: FIG. 279.] - - [Illustration: FIG. 280.] - - [Illustration: FIG. 278.] - - [Illustration: FIG. 281.] - - [Illustration: FIG. 282.] - -First of all, the frame of the rest must be accurately at right angles -to the spindle, which fits into the socket. These should, therefore, -be turned together, supposing the amateur not to have a planing -machine. The whole may be mounted as Fig. 282, where A represents the -carrier plate or chuck; B, the driver, the tail of which should be as -long or nearly so as the frame from _c_ to D; F is the side tool to -be fixed in the slide rest for metal. The effect of this arrangement -is to plane the face of the slide with transverse strokes instead of -lengthwise. It may be afterwards finished and polished with oilstone -powder on a flat slab of planed iron. When the face is finished, -the whole must be reversed, the pin of the carrier plate will bear -against the frame, which thus acts as a driver, and the spindle must -be turned. In this way accuracy is ensured if the slide rest used is -carefully set. The chamfered sides of the slides are difficult to work -with the file, but may be so done with care, and with a template of -the desired bevel as a guide. The great secret is to take plenty of -time, not to press too much upon the file nor to move it too quickly -over the surface; fine even strokes, especially towards the finish, -must be given, and a final polish with oilstone powder and oil used -on a piece of a stick. In turning the screw a back stay must be fixed -opposite to the tool in the slide rest to insure the contact of the -cutting edge without bending the work. - -Presuming that the screw will be cut with stock and dies, it may be -stated as a caution that the latter must not be tightened except at -the commencement of cutting the thread deeper. The return of the tool -by a backward motion (or unscrewing), should not be used as a cutting -action, and therefore, should be carried on with the dies in the same -position which they had during their descent. - -At the beginning, therefore, of each downward movement the dies must -be tightened and oiled, and they must not again be touched till the -bottom of the screw has been reached, and the upward movement also has -been completed, so that they have arrived again at the starting point. -If tightened at any other time the screw will be either conical or of -a wavy section, either of which forms would be fatal to its use. The -castings for such a rest should be of malleable iron, if possible, as -being much more easy to work; the guide bars may be of gun metal, as -also the chamfered bars, which work on the main frame. This will give -a more finished appearance, and will on the whole be more durable and -satisfactory. - - - THE ECCENTRIC CUTTER FRAME. - -One of the most useful tools for ornamentation, especially of plain -surfaces, such as the top of a box cover, is the eccentric cutter, -Fig. 283. The shank, A, lies in the receptacle holder of the slide -rest, and is drilled throughout to receive a steel spindle, carrying -at one end a double pulley, B, to receive the cord from the overhead -motion, and at the other frame, E, with its leading screw, of which -the movable milled and graduated head is seen at H. This frame has -one surface, level with the centre of the main spindle, which is cut -away as shown, and, consequently, as the point of the tool is on its -flat side, which latter rests upon the frame (the bevel being below), -this point can, by the tangent screw, be brought into a line with the -centre of the main spindle, so that when the cord from the overhead -is passed round B, the spindle revolves with great rapidity, and the -point of the tool, K, in the position described, makes a simple dot. -By turning round the milled screw head, H, either by the thumb and -finger or by a small winch handle, fitted on the square part beyond -the head of the screw, the tool holder, D (which is in one piece with -the nut of the leading screw), is made to traverse the frame, and the -tool will cut a circle small or large according to the eccentricity -thus given to it. In Fig. 285 D, is the tool holder on the front of -the frame; C, the end of the spindle; L, a bell-shaped washer, which -is acted on by the small square-headed screw, drawing D towards the -frame and clamping the tool. The whole is in the figure of full size. -The tool holder is in one piece with the nut, through which passes -the leading screw, and which is continued as a screw for the action -of the bell-shaped washer and tightening nut; hence it is necessary -to allow a degree of play between the nut and leading screw, to -prevent bending the latter when clamping the tool. This is effected -by filing off the threads in the nut at the top and bottom, to render -the whole slightly oval. The remaining threads suffice for the action -of the leading screw: a very slight degree of play in the required -direction will be found sufficient. The powers of the eccentric -cutter frame will be found sufficiently extensive to make it a most -serviceable, perhaps necessary, piece of lathe apparatus. If it cannot -be said absolutely to supply the place of the eccentric chuck, it has -nevertheless the advantage of great lightness of construction, lowness -of cost, and ease of manipulation. The weight of the eccentric chuck, -whether single or double, as of all chucks in which sliding plates -are used, is a sad drawback to their value--a drawback unfortunately -beyond remedy, and specially felt when the slides are drawn out to -a great degree of eccentricity. Combined together, these two form a -_compound_ eccentric chuck, and in this way are capable of nearly -everything in the way of eccentric ornamentation. Where the _chuck_ -is not to be had, it is by all means advisable to procure the cutting -frame, for which the writer confesses a great partiality. It appears, -indeed, to him a far more rational proceeding, as it is also now of -extensive application, to act upon fixed work by revolving or moving -tools, instead of proceeding in the contrary way; and all these little -tools used with the overhead apparatus are so lightly and elegantly -constructed, and so well adapted for the parts they have to perform, -that the originator of them (_native talent devised them_), deserves -to be well and lastingly remembered; instead of which it is doubtful -whether his name is even known. (_Sic transit_ is a quotation too -stale for this work.) - - [Illustration: FIG. 283.] - - [Illustration: FIG. 285.] - - [Illustration: FIG. 285B] - -To cut circles deeper in one part than another--the shell pattern, -for instance--with this tool, it is not necessary to alter the level -of the sole of the rest, as it is when the eccentric chuck is used -with a fixed tool, as it suffices to set the rest itself at an angle, -by moving it round in the socket, so that the revolving tool should -touch the face of the work sooner at one point than at an opposite -one. In the same way the work may be considerably undercut on one -side of the circles, by giving the angular set to the rest, and -placing a tool in the holder, with a point of the form shown at 285 -B. There is nothing prettier than this undercut work when well and -sharply done, for which purpose the tool should not only be rendered -keen on the hone, but burnished and polished on the brass and iron -slabs already described. - -The following remarks on the work of this cutter frame on flat -surfaces only, will be useful to the reader in designing and working -out the various combinations of circles, intersecting or otherwise, -which it is calculated to produce. On a surface represented by 286 A, -the line of circles, _a, a_, is on a diameter, and, supposing them to -be described by the eccentric cutter (or by a simple double-pointed -drill), their centres are obtained by means of the leading screw of -the slide rest, moved the requisite number of turns between each cut, -while the work is retained in a fixed position on the mandrel. But -if the line of circles is on such a line as _b b_, above or below -the centre, and consequently not on a diameter, it is plain that no -movement of the slide rest or cutter, or both, can avail to place -them in position, except with great difficulty and tedious working -with the division plate of the lathe and the screw of the slide rest. -Hence the eccentric chuck must be brought into play, and being fixed -with its slide in a vertical position, the screw is turned and the -work is lowered thereby until the line _b, b_, is on a level with the -point of the tool. The eccentric cutter or double drill will then -suffice to work the row of circles. When the centres of the circles -are themselves on parts of the circumferences of other circles, the -division plate of the lathe or of the eccentric chuck will be called -into requisition, according as these circles are concentric with -the mandrel or otherwise. In Fig. 286B, the curved lines are parts -of circles of equal size with that representing the surface of the -work, and their centres lie on one and the same diameter, viz., at -opposite extremities of the line, _a, b_. Being thus eccentric to -the work, the division plate of the chuck is used to arrange the -intersecting circles of the pattern--its slide having been first -drawn down, until the centre of the arc to be worked with circles -is brought opposite to the tool. The work will be in position when, -on turning the mandrel slowly, the cutting point of the tool passes -across its centre. The division of the original circle is in this -instance into four parts, two of which are thirds, and two sixths of -its circumference. The arcs of circles are also lines equal to thirds -of the circumference of the work. It is well to remember this division -of a circle by other equal circles described round it from points -on its circumference, these circles passing through the centre. The -original circle will in this way be divided, as shown at C, into six -equal parts. To produce it with the aid of the eccentric cutter is -easy. Set the tool of the cutter first to the centre of the work, so -that on revolving it will make a simple dot. This should always be -done, whatever pattern is subsequently to be cut. Fix the index of -the division plate of the lathe at 360. Move the screw of the slide -rest until the point of the cutter, on being advanced, rests on the -circumference of the circle previously cut upon the work, or on the -circumference of the work itself, if the divisions are to reach the -edge. Screw back the _tool_ (not the rest) until its point reaches -the centre of the work and cause it to revolve so as to cut one arc. -Move the lathe pulley forward to 60° and cut a second arc, and so on, -advancing 60° each time, and the figure will be cut. This division -of the circle will form the groundwork of many handsome patterns. -When the arcs thus formed are intended merely to be the lines of -centres, and not themselves to form integral parts of the pattern, -they should, nevertheless, be marked with a pencil in the tool holder, -if possible, as there will be less liability to error in working -the proposed pattern. In the present advanced stage of the art of -turning, mere surface work done by the eccentric cutter is rather -apt to be despised, owing to the extended powers of Ibbetson's or -Plant's geometric chuck; but, valuable as the two latter are, they are -necessarily so costly that few can obtain them, whereas the little -cutter frame is comparatively cheap, and it is really capable of very -exquisite work in skilful hands. - - [Illustration: FIG. 286A] - - [Illustration: FIG. 286B] - - [Illustration: FIG. 286C] - - - SEGMENT ENGINE. Fig. 287. - -In very many cases of ornamentation it is required that the mandrel, -instead of making an entire revolution, should stop at a given point -in both directions, so that, for instance, the turner should be able -to move it 60, 80, or 100 divisions to and fro, with the certainty -of its not advancing beyond that distance. This is effected by the -racked and divided brass wheel B, fixed on the mandrel against the -small end of the pulley. This wheel is sufficiently thick to allow of -racking part of its edge to be acted on when necessary by the tangent -screw, and leaving the other part for divisions, which are generally -seventy-two in number, and marked in figures at every sixth division. -On the other side of the plate are a number of holes drilled through -its whole thickness to receive stop pins, Fig. 289, P, which are sawn -through as shown, that they may spring, and fit the holes tightly. -There are seventy-two holes corresponding with the divisions. These -pins are about 3/16ths of an inch diameter, generally with flattened -heads, and a hole through them to receive a pin to aid in removing -them. The holes are sometimes made in the edge, instead of the side -of the segment plate, but the latter is the best position. At Fig. -288, T, is seen the interior part of the poppet, with a piece of brass -let in, and fixed securely, in which are inserted two screws, against -which the segment stops abut, and prevents further rotation of the -pulley. Side by side with this latter piece is placed the frame which -carries the tangent screw. It is shown at Fig. 289. This frame is not -fixed to the base of the poppet, but pivotted at _e_, between two -short standards screwed into the poppet for that purpose. When not in -use, the whole frame, therefore, drops down towards the front, but -it can be raised by the small cam, K, Fig. 289, so as to gear with -the worm wheel. In many cases the latter is not used, but the pulley -turned by hand. The screw, however, gives a steadier and more easily -regulated movement, essential in delicate operations, and sometimes -convenient, even when the stops do not require to be inserted. The -use of the cam, acting on the frame which carries the tangent screw, -is now generally followed in the eccentric and oval chucks, and also -in the dome chuck. It enables the workman, by throwing out of gear -this part, to turn the worm wheel with the fingers, to set it at the -required number on the division plate, a slow process when effected by -the screw. - - [Illustration: FIG. 287.] - - [Illustration: FIG. 289.] - - [Illustration: FIG. 288.] - - - HOLTZAPFFEL'S ROSE CUTTER FRAME. - -Among the newer devices for ornamental turning, must be mentioned the -rose cutter frame of Holtzapffel and Co., an ingenious adaptation -of the principle of the rose engine, without the drawback of -cumbersomeness and costliness. It works like the ordinary eccentric -and other cutters by a cord from overhead motion. The apparatus is -represented in Fig. 290, and its various parts in Fig. 291, &c. - - [Illustration: FIG. 290.] - - [Illustration: FIG. 294.] - - [Illustration: FIG. 291.] - - [Illustration: FIG. 293A.] - - [Illustration: FIG. 293B.] - -In the first of these figures, A is the shank, fitting the receptacle -of the slide rest, and drilled to receive a hardened spindle, at one -end of which is a worm wheel, turned by tangent screw B C, and shown -again at A, B, C, Fig. 292. By this are turned the parts beyond K, -namely, the frame D, carrying the tool, as in the eccentric cutter, -adjacent parts S, representing chamfered bar, P, back plate, and -O, which is a round piece in one casting, with the back plate, and -having a hole through it for the coiled spring seen between O and N. -All these are secured to the spindle, and turn together as one piece -with it. Fig. 291 is a front view of these parts. H is the back plate -of brass, with steel chamfered bars on its face, E, E, as in the -eccentric chuck. Between these slides the plate, D, D, to the face -of which is attached the long steel frame, carrying the tool holder. -Close to the letter H, it will be noticed that a slot is cut in the -back plate, through which projects a hard steel pin, screwed into -the back of the sliding plate. This is seen at O, Fig. 290, and is -attached to one end of a coiled spring, the opposite end of which is -secured to a pin fixed in the back plate of this part. The pin O, is -thus kept in contact with the edge of the rosette or pattern plate, -K, and, as the whole turns with the spindle while the rosette is -fixed, the pin, or rubber, is compelled to follow the undulations of -the pattern, the motion being, of course, communicated to the tool. -An inspection of Fig. 294 will show the arrangement of the parts on -which the rosettes are fixed, and which is capable of turning, but -does not, unless the tangent screw and wheel, H, are brought into -requisition, as will be presently explained. The end of the main shank -of the instrument is round, as seen at C, the worm wheel B being -screwed fast, by four small screws, to the end of the square part of -the shank. Upon this rounded end fits what may be called the sleeve -E, to which is fixed the tangent screw, and on which also are placed -the rosettes. The latter have a large central hole, Fig. 293, A and B, -and fitting closely beyond the screw F, F, of the sleeve, and, being -prohibited from turning upon it by a small key or feather, are secured -by a screwed ring or ferrule seen at L, Fig. 296, the edge of which is -milled. At F, Fig. 291, is seen a short stop, or set screw, the head -of which is divided into ten degrees. By this, the rubber is prevented -from penetrating to the bottom of the undulations on the edge of the -rosette, and, if it is allowed only just to touch the summits of them, -the tool will cut a circle. Thus, as the screw stop can be accurately -set, one rosette will produce at pleasure graduated waved lines, the -waves growing less and less undulated as the centre (or circumference) -of the work is approached, giving a most delicate and chaste pattern, -and _chased_ it certainly is. - -Another variation of the pattern producible from any rosette results -from the frame of the tool holder being extended beyond the axis -of the spindle in both directions. When the tool is on that side -of the axis nearest to the rubber pin, the undulations of the -rosettes will be so followed as to produce their exact counterpart -on the work. When the tool-holder is on the other side of the axis, -the undulations become reversed, the raised parts of the rosettes -producing hollows and _vice versa_. It may here be mentioned that in -the case of the rose cutter, eccentric, and universal cutter, and -similar apparatus, the screw heads carry ten chief divisions and ten -smaller divisions. The screws are cut with ten threads to the inch, -so that one turn advances the slide, or the tool, or wheel as the -case may be, one-tenth of an inch. One large division, therefore, -produces a movement equal to one-hundredth, and one small division one -two-hundredth of an inch. If the screw is small it is generally cut -with a double thread equal to one-twentieth of an inch. It is evident -that in addition to the movements of the various parts of the rose -cutter, the turner also has in his power those of the slide rest, and -of the division plate on the lathe pulley, by one or both of which -further complications become possible. Six modifications of pattern -produced from one rosette alone are shown in Holtzapffel and Co.'s -catalogue, and these may be further multiplied according to the taste -and skill of the operator. - -It is not possible to apply rapid movement to this rose cutter, else -the rubber would probably miss touching the rosette in places; hence -the tangent or worm wheel is used to give motion to the central -spindle. An end view of this is given in Fig. 292. The object of the -other tangent screw is, to move the sleeve and therewith the rosette -at pleasure, so that the higher parts of the undulations in the second -cut may, if desired, be arranged to meet the lower parts of the same -in the first cut or to fall intermediately. The effect of the gradual -shifting of the rosettes in this way is perfectly marvellous, and the -writer much regrets that he is unable to supply specimen plates, as he -is not in possession of the rose cutter. In the end of Holtzapffel's -latest edition of his catalogue are several such specimens, but -without any drawing or description of the instrument, the cost of -which is moreover omitted. - - [Illustration: FIG. 292.] - -The centres of circles cut by this eccentric tool will be always -regulated in regard to position by the slide rest, because these -centres are, as explained, always in a line with the centre of the -spindle. Hence, to place a circle in any desired position, it is only -necessary to determine its centre, and, after drawing back the tool by -means of the screw till its centre runs truly as a mere drill, turn -the screw of the slide rest until the point touches the required spot. - - - UNIVERSAL CUTTER FRAME. - -This is represented in Fig. 284, in its latest improved form. It -consists of a shank, A, which fits the tool receptacle, and is bored -throughout its length for the reception of a central steel spindle, -to which is securely attached at one end the worm wheel, G, acting -as a dividing plate, and at the other the crank-formed frame, B, C, -with its small poppets, D, D. These are sawn lengthwise, and thus -spring upon the centre screws, which pass through them and carry the -revolving cutter spindle, K, L, M, in the centre of which is a slot to -receive the tool, the latter being clamped by the tightening screw, -L. There are certain points to be attended to in the construction of -this instrument, which must on no account be neglected. In the first -place, the screws which pass through the poppets must lie in the line -which would bisect at right angles that of the main spindle in the -same plane. A line, in fact (as dotted), passing from screw to screw -will pass across the centre of the end of the spindle. In the next -place, when the tool-holder, with its pulleys, is in place between D, D, -this line must be even with the _top line_ of the central mortise, -H, for the _point_ of the tool is level with its upper surface, it -being bevelled below; and it is essential that this point be capable -of being so placed as to form a continuation of the centre of the main -spindle. At E, E, are shown two of four thin pulleys. The two front -ones are removed to show the poppets. They should not be made thicker -than necessary, in order to avoid their interfering with the action of -the tool. Either pair will be used with either pulley, K, K, according -as the right or left side of the instrument is the highest, for, as -will be explained, the cutter frame is used at all angles between -the horizontal and the vertical lines, the cuts being consequently -inclined in either direction, left, or right, at pleasure. The centre -screws and points of the tool spindle must be carefully hardened. -Before commencing to use this cutter, it is necessary to test the -centrality of the point of the tool. Place the latter in its holder. -Let the part C of the instrument be turned till vertical; cause the -tool to revolve and to cut a light line or scratch on the face of the -work. By means of the tangent screw cause C to become vertical in -the opposite direction, so as to bring the other pulley upwards, and -with the small screws in the poppets set the revolving tool holder, -till the tool falls exactly on the line first made. It is, of course, -understood that the line in question passed through the _centre_ of -the work. If in both positions of the tool the central point is passed -through, the cutter tool is correctly placed. The poppet screws are -for this purpose specially, though sometimes used to place the cutter -purposely above or below the centre of the work. Compared with the -old form previously given, this pattern of universal cutter is very -superior. - - [Illustration: FIG. 284.] - - - ROSE ENGINE. - -The rose engine, as hitherto constructed, has not been entirely -supplanted by the neat little apparatus already described, but is -still used almost universally by the watch case makers; and its -construction differs little, if at all, from that described by -Bergeron; although the slide rest used with it is somewhat modified -and improved. There are two kinds of rose engine, in one of which -the mandrel with its poppets and fittings oscillates between centres -fixed beneath the lathe bed; while in the other, the frame carrying -the slide rest is thus movable, the mandrel head remaining stationary -as in an ordinary lathe. In both cases the mandrel is allowed a -to-and-fro or pumping movement in its collars; as the rosettes used -are cut upon the face as well as upon the edge; and the rounded parts -of an article can be operated on as well as the plane surfaces. - -The second pattern, in which the poppet remains a fixture, will be -first described, because it is capable of being applied to an ordinary -lathe for surface work, and if the lathe has a traversing mandrel, it -can be completely fitted for rose work. - -The drawings and description annexed are from Bergeron's work; but the -slide rest there represented, and arrangement of screwed mandrel, are -omitted as obsolete:-- - -A strong iron frame, A, A, Figs. 295 A, 295 B, and 296, is made -with one of the ends carried up and branched, so as to embrace the -mandrel and rosette; which latter is attached to the back part of -the chuck which carries the work. The top of the frame is double, so -as to form of itself a lathe bed of small dimensions, upon which an -ordinary slide rest can be fitted. It must, however, be used with a -short socket, or it will be too high; as the top of the frame alluded -to stands slightly above the level of the bearers. B, is a point of -hardened steel which fits into a conical hole in the bottom of the -lathe poppet, or (if this is not long enough to reach a good way down -between the bearers) into a piece of iron arranged for the purpose -similar to that now to be described, and which is again shown in Figs. -297 and 298. This is a kind of poppet in a reversed position, the -clamping nut and screw being above the bed, and the head with centre -screw below. The frame lies, therefore, between the mandrel head and -this reversed poppet, or between two of the latter, and oscillates -upon their centres whenever the projections or depressions of the -rosette compel it to assume such motion. - - [Illustration: FIG. 295A.] - - [Illustration: FIG. 295B.] - - [Illustration: FIG. 296.] - -Fig. 299 is a section of the chuck which carries the rosette, the -latter being shown in position. A, is the body of the chuck; B, the -inside screw to fit the mandrel. On the outside of this part are a -few turns of a somewhat finer thread, beyond which a plain part is -left next to the flange, C, and on this the rosette is placed, and is -clamped by the nut, cut outside into beads, or milled, or left plain -and drilled for the insertion of a lever pin; this nut is marked D -in the figure. It will be seen to lie within a recess formed in the -face of the rosette, E. The latter is shown in Fig. 300. A, is the -recess just alluded to; B, C, the pattern on the face and edge; D, the -large hole in its centre, allowing it to be slipped on the back of -the chuck. It is prevented from turning on the latter by a pin, which -fits into the small hole, F. From the front face of the chuck rises -a conical pin, G, similar to that on the eccentric chuck, over which -fits the circular division plate, I, with its projecting screw, H, to -hold the ordinary chucks. This plate is recessed at the back, leaving -a mere ring of metal, _e, e_, which fits a corresponding circular -groove, and secures the steady movement of the plate, which is fixed -by a conical washer and screw, as seen in the plate. This division -plate is formed with cogs, into which a stop falls, as described, -when treating of the eccentric, but the divisions are differently -arranged, the cogs being divided into sets of eight or ten teeth. Let -the whole circumference be first divided into six equal parts, and, -beginning at the first division, cut six or eight teeth, as if the -whole circle were to be divided into 60. Pass to the second portion, -and cut eight teeth, as if the circle were to be divided into 72. Let -the third carry eight teeth, with a pitch of 80 to the circle; the -fourth a similar number, with a pitch of 84; the fifth 96; the sixth -100 to the circle. These must be cut with the same cutter, so that the -spring click, or stop teeth, may fit any of the six sets. There will -be several undivided spaces, which are to be left plain. The several -sets are to be marked in numbers, so that the pitch may be discovered -at a glance, and the teeth in each being so few will hardly require -separate numbering. The part of the apparatus which carries the -rubber--that is to say, the heads of the branched part of the swinging -frame, are made flat on the top, which projects on three sides, -forming small tables on which the actual holder or clamp can be fixed -by a turn of the screw, X, in the first figure. The rubbers are merely -flat pieces of steel, with edges sufficiently sharp to penetrate to -the lowest depths of the undulations and recesses on the rosettes, but -rounded off and polished, so as not to cut and damage the softer metal -against which they act; other materials have been tried, as ivory, and -the harder tusk of the hippopotamus, but hard steel is most generally -preferred. It is, of course, necessary that the rubber press with -some force against the rosette, which force should, moreover, admit -of being regulated at pleasure. This is effected by a spring of steel -under the lathe bed, to the end of which is affixed the arm, W, which -has a ring handle nearest to the operator, and is perforated with a -row of holes from end to end. This arm is flat, and falls into a fork -at the end of the tail piece, Y, which is seen in the second figure -attached to the centre of the lower bar of the frame. A pin passes -through holes in this fork, and through one of those in the arm. By -this arrangement it is easy to regulate the force which the spring -shall exercise, as this will be increased by moving the pin nearer -to the spring, and diminished by placing it in a hole nearer to the -ring handle. In forming the rosettes great care should be exercised -to make the corresponding parts agree. The depth of similar hollows -must be precisely equal, and elevated portions intended to match, must -do so with great accuracy. Supposing, for instance, a rosette to be -made with ten elevations and ten recesses, all of equal curves. If -these are accidentally unequal, and it is desired to arrange a set of -these waved rings one within the other, so that the depressions of -the one shall be opposite to the elevations of the other, or so that -this effect shall take place gradually--if the curves of the pattern -are unequally cut the several portions of the device will not tally, -and an irregularity will be produced of disagreeable appearance; an -inspection showing at once that such irregularity is not part of the -device, but unintentional and erroneous. This leads to a consideration -of the division plate of this rose engine, and an explanation of the -object of its peculiar construction. The pattern of the rosette is, -as it were, in sections; either similar elevations and recesses are -alternately repeated, or there may be a variety of such, extending -over a part of the circumference, and forming a certain complete -device, which may then give place to a second pattern, extending a -similar distance; and these two may alternate regularly round the -circumference. Each of these sections must be of precisely similar -length, and the repetition of the pattern must also be precisely -similar, for the reason stated above. - - [Illustration: FIG. 299.] - - [Illustration: FIG. 300.] - - [Illustration: FIG. 297.] - - [Illustration: FIG. 298.] - -It is evident that all possible alternations of the device or set -of devices may be obtained by means of six or eight notches of the -division plate; for, by moving it forward to that extent, the whole -pattern may be compassed. In treating of the second form of rose -engine, and of the method of using it, this will again be adverted to, -and illustrated by an example. - -Hitherto we have spoken only of the use of the pattern on the edge of -the rosette, but, as already stated, it is frequently repeated on the -face, and by this means it becomes easier to work upon the outside of -a cylindrical piece, as well as on the two ends. Patterns thus cut on -the face of a rosette tend, of course, to move the mandrel to and fro -in its collars, which is only possible when the lathe is made on the -plan of a screw-cutting or traversing mandrel lathe. The spring which -keeps the rubber in contact with the face of the rosette is shown at P. - -The head on the top of the arm, which forms the clamp or holder of -the rubber, must be turned round to face the rosette, or a separate -rubber must be used, which passes through the clamp at right angles -to that used in surface work, and the frame must be prevented from -oscillating by a stop which fits between the bearers of the lathe, and -embraces the upright side of the frame. The top of the slide rest must -be turned round, or a side tool used. In this case, the rest and frame -with its rubber become fixtures, as in ordinary turning, the mandrel -and work being alone moved in correspondence with the pattern on the -face of the rosette. It would indeed be much better to do away with -the frame altogether, fixing the rubber to an upright pedestal mounted -on the lathe bed, and using the slide rest in the usual way, were it -not that in general the work is constantly being varied, the side -and face being worked in turn--and the apparatus is rather cumbrous -to remove and re-mount often. It is, nevertheless, easy to finish the -ornamentation of plane surfaces first, and then to remove the frame -altogether, and substitute a fixed rubber, as stated. - -The rose engine now described has certain evident advantages over the -rose cutter frame, and is capable of the most exquisite devices. It -may be, perhaps, a mere question of taste, whether rose engine work -finely executed is not in point of beauty, superior to any that can -be done by geometric chucks, however elaborate. That it is so, is -decidedly the writer's opinion, more especially when this apparatus is -used in combination with the oval chuck. Moreover, there is nothing in -the form of rose engine described to make it a very expensive article, -or beyond the skill of an amateur; and with a set of only three -rosettes, the patterns may be varied continually, and multiplied--if -not _ad infinitum_--yet quite sufficiently for the display of skill -and taste of the operator. - -In using the rose engine, it is necessary to carry the cord to the -pulley from a very small wheel on the axle. Sometimes the lowest speed -pulley of the flywheel may answer, but if the recesses of the rosette -are deep and sharp, or only slightly rounded, it may become necessary -to mount a still smaller wheel on purpose; else the rubber will jump -over and miss parts of the design, thereby spoiling the work. The -watch-case turners, indeed, altogether dispense with the flywheel, and -use instead a small pulley, fixed to the side of the lathe bed, and -turned by hand. - -These artificers always use a more elaborate form of rose engine, -which will be presently described, and which is the most perfect in -detail of all similar contrivances, but it is necessarily costly, and -cannot be said to be well adapted for plain turning also, except in a -limited degree. The work, if not of soft material, like a watch-case, -should be turned first of all upon an ordinary lathe, the mandrel -screw of which is a counterpart to that of the rose engine, and the -latter should merely be used for the final cut, to perfect the form of -the material previous to its ornamentation. - -In the Appendix will be found a new method of obtaining the required -oscillatory motion of the rose engine, which might apparently be -applied to tool holder[22] frame here described, or to the poppet head. - - [22] _I.e._, the main frame carrying the slide rest. - -The rose engine proper is arranged with an oscillating poppet head -carrying the mandrel and its rosettes, the tool being stationary. The -following account of this machine, and the drawings, are copied almost -exactly from Bergeron. The modern rose engine is not indeed made with -the projecting lugs referred to as intended for the application of -the guide ring in oval turning, as this guide is now altered to fit -a poppet head of ordinary form, as already detailed. The pulley and -division plate are also of obsolete form, but as the main arrangement -of parts described are sufficiently similar to that now followed, -Bergeron's drawing and description have been retained. Fig. 302 is -a longitudinal view, and Fig. 303 a transverse view of the working -parts of this lathe. A, A are the poppets, which are in one casting, -with the connecting piece shown by the dotted lines, which latter -has a tail piece firmly attached to its centre, to which a spring -is affixed as in the lathe previously described. In the drawing the -cylindrical collars carrying the mandrel are split, so that in case -of wear they can be tightened in the usual manner by a screw at the -top of the poppet marked B, 303. The lugs, _f, f_, with square holes -_e, e_, are for the application of the guide for oval turning, the -latter being originally a ring with slotted arms on either side. The -points of oscillation are precisely similar to those of the rose -engine first described, two short poppets C, Figs. 302 and 303, having -centre screws, whose points fall into conical holes made in opposite -faces of the poppet, a little below the level of the lathe bed. These -are formed with a slit to receive the stop _h_, which is hinged at -the point _o_, and which, when raised by a wedge, catches into a -small projection _p_, thereby fixing the poppet in a perpendicular -position and preventing its oscillation. The rose engine can then be -used as an ordinary lathe, to finish the preparation of the work to be -operated on, which should, if possible, be commenced and mainly formed -on an ordinary lathe, the mandrel of which is a counterpart of that -of the rose engine. The tail piece, E, does not require a separate -description, being precisely similar to that already described. The -to-and-fro movement of the mandrel caused by the action of the -rubbers on the face of rosette, is also arranged in a manner similar -to the last. F is the spring, turning in the middle of its length -on a pin in a piece of iron fixed on the bed, so that if both ends -wore free it could swing backwards and forwards between the cheeks -of the lathe on this pin as a centre. The upper end of this spring -is branched in a semicircular form to embrace the mandrel, this fork -falling into a groove formed to receive it. It can thus be brought to -bear against either of the shoulders visible at this part. The lower -end of the spring fits into a notch, or rather a slot in the arm H -of the second figure; the handle of this arm being L in both figs. -This piece is pivotted at K, and at its other end falls into one of -the notches in the retaining plate, G, of the first figure. By this -plan the tension of the spring, can be brought against the mandrel in -either direction at pleasure, for if the lever is placed in one of -the left hand notches, the tendency of the spring will be to move the -mandrel towards the right, and _vice versa_. The tension of the spring -can also be regulated by the use of the groove B or X at pleasure. In -the second figure of Bergeron's the piece which at first sight appears -to be a continuation of the holding down bolt of the short poppet -carrying the centre screw, is the tail piece or lower end of the long -spring just described, and its reduced extremity is visible passing -through a short slot in the lever H, near the handle of which appears -the _edge_ of the notched piece G of the other figure. All the above -parts are commonly of iron, the following are in brass or gun metal. - - [Illustration: FIG. 303.] - - [Illustration: FIG. 304.] - - [Illustration: FIG. 302.] - -On the bed and parallel to it, two pieces of brass, or standards, -rise, similar to H in the first figure, the two being opposite to each -other, one on each side of the mandrel, as shown in the second figure. -Both these are firmly secured to the bed by long bolts and nuts, it -being of the utmost importance that they should not move or vibrate in -the least. They are in addition united to each other by two horizontal -braces, one of which is seen at N in the second figure. At _l, l_ -are seen two rectangular notches, which are the ends of grooves made -in the upper part of the head piece, H, and which traverse its whole -length. They receive the crooked part, _a_, of the rubber holder, -Fig. 304, so that the latter can be slid along this bar, and brought -opposite to any one of the rosettes, after which it can be secured in -position by the screw, _b_, Fig. 304. The mandrel is thus arranged. -It is cylindrical, with a shoulder against which the chucks can rest, -as in an ordinary traversing mandrel, and a similar but reversed -shoulder at _g_, Fig. 302. Against the latter abuts the end of an -accurately turned sleeve of brass, which fits over the mandrel with -slight friction, so as to have no shake or play upon it. Upon this -sleeve the rosettes are placed. They fit accurately over it, and are -prevented from turning round upon it by a feather extending the length -of the sleeve, which fits into a corresponding notch cut on the inside -of the rosettes. These are arranged in pairs back to back, and each -couple is separated from the next by a short sleeve or ferrule, which -Bergeron recommends to be of wood, as tending to hold the rosettes -more securely than metal when pressed together by the nut at the end -of the set. The fibres of the wood are to be placed parallel with the -mandrel, because there is no shrinkage of this substance as regards -its length. The pulley is fixed beyond the rosettes on a part of the -mandrel filed into six faces for that purpose, and lastly comes the -nut, which secures all the parts to their several positions, but which -nevertheless does not so jam them together but that the mandrel can be -turned within the sleeve when the positions of the rosettes are to be -changed in the course of working a pattern. The division plate is not -attached to the pulley, though lying close upon its surface. It slips -on to the sleeve on which the rosettes fit, and its spring-catch only -on the face of the pulley. Thus the latter is held to the sleeve and -its fittings when the catch is down, so that all turn together, but, -when the catch is raised, the division plate, carrying with it the -rosettes, can be turned round upon the mandrel as may be required. It -is not necessary to repeat what has been said respecting the manner -of graduating the division plate, as that used with the lathe already -described is in that respect a counterpart of what is used with the -rose engine now treated of. - - [Illustration: FIG. 305, 306.] - - [Illustration: FIG. 307.] - -The following description of the method pursued in turning a pattern -shown in Fig. 307 will suffice to show the working of the rose -engine:--First, says Bergeron:--It is not enough to know the general -construction of the rose engine, it is necessary to know thoroughly -the particular one in use, _i. e._, as regards the details of its -construction, the slight defects or imperfections it may chance to -have, and the means whereby they may be lessened or corrected. It is -necessary, in addition, to know well, and to have always at hand, the -numbers of each rosette, or any rate to have a table of them which -can be readily referred to. It is equally necessary to recognise at -a glance the various sets of divisions on the division plate, for -which purpose, and that no mistake may be made, such numbers ought -to be engraved upon each. The same holds good with regard to the -slide rest, and, in addition, practice should be frequent upon box or -other inexpensive material by which the turner may have made himself -perfect in the several combinations possible, and the various effects -producible by the rosettes and different shaped tools over which he -has control. It is thus, by actual experiment only, that the turner -can become acquainted with the powers of his own lathe and apparatus, -and thus only, after working out the patterns already executed, will -he be in a position to design new ones, and to work with ease and -certainty. The rose engines are usually fitted with tools of variously -shaped edges, as shown in Figs. 305 and 306, by this means a pattern -of some width and great variety is of course produced at once, and -by one rosette. In the following, however, a tool with single point, -Fig. 308, is to be used. This simplest design is supposed to be on -the cover of a box or other plane surface, and it is evident that -the movement or oscillation required of the mandrel is that at right -angles to the bed of the lathe. To obtain this movement, when the -rubber is fixed in its clamp, on the side of the workman, as it is -necessary that the rubber should press against the rosette through the -medium of the spring, the handle of the lever, Fig. 302, must be drawn -forward towards the operator, and kept by a pin, as described, passing -through it and the tail piece of the mandrel frame. The tension must -not be too great, especially if the rosette to be used is deeply -indented, and care must be taken to free the frame from the action of -the stop, _p_, by removing its wedge before making any attempt to try -the pressure by moving the mandrel. The design under consideration is -produced from rosette numbered 2 in the drawing, and in fixing the -rubber care must be taken that it does not bear against the adjacent -rosette. Choose a rosette of forty-eight teeth or undulations, and -as the second circle of ornamentation exactly intersects the first, -the raised part of the one falling under the depression of the other, -and as it were _halving_ it, the set of divisions on the click plate -to be used will be twice 48, or 96. Place the rest parallel to the -face of the work and so that the forward motion of the tool shall be -perpendicular to it. By means of the leading screw of the rest, place -the tool near the edge of the work and level with the centre, and -gently moving it forward and putting the lathe in motion, commence -the cut. After having made a light cut, without moving the tool, stop -the lathe and judge of the depth of cut, and if sufficient, screw up -the stop screw of the slide rest, to insure all the following cuts -penetrating to the same depth. Observe the position of the tool as -marked by the graduations of the slide rest, and then withdrawing -it from the cut, move the click plate one notch, which will divide -exactly in half the several undulations of the rosette. By the rest -screw move the tool towards the centre of the work and mark the -number of divisions passed over, so that the circles of undulations -may be equidistant, and cut a second. Now for the third, _go back or -advance_ on the click plate one division, for the position of the -undulations in the third is precisely that of the first circle. It is -indeed immaterial whether an advance or retreat of one notch is made -in this case, but now is evident the reason for not dividing the plate -equally all round, five or six teeth being ample for each division. If -there are eight rosettes the plate should be first divided into eight -parts, and each rosette having a different number of undulations, -these eight parts should be divided into degrees proportionate to -the numbers on the rosette, the one being a multiple of the other. -In working the _side_ of a cylinder, that of a box, for example, the -longitudinal movement of the mandrel is required, the poppet being -retained immovable by the wedge and stop. The tool is to be placed at -right angles to the side of the work, the rubber brought to bear on -the face of the rosette. The method of working will be self-evident, -after the description already given. It is impossible in a brief work -like the present, to go into details of other patterns referred to and -illustrated by Bergeron, one or two of which are nevertheless of great -beauty, and are executed with the aid of the eccentric chuck mounted -on the mandrel of the rose engine. There is, however, a different -class of work, to which reference will be made in our next, and we -shall also give a description of a simple addition to the slide rest, -used by watch case turners, which does away with the necessity of -counting the number of divisions upon this instrument when used as -above. - -The slide rest used by the watch case turners is almost identical -in form with one figured and described by Bergeron. It is necessary -that the tool holder should have a circular motion, somewhat similar -to that of a spherical rest, in order to reach the sides and curved -surfaces of the articles to be engine turned; hence the tool -receptacle and its bed work upon a central pin. The pin here called -"the bed" is usually a flat brass plate of a quadrant form, the -central pin being at the apex, and carrying on its face the guides for -the tool receptacle. The pin on which it turns is a reversed truncated -cone rising from a similar flat plate, which itself forms the sole -of the rest, or traverses the lower frame as usual; when the tool is -beyond the central pin, it will ornament conical surfaces, and _vice -versa_. On the edge of the arc is a racked part, and a tangent screw -works into it. The tool is moved to and fro by a lever, as usual, the -depth of cut being regulated by a stop screw. These details being -already entered into, in treating of slide rests and chucks, need not -be more specially explained here; but a contrivance for regulating the -traverse of the upper part upon the frame underneath, is ingenious and -serviceable, and will therefore be described. The end of the leading -screw is fitted with a ratchet wheel of the same construction as -that of the ratchet brace for drilling, patented by Fenn, of Newgate -Street, to which in the same way a handle and spring are attached, -as shown in the drawing, Fig. 309, A, and Fig. 310. The handle rises -between two semicircular plates drilled in the face, with holes for -the reception of stop pins, B, C. These regulate the traverse of -the handle, and thence of the screw. If the former, therefore, is -thrown over till the left stop is touched, and then pulled forward to -the other stop, between each cut of the tool, the latter will leave -equidistant spaces upon the work, without need of counting divisions -at each cut. As a traverse of one inch or more of the lever handle -at the place of the stop pins only moves the screw a very minute -quantity, the holes for the pins need not be very close together even -for fine work. This is a very simple contrivance, and perfect in -action, enabling the operator to work with ease and certainty, and -with great speed. - - [Illustration: FIG. 309.] - - [Illustration: FIG. 310.] - - - RECTILINEAL CHUCK. - -Fig. 311 represents a modification of the eccentric chuck, when the -latter is used as a fixture, to present to revolving cutters and -drills the different parts of the work which is to be operated on. The -eccentric chuck is commonly made to slide in one direction only, and -the traverse is limited. In the present case there is ample traverse -in both directions, the slide being arranged to descend to the lathe -bed, and upwards to an equal degree. A is a cross section of this -chuck, the length of which is 7-1/2 inches. It is very strongly made -in brass, and is altogether much more substantial than the eccentric -chuck. B and C are the guide bars, between which works the sliding -part. The nut of the leading screw is below this as usual. The tangent -wheel has 120 teeth, and is thus divided: 0--12--24, &c. The tangent -screw head is divided thus: 0--1--2--3--4--5, with half divisions, -marked but not numbered. This rectilineal chuck is most commonly used -in a vertical position, but may be otherwise placed. In using it for -any work likely to bring a strain upon it, the ordinary spring index -attached to the lathe for use with the face plate, should not be -entirely relied on to keep it in position. It is safer to make use in -addition of the segment engine stops or other available contrivance. -The special function of the chuck is the production of straight lines -on the face of work forming stars or radial flutes, which can be -worked with a drill. Fluting is also readily done by its aid, with the -addition of the vertical eccentric, or dome chuck, already described. -Its use is, however, by no means confined to ornamental work--small -tenons, mortises, and even dovetails are producible by it; and in -fitting together the various parts of temples, shrines, and similar -complicated specimens, its uses will be innumerable; and here may be -noted the extension of the lathe and its apparatus to work apparently -in no way suited to it. It has now become more of a universal shaping -machine than it used to be, owing to the great accuracy of the work -done by it, and the variety of fittings that can be added to it. In a -later page will be found a drawing and description of a new device of -the kind--a planing machine, devised by an ingenious and first-class -maker, Munro, of Lambeth, and patented by him. Mention is made of it -in this place, because the rectilineal chuck is in some degree capable -of similar work. The slide moved up and down by a screw the handle -of which is of extra length to allow the vertical traverse, is also -capable of being moved by a cam-eccentric chain or rack and cogged -wheel, so that by pulling down a handle the slide may be made to slide -up and down more rapidly than by the screw motion; any piece of wood -of rectangular or other figure may thus be planed on the face, by -being fixed on the rectilineal chuck, and acted upon by a fixed tool -in the slide rest, the latter affording the horizontal traverse of -the tool across the face of the work, the former the perpendicular -movement of the material. If a slide rest is thus arranged in -combination with the chuck in question, and the lathe bed is imagined -to be set up on end with the chuck downwards and horizontal, the -whole will become, in fact, a precise counterpart of those planing -machines, the bed of which traverses to and fro, with the work under -a fixed tool. Munro's arrangement is, of course, of far more extended -application, and more suited for metal work; but for lighter and more -delicate operations of a similar kind the rectilinear chuck and slide -rest will be found very serviceable. It is with such an adaptation of -this chuck as has been alluded to, namely, a quick speed movement of -the slide by a lever handle, that the rays are drawn so exquisitely -fine and close upon the faces of many gold dial plates of watches, -the handle being arrested by a stop at any given point, so that these -rays shall not transgress their appointed limits. It will be hardly -necessary to allude to those other applications of this apparatus, or -other particulars in which it is identical with the eccentric chuck, -as the description already given of the latter applies to both alike, -the extra traverse of the present in both directions being its chief -distinguishing feature. - - [Illustration: FIG. 311.] - - [Illustration: FIG. 312.] - - - EPICYCLOIDAL CHUCK. - -This chuck has been in use for many years, and has in consequence -been of late rather neglected. It is, nevertheless, the parent of -those more elaborate contrivances included under the general title of -Geometric Chucks, of which Ibbetson's stands first in order of date, -and possibly of merit, though this last qualification may admit of -question. The epicycloid, defined mathematically, is a curve described -by the revolution of a point in the circumference of a circle, when -the latter is made to roll upon the concave or convex side of another -circle. A pin in the rim of a wheel revolving round and in contact -with another wheel, therefore, describes this curve, which constitutes -two or more loops, as will be seen by the annexed illustrations. The -number of these loops is variable, and the chuck will produce almost -any number by changing the pinions, and thus altering the relative -velocities of the revolving parts. The following description will -make the action of this chuck clear, and enable any good mechanic to -construct one for himself. In the first place, the above remarks show -a necessity for a fixed wheel, round which another may revolve. Fig. -313 represents this attached to a plate of brass, which can be fixed -to the lathe head, the mandrel passing through its centre. This is -the original pattern of plate, and need not, of course, be adhered -to, as the form can be modified to suit the lathe to which it is to -be applied. It is merely necessary to affix such a wheel to the face -of the poppet, so as to be concentric with the mandrel [a plan done -away with, however, or rather reversed, in Plant's geometric chuck]. -The epicycloidal chuck, which screws to the mandrel as usual, consists -of a foundation plate of brass, A, Fig. 314, behind which is mounted -the cogwheel, B. The axis of this wheel passes through the plate, -and is carried by another plate, _e_, which is curved and adjustable -upon the former. The axis of this wheel carries a small pinion, D, so -that the whole turn together. This pinion being one of a set of change -wheels, necessitates the possibility of adjusting the plate which -carries its axis, as all the several change wheels must gear with E, -which always retains its position on the chuck. The sliding plate in -question being put in place, is clamped by the screw F. A plate of -iron, G, of the form shown, and of sufficient thickness for the secure -attachment of the wheel and of the screw which carries the ordinary -chucks, is fitted to turn on the axis of the wheel E. Its larger end -traverses within the arc H, which is graduated. The arc is bevelled -underneath, serving to hold down securely to the foundation plate the -piece of iron which is chamfered to fit it. At the left side of the -back plate is seen a stop, L, which is placed in such a position, that -when the iron plate rests against it, the screw M is concentric with -the mandrel, and work may be turned as upon an ordinary chuck. To -throw the iron plate, and consequently the nose of the chuck, on one -side, or in other words to place the work eccentrically, the screws -which retain the arc are loosened and the adjustment made by hand. The -eccentricity is marked by an index on the iron plate, which points -to the graduations seen upon the face of the arc. The eccentricity -being determined, the arc is again screwed down to retain the movable -plate in its new position. [Although this is Bergeron's method, it -appears vastly inferior to the plan of racking the edge of the iron -plate, and moving it to any required degree of eccentricity by the -aid of a tangent screw.] When made as above, the chuck will produce -loops varying in number according to the relative dimensions of the -pinion (or change wheels gearing with E) and the central wheel, M. -If the latter has 120 teeth, and the change wheel 60, two loops will -result. If the pinion has ten teeth, the number of loops will be 12, -and so forth. The practical _limit_ to the number depends on the -possibility of diminishing the pinion in size and number of cogs, -and still keeping the latter of such size and pitch as to gear with -E. If, therefore, a larger number of loops is required than can be -obtained thus, it becomes necessary so to modify the form of chuck as -to permit of intermediate change wheels, and when the modification is -carried out, we have the geometric chuck, the most perfect, but the -most complicated and expensive of all. To understand the nature of the -work, the following is given in clear language by Bergeron, and will -sufficiently explain and simplify matters. - - [Illustration: FIG. 313.] - - [Illustration: FIG. 314.] - - [Illustration: FIG. 315.] - -If one considers the movement of the piece (of work) when the wheel -M is concentric with the mandrel, it will be perceived that although -it makes two revolutions upon its axis, yet inasmuch as it has no -eccentricity it will describe no particular curve or figure; but if an -eccentricity of three divisions is given to it, two buckles or loops -will result as in Fig. 315. Before cutting the material, however, -approach the tool as near the work as possible, and putting the lathe -in motion, observe whether the buckle[23] passes too near the centre -or too far from it, and also how near it goes to the circumference. -If another change wheel with forty teeth instead of sixty is -substituted, the slide C, being adjusted accordingly, three loops -will be described (forty being one-third of one hundred and twenty), -but it is always necessary before actually cutting the material, to -try whether the buckles will pass near to the centre without going -beyond it. The result of the latter movement will be shown presently, -as it entirely alters the appearance of the pattern. The divisions -commence on the arc at the left hand, the index resting at 0° when the -plate is against the stop L, and the screw of the chuck concentric -with the mandrel. The preceding figure of three loops will become -similar to Fig. 317, retaining the same wheels and some degree of -eccentricity, but by means of the slide rest moving the tool towards -the circumference, so that the buckles overlap the centre. The effect -thus produced is, that of a set of three curvilineal triangles of -which the apex of one falls upon the base of the next. The use of this -chuck is stated to require upon the part of the operator more care -than any other, as regards the derangement of work or tool in the -least during the operation, as, if either is once moved in the least -out of position, it will be found next to impossible to strike the -line again, owing to the peculiar nature of the curve, for although -the tool may be replaced upon any one part of the line already cut -with the intention of deepening--it is by no means certain that it -will trace the same curve again. This curve, says Bergeron does not -produce an agreeable effect on the cover of a box, unless it is -very finely cut, the tool, therefore, should be very sharp in the -angle and very keen. Bergeron specially mentions this in reference -to filling the cuts with thin strips of horn or shell, a method of -inlaid ornamentation not much known or admired in the present day, but -to which allusion may probably be made again in this series. To form -the second set of loops, which are parallel with the first in these -designs, it is only necessary to use the leading screw of the slide -rest, to move the tool nearer to or further from the centre, while the -eccentricity and the arrangement of change wheels remain as before. It -is scarcely necessary to detail the formation of the larger series of -four loops and upwards, as these are simply the result of different -sized change wheels: the following principles, however, by which -the buckling of the several loops is controlled or prevented, may -perhaps be serviceable. "When, for example an eccentricity of sixteen -divisions is used--if the tool is placed at a distance of two such -divisions from the centre of the piece, a line only will be produced -of as many _curves_ as the wheel or pinion D would produce _buckles_. -If the tool is moved further from the centre by a quarter division, -the angles (connecting the curves) will be more defined, but still -no buckles will be made. A little further movement of the tool will -produce very small buckles which will thus gradually increase as the -tool is set further and farther from the centre--until at last when -the curves pass beyond the centre, the result is arrived at already -shown in Fig. 317. Another form of this chuck is shown in 318, in -which, instead of the iron plate being pivotted for the purpose of -eccentricity upon the axis of the wheel E, a parallel slide motion is -given to the main wheel by guide bars, as in the eccentric and oval -chucks. This form is figured in "Lardner's Cabinet Cyclopædia." The -large front wheel carrying the screw for chucks is pivotted to the -slide C, and protected by a plate D which nearly covers it. The wheel -L, is arranged to follow this slide, so as to remain in gear with the -large wheel without leaving the fixed wheel or ring on the face of -the poppet. In both patterns of this chuck the front wheel is used -as a division plate, being moved in either direction as many cogs as -desired to produce interlacing of the looped designs. It is better, -however, to add a racked division plate and tangent screw, as in the -eccentric chuck to act as one piece with the chuck screw, and with -the latter turning on a conical pin in the centre of the large wheel -underneath. The above apparatus requires to be used with a slow motion -owing to the complication of parts, and the whole ought to be so well -constructed, that the various wheels revolve with perfect smoothness -and without shake or noise. - - [23] The word _buckle_ is used to signify the small loops--not the - large curves. - - [Illustration: FIG. 316.] - - [Illustration: FIG. 317.] - - [Illustration: FIG. 318.] - - - THE SPIRAL CHUCK (FIG. 319). - -There is no class of work on the whole more interesting than that -executed by the aid of the spiral chuck, especially with an addition -to be described here. This apparatus has grown, almost as a matter -of course, from the adaptation to the ordinary lathe of the system -of change wheels for the production of screws of various pitches. A -spiral is, in fact, a screw with very extended pitch, the threads -either closely enwrapping a cylinder which forms the core or body of -the screw, or being entirely separate and independent of such core, -the latter being by far the most light and elegant. The chuck here -described is used with the same arm or bracket as has been already -spoken of, standing out from the poppet to carry change wheels, and -is itself adjustable to suit different diameters of the same. In -the sectional view of this chuck given here, A, H, is the body with -internal screw as B, to fit the mandrel. The cog wheel of the chuck -which gears into the first on the movable arm or standard, is cast -with a large central hole to allow it to be stopped on at D, where it -is retained by a nut C. This permits a change of such wheel for one of -different size or for the apparatus to be presently described. - -Thus far the chuck is only applicable to the production of screws -or spirals with a single thread. F, is a dividing plate with racked -edge acted on by the tangent-screw E, and carrying the screw, G, a -counterpart of that upon the mandrel. This plate carries 96 divisions -or teeth. The latter may be used with a spring click if preferred; but -the racked edge gives perhaps the more delicate power of adjustment. -The spiral chuck constructed in this way is capable of producing -any required number of screw threads or spirals, solid or detached, -and of any ordinary pitch. It is, however, chiefly intended for the -production of spirals or twists for articles of _virtu_. The method -of proceeding has already been described in a previous page. It is -one rather of care than skill, as the lathe apparatus ensures the -correct movement of the tool where the shape of the latter determines -the form of thread, angular, round, or moulded at pleasure. A few -of the tools required are shown in the drawing. For finishing the -rounded threads, Nos. 3 and 4 may be used, which are similar to those -required for turning ivory rings, the one completing half the thread, -the other applied in the opposite direction, meeting the cut of the -first and finishing the operation. As it is necessary to get round to -the back of the threads in this case, no inner mandrel can be used to -support the work, and, therefore, great care and delicate handling -are necessary to prevent breaking the twists. The stops should also -be used upon the bed of the slide-rest, to limit the traverse of the -tool and prevent it from striking the shoulder, and destroying any -bead or other moulding formed there. This is more specially needed, -when there are two or more such twists rising from the same base (that -is when there are two or more threads to the screw). The additional -apparatus now to be described, adds considerably to the powers of the -spiral chuck. It is called the reciprocating apparatus, and its effect -is, to cause a to and fro movement of the work, at the same time that -the motion of the tool is continued in a horizontal direction. Fig. -320 shows the simplest of the effects thus produced. The screw is -commenced and carried to any desired distance on the cylinder. The -action and horizontal traverse of the tool is continued, but that of -the cylinder reversed, and the cut is thus carried upwards. The tool -may be a revolving cutter, the action of which, being continuous and -in the same direction, would seem preferable, as the greater the -speed with which the tool attacks the material the better is generally -the result in work of this kind. A fixed tool, moreover, must have a -central edge chamfered above and below, and there is also a tendency -with any such fixed tool to unscrew the chuck, as the resistance -occurs in that direction in the upward cut. - - [Illustration: FIG. 320, 321, 322, 323, 324, 325.] - -The details of the arrangement are as follows:--The several parts -being drawn of full size, Fig. 321 A is an eccentric capable of -slight adjustment by the use of either hole, one being further from -the centre than the other. Fig. 322 gives another view of this -eccentric, which is precisely similar to that used in model engines. -It is turned as a circular plate of gun-metal, with one flange. The -plate being five-tenths of an inch thick, a second plate, forming -another flange, is attached by four small screws, after the ring of -the eccentric is in place. This ring is of iron, or, still better, -of steel, and is made in one piece, with the arm B, which is six -inches long; the main part of it is flat, but it is rounded towards -the end, and turned at E, after which it is again flattened to work -against the arm D, or still better forked to embrace the latter. It -will be seen that D is also a flat plate, with a turned ring similar -to the first, but without the enclosed eccentric. In this is drilled -a series of ten holes, into any of which a pin can be fitted, so as -to unite the arms B and D, the pin becoming a hinge or centre of -oscillation. The circular ring of the part D fits on the part D, D -of the chuck, on which it can be secured by the ferrule C, the arm -D being then in a vertical position. The holes in the eccentric can -(either of them) be fitted over and secured to the end of the leading -screw of the slide-rest. The handle being then placed on the other -end of the screw and turned by the hand, the eccentric will cause the -arm D to oscillate to and fro through the medium of the connecting -rod B, thereby giving to the chuck, and to the work attached to it, -a similar to and fro movement. The extent of this movement depends -upon the length of the lever D brought into action. With the pin in -the holes 1, 2, 3, the oscillation will be inconsiderable, but with -the pin in either hole numbered 8, 9, 10, it will be much increased. -In the first, therefore, a short wave, Fig. 320, will result; in the -second case these will be more like Fig. 320 B. This apparatus will -completely alter the character of a spiral, which, if cut through a -hollow cylinder (as in the case of _detached_ twists) becomes a zigzag -of curved sides curious enough to behold. The apparatus, it must -be understood, is worked entirely by the handle of the slide-rest, -the lathe-cord being thrown off unless the latter is carried to the -overhead instead, to put in action revolving cutters. The reciprocal -action is, in fact, a self-acting segment engine. - -It has been already stated that for the production of spiral work -revolving cutters are preferable to fixed ones, unless, indeed, it is -required to finish up a perfectly round thread, when Figs. 3 and 4 -of the tools drawn are required. Revolving cutters must be placed in -the frame of the universal cutter and set to the rake of the thread. -Drills may be used for the reciprocating movement, as they make very -clean work, and the rake need not with these be attended to. In face -work drills are specially to be used to produce patterns like Fig. -325, and others derived from this simple one. An additional apparatus, -represented in Fig. 323, is required for the latter process, to enable -the rest to be turned in its socket so as to face the work, and -notwithstanding the alteration of its position still to keep up the -gearing of the wheels. A rest socket to be made and mounted as usual -is fitted with a stem surmounted by an accurately drilled boss A, -through which passes a spindle fitted with the wheel C, to gear with -that on the arm carrying the change-wheels, and which may be changed -for one of larger or smaller size. This is for cutting such work as -Fig. 324, representing, of course, only a single spiral, very open and -of itself of no beauty, but which by intersection of other spirals -can be converted into a pattern of great elegance. When it is desired -to produce the waved spiral the eccentric is fixed to the rod instead -of the wheel C, and the work proceeds the same as when a cylindrical -surface is to be worked. In the Fig. shown the division plate of this -chuck is of course used. - - [Illustration: 1.] - - [Illustration: 2.] - - [Illustration: 3.] - - [Illustration: 4.] - - [Illustration: 5.] - - [Illustration: 6.] - -It is evident that the variations producible by working intersecting -spirals and waved lines are very numerous, and these may be -additionally varied by the combination of eccentric and spiral -movements. - -The following six patterns are re-engraved from Valicourt's Hand -Book, which is almost identical with that of Bergeron. They were not -engraved in time to be inserted under the head of eccentric chuck -work. The notation and description annexed is from a manuscript book -kindly lent to the writer by an amateur. "_Bed-plate_," 4 deg., must -be taken to mean that the work is shifted (on one of the beds of the -chuck) four of the marked divisions for eccentricity, counting from -the axial line of the mandrel. - -"_Slide rest_, 4 deg.," means that the cutting tool is moved four -corresponding divisions in its bed for radius of the circle to be cut; -and so throughout. - -"4 *," means four times repeated. - -The cutting tools, unless otherwise expressed, are double angled, and -"25 cutting tool," means 25 deg. of cutting edge. - -Holtzapffel's scale of divisions is - - [Illustration] - -The scale used in Valicourt is which is that here quoted. - - [Illustration] - -If bed-plate and slide rest are both equally diminished at each cut, a -shell results, with the close part internal. If bed-plate is increased -and slide rest diminished, the close part of the shell is external. - - -SPECIMEN I.--Tools 25, 32, 36; Click-plate 96 or 288. - - Bed-plate moved. Slide rest moved. Circles done. Tool. - - 3 2 12* (1 done 7 missed) 25 - 6 1 12* (1 done 7 missed) - 10 3 48* (1 done 1 missed) 36 - 3 16 24* (1 done 3 missed) - 23 4-1/2 4* (16 done 8 missed) - 29-1/2 2 96* 25 - 33 1 96* - or 33 5/8 288* - - -SPECIMEN II.--Tools 28, 36; Click-plate 288. - - Bed-plate. Slide rest. Circles done. Tool. - - 1 1/2 12 28 - 4 1-1/2 12 - 7-1/2 2 4 (8 done 4 missed) 36 - 13 3-1/2 24 28 - 19-3/4 3-1/2 4 (16 done 8 missed) 36 - 19-3/4 1/2 4 (in spaces) - 21-3/4 1 4 (above last) - B 17-3/4 m 1 4 (below last) 36 - 30 1/2 12 (20 done 4 missed) 28 - - 29-3/8 1/2 12 {( 1 " 18 " ) - {( 1 " 4 " ) - - 28-3/4 1/2 12 Ditto. - 28-1/8 1/2 12 - - 27-1/2 1/2 12 {(15 done 4 missed) - {( 1 " 4 " ) - - 26-7/8 1/2 12 {( 1 " 18 " ) - {( 1 " 4 " ) - - 26-1/4 1/2 As before - 25-5/8 1/2 Ditto. - 25 1/2 12 (20 done 4 missed) - - From B to here, border, if with 96 click-plate, not good-looking; - tool a boring-bit. - - 33-1/16 7/8 12 (7 done 1 missed) - - 31-9/16 13-16th 12 {(1 " 5 " ) - {(1 " 1 " ) - - 29-1/16 3/4 12 {(1 " 1 " ) - {(5 " 1 " ) - - 27-9/16 11-16th 12 {(1 " 1 " ) - {(1 " 5 " ) - - 25-3/4 3/4 12 {(1 " 1 " ) - {(7 " 1 " ) - - -SPECIMEN III.--Click-plate 96. - - Bed-plate. Slide rest. Circles done. Tool. - 1-1/4 1-1/8 8 36 - 4-1/4 2-1/8 24 - 5-1/8 11-3/4 24 - 21-1/2 4-3/4 96 - 27-3/4 1-1/2 96 28 - - -SPECIMEN IV. - -The centre of this is a star of six curved rays, described by fixing -the cutter at the centre and turning the mandrel by hand through so -many divisions--for convenience so many 48ths of the circumference. -These rays are marked by B. (The segment stop is constructed for this -very kind of work, and is to be used in the present case):-- - - Bed-plate. Slide rest. Arcs done for star. - 5 B 5 6 (12/48ths of the circle) - 5 B 5 12 (11/48ths " ) - 5 B 5 12 (10/48ths " ) - 5 B 5 12 ( 8/48ths " ) - 14-1/8 5 24 (2 done, 2 missed) - 19-3/4 1/2 96 - 24-1/4 4 32 - 29-1/2 2-1/2 32 (intersecting) - 30-1/2 2 32 - - -SPECIMEN V.--Catherine wheel; tool 28. - -The ground grailed by concentric circles contiguous to each other. The -arcs by fours, all of same radius. - - Bed-plate. Rest. Arcs done. - 0 1/2 3/4 1-1/4 &c. (for grailing) - B 30 30 12 (16/48) - (Repeat at three next divisions.) - - -SPECIMEN VI.--Tools 28, 36; Click-plate, 288. - - Bed-plate. Rest. Number. - 1-1/4 1 8 done - B 12 12 12-7/48 (to meet next circle) - 4-3/8 17 24 - 30 1/2 12 - 29-1/2 1 12 - (On same radius as the last, and surrounding it.) - 29 1-1/2 12 - 28-1/2 2 12 - 28 2-1/2 12 - 27-1/2 3 12 - 27 3-1/2 12 - 26-1/2 4 12 - 23-1/2 1 12 - (3 done, 21 missed between last, or if click-plate 96.) - 25 1 12 (between last) - -Although in the matter of beauty the patterns here given are by no -means comparable to many others, especially to some lately published -from blocks cut by Mr. George Plant, for the _English Mechanic_; -they are, by their comparative simplicity, well selected to give the -learner a good idea of designing and working with the eccentric chuck. -It is not, indeed, proposed by the writer to multiply patterns, as -mere copying of such is of small interest to those who are really -endued with taste and skill; and the variations producible by -combinations of different numbers of divisions of the click-plate and -slide rest are of such infinite number, that printed designs of a -score or two would not serve to teach the nature of this work better -than the half dozen now before the reader. When a new chuck, indeed, -is brought out, it is well to give a few specimens of its work, to -show the possible purchaser its value as a means of ornamentation and -the extent of its capabilities; but when these are understood, the -purchaser had much better design for himself, instead of becoming a -lazy imitator and copying patterns laid down by others. Details of -designs that are presented in a tabular form remind us sadly (for we -are married) of the old "_knit one, drop two_," "_purl_" or some such -mysterious and, to us, detestable jargon wherewith ladies were, or -are, wont to worry the ears of mankind. - - * * * * * - -The chuck of Professor Ibbetson, and the elliptic cutting frame -of Captain Ash, are not introduced here, partly because this work -has reached its intended limit, and partly because the inventors -themselves have published separate works entirely devoted to a -description of the arrangements and capabilities of their respective -chucks. A brief notice is appended of Plant's geometric chuck, -contributed by the inventor to the pages of the _English Mechanic_.[24] - - [24] See Appendix. - - * * * * * - -The author now concludes his pleasant labours, the result of which -is contained in the preceding pages. These labours have been -lightened, and the work itself benefited, by several kindly-written -remarks received from various readers of the _English Mechanic_, -while the articles were in course of production in that paper. -Criticisms and suggestions also came to hand in which no such kindly -feelings appeared. These also have, nevertheless, had an equal share -of attention, and where they appeared to be of value they have -been turned to profit, and have resulted in various more or less -important alterations and additions. "The Lathe and its Uses," thus -re-arranged and modified, must now take its chance in the world with -other productions of a similar character; and the writer hopes it -may suffice to help those who need such assistance, and may be well -received by others who though able to walk alone may yet cherish a -kindly feeling for the friendly walking-stick. - - - - - APPENDIX. - - - PROFESSOR WILLIS'S TOOL HOLDER FOR THE SLIDE REST. - - [Illustration] - -This--described and drawn first in "Holtzapffel's Mechanical -Manipulation," to which work the author, and, indeed, most authors of -books of the nature of the present, are indebted for much of their -information--is now become very general, and from its perfect action -ought to be universally used in all factories in which the lathe bears -a part. It permits the tool to be set at any required angle upon the -bed of the slide rest, and holds it securely when placed in position. -It is likewise so constructed as to be easily removed from the table -of the rest, so that other forms of apparatus may be attached if -desired. One nut only has to be turned to fix the tool, this nut -turning on a strong central screw, A, in the figure, the lower part of -which, as far as the shoulder, is screwed into the top plate of the -rest. This shoulder is directed to be made with flattened sides, so -as to be capable of being unscrewed by the application of a wrench. -The actual clamp is a triangular piece of cast or wrought iron, B, in -the centre of which is a hole to allow this piece to go easily over -the screw. The hole is hollowed out into a cup-shaped cavity, into -which fits a hemispherical washer, shown at C in the section. The -clamping nut, D, acts upon this washer, which permits the triangle -to take up a position not _necessarily_ quite parallel to the bed of -the slide rest, and thus a tool whose upper and lower surfaces may -not be strictly parallel will be securely grasped. The piece called -triangular is not precisely of that form, but of the shape shown in -the second figure, in which E, E, represent two hard steel pins, -slightly projecting--one of these, E, appearing in the first figure. -These pins rest upon the upper surface of the tool. At the third -angle the clamping piece is drilled and tapped to receive a screw, -which must work stiffly in this hole. Thus when a tool is placed in -position, as shown, the clamping nut maintains a pressure upon the -three points beneath the apices of the triangle. As thus arranged the -tool would be stiffly and securely held; but Professor Willis has -added a second triangular piece, nearly similar to the first, except -that it is provided with a boss, in which a notch or groove is cut, K, -in both figures, into which the point of the small screw falls. This -lower triangle, which is free to revolve round the central screw, is -also cut away at the line L, L, of the second figure, so as to form -a guide or rest for the side of the tool, which is thus kept at the -same distance from the central screw, and placed in a moment exactly -under the studs or points of the upper plate. A careful inspection of -the two drawings will make the precise arrangement clear. In _making_ -it, which is not very difficult, care must be taken to make the -triangle of such size and so to place it, that no angle can overhang -the top plate of the rest, in whatever position it may be. The hole -in the upper triangle or clamp must be tolerably large and slightly -conical--the base of the cone upwards, to allow this piece to take -up a bearing, as described. The hemispherical washer is always in a -horizontal position, and the hole through it may be only of sufficient -diameter to allow it to pass freely over the central screw. - - - MUNRO'S PLANING MACHINE TO BE ATTACHED TO THE LATHE, AND WORKED - WITH THE FOOT. - -In the _English Mechanic_ of Nov. 2, 1866, a brief notice was given of -the above. The author of the present work having carefully inspected -the machine and seen it in operation, considers it of such great -value to the amateur mechanic, as well as to the professional turner -of metal work, that he has had an engraving of the machine carefully -made from a photograph, and has here appended it to illustrate the -description given. - -It is a lathe for planing, cutting key-grooves in wheels, collars, -&c., and cutting racks on the teeth of wheels. The lathe is of the -usual construction, but outside the right hand standard is fixed a -vertical spindle, which is made to rotate by a pair of bevel wheels, -the pinion being fast to the end of the crank shaft, and in contact -with a wheel of double the number of teeth on the vertical spindle. -On the top of the latter is a crank-plate, which will give a stroke -of ten inches or less at pleasure. The planing-machine is fixed by -two bolts to the lathe-bed, and a connecting rod is attached to the -sliding plate or bed of the planing machine, the other end of which is -made fast to the pin of the crank-plate. The work is clamped by simple -means to this sliding bed, and thus passes to and fro under the tool -which, by self-acting gear, is made to traverse sideways after -each stroke as in the large planing machines. The whole works almost -noiselessly and with the greatest ease, each part being accurately -fitted, and the whole well finished. For such purposes as planing -the face of the slide valve and its bed in small engines, or shaping -the guide bars of eccentric and other chucks, facing the frames -of slide-rests, &c., it is exactly what is needed by the amateur, -rendering the workshop complete for all purposes without the necessity -for adding a large and separate planing machine, which takes up room -that cannot always be conveniently spared. With such a lathe as that -in the frontispiece, fitted with one of these planing machines, there -is scarcely a model of machinery that could not be made. Any of our -readers interested in mechanics would be wise to trip over to Lambeth -and view the machine in operation; and the writer will guarantee, not -only the most civil and obliging attention from the inventor, but the -greatest pleasure and satisfaction from the working of the machine -itself. There is a _simple arrangement_ for key-grooving and slotting, -by attaching the upper slide of the ordinary rest to the crank plate -of this machine, in which case most of the apparatus is removed. - - [Illustration: MUNRO'S MACHINE TURNING LATHE FOR PLANING, ETC.] - - - HICKS' EXPANDING MANDREL. - -Mention of this has been made in the body of the work. It is used for -turning rings and washers, and various sizes of these can be turned -upon the same mandrel, so that a set of three will suffice for all -the work likely to be met with even in the largest factories. Fig. -1 represents the mandrel complete. F, F is the central part, with -a conical boss, A, cast upon it, and the whole turned with great -accuracy. Four longitudinal dovetailed slots, seen plainly in Fig. 3, -are then planed in the conical part, and into these are fitted -steel wedges, Fig. 2, A and B, and B, Fig. 3. C, Fig. 1, is a hollow -conical washer, which can be advanced over the central part when -driven forward by the nut D. This washer, acting on the ends of the -sliding wedges, causes them to move towards the large end of the cone -A, and, from the form of these and of the cone, any washer or ring -will be held tightly when placed outside these wedges, and will also -be mounted concentrically. - - [Illustration: FIG. 1.] - - [Illustration: FIG. 2.] - - [Illustration: FIG. 3.] - - - TURNING SPHERES BY MEANS OF TEMPLATES. - -It is but right to state that the above method has been objected to by -a practical workman, whose business has led him to study the matter -closely. He states that it is impossible in this way to effect the -desired object. As the writer has not been able to test the working -of the apparatus on his own lathe, he felt inclined, at first, to -withdraw the whole chapter. The objections offered, however, were -not, to his mind, entirely satisfactory; and the opinion of other -equally scientific and practical men being favourable, the chapter -has been retained. It is possible, nevertheless, that there may be -a mathematical reason which the writer is not competent to work -out, and the objector being a man of great mechanical knowledge and -experience, his remarks are worthy of consideration. The practical -(not insuperable) difficulty appears to be the production of a proper -tool for this work. - - - PLANT'S GEOMETRIC CHUCK. - -This chuck is put in motion by an entirely new method; none of its -parts being attached to the lathe head, the whole can be put in motion -or released in an instant, and without stopping the lathe. - -The whole of its work is executed by the continuous motion of the -lathe, so that, when the chuck is adjusted, any figure (no matter how -complex) may be begun and completed without once stopping the lathe. - -By the different arrangements and adjustments of the chuck and slide -rest, an infinite variety of the most beautiful geometrical figures -may be produced; and some of them of so strange and fortuitous a -nature as to bid defiance to any imitation. - - -_Description of the Drawings._ - -Fig. 1 is a front view, and - -Fig. 2 a view of the back of the chuck. - - [Illustration: Fig. 1.] - - [Illustration: Fig. 2] - - [Illustration: FRONT ELEVATION.] - - [Illustration] - - [Illustration] - - [Illustration] - - [Illustration] - - [Illustration] - - [Illustration] - -A A. The foundation plate screwing on the plate of the mandrel and -carrying the whole of the other parts of the chuck. - -B, C. The two driving wheels giving an independent motion to the chuck. - -D. Angular wheel moving freely on the wheel C for the angular -adjustment of the figures. - -E. Pinion of any number of teeth fitting on the shaft carrying D and C. - -H. Large wheel of 120 teeth, forming the foundation of the second -part, and driven from the pinion E by the wheels F, G, and T. - -L. Large wheel of 96 teeth driven by the pinions and wheels U, I, -J, K, and forming the foundation plate of the third part, M, which -carries the nose of the chuck. - -N, N. Self-adjusting radius plates for carrying the various change -wheels. - -O, P. The eccentric slides of the first and second parts. - -Fig. 2 shows the arrangement of the driving wheels and pinions on the -back of the chuck. - -The working of the chuck is as follows:-- - -If the pinion E has 20 teeth, and is geared direct into the wheel H, -by means of an intermediate wheel, it will give six loops inwards if -the motions are similar, and outward loops if the motions are contrary. - -If the wheel H is driven from the pinion G it will give 12, 24, or 48 -loops. - -Pinion of 24 teeth will give 5, 10, 20, or 40 loops. - -Pinion of 30 teeth will give 4, 8, 16, or 32 loops. - -Pinion of 40 teeth will give 3, 6, 18, or 36 loops. - -Pinion of 60 teeth will give two loops inwards, if the motions are -similar, but, if the motions are contrary, it will produce an ellipse -of any proportion from a straight line to a circle. - -Other combinations will give circulating or overlaying loops. - -By the different arrangements of wheels and pinions on the plates N, N -any number of loops can be produced up to 2,592 in the circle. - -On the opposite page we illustrate some work executed with this chuck -by Mr. Plant. - -Fig. 3 is a side elevation of the chuck full size. - -A, A, the foundation plate screwing on the nose of the mandrel, and -carrying the whole of the other parts of the chuck. - -B, C, the two driving wheels giving an independent motion to the chuck. - -D, D, angular wheel moving freely on the wheel C, for the angular -adjustment of the figures. - -E, E, pinion of any number of teeth fitting on the shaft carrying C -and D. - -H, H, large wheel of 120 teeth, forming foundation of the second part, -and driven from the pinion E by the wheels F, G, and T. - -L, large wheel of 96 teeth driven by the wheels and pinions I, J, K, -and forming the foundation of the third part, M, which carries the -nose of the chuck. - -N, N, self-adjusting radius plates for carrying the various change -wheels, &c. - -O, P, the eccentric slides of the first and second parts. - -Q, R, the screws working the eccentric slides. - - -A PAPER ON THE PRINCIPLES WHICH GOVERN THE FORMATION AND -APPLICATION OF ACUTE EDGES, WITH SPECIAL REFERENCE TO FIXED -TURNING-TOOLS, CONTRIBUTED BY MR. DODSWORTH HAYDON. - - "The formation of the tools used for turning and planing the - metals is a subject of very great importance to the practical - engineer, and it is indeed only when the mathematical principles - upon which such tools act are closely followed by the workman - that they produce their best effects."--Holtzapffel, vol. 2, p. - 983. - -As the best lathe can do no more than place the work in the most -favourable position for the operation of the tool, and the best tool -can only do good work when _applied_ as well as _constructed_ on true -principles, no argument is needed to prove the truth of the statement -taken as the text of this paper. - -But while many of our most eminent practical authorities, such -as Nasmyth, Holtzapffel, Babbage, Prof. Willis, and others, have -contributed valuable papers on the subject, no single writer can be -said to have embodied all that should be known upon it as a whole. - -Principle may be looked upon as the essence of practice, and in -connection with this particular subject, the reduction of practice -to principle is of comparatively modern growth. This will account -for the fragmentary character and occasional difference of opinion, -which marks the treatises of the above-named eminent authorities when -compared with each other. As a step towards some more concise and -perfect code of principle, I have endeavoured to collate and arrange -in consecutive order, all those laws which govern the action of acute -edged turning tools. - -The object of this paper is not to supply patterns of tools, as the -best form will be no better than the worst unless properly applied; -but to set forth those general principles, which may enable the -workman to distinguish between forms which are accidental and those -which are essential, and thus to make the shape of any tool his -servant rather than his guide. - -Whatever the shape or purpose of any acute-edged tool may be, its -action will always depend on the manner in which the extreme edge is -applied to the surface acted upon; and as the same laws govern the -action of every acute edge, whether formed on a razor or a tool for -cast iron, it will assist a clear comprehension of this subject to -consider first the action of edges generally, without reference to any -particular tool. - -The same edge may be made to act in four different ways, viz.: to -cut, dig, chatter or scrape. Digging and chattering are intermediate -stages between cutting and scraping, and are fatal to good work. Thus -_cutting_ and _scraping_ remain the two standard principles, on one of -which every tool should be made to act; and while cutting depends on -the penetration of the edge, scraping results from using an edge so -that it cannot penetrate. Consequently, the conditions most favourable -to cutting will give the key to both principles of action. - -Every cutting edge is simply a wedge, keen enough to guide its own -path without depending on the grain or other accidental line of -separation in the material on which it is employed; and when such a -wedge is forced into any substance, it will show a constant tendency -to penetrate in a line with that face which receives most opposition. -The comparative amount of opposition which each face receives, will -be determined either by one having more of its surface in contact -with the material than the other as in Fig. 2, or by the material -giving way on one side, as in Figs. 1 and 3. These last two figures -illustrate the action of all _paring_ tools, to which class cutting -lathe tools belong. The dotted lines are added in Fig. 2, to show that -the action of the edge is the same, whether it be formed by one or two -bevels. - - [Illustration: ILLUS. No. 1] - - [Illustration: ILLUS. No. 2] - - [Illustration: ILLUS. No. 3] - -Thus in all cases,--except when an edge is applied so that the -pressure is equal on both faces,--one face will guide the course of -the edge, and in paring tools this will always be the lower face, or -that next the surface of the work. - -The first consideration in placing any paring tool must therefore -always be that, _the lower face of the edge should lie as nearly as -possible in a line with the direction the cut is intended to follow_, -so as to place the whole edge in its natural wedge-like position: for -when any edge is compelled to act in a manner contrary to this, it -will assuredly assert its natural tendency by digging and chattering -in the direction of its lower face. But when the action of the tool -is continuous as in turning, planing, or boring, care must be taken -that this face of the edge does not actually rub against that of the -work; and, to avoid this, Nasmyth recommends that the face of the edge -should be inclined from the surface of the work at an angle of 3°. -Babbage calls this angle "the angle of relief," because it relieves -the friction; and to show how little variation is admissible in this -angle, Holtzapffel places its maximum at 6°. In cylindrical work the -angle of relief is estimated from a tangent to the circumference. -Thus, in Figs. 4 and 7, the lines C, D, may represent plane surfaces -or tangents at pleasure, and in either case the lower face of each -edge is supposed to make an angle of 3° with these lines respectively. - -An examination of the nature of the force required to separate any -shaving will show the importance of close attention to the above -rule. Babbage has pointed out that this process involves two forces, -which, though simultaneous in their action, are distinct in the -nature of their operation. The first is that necessary to divide the -material atom from atom, and depends on the kind of edge employed. -The second force is that required to wedge back the shaving, so as -to make way for the further progress of the edge, and depends on the -manner in which it is applied to the work. Now in fibrous and cohesive -materials, the amount of force required to wedge back the shaving is -usually greater than that required to effect the initial penetration, -and must always depend on the angle which the _upper surface_ of -the edge makes with the face of the work; while it is obvious that, -whatever the acuteness of the particular edge employed may be, this -angle will be reduced to the minimum obtainable with such an edge, -by keeping its lower face as close as possible to the surface from -which the shaving is being wedged off.[25] A comparison of Figs. 4 -and 5 will illustrate this. Both edges are supposed to be of the same -acuteness, viz., 60°, and in Fig. 4, where the angle of relief is -only 3°, the edge of 60° will wedge off the shaving at the smallest -available angle, viz., 63°, while the position of the same edge in -Fig. 5 increases this angle to 90°. - - [25] In adopting Mr. Babbage's arguments I have varied their form. Mr. - Babbage takes the square of 90° and divides it into three parts, viz.: - - Angle of relief 3° } - ditto edge 60° } 90° - ditto escape 27° } - - The angle of escape is thus estimated from the horizontal line - perpendicular to a base line presented by the surface of the work or - by a tangent to it. But as the value of this angle depends directly on - its relation to the base line, and has only a complementary relation - to the horizontal line, I have thought it better to confine the - illustration to the same base as being more directly connected with - the wedge-like action of the edge. - -Thus, as far as regards the force required to bend back the shaving, -the edge of Fig. 5 might just as well be nearly square, or 87°, taking -off 3° for the angle of relief. Indeed, this less acute edge would -work better than one more acute but badly placed, as in Fig. 5; for -the lower face here points too much _into_ the work, creating the -tendency to dig explained above. The same arguments and illustrations -apply with equal force to drills and boring tools, and Fig. 5 may -be looked at as representing one edge of a common drill, in which -the acuteness is obtained by bevelling the under sides only, leaving -the upper face of each edge perpendicular to the surface acted upon. -Nasmyth has pointed out that the less acute drills of this class are -made the better and more smoothly they will cut; for, so long as the -upper faces are left square to the surface of the work, increasing the -bevel of the lower faces can only increase the tendency to dig and -chatter. Thus, whenever acuteness is desired in any cutting edge, it -should always be obtained from the upper face; and the dotted lines -in Fig. 4, suggesting a tool for metal in one case, and a common -wood-turning chisel in the other, are added to illustrate this, by -showing that the line of the lower face is common to both. No tools -afford a better illustration of this principle in boring tools than -the American twist drills, which owe the ease and beauty of their -action to the spiral flutes being placed so as to give the necessary -acuteness from the upper face of each edge, thus allowing the lower -faces to be kept as close as possible to the surface of the work. -There is yet one more important practical advantage to be gained from -adopting the smallest possible angle of relief. The arrow in Figs. 4 -and 5 shows the direction in which the strain of the cut will fall on -the edges respectively. It has been shown that the position of Fig. -5 increases the amount of strain on the edge, and yet it is apparent -that it is less able to bear this increased strain; for while this -falls on Fig. 4 in its strongest direction--viz., almost down the -length of one face--it falls on Fig. 5 _across_ the end of the edge, -thus rendering it far more liable to wear and fracture. - -It is therefore evident that, in treating plane surfaces, the cutting -action of any acute edge is most favoured when its lower face is -placed nearly parallel with the surface acted on; and in treating -cylindrical surfaces, when the same face occupies the same position -with regard to some tangent of the circumference; or, in other words, -when the lower face is almost at right angles to some radius of the -circle, as in Fig. 4: and it follows that the tendency to penetrate -will be most effectually counteracted when a line at right angles to -the surface, or a radius of the circle, as in Fig. 6, bisects the -edge, making each face equidistant from the surface which moves across -it. Thus, Fig. 6 represents the _scraping_ position; and it is obvious -that all bow-drills or other tools, which are _said to cut both ways_, -must really act on the scraping principle. - -Practical illustrations in support of the universal application of -these principles might be multiplied indefinitely; but two very -common operations will suffice to prove that the position of the edge -determines the nature of its action. If a penknife be not held with -its blade perpendicular to the paper, when used for scratching out, it -will be sure to hang and chatter; and the flatter a razor is held to -the skin in shaving the more free will the chin be from uncomfortable -digs and chatters afterwards. - -The conditions which next demand notice in the case of turning-tools -are those which must be observed to preserve the proper position of -the edge under the strain put upon it. These relate to the form of the -tool, and, in the case of cylindrical work with fixed tools, to the -part of the surface at which the edge of the tool should be applied. -Drills and boring tools require little notice in this respect, for, as -the strain is round their axis, it is only necessary that their shafts -should be strong enough not to twist or bend. It must, however, be -remembered that when common drills are required to be very acute, the -edges should be thrown up a little or hollowed out so as to give the -acuteness on the upper face as explained above.[26] - - [26] The common form of drill is rendered far more efficient with - wrought iron and materials that require _cutting_, by twisting the - flat shaft when hot, so as to reverse the position of each edge after - the manner of a screw-auger. The lower faces can then be kept as - close as possible to the face of the work while the twist will give a - moderate degree of acuteness on the upper face. - -Hand-turning is simply a matter of manual dexterity, and as any -part of the same plane or the same circumference presents the same -surface to the edge of the tool, the correct relation between the -edge and the surface can be obtained in many places, and therefore -the particular point at which the edge should be applied is simply -a matter of personal convenience, and may vary with the height of -the lathe or that of the workman, or the shape and nature of the -tool employed. The use of the graver affords a good illustration of -this; and it may be remarked, in connection with this tool, that none -is more simple in construction, more perfect in principle, or more -convenient in application. When its use is once thoroughly mastered -it will do anything from smoothing a pin to roughing out a cylinder -four or five inches in diameter. The graver is simply a square bar of -steel ground off obliquely at the end; and by varying the obliquity of -this slope the act of grinding one plane face will give two cutting -edges of any desired acuteness, and three heels from which to use -these edges at choice. In hand-turning only one edge of the graver -is used at a time, and the lozenge-shaped face is made the lower -face common to each edge. Now, when the graver is used for roughing, -the point is generally buried in the clean metal _below_ the central -line of the work, and the lower face is placed against, and takes the -shaving from, the little shoulder which it forms on the cylinder. When -the graver is used for smoothing, the lower face is placed nearly -flat against the face of the work, and the edge is generally made to -bite on, or a _little above_, the central line. But for very light -finishing cuts the graver may be used from the heel at the bottom of -its lozenge face, and in this position its point is over the top of -the work, bringing the biting part of the edge _still more above_ -the central line. Thus, the only three points to consider in placing -the tool in hand-turning are--first, that the lower face of the -edge should occupy the proper position with regard to the surface; -secondly, that the handle of the tool should come up conveniently -to the hands of the operator; and thirdly, that while these two -conditions are observed, the heel of the tool should be able to take a -firm bearing on the rest. - -The best rule for hand-turning is, therefore, to apply the tool to -the work, with these ends in view before fixing the rest, and then to -bring that up to the necessary position. - -When the heel of any hand tool has a firm bearing on the rest, and the -edge is applied in the wedge-like position, the preservation of this -during the progress of the work depends on delicacy of touch rather -than muscular power. But when the edges are applied out of their -natural line, it puzzles a strong wrist to keep them to their cut at -all without digging into the work. This affords the best practical -illustration of the necessity of careful attention to the position of -slide-rest tools, which are deprived of all power of accommodation to -the sense of touch, and which therefore require accurate adjustment in -the first instance. - -For the motion of the tool is now confined to that of the rest, and -as this moves in horizontal planes, the edge of the tool must be -applied to the work on that parallel plane which passes through the -lathe centres. The reason for this rule will be at once apparent, if -the edge be not placed on this central line in facing up a plate--for -then it will lose its cut before reaching the centre, leaving a core -untouched. Now although it would require an exaggerated error in the -position of the edge to lose cut altogether in turning a cylinder, yet -this example proves that, unless the edge be applied exactly on the -central line the relative position between it and the surface of the -work, on which the cutting action depends, will imperceptibly change -with the reduction of the work; and supposing this to vary much in -diameter, the same tool may cut beautifully on one part and badly on -another. Fig. 4, which illustrates the cutting action of the edge, -has been purposely placed on a part of the circle where a slide-rest -tool could only act for a very short time, in order to draw attention -to the difference between those conditions which govern the cutting -action, and those which depend on the motion of the rest from which -the tool is used. It is obvious that if Fig. 4 were moved inwards on -a horizontal line the edge would pass over the smaller circle without -touching it. The illustration is of course exaggerated, but it proves -that Fig. 7 is the only position in which the tool will cut over -varying diameters without some change in the relative positions of its -lower face and that of the work. Hence the usual instructions to apply -the edge about the centre of the work. But Babbage has observed, that -however good this direction may be as far it goes, it is insufficient -and liable to mislead when given alone. It is impossible to do away -with elasticity when the tool is supported at some lateral distance -from the line of strain, as in the slide rest or planing machine; and -unless this elasticity is counteracted by the position of the tool, it -may upset the best position of the edge. To meet this, Babbage gives -the following rule--First, consider whereabouts the tool itself will -bend under strain on its edge, when fixed in the rest; and then take -care that this part of the tool, which Babbage calls "the centre of -flexure,"--is placed above a line joining the centre of the work and -the edge of the tool. Fig. 7 will explain the reasons for this rule -and the consequences of neglecting it when there is much strain put on -the edge. - -Let E, I, F, be the line joining the centre of the work and the edge -of the tool. Then if G above this line be the centre of flexure, -when the tool bends its edge must follow some part of the arc, H, I, -J, from G as a centre, and will be thrown out of the work. But if K -below the line, E, I, F, be the centre of flexure, then, under the -same circumstances, the edge will follow some part of the arc L, I, -M, from K as a centre, and must dig into the work. It is important -to recognise this principle, because while it shows that every tool -in which the top of the edge stands _above_ the shaft must be liable -to the evils resulting from elasticity, it shows also that even -cranked tools may fail to obviate the danger, unless care is taken to -place the weakest point in the shaft above the central line. Babbage -remarks, that although it is not always possible to strengthen any -part of a tool, it is always possible and sometimes desirable to make -some particular point weaker than the rest, by cutting away a little -where the weak point should be. Fig. 9 shows that the crank principle -may be applied in another form, and although the crank is upwards in -this case, the same object is attained by making P the weakest point, -and placing it above the central line, N, O. This form, however, is -only used for light finishing cuts; for any unnecessary length of -crank evidently adds elasticity, and Holtzapffel observes that, "in -adopting the crank form tools the principle must not be carried to -excess, as it must be remembered we can never expunge elasticity from -our materials, whether viewed in relation to the machine, the tool, -or the work." The crank, therefore, should only be just sufficient -to give the edge the right direction if the tool should spring; and -Holtzapffel remarks, that as a tool will generally bend somewhere in -the central line of its shaft, it is sufficient if the top of the edge -is kept on or just below this line, as in Fig. 8. Referring again -to Fig. 7, and looking at the line C, D, as a plane surface, and I, -F, as a line perpendicular to that surface, the same arguments and -illustrations apply to the form of a tool in the planing machine. The -point at which the tool is now applied ceases to be of moment. - -Having considered the conditions necessary to insure the best cutting -action of acute edges and the preservation of that action during the -progress of the work, it remains to treat of the edges most suitable -to particular materials, the method of giving them any desired angle, -and the manner of applying slide-rest tools so as to obtain the best -work with the least expenditure of force and time. - -Willis observes that different metals and qualities of the same -metal require to be treated with edges differing in their degree -of acuteness, and all the standard authorities concur in giving -the following code as near enough for all practical purposes. The -modification of these angles is ruled by the general principle -that fibrous and cohesive materials require more acute edges than -crystalline and granular substances, as will be apparent in the -following code:-- - - Wrought iron and steel 60° - Cast do. do. 70° - Roughing brass 80° - Finishing do. 90° - -Thus the edges available for the metals commonly treated in the lathe -find their maximum at 90° and minimum at 60°. The maximum requires no -explanation, as when any edge is larger it ceases to be an acute edge. - -With regard to the minimum of 60°, Babbage has pointed out that this -is dependent not only on the strength necessary to resist the strain -of the cut, but further and chiefly on the temper which must be -preserved in the edge; and if this be less than 60° the mass of metal -composing the extreme edge will be too small to carry off the heat -generated by the cut, consequently the extreme edge would soon lose -temper and become useless. - -But these different edges are formed in very different ways according -to the purpose for which the tool is intended; and this will be best -understood by comparing the action of a hand-turning chisel with that -of a pointed slide-rest tool. In the first case the edge is applied at -an oblique tangent to the surface, and removes the shaving by passing -under its whole width, much after the manner in which an apple is -pared, or a ribbon unwound from a stick, when the lower edge of one -turn just overlaps the top edge of the turn below it, and so on. In -this case the shaving can be cleanly detached by one straight edge. -But the position and motion of the slide-rest tool being perpendicular -to the axis of the work, its action becomes that of uncoiling rather -than paring; and as a cord or wire wound round a stick touches the -face of the stick in one direction, and the coil next to itself in -another, so in this case the width and thickness of the shaving lie -in opposite directions, as illustrated by the dark band in Fig. 10. -Consequently, unless the shaving be cut simultaneously in these two -directions--viz., from the face of the work on one side, and from -the matter under removal on the other, it is obvious that it must be -_torn_ from the work in one direction, thus increasing the labour and -spoiling the appearance of the work if the tearing should be from its -face. Now, in practice, at any rate in the rough cut, it is usual to -take the width of the shaving from the superfluous matter; and if the -tool be placed, as in Fig. 11, it can only cut on one edge; thus the -edge of the shaving will be torn from the face of the work, while the -point of the tool will trace a fine thread in its progress along it, -leaving the face with a rough unfinished appearance. - -But if the edges be formed so that they can be placed as in Figs. 10 -and 12, then both can cut simultaneously, and the screw-like trace -of the point may be obliterated. This method of using the tool will -leave the work with a good face from the first rough cut, leaving -very little for the finishing cut to do; in addition to which the -labour will be reduced to a minimum, thereby permitting a much heavier -cut from the same amount of force. In turning any plane surface the -corner of the edge should be sufficiently relieved from it to avoid -the danger of catching; but, in turning cylindrical surfaces, if the -tool be carefully made and placed, the slope of the upper surface -will carry the corner out of cut. Experiment must decide the exact -adjustment; but the great aim should be to keep the face of the tool -next the work as nearly parallel with it as possible, because it is -only that face which leaves any trace of the tool's action on the face -of the work--the action of the other edge being lost with the shaving. - - [Illustration: ILLUS. No. 4] - -Thus tools may be broadly divided into two classes--viz., single-edged -and double-edged--remembering always that this distinction refers -to the manner in which they should act, and not to the number of -edges which it may be convenient to form on the same tool. In -single-edged tools, whether there be one or many edges, each edge acts -independently in removing its own shaving, and may therefore be formed -separately. In this case a longitudinal section, showing the angle of -the point, will give a true idea of that of the cutting edge. But, in -the case of double-edged tools, as the two edges should co-operate in -the removal of the same shaving, they must also be formed so that, -while each lower face can occupy its proper position with regard to -that surface of the work opposed to it, both edges shall possess -the same degree of acuteness. In this case the two edges are formed -by three planes--viz., two side faces and one upper surface common -to both; and the angle of the point is now not only not that of the -cutting edges, but has not even any fixed relation to them, for the -cutting edges may vary some 25° or more on the very same longitudinal -section of the point. - -Prof. Willis has pointed out that in these tools the angles of the -cutting edges depend on the _section_ and _plan_ angles of the point -_conjointly_ (Fig. 8 is a _section_ view; Figs. 10, 11 and 12 are -_plan_ views). From this it follows that cutting edges of exactly the -same angle may be obtained by a great variety of combinations in the -plan and section angles; and in note A, U, of Holtzapffel's work, -vol. ii. p. 994, Prof. Willis has given a table, showing some of the -different combinations by which cutting edges of certain angles may be -produced with accuracy and simplicity. The following short table is -arranged from this source and though much abbreviated will be found -sufficient for all ordinary purposes. - - [Illustration: - - +-------------------------------------+ - |PLAN ANGLE WITH SECTION ANGLES | - | +-------+-------+-------+ - | 140° | 79.5° | 69° | 58° | - | 120° | 78.5 | 67 | 55 | - | 100° | 77 | 63.5 | 49.5 | - | 90° | 76 | 61 | 45 | - | 70° | 72.5 | 53.5 | 29 | - | +-------+-------+-------+ - |WILL GIVE ------- CUTTING EDGES | - | -------+-------+-------+ - | 80° | 70° | 60° | - +---------------------+-------+-------+ - ] - -The graver will again serve to illustrate the use of this table; -for although only one edge is employed at the same time in hand -turning, it belongs properly to the double edged class. This will be -very apparent if a graver is held point upwards side by side with a -point tool, and the dotted lines are added in Fig. 8, to make the -similarity of form more evident. Now Holtzapffel has said of the -graver when employed for its original purpose of engraving, that "no -instrument works more perfectly," pointing out that, while both the -edges are engaged in cutting the same shaving, both the lower faces -of the edges are respectively inclined at the smallest possible -angle from the sides of the V-shaped groove. Fig. 10 has already -been used to illustrate the best position of the slide-rest tool, -and if the illustration be turned round until the letters Q, R, read -horizontally, and this line be taken to represent a flat surface -with the graver acting upon it, it will be seen that the shaving is -removed in exactly the same manner in both cases; the only difference -being that the section of the shaving is triangular in one case and -rectangular in the other. But so far as the tool is concerned the -action is identical in each case, thus proving that every point -tool may be so made and placed as to merit Holtzapffel's eulogium -on the graver, and that this simple tool is in fact the type of all -double-edged tools. - -The graver being made from a square bar has of course a plan angle of -90°, and using it to illustrate the table, we will suppose that it is -desired to give it two cutting edges of 60° each. Referring to 90° -under the heading of "plan angle," 45° will be found on this line in -the column over "cutting edge" 60°; denoting that the section angle of -the point, _i.e._, the slope at which the graver is ground, must be -45° to give the desired edges. In the same way, if the section angle -were 61° the cutting edges would be 70°. But taking the plan angle of -120°, the table shows that this would produce the same cutting edges -of 60° with the larger section of 55°; and from this we have the -important rule that, _in obtaining cutting edges of any given degree -of acuteness the larger the plan angle is made, the larger also may -be the section angle_. Thus pointed tools though constructed on the -principle of the graver are an improvement on it in its simple form; -for by making both plan and section angles as wide as possible, it is -obvious that the strength and durability of the point will be much -increased. It is, therefore, always better to give slide-rest tools -a large plan angle, as in Fig. 12; and plan 120°, with section 55°, -will be found a very useful and durable tool for surfacing purposes -with wrought iron. When there are rectangular corners to cut in and -out of, of course the plan angle cannot be more than 90°, and then -it is well to sacrifice a little of the acuteness, as the section of -45° makes the point rather too weak. It is also worthy of remark as -a mathematical fact, that unless the plan angle exceed 60°, it is -impossible to obtain two cutting edges of that degree of acuteness; -and in any case, such a plan angle would be radically bad, because it -could not be used on the double-edged principle without _undercutting_ -the shaving. It is somewhat remarkable, in connection with this point, -that while Holtzapffel, vol. ii. p. 536, recommends prismatic cutters, -he should add a footnote which indirectly but most conclusively -corroborates Prof. Willis' condemnation of that particular form, by -admitting that the proper degree of acuteness cannot be given to both -edges. - -As the practical result of a circular edge is to cut in two opposite -directions,--the edge passing gradually from one to the other,--so -round-nosed tools belong properly to the double-edged class, and are -open to great objections unless carefully formed on this principle. - - [Illustration: ILLUS. No. 5] - -This is illustrated in Fig. 13, representing an oblique section of a -round bar; and supposing the section to be made at an angle of 45°, -it is obvious that the highest part of the edge at S will be exactly -of this angle, while the lower point at T will be 135°, and the side -points at U and V will be 90° each. Thus, between the point S and the -points U and V on each side respectively, the edge will gradually pass -through a range of 45°, consequently no two adjacent points on the -same side will be of the same angle, and the highest point S may be -too acute to stand while the lowest, U or V, is too blunt to cut. - -Whenever, therefore, it is intended to round the nose of the tool, it -should be first formed as a double-edged point tool, with a section -angle agreeing as nearly as practicable with the intended degree of -acuteness in the edge, so as to secure the highest points from being -too weak, and the table given above will show what plan angle must be -used, in combination with this section, to secure any part from being -too blunt. - -Thus, supposing a circular edge of about 60° is desired, the section -of 58° approaches this most nearly, and if the plan of 140°, which, -with this section, gives two straight cutting edges of 60°, be -adopted, there can only be a variation of 2° in different parts of the -edge. But it will be observed that this combination admits of very -little rounding; and although less acute edges, being obtainable with -a smaller plan-angle, admit of rather more rounding, it may be taken -as a general rule that when any tool is much rounded on the nose, so -as to present a large segment of a circle, different parts of the edge -must vary considerably in acuteness. Although Professor Willis objects -to rounding the nose of a tool at all on account of the necessary -variation in the character of the edge and some other reasons, I -am disposed to think that when the tool is carefully formed on the -principles given above, it is very advantageous to round off the point -slightly for taking heavy cuts; and I have found this form a favourite -one in such workshops as Woolwich Arsenal and Portsmouth Dockyard. But -care must be taken to place the nose of the tool towards the width -of the shaving (presuming that this is taken from the matter to be -removed, as it usually is,) for unless the edge is straight, and -almost parallel with the face of the work as it leaves it, the face -would be marked with a series of concave grooves of greater or less -width, according to the feed given to the tool; and even when this is -very slow, if the curved part of the edge were placed towards the face -of the work it would present the appearance of corrugated iron, when -examined under a magnifying lens. Willis further advances against the -round nose that, as the shaving removed by it must be of a curvilinear -section, it will oppose more force in rolling itself off the edge, -than a flat shaving. This would be quite true if a flat shaving could -be rolled up on itself like a piece of tape or ribbon; but I think the -professor has overlooked the fact that when two cutting edges have one -common upper face the shaving must be bent laterally as well as in its -length; and I am disposed to think, from practical experiment, that -there is very little difference on the point of the force required, -and that when a point of large plan angle is just rounded off it -stands better and cuts sweeter than when the point is not so rounded. -But this only applies to heavy cuts, and for ordinary surfacing work -nothing can act more perfectly than a point tool of wide plan-angle -placed as described above. If a double-edged tool, with edges of 60°, -be thus used in turning wrought iron or steel, and be well lubricated -with clean water during the progress of the work, its face may be left -with a burnished brilliancy that a touch of the finest emery would -spoil. But, as the scheme of this paper is confined to the principles -which determine the action of edges, and the rules by which those -edges may be formed with certainty, it will be well to conclude these -remarks with a few hints as to the construction of ordinary slide-rest -tools. Bearing in mind that all double-edged tools belong to the -graver class, it is well to form the side faces carefully in the first -instance, and then never to alter these, but to keep the tool in order -by grinding in the upper surface only, just as the graver is treated. -Nasmyth's cone gauge, illustrated in Holtzapffel, vol. ii., p. 534, -and also in "Baker's Mechanism," p. 236, affords a ready means of -forming the side faces with accuracy. But the range and convenience -of this gauge is much increased by dispensing with every part of the -arrangement, except the cone itself. This can be made of any piece -of stout metal bar turned truly, with the slide-rest set at an angle -of 3°, and the base should be broad enough to stand steady by itself -when squared off truly in the lathe, as in Fig. 14. Two marks can -then be made upon it: one as at W, showing the exact height of the -lathe-centre when the cone stands on the bed of the lathe, and another -as at X, showing the height of the centre when the cone is placed on -any given part of the slide-rest. Thus, in whatever direction the tool -is to be used, its adjustment can be accurately made in the first -instance on the slide-rest itself, and again tested after the tool is -clamped down. - -It is too common a practice in setting slide-rest tools to wedge up -one end or the other, with regard only to the application of the edge -on the central line. But this generally sacrifices the position of the -lower faces, which is essential, to a consideration which has been -shown to be only secondary. The best plan is to keep several strips, -varying from 1/32 to 1/2 inch in thickness, but all about as long and -wide as the shaft of the tool. These can be made of bar iron for the -thicker strips, and sheet iron or tin for the thinner ones; and by -using any two or three of these together, the tool can be packed up -parallel to the bed of the slide-rest. The adjustment of the edge can -thus be made with the greatest ease and certainty without altering the -relative position of the lower faces. - -It may be well to remark that in using the cone gauge, it is the lower -faces of each edge which are to be tried against it, and not the front -line of the point, as the inclination of this rule will vary slightly -with variations in the plan-angle of the tool, although the slope of -the faces remains the same. But the section angle is always to be -estimated from the front line, whatever its slope may be. - - [Illustration: No. 6] - -When the principles which this paper has endeavoured to embody are -once thoroughly understood, no handy workmen need ever be at a loss -to form and apply his edges with the best effect under any shape the -circumstances may require. The first point to be observed is the -manner in which the work should be attacked--that is to say, whether -the removal of the shaving or scraping requires the use of a single or -double-edged tool. The next point is the position of the lower face -or faces of the edges, so that they may be applied in the required -direction, and in the position explained above. This involves the -nature of the treatment best suited to the material, both as regards -the kind of edge employed and the principle on which it should be -applied--viz., cutting or scraping. In double-edged tools the position -of the two lower faces determines that of the point, which is simply -an accident resulting from the meeting of the cutting edges; but -which, when so determined, affords a guide for the slope of the upper -face. This must be so ground that it gives each edge the same degree -of acuteness. Thus, in Fig. 15, the point of the tool being at A, the -slope must be made in the direction A, B; while, in Fig. 16, the point -being at C, the slope of the upper face must be in the direction C, D. - -The writer is fully aware that those who expect to find "a rule of -thumb" in this paper, will be miserably disappointed. But while he -is conscious that the principles of which he has treated admit of -a much fuller and yet more concise definition, he would remind the -novice that there is "no royal road to learning," and that where -practice of hand is wanting it can only be supplied by greater -knowledge of principle. His object will therefore be fulfilled if -this supplementary paper can supply any explanation or illustration -of principle that may add to the practical utility of a work so -exhaustive of its subject as "the Lathe and its Uses." - - - DETACHED-CUTTER HOLDERS. - -Where amateurs experience inconvenience in making their tools from -the want of a forge, the use of detached cutters in a tool holder -will be found of the greatest advantage for outside work. Even in -plain turning there must always be some special forms for cutting -into odd corners and deep grooves; but with a good tool holder and -a grindstone, which is an indispensable piece of furniture in every -metal turner's shop, the cumbrous array of slide-rest tools may be -reduced to a few special forms and a very small box of cutters. These -also possess another great advantage; for the spirit of the old adage -quoted by Holtzapffel-- - - "He that would a good edge win - Must forge thick and grind thin," - -may be carried out far more conveniently than in the case of whole -tools which are generally filed into shape before tempering, and when -worn down must go to the fire again and have the process repeated. But -the detached cutter admits of being tempered evenly throughout its -whole length and ground up afterwards as long as it lasts, without -going to the forge again to the deterioration of the steel. - -The patterns of tool-holders are innumerable, but very few are good -for general service, because most of them are arranged so that the -natural sides of the cutter are used for the face or faces of the -edge. Thus either the plan angle of the point is limited to the angles -presented by the transverse section of the cutter employed, or else -the section angle is fixed by the position in which the cutter is -clamped. Holtzapffel's arrangement is open to the first objection, -Babbage's to the second. To obviate this inconvenience, Prof. Willis -arranged a holder which clamps the cutter at an angle of 55° from -the horizontal line. Thus no side can be used either for the lower or -upper face of the edge, but any faces can be ground upon it; and the -plan and section angle of the edge may be varied at pleasure within -the whole range available for metal turning. Prof. Willis's holder -for the cutter is almost a facsimile of his admirable tool-holder for -the slide-rest, than which none is more convenient or can act more -perfectly. But the arrangement is a little complicated for a cutter -holder, and must be very carefully made with the knowledge of certain -laws, if it is to insure a perfect grip of the cutter. It is also -designed for the use of sound wire cutters which require filing flat -on one side. - - [Illustration] - -Adopting Willis's inclination for the cutter I have found that all its -advantages may be secured with a simpler form of holder and common -square for steel for the cutter. The holder is simply the modification -of an old pattern to suit the inclination of 55°, and the sketch needs -little explanation beyond saying that the nick in the solid part -should be rather less than a square angle, and made perfectly true all -the way down, or, if anything, rather hollowed in the middle, so as -to insure the greatest amount of pressure at the top and bottom, as -otherwise the cutter might not sit quite true and firm. The angle at -the end of the strap against which the cutter bears should be rather -_more_ than square, both to allow for any want of exact truth in the -squaring of the cutter and to avoid the wedging action which would be -set up on tightening the screw if this angle were _less_ than square, -as this could of course create a risk of splitting the strap. The end -of the screw and the cup in which it fits should be round, as this -allows of a little play and insures a truer grip in the strap than a -pointed screw working into a conical hole. A perspective sketch of a -detached cutter is added, with dotted lines to show how exactly the -arrangement of the faces can be accommodated to the positions which -have been shown to be the best in solid tools for the slide-rest. - - D. HAYDON. - - - NEW FORM OF ROSE ENGINE BY E. TAYLOR. - -Seeing that the Editor of the above Articles has illustrated and -described Holtzapffel and Co.'s Rose Cutter and two methods of -executing rose cutting, the latter being the ordinary rose engine, I -am induced to send you a description of a method that I have adopted -whereby I can with considerable despatch execute this description of -turning. - -I will first preface my description by saying some thirty years ago -I purchased Ibbetson's Book on eccentric turning, and I was so much -taken with it and the illustrations, that I determined to make myself -in accordance with his description and engravings an eccentric chuck; -and although I was a long time about it, being at the time much -otherwise engaged, I succeeded beyond my expectations, and was enabled -to do some very fine work with it; and I have never regretted the time -I spent over the chuck, as I became familiar with metal turning and -screw cutting _flying_ in the lathe, which latter I was surprised to -find how easily I could execute. However, I was much disappointed in -the usefulness of the chuck (Holtzapffel's eccentric cutter, which I -purchased is far more useful), and also with the tediousness of using -it (fancy stopping the lathe to alter the chuck 360 times or 180 times -to cut a row of circles either distinct or overlaying each other), -and there was also a certain vibration occasioned in using the chuck -which I also disliked. I therefore determined to cut up some rosettes -and convert my headstock into a rose engine, to effect which object -I got Holtzapffel and Co. to return up with a new steel collar and -make my mandrel traversing. I cut myself a rosette both ways with -16 waves, and I was much pleased with the variety of work I could -perform with this one, but the rosette took me a long time to make, -and disheartened me from cutting up a variety. It, however, occurred -to me that if I added an extra mandrel by the side of and attached to -my headstock, and on which extra mandrel, if I had an eccentric chuck -connected with a rod to the wall of my room, I could get my headstock -to oscillate, and by connecting and multiplying wheels cause as many -waves on each revolution of my principal mandrel I pleased; this after -much time and patience I succeeded in doing, and worked it with the -hand motion often adopted for rose work. After between two and three -years, I put the extra mandrel over my principal mandrel instead of by -the side as before, to enable me to dispense with the hand motion and -to work the upper mandrel with the slow motion on my lathe wheel, and -which I found a very great improvement, and I now give the details of -the plan I have adopted for the benefit of your numerous readers. - -The drawings are to a two-inch scale, or one sixth of their full size. - -Fig. 400 is a side view of my headstock (part in section) with the -upper mandrel, A, added, showing the connection by an intermediate -spindle, B, with the large cog wheel, C, on my lower mandrel, D, and -other additions. - -The back centre, E, of my headstock is connected with the back screw, -F, and drawn out or pushed in with it, and is fixed by the set screw, -G. When drawn out the steel screw, H, at the end of the mandrel, D, -removes to receive the screw guides which are then fastened by it, and -the piece, I, with segments of a thread to match the guides, is slid -up by a wedge to the guides and then fastened by the screw J, I, can -also fix some roses cut on the side, and other apparatus with this -screw H.[27] - - [27] It is not a good plan to make the point, E, movable. It would - be better to slip the guides or rosettes over it: and generally to - arrange this part as usual with a traversing mandrel, P, H. - -The large cog wheel, C, is screwed up with the screw, K, to the -mandrel pulley, L. On the front of the pulley is the division plate as -usual. - -The intermediate adjustable spindle, B, is carried in a frame shown -separately by Fig. 405; it is allowed to rise or fall as may be -required for the wheel, M, to gear with the great wheel, C; provision -being also made for an intermediate wheel, N, (see Fig. 403) to -connect the wheel, O, with the wheel, P, on the upper mandrel when -required. - -The eccentric chuck is fixed on screw Q of the upper mandrel. - -Fig. 401 is a plan of the mould for the back cast-iron upright, fixed -to the headstock with screws at the foot, showing the circular grooves -1, 2 and 3, necessary for the spindles for the connecting wheels; the -centre hole, 4, is for the gun-metal collar, or the upper mandrel. - -Fig. 402, is a plan of the mould for the front cast-iron upright; the -centre holes 1 and 2 are for the collars of the mandrels. No. 2 is -made to just fit over the steel collar of the lower mandrel, and is -fixed to the headstock by a brass rose and three screws; it is also -fixed at the foot with two screws to the headstock. - -These two castings, 401 and 402, are bolted together with two bolts -and nuts through the holes 5 and 6, as shown in Fig. 400. Fig. 403, -is a back view of the additions, showing the cog wheels and their -connections, also the brass bearings for the lower mandrel required -when allowed to traverse. This was a solid piece of brass with a hole -bored out and ground to fit the mandrel. It was then drilled the whole -depth in two places, for two steel steady pins, _b_, _c_, made to fit -quite tight, and at both ends for bolts and nuts, _a_, _d_, afterwards -sawn in two with the circular saw, and when put together and two holes -drilled through the thickness for fixing it was put in its place, -adjusted, and re-ground on. The holes for fixing were very carefully -continued through the cast iron upright, and the whole was finally -fixed with two screw bolts and nuts. - -Fig. 404, is a front view, showing the eccentric chuck, R, on the -upper mandrel, the slide of which when used is connected with the -bracket in the wall, Fig. 406, causing the whole apparatus to -oscillate in proportion to the eccentricity of the chuck on its -centres one of which is marked at S. The chuck has a circular movement -for laying the waves in any position with one another, but which also -is effected by another plan to be presently described. The whole -poppet with its fittings is hung on centres similar to the rose engine -described in this work. The top part of the bed T removes, and the two -screws, one shown at V, are taken out to allow the oscillation. The -large cog wheel has 192 teeth. - - [Illustration: FIG. 400.] - - [Illustration: FIG. 401.] - - [Illustration: FIG. 402.] - - [Illustration: FIG. 403.] - - [Illustration: FIG. 404.] - - [Illustration: FIG. 405.] - - [Illustration: FIG. 406.] - -The whole of the additions to my headstock were all of my own fitting -up. The brass cog wheels were bored out and ground to fit an arbor -made on purpose, exactly corresponding in diameter with the ends -of the spindles so that they might fit indiscriminately on either -spindle. When turned up, the teeth were cut with a circular cutter, -which I made just of the exact shape and thickness required for the -space between the teeth. The cutter was turned of steel; then wrapped -in leather and enclosed in sheet iron. It was then put in the fire, -made red hot, and left for the fire to go out, the next day being -soft, it was cut with sharp chisels into a circular file and hardened, -and with it in the cutter frame the teeth of the wheels were cut. The -central boss of each wheel has a notch cut across the face to receive -a pin in the arbor and in the spindles, which prevents the wheels from -turning round on the latter when screwed up. - -This rose engine works beautifully smooth and easy, and ornamentation -can be done with it with greater rapidity than with the ordinary -engine, by arranging the connecting wheels so that the upper mandrel -makes so many waves and one-half, one-third, one-fourth, one-fifth, -one-sixth, or any other part of a wave, on each revolution of the -lower mandrel, because then it requires certain revolutions of the -lower mandrel before the tool comes into the same cut again--say, -for instance, it makes 4-5/6 waves on each revolution, then it takes -29 revolutions of the upper mandrel to complete the pattern, whereby -certain patterns are completed without stopping the lathe, which is -an advantage that the rose engine proper does not possess. Another -great advantage is, that the waves can be either flat, sharp, or -intermediate, as required for large or small work, by altering the -eccentric chuck on the upper mandrel. - -I give a few specimens, not for the beauty of design, but to -illustrate the working of the engine. The centre of Fig. 407 is -performed by having a wheel of 80 teeth on the upper mandrel, -connected with one of 25 teeth on the intermediate spindle, which has -another of 50 teeth connected with the large wheel of 192 teeth on -the lower mandrel; thus, 80/25 50/190 = 1-1/5 producing on each -revolution of the lower mandrel one wave, and one-fifth of another -wave, requiring six revolutions to complete the pattern. - -The remainder of the pattern is completed by wheels, 16, 50; 48, 192 -making 12-1/2 waves on each revolution of the lower mandrel, requiring -25 waves to complete the pattern, and laying the waves over each -other, and with the slide rest movement of the tool. - -Fig. 408 is produced by wheels 32, 48; 24, 192 making 12 waves. The -centre is done by altering the eccentric chuck each time. It was -purposely executed askew, by the tool not being placed in the centre, -to show the importance of doing so for some patterns. The rim was -executed with the same wheels, and with the slide rest movement of the -tool, and, after two cuts, the chuck turned half round, to lay the -waves over each other for the other two cuts. - -Fig. 409 is all executed with wheels 96, 30; 25, 192 making two -waves and two-fifths of another wave, requiring 12 waves to complete -the pattern. The two centre rims produced by placing the tool above -the centre. The outside by four movements of the slide rest tool, -illustrating how soon patterns are produced, and when well cut up look -very pretty. - -Fig. 410 is executed with wheels 80, 50; 25, 192 making four waves -and four-fifths of another wave, requiring 24 waves to complete the -pattern. The centre is all done without stopping; the outside rim by -altering the eccentric chuck four times, to make each successive wave -flatter. - -Fig. 411 is an illustration of the upper mandrel, making 5-1/3 -revolutions to one of the lathe, requiring 16 revolutions to complete -the pattern and slide-rest movement. - -Fig. 412. The outer pattern of this figure is produced by the upper -mandrel making 12-4/5 revolutions to one of the lathe, requiring 64 -revolutions to complete the pattern. The centre is a rosette of 5 -waves, slide-rest movement and placed across each other. - - [Illustration: FIG. 407.] - - [Illustration: FIG. 408.] - - [Illustration: FIG. 409.] - - [Illustration: FIG. 410.] - - [Illustration: FIG. 411.] - - [Illustration: FIG. 412.] - -Fig. 413. The whole of this pattern produced by the upper mandrel -making 3-3/5 revolutions to one of the lathe, producing 18 waves -across each other with slide-rest movement for the middle rim. - -Fig. 414 illustrates a rosette of nine waves with slide-rest movement, -and 3 divisions of the circular movement of the eccentric chuck for -each successive line, producing the waved appearance. - -Fig. 415 illustrates a rosette of 24 waves with the slide-rest -movement. - -Fig. 416. Another illustration of a rosette of 24 waves, rather more -sharp than in Fig. 415, with slide-rest movement and 9 divisions of -the circular movement of the eccentric chuck, giving it a pleasing -circular waved appearance. - -Fig. 417. Also another illustration as the last, but with the waves -much sharper, the slide-rest movement and only two divisions of the -circular movement of the eccentric chuck producing the star-like -pattern. - -Fig. 418 illustrates also a rosette of 24 waves, with the eccentric -chuck turned half-way round with each movement of the slide-rest, -producing the pattern so often seen on the back of watches, only being -on wood it is on a larger scale. - - [Illustration: FIG. 413.] - - [Illustration: FIG. 414.] - - [Illustration: FIG. 415.] - - [Illustration: FIG. 416.] - - [Illustration: FIG. 417.] - - [Illustration: FIG. 418.] - -The above illustrations are sufficient to give a distinct idea of the -working of my engine, and the last four show how easily patterns are -multiplied and varied. - -The whole of the preceding patterns were executed by the wood being -chucked in the lathe in the usual ordinary way without any particular -chuck whatever, but in combination with any of the ornamental chucks -innumerable patterns can be produced. - -Fig. 419 is one illustration with an eccentric chuck on the lathe -mandrel. - - [Illustration: FIG. 419.] - -That my description may be complete I will now give drawings of my -eccentric chuck for the upper mandrel. It requires to be constructed -differently to the ordinary eccentric chuck, as the circular movement -requires to be always _central_, and only the slide carrying the pin -to receive the rod must move eccentrically. - - [Illustration: FIG. 420, also 422.] - - [Illustration: FIG. 421, also 423.] - -Figs. 420 and 421, are full-size drawings of my eccentric chuck on my -upper mandrel, used for producing the foregoing specimens. In this -case I have preferred a wood foundation, as not being so likely to run -off as metal, on reversing the motion which is sometimes necessary -on account of idle wheels for the connections. I used a piece of -well-seasoned Spanish mahogany, taking care that the grain of the -wood was at right angles with the length of the screw of the mandrel. -A piece of brass is screwed at the back to prevent the screw cutting -into the wood. Fig. 420 is a section, and Fig. 421 a front view of -the chuck, and I think all sufficiently clear. I will just say the -long fine threaded screw I cut up with the stocks and dies in the -lathe, using steel wire of the necessary size. This I manage easily, -and keep the wire straight _by allowing it to expand in length_. I -chuck the steel wire concentrically, and removing the centre from the -back poppet, substitute a brass centre with a hole the size of the -steel wire, which is allowed about a quarter of an inch entry. I then -turn down a little below the depth of the intended screw thread for -about half an inch in length next the back centre, to allow the dies -to come back to be tightened up, and which must only be done at the -commencement and not on the return motion of the dies. The collar on -the screw is a piece of brass with a hole of a size to drive on the -wire tight, and is then pinned on and turned up true, and finished -with the division marks. - - - OVAL TURNING AND ROSE CUTTING WITH TEMPLATES WITH MY - APPARATUS. - -Figs. 422 and 423 are full size drawings of my chuck, with circular -movement for templates for my upper mandrel, which has also a wood -foundation. Fig. 422 is a section, and Fig. 423 is a front view. - -By removing the eccentric chuck from the upper mandrel, and -substituting the chuck Figs. 422 and 423 with a circular movement, -to receive templates of any pattern, OVALS with the oval -template can be turned and also with any irregular templates, patterns -cut and placed in any direction over each other, by causing the -templates to work against a rubber or roller as most desirable, with -an india-rubber spring to keep them together. - -The following illustrations will give some faint idea of productions -from templates. - -Fig. 424, is the production of an oval template and slide-rest -movement, both mandrels making equal revolutions. - -Fig. 425 the same as Fig. 424, with the patterns laid across each -other by turning the circular movement of the chuck 12 divisions. - -Fig. 426, is from an oval template, which is caused to make two -revolutions to one of the lathe mandrel producing 4 waves and -undulations and with the slide-rest movement. It will be perceived in -this case the form of the _oval_ is superseded by another pattern, and -shows how great a change in the form of patterns from templates my -rose engine with change wheels effects. - -Fig. 427, is also from an oval template, caused to make 5 revolutions -to one of the lathe, and with the circular movement of the chuck -and the slide-rest movement, and in this case the form of the oval -is also superseded. Indeed, none but those who have made the matter -their study would have the slightest idea that this pattern could be -produced from an oval template. - -Fig. 428, is also from an oval template, it is finer than 427, but is -done in the same way by the template making _nine_ revolutions to one -of the lathe mandrel. - - [Illustration: FIG. 424.] - - [Illustration: FIG. 425.] - - [Illustration: FIG. 426.] - - [Illustration: FIG. 427.] - - [Illustration: FIG. 428.] - -The above are a few specimens of the oval, but sufficient to draw -attention to the great variety of patterns that can be executed, -and these illustrations have only been made to go even revolutions -with the lathe mandrel; but of course can be made to go, as already -described, uneven revolutions, laying the lines over each other for -variety of patterns. - -Fig. 429, is a curiosity from a square template with equal -revolutions, the outside rim and inside pattern by the circular -movement of the template chuck. - -Fig. 430, is also from a square template made to go two revolutions to -one of the lathe and with the slide-rest movement. The centre pattern -with the circular movement of the chuck. - -Fig. 431, is the production of a heart-shape template, and with the -slide-rest movement and the patterns laid across each other, the -mandrels making equal revolutions. - -Fig. 432, is also from a heart-shape template made to go two -revolutions to one of the lathe and the slide-rest movement. But in -this case the slide-rest tool is used _on the opposite side of the -lathe bed_ to the roller against the template, and therefore reversing -the pattern, that is, the projections of the pattern are the hollows -of the template, and _vice versa_. I have introduced it to show how -easily patterns are multiplied in the most simple way. It will also be -observed that the form of the template is superseded. - -Fig. 433, is another illustration of the heart-shape template, but -made to go five revolutions to one of the lathe, with the circular -movement of the template chuck, and the slide-rest movement, and in -which case the form of the template is entirely superseded. - -Fig. 434, is also a similar illustration to 433, only finer; they can -be of course as fine as desired. - -The above are, I think, sufficient to illustrate the productions from -templates, some very pretty patterns can be executed. My object is -more particularly to exhibit the use and extended application of my -rose engine, and it will be perceived the last two are not the most -easily working templates. - -The variety of patterns that can be executed with this engine are -so innumerable that one may say they are infinite. Well may you in -your article quote what Bergeron says of the rose engine, "that it is -necessary to know thoroughly the particular one in use." - -I also make use of the cogwheel on my mandrel, by connecting it by a -spindle and the change wheels with a large compound slide rest, for -executing spiral turning, and also with my slide rest for ornamental -turning, for small spiral work; and with a chuck with a circular -movement I can cut several spirals to one stem. - - [Illustration: FIG. 429.] - - [Illustration: FIG. 430.] - - [Illustration: FIG. 431.] - - [Illustration: FIG. 432.] - - [Illustration: FIG. 433.] - - [Illustration: FIG. 434.] - -In concluding my description I will say the specimens given have all -been cut on a plain surface, and this has been unavoidable on account -of printing, but for the information of those unacquainted with the -rose engine, the very great advantages of which over the eccentric -and geometrical chucks are that the work can be executed on concave -or convex surfaces. I make use of mine for ornamenting the roofs of -temples and Chinese pagodas, either domed, curvilinear, or circular -pointed, by representing them covered with shingles, &c. The geometric -chuck will produce very beautiful intricate lacework, but not more so -than my apparatus, as they both are on the same principle of change -wheels, and can both produce equally fine work; but with my apparatus -the work is always concentric with the mandrel, and therefore much -more pleasing to execute. - - ELIAS TAYLOR. - - Hartford Villa, Patcham, near Brighton, Sussex. - - - JUDD & GLASS, PHOENIX PRINTING WORKS, DOCTORS' COMMONS, - E.C. - - - - - ADVERTISEMENTS. - - ESTABLISHED A.D. 1822. - - [Illustration] - - JAMES LEWIS. - - 41, GREAT QUEEN STREET, LINCOLN'S INN FIELDS, - - (Late LEWIS & SON, of Wych Street, Strand), - -Engineer, Machinist, Lathe and Tool Maker, and Modeller of New -Inventions, for English or Foreign Patents, from Drawings or -Specifications, in Brass, Iron, or Wood. - -Also Manufacturer of Steam Engines and Boilers for driving Amateur -Lathes, Pleasure Boats, &c., the Boilers fitted with Messrs. Field's -Patent Circulating Tubes; whereby a great saving of Fuel and space is -effected; or can be fitted for Gas. - - Model Steam Engines and Boilers kept in Stock, and the different - parts may be had for making the same. - - _Estimates given for all kinds of Work. Country Orders - punctually attended to._ - - - - - JOSEPH LEWIS'S. - - PATENT - - COMBINED DRILL, CIRCULAR SAW, - AND FRET MACHINE. - - [Illustration] - -_Patterns and designs for Picture Frames, Brackets, Reading Desks, -etc., from 3d. each, or 2s. 6d. per dozen assorted._ - - To fix on Lathe £3 0 0 - Ladies' Machine 4 0 0 - Ditto ditto 5 0 0 - Gentlemen's ditto 5 0 0 - Ditto, with drill 6 10 0 - Gentlemen's Machines with Circular Saw 8 0 0 - Ditto, ditto, ditto, with the improved - Saw-shifting Apparatus complete 9 10 0 - -Best Saws from 4-1/2d. per doz., 4s. per gross. Ornamental Drills from -1s. each. - -51, HIGH STREET, BLOOMSBURY. - - [Illustration] - - JOSEPH LEWIS, - -ENGINEER, MACHINIST, LATHE AND TOOL MAKER, AND MODELLER OF NEW -INVENTIONS. - -Manufacturer of every description of Plain and Ornamental Lathes, -Chucks, Slide Rests, Tools, Drills, over-hand motions, Division -Plates, &c. - -Lathes £8 0 0, £10 0 0, £12 0 0, £14 0 0, £16 0 0, £25 0 0. - -Amateurs supplied with Castings, Forgings of Lathe Engines, &c., and -assisted in making the same. - - [Illustration] - - JOSEPH LEWIS'S - - Apparatus for cutting Screws of all nitches, self-acting, made and - fitted to any Lathe. - - 51, High St., Bloomsbury, London. - - - - - JAMES MUNRO, - - (_From Messrs. HOLTZAPFFEL & Co._) - - - ENGINEER, MACHINIST, - - LATHE AND TOOL MAKER, - - MANUFACTURER OF ALL KINDS OF - - LATHE APPARATUS FOR PLAIN OR ORNAMENTAL TURNING, - - DIE STOCKS, TAPS, SCREW TOOLS, OVAL AND ECCENTRIC CHUCKS, CUTTING - FRAMES, &c. - - 4, GIBSON STREET, WATERLOO ROAD, - - LONDON, S. - - [Illustration: MACHINE TURNING LATHE FOR PLANING, ETC., ETC. INVENTED -BY J. MUNRO.] - - [Illustration: HAND PLANING MACHINE.] - - * * * * * - -JAMES MUNRO respectfully invites the attention of Amateurs -and Manufacturers to the excellence of workmanship and construction of -the various descriptions of Lathe Machines and apparatus produced in -his manufactory, which has secured the approval of numerous patrons. - - * * * * * - - Specimens may be seen at the Museum of Patents, South Kensington. - - - - - THE ENGLISH MECHANIC - - And Mirror of Science, - - IS AN ILLUSTRATED RECORD OF - - Engineering, Building, New Inventions, Photography, Chemistry, - Electricity, &c., &c. - - * * * * * - -Weekly, price 2d.; post 3d. Monthly parts, 9d.; post 11d. Quarterly -Subscription, post-free, 3s. 3d. Vol. VI. now ready, 7s.; post-free, -8s. - - * * * * * - - (From the _Weekly Times_.) - - "Technical education forms just now a topic of more than - ordinary importance, and, as far as we can see, 'The English - Mechanic' fills a large space in providing technical food for - the workmen of Great Britain. There is scarcely a subject in - the scientific or mechanical world that is not practically - described in this excellent journal, and all the technicalities - explained with a particularity quite remarkable. Here the - workman in all departments of trade will find something to - interest him, and many things explained by which he will be - able to make the best use of his knowledge. The editor is - always anxious to satisfy the cravings of his readers by giving - every information possible to those who may require it. The - trouble taken in this department is apparent on reference to - the 'Letters to the Editor' and 'Replies to Queries,' both - of which form original, very important, and useful features - of the magazine. Under the head, also, of 'Our Subscribers' - Exchange Club,' a means is opened for persons to exchange one - article for another on mutually advantageous terms, and for this - accommodation no charge is made. For instance, one correspondent - says he has a silver watch which he would exchange for 'The - Lives of Eminent Men;' another wants 'a cottage piano' for 'a - three-horse power horizontal engine;' and a third has 'a hand - sewing machine,' which he would give for 'a parallel sliding - vice.' The illustrations of 'The English Mechanic' are worthy - of all praise; they are drawn with an exactness which is so - necessary, and so much appreciated by workmen, and are also well - printed. Throughout the whole publication there is a visible, - a practical, and technical knowledge of a high order--a kind - of knowledge that is highly prized by all mechanics and men of - science." - - * * * * * - - (From the Morning _Advertiser_) - - "'The English Mechanic.'--Illustrated with appropriate - engravings, this valuable periodical is replete with information - of the most valuable kind in every department of engineering, - and in all applications of the principles of physical science. - Its contents are exceedingly varied, and embrace, in a form - adapted for immediate and convenient reference, a well-digested - account of any noteworthy progress made in the mechanical or - chemical arts, at home or abroad. For all purposes of the - inventor, we do not know a periodical more likely to give him - that assistance which he could expect to derive from recent - means and appliances." - - * * * * * - - (From the _Observer_.) - - "'The English Mechanic and Mirror of Science' is a publication - which contains much that is new and instructive in various - branches of science." - - * * * * * - - Now ready, price 9d.; post free, 10d. - -THE ENGINEER'S SLIDE RULE, and its APPLICATIONS. A complete -investigation of the principles upon which the Slide Rule is -constructed, together with the method of its application to all -purposes of the Practical Mechanic. - - * * * * * - - Published by the Proprietor, GEO. MADDICK, 2 & 3, Shoe Lane, - Fleet Street, - _And to be had of all Booksellers._ - - - - - ESTABLISHED A.D. 1810. - - [Illustration] - - W. J. EVANS, - - =ENGINE, LATHE AND TOOL MAKER, AND GENERAL MACHINIST,= 104, - WARDOUR STREET, SOHO, LONDON. - - TURNING, PLANING, SCREW AND WHEEL CUTTING TO DRAWINGS AND MODELS. - - Amateurs' turning Lathes of every description for Plain, Eccentric, -Oval and Ornamental turning, also the various tools and apparatus the - Mechanical Arts. - -_Instruction given to Amateurs in Plain and Ornamental Turning in all - its Branches._ - - Contractor to Her Majesty's War Department. - - * * * * * - - LATHES, - - =AND EVERY DESCRIPTION OF TOOL FOR AMATEUR TURNERS.= - - Lathes complete, £7 5s., £9, £11, £16 16s. - - CHUCKS & ALL KINDS OF APPARATUS FITTED TO LATHES. - - =Engineers' Files and Tools of every description. - - AMERICAN TWIST DRILLS=, - - _And Self-centering Chucks for holding all sized Drills._ - - =AMERICAN SCROLL CHUCKS OF ALL SIZES= - - Can be readily fitted to any Lathe. - - * * * * * - - JOSEPH BUCK, - =124, NEWGATE STREET, E.C., - And 164, WATERLOO ROAD, S., LONDON.= - - - - - W. BLACKETT, - - HOPE IRON WORKS, - - SOUTHWARK BRIDGE ROAD, LONDON, - - MANUFACTURER OF - -Engineers, Millwrights, Iron Ship Builders, and Boiler Makers' Tools. - - - [Illustration: PLANING MACHINE.] - - [Illustration: SCREW CUTTING FOOT LATHE.] - - [Illustration: SLIDING AND SCREW CUTTING LATHE.] - -The Machines usually on hand consist of large and small Boring -and Drilling Machines; Universal Shaping, Planing, Slotting, -Bolt-screwing, Single and Double ended Punching and Shearing Machines; -a variety of Self-acting, Sliding, and Screw-cutting Lathes, Hand -Lathes, Foot Lathes, Compound Slide Rests, Planed Iron Lathe Beds, -Ratchet Drill Braces, Screwing Tackle, Screw Jacks, and other Tools, -such as are usually required in Engineering Establishments. Tools not -in stock made to order. - - - - - ADVERTISEMENTS. - - By Her Majesty's Royal Letters Patent. - - [Illustration] - - - CUNNINGHAM AND CO., - - 480, NEW OXFORD STREET, LONDON, W.C., - - ORNAMENTAL WOOD - - AND - - METAL CUTTING MACHINES, - - AND - - DRILLING APPARATUS. - - ADAPTED FOR LADIES' USE. - - [Illustration] - -=Useful to the following Trades=--Organ Builders--Cabinet -Makers--Pattern Makers--Chair Makers--Gun Case Makers--Marqueterie -Makers--Toy Maker--Jewel Case Makers--Carvers--Cutlers--Leather -Cutters--Engravers--Jewellers--Chandelier -Makers--Electrotypers--Stereotypers--&c. - - - Will cut Brass a Quarter inch thick with ease. - - The working of the Machine is very simple, and can be learnt by an - amateur in five minutes. - - - Patentees of the - - CAM ROLLER BUFFING, - - FOR - - Preventing Noise in Machinery. - - [Illustration] - - _See ENGINEER, Jan. 24th, 1868._ - - - - - W. J. CUNNINGHAM AND CO. - - -Beg to call the attention of the Public to their newly-invented -Ornamental Wood and Metal Cutting Machine. Its extreme simplicity of -construction precluding the possibility of speedily getting out of -order, having no springs, and its peculiar adaptability to all kinds -of fret-work render it at once an acquisition and an indispensability -where accuracy, expedition, and high finish are required. The working -is exceedingly easy, requiring no more exertion than an ordinary -Sewing Machine for ladies' use, and making as little noise. Its great -utility, combined with neatness of construction, fits it not only -for the workshop, but the drawing-room of the amateur. The saw takes -the place of a pencil in the hands of the operator, enabling him to -produce the most elaborate artistic designs in wood-work. Box or other -hard texture woods, 1 inch thick, are as readily sawn through as the -finest veneer; metallic plates of 1/8 inch thick are also speedily -pierced. Magnificent specimens executed by this machine, which have -been universally admired for their extreme delicacy and perfection, -and acknowledged to be unrivalled, may be seen at the inventor's -address. The length of stroke of the saw can be varied to the work -in hand. A simple mechanical contrivance is attached for blowing the -sawdust from the saw whilst working, also a Circular Saw. - -An equally valuable invention is W. J. C. & Co.'s PATENTED -DRILLING APPARATUS which is with the greatest advantage combined -with the Sawing Machine, enhancing and enlarging its range of -usefulness, or it may be adapted to a lathe, or as a distinct machine. -Its great advantages over the ordinary lathe for drilling purposes -must be apparent when by the addition of this apparatus to a 5 inch -centre lathe the operator is enabled to drill in the centre of three -or more feet, and the drill being vertical and worked by leverage, -greater accuracy and facility is ensured. For ornamental purposes it -surpasses all hitherto contrived methods, not being limited to one -centre around which to describe curves, angles, circles, or any other -mathematical figure, the operator is at perfect liberty to describe -every conceivable device the fancy can dictate. - - - Advantages and Capabilities of this Machine. - - _This Machine can be adapted to any Lathe, see page 131._ - - This Machine has a Circular Saw. - - This Machine has a Vertical Saw. - - This Machine has a true Parallel Motion. - - This Machine has no Springs whatever. - - This Machine has a Bead and Moulding Apparatus. - - This Machine has a Planing Apparatus. - - This Machine has a Drilling and Grooving Apparatus. - - This Machine has a Kinography that will engrave hundreds of - different patterns on wood or metal. - - This Machine will cut Spirals and Ovals. - - This Machine has a Pentagraph, for reducing, enlarging, and - cutting on the face of wood any drawing from paper or fret-work. - - _Circulars and all particulars on application._ - - -Every kind of Materials, viz., Saws, Fret Patterns, Fancy Wood Drills, - Cutters, &c., kept in stock. - - - MANUFACTURERS OF TURNING LATHES. - AND ALL KINDS OF MECHANICAL TOOLS. - - - - - MOSELEY AND SIMPSON, - - LATE - - JOHN MOSELEY & SON, - - 17 & 18, KING ST. - - AND - - 27, BEDFORD ST., - - COVENT GARDEN, - - LONDON, W.C. - - ESTABLISHED 1730. - - [Illustration] - - [Illustration] - - LATHE AND - - TOOL MANUFACTURERS, - - &c., &c. - - PRICE LIST OF LATHES. - - -Turning Lathe, Iron Frame and Bed planed true, Wood Tool Board, Iron -Cone Mandrel, Cylinder poppet head, Rest and two Tees, Turned Grooved -Wheel Crank, Treadle complete with 3 Chucks:-- - - No. 1. 3-1/2 inch centre, and 2 foot 6 inch Bed £10 10 0 - " 2. 4-1/2 " " 3 " Bed 12 12 0 - " 3. 5 " " 4 " " 15 15 0 - " 4. 5 " " 4 " " } - with Brass Pulley and Slide Rest } 21 0 0 - " 5. 6 inch centre and 4 feet Bed with Slide Rest - complete 25 0 0 - " 6. 7 inch centre, 6 feet Bed, self-acting, and - Screw Cutting leading Screw, and 22 Change - Wheels 40 0 0 - -For Lathes of other descriptions, Estimates are furnished on -Application. - - - TURNING TOOLS. - - s. d. - Chisels for Soft Wood, the set of 6 handled 8 0 - Gouges " " 9 0 - Tools for hardwood and metal, handled and ready for use, - per dozen 15 0 - Drills handled 0 7 - Arm Rests Handled 2 6 - Callipers from 1 0 - Turner's Squares from 6 0 - - - All Kinds of Chucks, Cutters, &c., made to order. - - -Transcriber's Note: - -1. Page 38, Bunhill-row, Covent-garden and Charing-cross seems to be - an old-fashioned way of writing. - -2. Italics are shown as _text_, bold is shown as =text=. - -3. Carat characters are shown as ^X. - -4. This table of contents has been created by the transcriber to aid - the reader. - -5. Footnote 20, Page 183: Footnote marker is missing. - -6. Page 238: starting the 3rd table, there is a fraction 33-1/14. This - has been changed this to 33-1/16, as it seems to be a mistake. - -7. Spelling errors such as guidepiece, sawgates, swiveljoint, tongueing - and whiteing have been retained as they are in the original. - -8. Discrepancies with 3/4-inch and 1/4in. have been retained as in the - original. - -9. Inconsistencies with images: - -a. Page 22: Fig 31D is incorrect in the book as E. Changed to 31D and - the fig. no. on the image has been removed. - -b. Pages 36 & 38: numbers 53-56 are repeated. - -c. Page 74: It seems the reference (Fig. 126) should be Fig.116. - -d. Page 89: There is no Fig. 137 or a reference to it. - -e. Page 99: The number 9 on the image is back to front. There does not - seem to be a Fig. 148, although it is referred to (page 98). - -f. Page 98: Fig. 148 is incorrectly numbered on the image as 143. - -g. Page 100: There is a 2nd reference to Fig. 149, which it seems has to - be an illustration of a pattern, but there is no 2nd Fig. 149. It - seems the Fig. nos. mentioned in the reference should be 150 to 153. - -h. Page 104: The illustration is incorrectly numbered as 153 (should be - 156). - -i. Page 107: The number 9 on the image is back to front. - -j. Page 111: The number 6 on the images is back to front. - -k. Page 112: Fig. 166 incorrectly numbered as 165. - -l. Page 141: There is no Fig. 204. (assumed to be the top image above - Fig.205). - -m. Page 159/160: Number repeat for Fig. 229. - -n. Page 160: There is no Fig. 230. Possibly the 2nd no. 229. - -o. Page 178-184: Numbers 246-255 are number repeats. - -p. Page 185/6: There is no Fig. 257, but no reference to it either, so - it is assumed this was an omission by the author. - -q. Page 189: There is no Fig. 261, although it is referred to on page - 189. The reference has been changed to Fig. 262, which it pertains - to. - -r. Page 201: Fig. 284 is out of sequence, it appears on page 209. - -s. Page 207: It seems the reference should be to Fig. 290, not 296 which - has no L in the figure. - -t. Page 231: Fig, 319 is referred to, but there is no Fig. 319. - Presumably the first figure on Page 233. - -u. Page 236: Illustration top un-numbered, presumably 4. - -v. Page 278: Figs, 422/3 is referred to, but there are no Figs. 422/3. - Based on extensive research, comparing two different copies of a - matching edition, and correlation of illustrations with the text, - it appears that the inconsistencies in numbering within the book make - it seem that something is missing. The images are in fact Figs. 420 - and 421. - - - - - - - - - -End of the Project Gutenberg EBook of The Lathe & Its Uses, by Anonymous - -*** END OF THIS PROJECT GUTENBERG EBOOK THE LATHE & ITS USES *** - -***** This file should be named 60819-8.txt or 60819-8.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/6/0/8/1/60819/ - -Produced by Karin Spence, Curtis Weyant and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from scans of public domain works at the -University of Michigan's Making of America collection.) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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- padding: 0; - text-align: center; -} - -.figright { - float: right; - clear: right; - margin-left: 1em; - margin-bottom: - 1em; - margin-top: 1em; - margin-right: 0; - padding: 0; - text-align: center; -} - -/* Footnotes */ - -.footnote {margin-left: 10%; margin-right: 10%; font-size: 0.9em;} - -.footnote .label {position: absolute; right: 84%; text-align: right;} - -.fnanchor { - vertical-align: super; - font-size: .8em; - text-decoration: - none; -} - -/* Poetry */ - -@media handheld { -.poetry { -display: block; -margin-left: 2.5em;} -} - -.poetry-container -{ - text-align: center; - font-size: 95%; -} - -.poetry -{ - display: inline-block; - text-align: left; - line-height: 100%; - -} - -.poetry .stanza -{ - margin: 1em 0em 1em 0em; -} - -.poetry .ih {margin-left: .5em;} - -/* Transcriber's notes */ -.transnote {background-color: #E6E6FA; - color: black; - font-size:smaller; - padding:0.5em; - margin-bottom:5em; - font-family:sans-serif, serif; } - </style> - </head> -<body> - - -<pre> - -The Project Gutenberg EBook of The Lathe & Its Uses, by Anonymous - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Lathe & Its Uses - Or, Instruction in the Art of Turning Wood and Metal. - Including a Description of the Most Modern Appliances For - the Ornamentation of Plane and Curved Surfaces. With an - Appendix, In Which Is Described an Entirely Novel Form of - Lathe For Eccentric and Rose Engine Turning; a Lathe and - Planing Machine Combined; and Other Valuable Matter Relating - to the Art. - -Author: Anonymous - -Release Date: November 30, 2019 [EBook #60819] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK THE LATHE & ITS USES *** - - - - -Produced by Karin Spence, Curtis Weyant and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from scans of public domain works at the -University of Michigan's Making of America collection.) - - - - - - -</pre> - - - -<div class="figcenter" id="frontispiece_s" style="width:358px;"> - <img - class="p2" - src="images/frontispiece_s.png" - width="358" - height="550" - alt="" /> - <p class="center xs p0">FIRST-CLASS 5-IN. CENTRE LATHE, WITH TRAVERSING MANDREL -AND OVERHEAD APPARATUS, BY JAMES MUNRO, LAMBETH.</p> - </div> - -<p><span class="pagenum"><a name="Page_i" id="Page_i">[i]</a></span></p> - -<h1>THE LATHE & ITS USES;</h1> - -<p class="center xs p2">OR,</p> - -<p class="center lg p2">INSTRUCTION IN THE ART OF TURNING<br /><br /> -WOOD AND METAL.</p> - - -<p class="center xs p4">INCLUDING</p> - -<p class="center sm p1">A DESCRIPTION OF THE MOST MODERN APPLIANCES FOR THE<br /> -ORNAMENTATION OF PLANE AND CURVED SURFACES.</p> - -<hr class="r5"></hr> - -<p class="font center gesperrt">With an Appendix,</p> - -<p class="center p2 xs">IN WHICH IS DESCRIBED AN</p> - -<p class="center p2 sm">ENTIRELY NOVEL FORM OF LATHE FOR ECCENTRIC AND ROSE<br /><br /> -ENGINE TURNING; A LATHE AND PLANING<br /><br /> -MACHINE COMBINED;</p> - -<p class="center p2 bold"><i>And other Valuable Matter relating to the Art</i>.</p> - -<hr class="r5t"></hr> - -<p class="sans center sm">COPIOUSLY ILLUSTRATED.</p> - -<hr class="r5b"></hr> - -<p class="center">NEW YORK:</p> -<p class="center">JOHN WILEY & SON, PUBLISHERS,</p> -<p class="center sm">NO. 2, CLINTON PLACE.</p> -<p class="center">1868.</p> - - -<p><span class="pagenum"><a name="Page_ii" id="Page_ii">[ii]</a></span></p> - -<hr class="chap" /> - -<div class="chapter"> - -<p><span class="pagenum"><a name="Page_iii" id="Page_iii">[iii]</a></span></p> - -<h2><a name="PREFACE" id="PREFACE">PREFACE</a></h2></div> - -<p>Although the title of this work is sufficient to declare its contents, -a few prefatory remarks may not be superfluous as to its design and -the manner in which that design has been carried out.</p> - -<p>It has ever been to the writer a matter of surprise and regret, that -although the art of turning has been so long and so successfully -pursued in this country, both by artisans and amateurs, no work has -appeared in the English language treating upon the subject, except one -or two sketches and imperfect treatises.</p> - -<p>Some years since Mr. Holtzapffel advertised a forthcoming series of -seven volumes, intended to supply this manifest deficiency in our -scientific and mechanical literature, and the subject would have been -handled by him in a thoroughly exhaustive and masterly manner.</p> - -<p>The untimely death of that gentleman occurred after the publication -of the first three volumes, which are indeed complete in themselves, -and of immeasurable value to the mechanic and amateur; but which -are unfortunately only introductory, "simple turning by hand-tools" -being the special subject of the proposed fourth volume. The present -proprietors of the firm of Holtzapffel & Co. having, in their -catalogue even up to the time of the most recent edition, continued -to advertise the seven volumes, amateurs especially have anxiously -hoped for the publication of some part at least of the remainder of -the series. That expectation is, it is to be feared, little likely -to be rewarded; and, not until that fact had been ascertained with -something bordering upon certainty, did the author of the present -work<span class="pagenum"><a name="Page_iv" id="Page_iv">[iv]</a></span> venture to take up the pen and endeavour to set forth the -principles and practice of an art which, like so many others, he has -found so absorbing and attractive, and withal so delightful a source -of recreation to mind and body. Several things, however, contributed -to make the writer hesitate to undertake such a work. In the first -place he was aware that a number of <i>possible</i> readers would probably -be more competent than himself for such a task, especially those whose -means might have enabled them to procure a large amount of the most -modern and approved apparatus connected with the Lathe, and whose -occupations might allow of more leisure for their extensive use than -falls to the lot of the writer.</p> - -<p>In the next place the risk of publication was such as he felt himself -hardly justified in encountering. Just at this time, however, chance -placed in his hand two or three numbers of the "English Mechanic," -in which some one else had begun, but speedily resigned, a series of -papers "On the Lathe and its Uses," compiled from American journals.</p> - -<p>The author of the present work at once put himself in communication -with the editor and proprietor of the above periodical with a result -now well known to the readers.</p> - -<p>The following pages are not, strictly speaking, a mere reprint -from the "English Mechanic." The papers have been carefully -revised and re-arranged; some statements, the correctness of which -appeared doubtful, modified or wholly withdrawn; while, in one -or two instances, whole chapters have been re-written, and the -suggestions and inventions relating to the Lathe, furnished by other -correspondents, embodied (when they appeared of real value) in the -work.</p> - -<p>But, in addition, a valuable Appendix is now published, containing -matter of great importance, contributed by one or two gentlemen, who -most kindly placed their papers at the service of the author. Foremost -among them stands a paper on the angles of tools, by Dodsworth Haydon, -Esq., of Guildford. A clever arrangement of Lathe for Rose Engine -Work, by the aid of the Eccentric<span class="pagenum"><a name="Page_v" id="Page_v">[v]</a></span> Chuck without Rosettes, is also -added from the pen of Mr. Elias Taylor, of Brighton; and one or two -matters, which did not appear so fully treated as they deserved in the -body of the work, have been resumed and more fully discussed in the -Appendix.</p> - -<p>The author gratefully acknowledges the suggestions of various -correspondents, amateurs and working men, from whom, as a rule, he has -not failed to obtain any required assistance.</p> - -<p>That the work, in its present form, is entirely satisfactory or -complete, the writer cannot pretend; that many errors have crept in is -highly probable; but, if it is acknowledged to be the best work <i>yet</i> -produced on the Lathe, and should prove in any degree serviceable to -amateur or artisan in the pursuit of this most delightful art—aye, if -it should stir up some abler pen to write a better and more complete -series, it will afford real pleasure and lasting gratification to</p> - -<p class="right" style="margin-right: 5%">THE AUTHOR.</p> - -<p><span class="pagenum"><a name="Page_vi" id="Page_vi">[vi]</a></span></p> - -<hr class="chap" /> - -<div class="chapter"> - -<h2>CONTENTS</h2></div> - -<ul> - <li><a href="#PREFACE">PREFACE.</a></li> - <li><a href="#INTRODUCTION">Introduction.</a></li> - <li><a href="#CHUCKS">Chucks.</a></li> - <li><a href="#HAND_TURNING">Hand Turning of Wood.</a></li> - <li><a href="#HOLLOWED_WORK">Hollowed Work.</a></li> - <li><a href="#CUTTING_SCREWS">Cutting Screws.</a></li> - <li><a href="#HOLLOWING">Hollowing Out Soft Wood.</a></li> - <li><a href="#AMERICAN_SCROLL">American Scroll Chuck.</a></li> - <li><a href="#METAL_TURNING">Metal Turning by Hand Tools.</a></li> - <li><a href="#OVERHEAD">Overhead Apparatus.</a></li> - <li><a href="#SELF_ACTING">Self-acting and Screw-cutting Lathes.</a></li> - <li><a href="#WHEEL_CUTTING">Wheel Cutting in the Lathe.</a></li> - <li><a href="#FRET_SAWS">Fret Saws to Mount upon the Lathe Bed.</a></li> - <li><a href="#TURNING_SPHERES">Turning Spheres.</a></li> - <li><a href="#HOBLYN">Hoblyn's Compound Slide-Rest.</a></li> - <li><a href="#SLIDES_AND_COMPOUND">Chucks with Slides and Compound Movements.</a></li> - <li><a href="#TURNING_OVALS">Turning Ovals, etc., by Means of a Template.</a></li> - <li><a href="#ECCENTRIC_CHUCK">Eccentric Chuck.</a></li> - <li><a href="#CURIOSITIES">Curiosities.</a></li> - <li><a href="#GROOVING_AND_MORTISING">Grooving and Mortising Small Work.</a></li> - <li><a href="#ORNAMENTAL_TURNING">Ornamental Turning.</a></li> - <li><a href="#ECCENTRIC_CUTTER">The Eccentric Cutter Frame.</a></li> - <li><a href="#SEGMENT_ENGINE">Segment Engine.</a></li> - <li><a href="#HOLTZAPFFEL">Holtzapffel's Rose Cutter Frame.</a></li> - <li><a href="#UNIVERSAL_CUTTER">Universal Cutter Frame.</a></li> - <li><a href="#ROSE_ENGINE">Rose Engine.</a></li> - <li><a href="#RECTILINEAL_CHUCK">Rectilineal Chuck.</a></li> - <li><a href="#EPICYCLOIDAL_CHUCK">Epicycloidal Chuck.</a></li> - <li><a href="#SPIRAL_CHUCK">The Spiral Chuck.</a></li> - <li><a href="#APPENDIX">APPENDIX.</a></li> - <li><a href="#WILLIS">Professor Willis's Tool Holder for the Slide Rest.</a></li> - <li class="hangingindent"><a href="#MUNRO">Munro's Planing Machine to be attached to the Lathe, - and worked with the foot.</a></li> - <li><a href="#HICKS">Hicks' Expanding Mandrel.</a></li> - <li><a href="#TURNING_SPHERES2">Turning Spheres by means of Templates.</a></li> - <li><a href="#PLANT">Plant's Geometric Chuck.</a></li> - <li class="hangingindent"><a href="#PAPER_ON_PRINCIPLES">A Paper on the Principles which Govern the Formation and - Application of Acute Edges, with special reference to Fixed - Turning-tools, contributed by Mr. Dodsworth Haydon.</a></li> - <li><a href="#DETACHED_CUTTER">Detached-cutter Holders.</a></li> - <li><a href="#TAYLOR">New form of Rose Engine by E. Taylor.</a></li> - <li class="hangingindent"><a href="#OVAL_TURNING_AND_ROSE_CUTTING">Oval Turning and Rose Cutting with Templates with my -Apparatus.</a></li> -</ul> - -<hr class="chap" /> - -<div class="chapter"> - -<p><span class="pagenum"><a name="Page_1" id="Page_1">[1]</a></span></p> - -<h2><a name="INTRODUCTION" id="INTRODUCTION">THE LATHE AND ITS USES.</a></h2></div> - -<p>The Lathe has now for many years been steadily making its way from -the workshops of our leading artisans to those of the amateur and -lesser stars of the mechanical world. This is but the natural result -of the various additions and improvements which have been introduced -into its construction from time to time. The unworkmanlike and -clumsy tool of olden days has long since been superseded by one of -admirable finish and perfect aptitude for its designed uses; and -now that its construction is no longer dependent upon the skill of -the workman alone, but upon machinery moving with the precision of -clockwork, the fitting of the various parts is accomplished with -the greatest ease and certainty. The sale being thus extended, the -price has considerably diminished—the monopoly enjoyed by one or two -makers no longer exists; and there are few of a mechanical turn of -mind who cannot now provide themselves with a lathe suited to their -requirements.</p> - -<p>Nevertheless, the adepts in the art of turning are by no means so -numerous as might be expected, and, among amateurs especially, it is -rare to find work executed in first-rate style by simple hand tools -requiring skill and practice in their use, so that it not unfrequently -happens that a workman who can turn out exquisite specimens of ivory -carving and ornamental lathe work, is but a fourth-rate hand with the -gouge and chisel.</p> - -<p>But however beautifully executed such ornamental work may be, the -<i>credit</i> is rather due to the tool than the workman, and a -well turned box with accurately fitting cover may bespeak more skill -in handiwork than the above elaborately designed specimen.</p> - -<p>Moreover the one requires lathe fittings, which are not always to be -had unless the purse is well filled, whereas the general mechanic -(amateur or professional) can provide the tools needed for the other; -hence we propose first of all to give some practical hints on plain -hand turning of wood and metal. The ordinary form of foot lathe is -well known and requires no special description, it is represented<span class="pagenum"><a name="Page_2" id="Page_2">[2]</a></span> in -the frontispiece of this volume. There are, however, certain points -of detail in its construction, to which it is necessary to direct the -reader's attention.</p> - -<p>First and foremost comes the mandrel, of which there are several -patterns, according to the special purpose for which the lathe may be -intended.</p> - -<p>Now of whatever form it may be made this is the essential part of -the lathe, and must run with the utmost truth in its bearings. -Imperfection here will be imparted to all work executed upon it, and -accuracy in this part alone will make up for any slight defects that -may occur in less important parts of the machine.</p> - -<p>For ordinary work in wood alone or in brass the best form is -represented in <a href="#i-p002s">Fig. 1.</a></p> - -<div class="figcenter" id="i-p002s" style="width:700px;"> - <img - class="p2" - src="images/i-p002s.png" - width="700" - height="320" - alt="" /> - <p class="center smcap">Figs. 1,2,3,4.</p> - </div> - -<p>The part <i>a, b</i>, should be cylindrical, with a feather let in to fit -a slot in the pulley shown in <a href="#i-p002s">Fig. 2.</a> This pulley, whether of hard -wood or metal, is thus slipped on the mandrel as far as the collar -<i>d, d</i>, and a nut <i>e</i>, screwed up tightly at the back of it, fixes -it securely in its place, from which it may be moved if requisite -and replaced without fear of being out of truth. This cannot be done -if the mandrel is squared at <i>a, b</i>, and the pulley driven on with a -hammer, as commonly done by inferior workmen. The part <i>c</i>, is made -conical, to fit a hardened steel collar of similar shape. The angle -of this conical part is of some importance, as if it is too small the -mandrel is apt to jam and stick tight in its bearings. 35° will be -found to work well. With regard to the length of this conical part, -opinions differ considerably, but it must be remembered that friction -is independent of the <i>extent</i> of the bearing surfaces and depends -on the force with which they are pressed together (in the present -case it depends on the tension of the lathe cord and the weight of -the material to be turned), so that a tolerably wide margin may be -allowed in this matter. Practically the question is decided by the -thickness of the casting of the poppet head, <i>which</i> is regulated by -the required strength and size of the lathe. The collar is sometimes -of<span class="pagenum"><a name="Page_3" id="Page_3">[3]</a></span> hardened steel, sometimes of brass. The latter would theoretically -cause less friction than the former, but practically nothing can beat -a well finished collar of hard steel. Collars of this material made by -the original Holtzapffel two generations back are now as good as ever, -perhaps even better. The centre, which screws up against the left-hand -end of the mandrel, should be of the form shown in <a href="#i-p002s">Fig. 3</a>—a plain -cylinder with a screw cut at each end to receive clamping nuts. The -central part is rather larger than the screwed parts, and passes truly -through the poppet head. This form is much better than a simple screw -with points, as the latter is not likely to keep the line of centres -in being screwed up into its place.</p> - -<p>It will be found of great convenience to have the screw on the nose -of the mandrel (and indeed <i>all</i> screws about the lathe) of standard -Whit worth pitch, as taps for the chucks are thus readily obtained, -and nuts and screws of the various sizes may be also procured to -remedy breakages and losses. Upon this subject, however, we shall have -occasion to treat more fully when we pass from the description of the -lathe itself to the work that is to be accomplished by its aid.</p> - -<p>The only form of back poppet that need be particularised is that made -with cylinder and leading screw. The simple pointed screw passing -through the lathe head tapped to receive it, not only requires -no special description, but it is only calculated for lathes of -the commonest design, as it is seldom that the line of centres is -accurately maintained by the point at every part of the revolution -of the screw. Moreover, the latter soon works loose in the poppet, -and for anything like accurate work becomes speedily useless. The -cylinder and <i>pushing</i> screw is indeed far superior to the form just -alluded to, and where cheapness is an object it has its advantages -over the first-named and best form. It is represented in <a href="#i-p002s">Fig. 4.</a> The -cylindrical part is shown at B, and may have at one end the usual -point, and at the other a small conical hole or hollow centre. It may -then be reversed in its bearings at pleasure, or other cylinders with -different shaped ends can be substituted, as may be found convenient. -Of course the pushing screw A is for the purpose of advancing the -cylinder, which is clamped by the small screw at C. The cylinder and -leading screw are shown in detail in <a href="#i-p003">Fig. 5,</a> which is the poppet -head bored throughout to receive the spindle or cylinder A. At the -right hand<span class="pagenum"><a name="Page_4" id="Page_4">[4]</a></span> this bore is enlarged to form a recess, B, to receive -the head of the leading screw, C. This screw is generally made with -a left-handed thread, so as to withdraw the back centre when turned -from right to left. The spindle A, A is bored, and a left-handed female -thread is cut from end to end—this however is turned off at the place -destined to receive the movable point or centre, and a hole slightly -tapering is cut, or if preferred a cylindrical hole is made and tapped -for the same purpose. The spindle has also a slot cut from end to end, -into which a screw enters from the poppet, preventing the spindle from -turning round while the internal screw is revolving by means of the -small wheel and handle fixed to its right hand end. The spindle is -now put in its place, the screw inserted and turned till the head or -flange, C, rests in the recess before mentioned—a flat plate, F, is -then attached to the back of the poppet by three or four screws, the -head of the leading screw passing through its centre; the small wheel -is then attached and the whole is complete.</p> - -<div class="figcenter" id="i-p003" style="width:524px;"> - <img - class="p2" - - src="images/i-p003.png" - width="524" - height="404" - alt="" /> - <p class="center smcap">Fig. 5.</p> - </div> - -<p>It is evident that by turning the wheel the internal screw is put -in revolution, and as it is prevented by its flange from assuming -any motion in the direction of its length, the movable cylinder will -instead be withdrawn or thrust forward.</p> - -<p>This form of poppet is the best that can be adopted and is of general -use in all first-class lathes. In addition to the movable point <i>g</i>, a -flange similar to H should be fitted. This will be found of great use -when the lathe is used for drilling, the piece of work resting against -it, while the pressure is regulated by the leading screw.</p> - -<p>There are, in addition to the flange and pointed centre, other pieces -of apparatus that can be substituted, as occasion may require, and -these will be hereafter described in this series. With regard to the -common rest for hand turning a lengthened description is unnecessary. -The T or tee should for wood turning be of the form shown in <a href="#i-p004">Fig. 6</a> at -A. It is often made as B, which is a very inconvenient pattern, as the -cross piece on which the tool rests cannot be advanced sufficiently -close to the work if the latter exceeds a diameter of two or three -inches. For metal turning the top of the rest should be flat, and -about one inch broad, as the heel of the hook tools used for turning -iron must be able to take a firm bearing upon its surface. Sometimes -a plate of brass is riveted on the flat top, as the tool takes a -firmer hold on this metal, and when the latter becomes defaced and -channelled it can be renewed without the cost of a new casting in -iron. The turner should be provided with two or three tees for metal -and for wood,—one may be long enough to have two legs and require<span class="pagenum"><a name="Page_5" id="Page_5">[5]</a></span> -two sockets, as shown at C. This is convenient in turning long pieces -of wood,—a very short tee, not more than an inch in length, should -also be provided, and if one tee is specially kept with a very level -and smooth edge, it will be found of great advantage in chasing -screws—indeed the latter work can hardly be managed at all if the top -of the rest is damaged and uneven. The next part requiring description -is the boring collar, without which even a hand turning lathe can -hardly be considered complete. This boring collar is intended so to -support one end of the work, instead of its being held by the back -centre, as to enable the workman to get at the end of it for the -purpose of drilling it. Suppose for instance the work in hand is a -tool handle, and that it is so far finished as only to require the -hole for the reception of the tang of the tool. If this is bored by -hand with a gimlet, it is seldom that the hole will be truly in the -axis of the piece, but when this is done in the lathe by the help -of the boring collar the bore will be truly central, and the tool -when in place will fall in the same line with the handle. This will -conduce to the correctness of the work in hand more than the amateur -or other workman might suppose, and a row of tools thus truly handled -and in good condition generally bespeaks an efficient and careful -artisan. There are several plans for boring collar of nearly equal -efficiency, and we shall describe one or two of the most common, and -also one invented by the author, and which, if carefully made, is of -great service. <a href="#i-p005">Fig. 7</a> represents a poppet head, B, which is but half -the height of the other poppets of the lathe—a side view of this is -shown at B, <a href="#i-p005">Fig. 8.</a> Near the top of this poppet is a hole through -which passes a bolt C, by which and its nut the circular plate A can -be securely clamped in any desired position, as it revolves freely on -the bolt as a centre pin. This plate is bored with a series of conical -holes, which are so arranged that their respective centres will be in -a line with the centres of the mandrel when any one of them is brought -into a position corresponding with the line <i>c, c</i>. The hole thus -brought into position for use (having been selected according to the -size of the work to be bored), takes the place of the back centre; -the end of the work rests in the cone, which is greased or soaped to -reduce friction, and the rest being fixed at the other side of the -boring collar, the drill can be readily used, and the bore afterwards -enlarged if necessary with any convenient tool. This boring collar is -generally made of iron, but a substitute of hard wood will<span class="pagenum"><a name="Page_6" id="Page_6">[6]</a></span> frequently -serve the purpose, and can be made by the amateur, who may be unable -to obtain one of more durable material. If made of wood the best -unguent will be soap or black lead, such as is used for grates, or a -mixture of the two. This black lead or plumbago (it has no lead in its -composition) will always be found serviceable where wood works upon -wood, and also to give a smooth surface to wooden patterns for casting.</p> - -<div class="figcenter" style="width:490px;"> - <img - class="p2" - id="i-p004" - src="images/i-p004.png" - width="490" - height="298" - alt="" /> - <p class="center smcap">Fig. 6.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" style="width:396px;"> - <img - class="p2" - id="i-p005" - src="images/i-p005.png" - width="396" - height="411" - alt="" /> - <p class="center smcap">Figs. 7,8.</p> - </div> - -<p>Where cost is an object, a simple substitute for the boring collar -is frequently made by the ordinary workman by a piece of board one -inch thick, shaped like <a href="#i-p006a">Fig. 9,</a> with a single hole of the size most -generally required; and the work is then fitted to the boring collar, -instead of the latter to the work. In turning tool handles, for -instance, where a few dozen are required all of the same size, or -nearly so, a device of this kind, which can be made in a few minutes, -is sufficiently effective. This form has been modified in two ways, -and either will be found convenient. In the first, the conical hole -is made of the largest size likely to be required, a set of boxwood -plugs are then turned to fit this hole and are themselves bored in a -similar way to suit various sizes of work. The form of these plugs is -shown in <a href="#i-p006bs">Fig. 10,</a> which is a side sectional view, and at B, where the -same is shown in perspective. Two small screws or pins <i>b, c</i>, <a href="#i-p006bs">Fig. 10</a>, -fitting into the holes <i>a, a</i>, <a href="#i-p006a">Fig. 9,</a> prevent these flange-shaped -plugs from turning round in the board as the work revolves. The -pattern of A, <a href="#i-p006a">Fig. 9</a>, may be varied, and is better made of hard wood, -and of a form which will afford a good bearing upon the lathe bed.</p> - -<div class="figcenter" id="i-p006a" style="width:314px;"> - <img - class="p2" - src="images/i-p006a.png" - width="314" - height="340" - alt="" /> - <p class="center smcap">Fig. 9.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p006bs" style="width:700px;"> - <img - class="p2" - src="images/i-p006bs.png" - width="700" - height="339" - alt="" /> - <p class="center smcap">Figs. 10,11.</p> - </div> - - -<p>The second modification is more difficult to make, but equally -effective. It is shown complete in <a href="#i-p006bs">Fig. 11.</a> This form, arranged by<span class="pagenum"><a name="Page_7" id="Page_7">[7]</a></span> -the writer, has many advantages over the two last-named, and is very -serviceable. A is the poppet, of the full height of the ordinary -lathe heads, or a couple of inches higher. B, the slide forming the -support of the piece to be bored. The form of the poppet without this -attachment is shown in <a href="#i-p007as">Fig. 12.</a> If for nice work it should be made -of metal and the face of it planed, but for general purposes hard -wood will suffice. <i>b, b</i>, <a href="#i-p006bs">Fig. 11,</a> are two pieces of brass forming a -groove or guide in which a slide B, with dovetailed edges is fitted -to work. This slide is bored, like the ordinary collar, with conical -holes of different sizes, and should be made of metal and planed on -back and edges. Over each hole is a mark, and this is to be brought to -a similar mark on the face of the poppet. The plate is then clamped -in position by a screw at the back of the poppet. One or more of such -slides may be fitted at pleasure, and in case of wear or damage these -are the only parts requiring to be renewed.</p> - -<div class="figcenter" id="i-p007as" style="width:450px;"> - <img - class="p2" - src="images/i-p007as.png" - width="450" - height="283" - alt="" /> - <p class="center smcap">Figs. 12,13.</p> - </div> - -<p>It is a good plan to arrange a socket and tee of a rest as <i>b, c</i>, -<a href="#i-p007as">Fig. 13</a>, at the back of this boring collar, especially as the position -of the tool will be always the same, so that the rest may be a -permanent part of the poppet. There is sometimes a difficulty with the -ordinary form of boring collar in advancing the rest T sufficiently -near the work (the foot of the poppet, and that of the rest preventing -it, by coming in contact.) There is another modification of boring -collar, forming at the same time a guide for the drill, which in -slender work, where the tool is long and fine, becomes almost a matter -of necessity.</p> - -<p>This consists in making such a guide cone as mentioned and shown -in <a href="#i-p006bs">Fig. 10</a>, B, but with a continuation containing a smaller hole -for the drill, as <a href="#i-p007b">Fig. 14</a>. Both this and the other shorter cones -above-mentioned may be made to screw into the poppet A, <span class="pagenum"><a name="Page_8" id="Page_8">[8]</a></span><a href="#i-p006a">Fig. 9</a>, -instead of being kept in place by the pins at <i>a, a</i>, of that figure. -In that case however the hole in the poppet must be cylindrical and -only used as a support for the cones themselves. In addition to -the use of these boring collars already alluded to, they serve for -the purpose of turning up the points of screws like those of lathe -centres. These are first formed between centres with carrier chuck, -the back poppet is then removed and the extreme point fitted through -one of the holes of the boring collar and the marks of the centre -turned off.</p> - -<div class="figcenter" id="i-p007b" style="width:432px;"> - <img - class="p2" - src="images/i-p007b.png" - width="432" - height="240" - alt="" /> - <p class="center smcap">Fig. 14.</p> - </div> - -<p>Another useful adjunct to the lathe is the back rest for supporting -long and slender articles, which would otherwise bend under the -pressure of the tool. The ordinary and simplest form is shown in <a href="#i-p008a">Fig. 15</a>, -and this is of general use with brush handle makers and others -whose work is confined to a few sizes and shapes only. A better form -is shown in <a href="#i-p008b">Fig. 16</a>. A support of wood or metal shaped like A is -clamped to the lathe bed. Through the upper part the slide B passes -and is wedged up so as to support the work—or the socket of a lathe -rest may be arranged to take the upright part A, which must then be -rounded, as shown at C.</p> - -<div class="figcenter" id="i-p008a" style="width:193px;"> - <img - class="p2" - src="images/i-p008a.png" - width="193" - height="350" - alt="" /> - <p class="center smcap">Fig. 15.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p008b" style="width:414px;"> - <img - class="p2" - src="images/i-p008b.png" - width="414" - height="350" - alt="" /> - <p class="center smcap">Fig. 16.</p> - </div> - -<p>A modification of the latter, communicated to the <i>English Mechanic</i>, -is shown in <a href="#i-p009as">Fig. 16<sup>A</sup></a>. Its construction and mode of application is -sufficiently evident without a detailed description. <a href="#i-p009as">Fig. 16<sup>B</sup></a> is -another form made in metal. It consists of two similar plates with a -triangular opening A, through which the work is passed, and which has -an oval slot D, by which the apparatus is secured to the short poppet -of the boring collar. Between the two plates slides a third, partly -visible at C, which can be clamped by a screw at B, this screw also -serving as a stud by which the plate may be moved. The work is allowed -to take up its own bearing in the triangular opening as it revolves in -the lathe. The clamping screw of the poppet is then secured, and the -centering thus made certain. The plate C is then made to descend so as -to touch the work, and<span class="pagenum"><a name="Page_9" id="Page_9">[9]</a></span> clamped in that position. This is a very good -central support for long slender articles.</p> - -<div class="figcenter" id="i-p009as" style="width:700px;"> - <img - class="p2" - src="images/i-p009as.png" - width="700" - height="449" - alt="" /> - <p class="center smcap">Fig. 16A,B.</p> - </div> - -<p>There is a plan practised by German turners by which the back rest -is in a measure superseded, and which may be mentioned here. It is -simply the peculiar method of using the left hand. This is placed on -the piece to be turned so that the fingers partly encircle the work -while the thumb rests in the hollow of the gouge, or upon the end of -the tool. The fingers thus form a back rest and keep the work pressed -against the cutting edge, which is further steadied by the thumb. As -the tool traverses the work the left-hand accompanies it, and with -a little practice a ramrod or similar long and slender article may -be readily and accurately turned. This position is shown in <a href="#i-p009b">Fig. 17</a>, -and though the novice will find it difficult to work thus, it is well -worth the trouble of mastering, as the method once acquired will be -found of very great service.</p> - -<div class="figcenter" id="i-p009b" style="width:400px;"> - <img - class="p2" - src="images/i-p009b.png" - width="400" - height="264" - alt="" /> - <p class="center smcap">Fig. 17.</p> - </div> - -<p>We have now described more or less in detail the principal parts of -the lathe as adapted for hand turning. Before we dismiss this part -of the subject, however, it will be necessary to say a few words -respecting the bed and lower fittings, the flywheel, treadle, and -their adjuncts.</p> - -<p>Beyond question the iron bed, planed as it now is at a moderate price, -by machinery, is the best that can be adopted, especially if it is -intended eventually to fit up the simple tool with slide rest and<span class="pagenum"><a name="Page_10" id="Page_10">[10]</a></span> -superior apparatus. Nevertheless, the pocket must in this case also -frequently decide the question of material. If wood is preferred by -necessity or otherwise, it should be <i>hard</i> wood, beech, or Spanish -mahogany, unless it is proposed to plate the surface with iron. This -latter plan costs little and, besides stiffening the bed, it prevents -the wear and tear caused by the constant shifting of the back poppet -and rest. A flat strip of iron one inch or an inch and a half wide -can be picked out from the stores of any village blacksmith straight -and level as it came from the rolls of the manufacturer. Selecting a -piece of the required length and breadth, the eighth of an inch thick -or rather more, the purchaser will have holes drilled and countersunk -at intervals of nine or ten inches, to receive ¾-inch screws. -These strips will have to be laid upon the top of the bed, at its -inner edges; they need not be let in flush with the surface unless -appearance is studied.</p> - -<p>They must then be screwed down firmly, and by means of a file worked -by both hands up and down their length (not across them) a good -surface may be readily obtained. If the iron is let into the bed this -filing will abrade the wood work, which is the reason why we prefer -screwing it on the surface. This method produces a very excellent and -durable lathe bed, and it will be free from much of the tremor which -is so disagreeable while working upon a lathe entirely of cast iron -unless the bed of the latter and the standards are more substantial -than is usual with small lathes.</p> - -<p>The standards supporting the axle of the fly wheel and bed may in like -manner be of wood or iron. Even when the bed is of iron these may -be of hard wood, although it is customary to make them of the same -material as the bed. If of beech, oak, or mahogany, as in some of -Holtzapffel's best lathes with iron beds, the tremor before alluded to -will be considerably lessened. Iron is nevertheless very neat, and is -quite the fashion with the majority of makers, but is too often faulty -in respect of solidity.</p> - -<p>The standards as a rule are too slight, an elegant pattern being -studied to the sacrifice of substance and weight, The bed and stand of -a lathe cannot be too strong and stiff.</p> - -<p>Respecting this matter of stiffness and solidity we seldom find it -sufficiently considered, and, even with practical workmen, a defect in -this particular is more frequently acknowledged and put up with than -remedied, although the <i>comfort</i> of a steady lathe is beyond question, -to say nothing of its superiority when good workmanship is studied -(as it always should be). The old French lathes made in the form of -a thick table with four stout legs, forming the bed and back-board, -are by no means to be despised as patterns; and instead of the usual -method of making but one standard at end of the bed, there can be no -question that two additional ones add considerably to the stability of -the machine.</p> - -<p><span class="pagenum"><a name="Page_11" id="Page_11">[11]</a></span></p> - -<p>The fly wheel should be sufficiently heavy and have three speed -grooves on the rim and two additional ones to produce a slow motion, -which is required for turning metal. The latter may be worked with -ease in this way when the article to be turned is small, but if -heavy work is likely to be encountered the back geared lathe, to be -hereafter described, must be substituted, and the slide rest will then -also replace the hand tools. The crank axle is generally supported by -two centre screws, the points being hardened, and also the ends of -the axles, which are accordingly made of steel, and the holes for the -centre screws neatly drilled and countersunk.</p> - -<p>This is however not the most perfect method, and as we are speaking of -better class lathes, as well as those of more common and cheaper make, -we must by no means omit to speak of a very superior way of fitting -the crank axle. The latter must be turned at both ends, the wheel -bored and slipped on, and keyed in its place.</p> - -<p>Two wheels of brass about two inches diameter, must then take the -place of the centre screws. These are called friction wheels, and they -must be placed sufficiently near each other to support the end of the -axle between them, as shown in <a href="#i-p011a">Fig. 17<sup>B</sup></a>, <i>a</i> and <i>b</i>. A pair of these -must be thus fitted to each standard, and after the axle is placed in -position a third may be placed above it to prevent the lathe cord from -lifting the axle out of place by its tension. The axle and friction -wheels will thus work together with an exquisitely smooth rolling -motion—there will be no tendency to thrust the lathe standards apart -as must result from tightening the ordinary centre screws, and the -friction of the axle on its bearings will be reduced to a minimum. -Any person acquainted with the use of the lathe may readily fit up -these friction wheels, and the time and trouble so expended will be -amply repaid by the superior ease with which the lathe can be used. We -may say the same of the chain and eccentric, which can replace with -similar advantage the crank and hook in ordinary use.</p> - -<div class="figcenter" id="i-p011a" style="width:391px;"> - <img - class="p2" - src="images/i-p011a.png" - width="391" - height="246" - alt="" /> - <p class="center smcap">Fig. 17B.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p011b" style="width:530px;"> - <img - class="p2" - src="images/i-p011b.png" - width="530" - height="334" - alt="" /> - <p class="center smcap">Fig. 18.</p> - </div> - -<p>For the latter the following arrangements are necessary. A is the -eccentric keyed to the crank axle, and may be either in the middle -of the same or, as in <a href="#i-p011b">Muir's</a> patent lathes, at one end outside the -standard. Around it passes the endless flat chain B (known as crank -chain). This also passes round a roller in the treadle shown at C. -This chain does not act as a mere link, but when the lathe is<span class="pagenum"><a name="Page_12" id="Page_12">[12]</a></span> in -action it moves round and over the eccentric and treadle roller. The -motion of the whole is smooth and regular, and, what is almost as -important, <i>noiseless</i>. In Muir's and other lathes the crank chain -is used without the eccentric, being applied to the crank instead. -Perhaps there is not much to choose between the two, but no one who -has studied the eccentric and observed its exquisitely gentle and -smooth motion in an ordinary engine can have failed to be struck by -these valuable qualities. It must however be remembered that its throw -is half that of a crank of the same eccentricity and the latter will -have the advantage in power size for size.</p> - -<p>In whatever position the lathe may be set up let the rise of the -treadle be moderate. It is exceedingly disagreeable to work at a lathe -where the rise of the foot board is so great as to bring the knee into -contact with the lathe bed, a consummation not infrequent in country -made ones.</p> - -<p>This is only to be escaped by giving up a certain portion of power. -Let A, B, <a href="#i-p012">Fig. 19</a>, be the line of the treadle when at rest; <i>c</i>, -the crank. To gain power we should let part A, E, be longer than E, B, -as in the sketch. But let this arrangement be made, and when the -crank is at its highest point, the line G, B, will show the position -of the treadle and foot board. Hence this kind of leverage is not -practicably available to any extent, and the length taken from foot -board to link may with advantage be even less than that from link to -the axle on which the treadle works. In lathes, of all machine tools, -it is essential that the workman should be able to stand easily, that -the movements of the leg and body should not be communicated to the -tool, the play of the treadle and such items of detail being of more -consequence than might at first sight appear, and any method tending -to diminish friction, vibration, and noise is well worth consideration -in planning this machine.</p> - -<div class="figcenter" id="i-p012" style="width:529px;"> - <img - class="p2" - src="images/i-p012.png" - width="529" - height="322" - alt="" /> - <p class="center smcap">Fig. 19.</p> - </div> - -<p>We may now suppose the reader the happy possessor of a well made foot -lathe, long or short in bed, high or low in poppet, according to his -need, but, of whatever size, carefully made and firmly fixed in a -well-lighted place, and if possible on the basement floor—an upstairs -workshop is objectionable owing to the certain vibration of a boarded -floor. He will now require certain chucks and tools, many of the -former of which he will have to make for himself.</p> - - -<h3 class="sc"><a name="CHUCKS" id="CHUCKS">Chucks.</a></h3> - -<p>No lathe can be considered well fitted until it is supplied with a -large number of chucks, by which strange term are signified the<span class="pagenum"><a name="Page_13" id="Page_13">[13]</a></span> -various appliances for fixing to the mandrel the article to be -turned. When it is considered how varied are the forms which present -themselves to the turner, it may readily be conceived that much -ingenuity has to be exercised in contriving methods for mounting his -work in the lathe; and when in addition to variety of <i>form</i>, variety -of <i>size</i> has to be taken into consideration, it is plain that a -large assortment of chucks is a necessary item in the workshop of the -turner. A vast number of these chucks are of necessity made of wood, -as required, and such wooden ones are altered from time to time to -suit different-sized work, till they eventually become so completely -used up as to be only fit for the fire. In addition, however, to -these, there are certain chucks of metal (chiefly brass or gun metal) -which should always be ordered with a lathe, or fitted to it before -any work (even the making of wooden chucks) can be satisfactorily -accomplished. The first of these, is represented in <a href="#i-p013">Fig. 20</a>, the part -A, screws to the mandrel; while the work is attached to the taper -screw B. The use of this chuck is to hold short pieces or flat discs, -which allow of a hole in the centre and require to be turned on the -face. It is only used for wood-work. This is the chuck to be selected -when it is desired to make a wooden chuck. A piece of sound wood -being chosen of the requisite size, and roughly rounded by the axe or -chisel, a hole is made in one face by a gimlet rather smaller than -the tapering screw. The piece is then firmly screwed to the latter, -the opposite end dressed with gouge and chisel, and the rest being -placed across the end, a hand-drill for wood is brought to bear upon -the piece. The hole thus made in the centre is then enlarged by any -convenient tool until its diameter is only a little less than that of -the screw cut on the lathe mandrel. An inside screw tool is then made -use of to cut a thread of the same pitch as that of the mandrel, or a -tap of similar size and pitch screwed into it (the former is the best -but most difficult method to a novice), the piece detached from the -taper screw chuck, which is removed, and the wood attached to the nose -of the mandrel on which it may now be accurately fitted and finished -to the requisite form and hollowed out or otherwise, as may be -necessary. Numberless articles may be in a similar manner turned upon -the above chuck such as the bottoms of candlesticks, ring or other -stands, bread-platters, small wheels, and so forth; it may therefore -stand as number one of these adjuncts to the lathe.</p> - -<div class="figcenter" id="i-p013" style="width:290px;"> - <img - class="p2" - src="images/i-p013.png" - width="290" - height="282" - alt="" /> - <p class="center smcap">Fig. 20.</p> - </div> - -<p><a href="#i-p014a">Fig. 21</a> is the face plate, another most serviceable chuck of almost -universal application in such work as surface-turning and boring, and -where a hole in the centre is inadmissible. To this belong various -dogs or cramps, a few forms of which are shown at <a href="#i-p014b"><i>a</i>, <i>b</i>, <i>c</i>, <i>d</i></a>.<span class="pagenum"><a name="Page_14" id="Page_14">[14]</a></span> -These hold the work firmly down to the surface of the plate, being -tightened from behind by screw nuts. It will be seen that there are -four slots and numbers of holes in the face plate, some of the latter -being tapped for screws. These slots and holes may be increased in -number, and some of the latter may be square instead of round, and -the cramps may be of all shapes and sizes, because sometimes it may -be required to hold down a flat piece of brass the eighth of an inch -thick only, and the next job may be to hollow an irregular block of -wood of three or four inches in thickness, or it may be necessary to -bore out the boss of a wheel, or to turn the rim—all of which, and a -hundred others, are cases in which the aid of the face plate will be -in requisition.</p> - -<div class="figcenter" id="i-p014a" style="width:300px;"> - <img - class="p2" - src="images/i-p014a.png" - width="300" - height="262" - alt="" /> - <p class="center smcap">Fig. 21.</p> - </div> - -<div class="figcenter" id="i-p014b" style="width:500px;"> - <img - class="p2" - src="images/i-p014b.png" - width="500" - height="280" - alt="" /> - </div> - - -<p><span class="pagenum"><a name="Page_15" id="Page_15">[15]</a></span></p> - -<p><a href="#i-p014c">Fig. 22</a> is the chuck specially used for turning rods of metal. It -consists of two parts, the body A, which screws to the mandrel, and -the piece B, which passes through a slot and is clamped by a small -screw at one side <i>c</i>. To these must be added the carrier which is -of such forms as <a href="#i-p014d">A<sup>1</sup></a>, <a href="#i-p015a">B<sup>1</sup>, C<sup>1</sup></a>. Above is shown a rod of metal to be -turned with this chuck in position for use. Of this we shall have to -speak again when we arrive at the subject of metal-turning. There -should be several sizes of carriers kept in stock, from ¼in. in the -largest part of the ring to 2in. or 3in., or even much larger for -heavy work. The amateur will, however, scarcely need these larger -ones. The usual method of making the wood-holding chuck for work that -is to be also supported by the back centre, is to have a socket cast -like <a href="#i-p015bs">Fig. 23</a>, C, with a central hole to take the fork A, which is held -in place by a set screw. This socket is useful for other purposes as -it will hold short pieces of iron to be turned, but<span class="pagenum"><a name="Page_16" id="Page_16">[16]</a></span> the fork is far -inferior for general work to the piece <i>b</i>; this is made of iron, and -the end of the cross (against which the wood to be turned comes) is -sharpened but must not be <i>too</i> sharp. The end of the piece of wood -has then two saw-cuts made at right angles to each other into which -the sharpened edges of the cross fall, <a href="#i-p015bs">Fig. 23</a> D, and the whole will -turn together without any chance of slipping. It often happens, when -the ordinary fork is used, that if the tool chances to hitch in the -work, the latter is either thrown quite out of the lathe, or the -centre of the fork retains its place, while the other two points slip -and score the work. This can never happen with the form B, which is -the most reliable pattern that can be devised for work of this nature.</p> - -<div class="figcenter" id="i-p014c" style="width:378px;"> - <img - class="p2" - src="images/i-p014c.png" - width="378" - height="297" - alt="" /> - <p class="center smcap">Fig. 22.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p014d" style="width:171px;"> - <img - class="p2" - src="images/i-p014d.png" - width="171" - height="350" - alt="" /> - <p class="center smcap">Fig. A1.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p015a" style="width:500px;"> - <img - class="p2" - src="images/i-p015a.png" - width="500" - height="437" - alt="" /> - <p class="center smcap">Figs. B1, C1.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p015bs" style="width:700px;"> - <img - class="p2" - src="images/i-p015bs.png" - width="700" - height="173" - alt="" /> - <p class="center smcap">Fig. 23.</p> - </div> - - -<p><a href="#i-p016a">Fig. 24</a> is to some extent self-centering. A piece of wood hollowed out -conically has three nails, or three-square saw-files so placed within -the cone as to present three sharp edges inwards. Any piece of wood, -if not too hard, will, if placed with one end in the chuck, while the -back centre is screwed against the other, centre itself in some part -of this cone, and, being at the same time held by the three sharp -edges, will necessarily revolve in the chuck. There are many cases in -which even in this rough form such a chuck will prove useful; but if -it were cast in metal and the three edges formed by slips of steel, -and the whole accurately turned, it would be a very efficient and -good self-centering chuck. In its more common form it is largely used -by the turners of mop and broom handles, who work rapidly and cannot -afford to waste time in chucking their work. With the above, the -lathe, if worked by steam or water power, is not even stopped,—the -screw of the back centre has a quick thread, so that a single turn -to or fro fixes or releases the work; and thus, one handle being -finished, another piece takes its place in the chuck, is fixed by a -half-turn of the back screw, and being set in rapid motion is turned -and completed by a practised hand in a couple of minutes or less.</p> - -<div class="figcenter" id="i-p016a" style="width:350px;"> - <img - class="p2" - src="images/i-p016a.png" - width="350" - height="161" - alt="" /> - <p class="center smcap">Fig. 24.</p> - </div> - -<p><a href="#i-p016b">Fig. 25</a> represents another useful chuck, generally of boxwood, called -the barrel stave chuck. It is turned conical, the largest part being -towards the mandrel; it is then wholly or partially drilled through, -after which saw-cuts are made longitudinally, as in the drawing. These -allow a certain degree of expansion when a<span class="pagenum"><a name="Page_17" id="Page_17">[17]</a></span> piece of work is fitted -into it, and it is tightened round the latter by driving on a ring of -iron or brass. This ring is sometimes cut with a coarse thread inside, -and a similar thread being chased on the outside of the chuck, it -is screwed upon the cone instead of requiring to be driven by blows -of a hammer. One important use of this chuck is to re-mount in the -lathe, for ornamentation by the eccentric cutter or other apparatus, -any finished work that could not be readily chucked in any other -manner, or to hold rings requiring (like curtain rings) to be turned -on the inside. Such articles will, from the nature of this chuck, be -truly centred at once; and their exterior parts will not be liable -to injury, as they would be by being driven into an ordinary chuck -hollowed out to receive them.</p> - -<div class="figcenter" id="i-p016b" style="width:230px;"> - <img - class="p2" - src="images/i-p016b.png" - width="230" - height="162" - alt="" /> - <p class="center smcap">Fig. 25.</p> - </div> - -<p>Another useful chuck for turning short pieces of metal such as bolts -and binding screws, and which is in a great measure self centering -is made of cast iron, and is usually called the dog-nose chuck, -represented in <a href="#i-p017a">Fig. 26</a>. This is made with movable jaw hinged, as more -plainly seen in B. The screw clamps these jaws firmly together, and -any small piece of work is thus securely held. The centering, however, -is not accurate, though sufficiently so for many purposes. The die -chuck (<a href="#i-p017b">Fig. 27</a>) is accurately self-centering, and although somewhat -expensive, is a valuable addition to the lathe. This chuck consists, -first of all, of a socket for screw to fit the mandrel, and round -flat plate of brass cast in one piece, as in <a href="#i-p017c">Fig. 28</a>. This must be -carefully turned and faced in the lathe. Two pieces of iron or brass -<span class="pagenum"><a name="Page_18" id="Page_18">[18]</a></span>are then screwed to the face, as B, B, <a href="images/i-p018a.png">28<sup>A</sup></a>, leaving a space between, -the sides of which are to be truly parallel. These pieces may either -be chamfered to form <span class="sans">V</span>-pieces, or may be rectangular on their inner -edges; at C, C, a part of each is cut away, and the outer or back -plate is also filed down to receive the small plates D, D. E shows a -groove in which a screw lies, half of which has a right and half a -left handed thread; this is shown in <a href="#i-p018a">Fig. 29</a>. It will be evident that -if this screw is placed in the groove of the bottom plate, and its -ends pass through the pieces D, D, which are screwed to the plates, -it can revolve in its bearings, but will have no endwise motion; -the collar F resting in a recess under the top plate D. This screw -passes through a projection in the back of the pair of dies, which -projection also goes into the same slot in the back plate in which -the screw works when turned by the key (<a href="#i-p017b">Fig. 27</a>, B.) -The above being nicely fitted, the dies moving evenly but stiffly in their places, the -plain top is screwed on, keeping all firmly together. This plate has -a long opening or slot (<a href="#i-p017b">Fig. 27</a>), through which the jaws of the dies -and part of the screw are visible. The ends of the screw should not -project, as any such projection is calculated to bring to grief the -knuckles of the turner—a consideration worth attention in every form -of chuck—the squared ends of the screw lie in a recess in the small -plates, as shown in the section of one of these plates (<a href="#i-p018a">Fig. 28<sup>X</sup></a>). -Into this recess the key fits over the screw end; and by turning this -the dies are simultaneously moved asunder, or closer together so as to -grasp centrally as in the jaws of a vice, any small article, such as a -screw or short rod of metal placed between them, A similarly contrived -chuck is often used under the name of a universal chuck, for holding -pieces of large diameter, and is very useful for<span class="pagenum"><a name="Page_19" id="Page_19">[19]</a></span> taking pieces of -ivory which have to be hollowed or otherwise worked, as will hereafter -be detailed. In this case the jaws may be semicircular in form, as <a href="#i-p018b">Fig. 30</a>.</p> - -<div class="figcenter" id="i-p017a" style="width:302px;"> - <img - class="p2" - src="images/i-p017a.png" - width="302" - height="304" - alt="" /> - <p class="center smcap">Fig. 26.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p017b" style="width:450px;"> - <img - class="p2" - src="images/i-p017b.png" - width="450" - height="241" - alt="" /> - <p class="center smcap">Fig. 27.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p017c" style="width:330px;"> - <img - class="p2" - src="images/i-p017c.png" - width="330" - height="326" - alt="" /> - <p class="center smcap">Fig. 28.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p018a" style="width:569px;"> - <img - class="p2" - src="images/i-p018a.png" - width="569" - height="423" - alt="" /> - <p class="center smcap">Figs. 28, 29.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p018b" style="width:343px;"> - <img - class="p2" - src="images/i-p018b.png" - width="343" - height="350" - alt="" /> - <p class="center smcap">Fig. 30.</p> - </div> - -<p>It is however, evident that these two chucks have a rather limited -range. The first can only be used for small work, and the only case -in which the latter can take firm hold all round the work is when -the jaws are just so far apart as that they form portions of the -circumference of one and the same circle. Practically they will hold -the work tightly under an extended range of sizes, and they are thus -of great use to the turner. The following is however more perfect in -operation, from the fact that it has four jaws instead of two which -meet concentrically. This may be made either with two long screws at -right angles to each other, with right and left-handed threads to -each, as in the die chucks, or more simply and, in some respects more -satisfactorily, with four distinct screws, all of the same pitch, and -all with squared ends of equal size, to allow of the same key being -used to turn them. It is possible to use such a chuck as an eccentric -chuck if desired, which is certainly a recommendation in its favour -over those which work always concentrically. The face of this chuck is -shown in <a href="#i-p019s">Fig. 31</a>. The ends of the four screws have a bearing in the -small centre plate <i>b</i>, whilst the collars or flanges rest in a recess -under the several plates <i>c, c</i>. The face of this chuck is graduated -by each die, so that it is easy to set the jaws concentrically or to -place one or more eccentrically to take in work of other shape than -round or square. The jaws of this form of chuck are used for two -purposes, either to hold work inside them like a vice, or externally. -A ring, for instance, requiring to be chased on the outside is slipped -over the jaws, which are then caused to recede from the centre so as -to hold<span class="pagenum"><a name="Page_20" id="Page_20">[20]</a></span> the work securely. If the latter does not run truly, one or -more of the screws can be slackened, and the opposite ones tightened, -or if the eccentricity appears to be in an intermediate part, two -adjacent screws will have to be thus slackened and the others -tightened. On the whole this is a most useful pattern of chuck.</p> - -<div class="figcenter" id="i-p019s" style="width:400px;"> - <img - class="p2" - src="images/i-p019s.png" - width="400" - height="363" - alt="" /> - <p class="center smcap">Fig. 31.</p> - </div> - -<p>The following is a very excellent self-centering chuck now coming -into extensive use. It has been noticed in more than one periodical. -The description annexed is extracted from the pages of the <i>English -Mechanic</i>. "The chuck hereby illustrated seems to be a very convenient -form, easily adjusted and holding the drill securely. It is also -well adapted for holding wire to be threaded. Every piece of which -it is composed is of cast steel well hardened. It can be furnished -with a shank to fit the hole for the centre, screwed on the spindle, -or slipped on the centre. No wrench is necessary, the gripe of the -fingers being sufficient to secure the shank of any drill. The -inventor claims that he has used a one-inch drill, in tenacious -wrought iron in one of them, receiving a shank of only three-eighths -of an inch diameter without using a wrench."</p> - -<p><a href="#i-p020">Fig. 31<sup>A</sup></a> represents the shell of the chuck with milled bosses for the -fingers. The core, B, is threaded and receives a steel wire spring -which is inserted into the rear of each jaw, so that when relieved -from pressure, the jaws open automatically.</p> - -<div class="figcenter" id="i-p020" style="width:400px;"> - <img - class="p2" - src="images/i-p020.png" - width="400" - height="320" - alt="" /> - <p class="center smcap">Fig. 31A.</p> - </div> - -<p>With this brief explanation, the operation of the chuck can be easily -comprehended. These chucks are made of two sizes, one with an opening -of three-eighths of an inch, and the other of three-sixteenths of an -inch, and they can be made of larger sizes. Patented by L. H. Olmsted, -Stamford, Connecticut, United States America.</p> - -<p>Another chuck of self centering design, has likewise appeared in the -periodical above named, into which it appears to have been copied from -an American paper.</p> - -<p>The accompanying engravings illustrate some improvements in<span class="pagenum"><a name="Page_21" id="Page_21">[21]</a></span> the -arrangement of chucks which have been recently patented in this -country, the inventors being Messrs. Smith and Haight, both of New -York, U.S. The first part of the invention refers to an arrangement -of adjustable chuck, by means of which tools and other articles of -different diameters may be held firmly in the jaws of the chuck. <a href="#i-p021a">Fig. 31<sup>B</sup></a> -is a longitudinal view of the chuck, partly in section. The -spindle, <i>a</i>, is fitted so that it may be inserted tightly in the -mandrel of the lathe. On the front end of the spindle is a conical -screw on which is fitted the cap, <i>b</i>; this part is formed with an -opening at the front end, having three longitudinal slots in it. In -each of these slots an adjustable jaw, <i>c</i>, is fitted, the inner part -of which is threaded with a female screw, to fit the conical screw on -the spindle, <i>a</i>. An outer casing <i>d</i>, encloses the front part of the -chuck, and behind this is fitted a loose collar, which is screwed into -the casing <i>d</i>, so as to connect the parts firmly together. By turning -the cap, <i>b</i>, with the casing, <i>d</i>, and collar, in one direction, the -jaws, <i>c</i>, are moved forward and project out through the openings, and -they may thus be adjusted to grip a tool or other article of small -diameter. The opposite motion of the cap causes the jaws to recede, -and in this way they may be adjusted to grasp articles of different -diameters.</p> - -<div class="figcenter" id="i-p021a" style="width:400px;"> - <img - class="p2" - src="images/i-p021a.png" - width="400" - height="268" - alt="" /> - <p class="center smcap">Fig. 31B.</p> - </div> - -<p>Another arrangement of the adjustable chuck is shown in <a href="#i-p021b">Fig. 31<sup>C</sup></a>, -which is a front view, and <a href="#i-p022s">Fig. 31<sup>D</sup></a>, a longitudinal section of the -same. A, is the body of the chuck, the front part of which is formed -with a rim or flange, in which are three radial recesses having -fitted therein the sliding jaws, B. In the rear of each jaw is a -bearing, in which is fitted a pin carrying a small lever, C, the -front end of which is rounded, as shown in the section, and enters a -slot made in the jaw, B; so that when the levers are moved outwards -they cause the jaws to contract or move towards the<span class="pagenum"><a name="Page_22" id="Page_22">[22]</a></span> centre. The -back part of the body, A, of the chuck is threaded, and on this part -is fitted a collar, D, and in front of this is a sliding collar, E, -which is connected to the collar, D, by means of a pin which enters -a groove formed in the latter. The sliding collar is prevented from -turning round on the body, A, by means of a feather, which works in a -longitudinal groove formed in the inner circumference of the collar. -Three inclined planes, F, are formed on the periphery of the collar, -E, which extend to the backward ends of the levers, C, so that by -moving the collar to and fro, the jaws, B, are caused to contract or -expand, according to the size of the article to be grasped. A short -cylindrical block, G, made of a conical figure internally is fitted -loosely within the chuck, A, and serves to centre the end of a drill -or other short article, but may be removed when it is desired to pass -a rod or other article through the body of the chuck. To provide for -the easy turning of the collar, D, it is shown as fitted with a hand -wheel, H. With this arrangement of the several parts, the jaws of the -chuck readily adapt themselves to drill or bit shanks as well as to -articles of parallel form, or of a tapered or irregular figure.</p> - -<div class="figcenter" id="i-p021b" style="width:400px;"> - <img - class="p2" - src="images/i-p021b.png" - width="400" - height="389" - alt="" /> - <p class="center smcap">Fig. 31C.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p022s" style="width:468px;"> - <img - class="p2" - src="images/i-p022s.png" - width="468" - height="550" - alt="" /> - <p class="center smcap">Fig. 31D.</p> - </div> - -<p>The chucks last named belong to the class of compound or mechanical -tools; and though their usefulness is beyond question, they need -not be considered absolutely necessary, as the work which they are -designed to facilitate can be and often is done without their aid. -Indeed, success in the art of turning by no means depends absolutely -upon the possession of expensive apparatus, and the amateur or -mechanic will find the advantage of ransacking his own brain for the -devising of divers makeshifts and off-hand contrivances—especially -in this chuck-making department.</p> - -<p>Among the simple expedients the following will be found well worthy of -adoption.</p> - -<p>A, <a href="#i-p023a">Fig. 32</a>, is a simple flange or flat brass plate with a boss behind, -similar to a small face plate, and is to be turned up, drilled, and -tapped to fit the mandrel. If the latter has a diameter of ¾ of an -inch, a few of these brass pieces should be cast from a set of wooden<span class="pagenum"><a name="Page_23" id="Page_23">[23]</a></span> -patterns ranging from two to three or four inches across the diameter -of the plate, and, after having been fitted to the mandrel and turned, -four holes, countersunk for wood screws, should be made, as shown in -the sketch. These are intended to do away with the necessity of boring -out and tapping each individual wooden chuck. They can be readily -attached to any piece of wood by four screws, and a few minutes will -be sufficient to adapt the same to any required purpose. A flat piece -of board, for instance, itself too thin, or of too soft substance to -permit of its being attached to the mandrel in the ordinary way, can -thus be made into a temporary face plate, or a ring cut out of it, or -any desired operation performed upon it. Indeed, these socket pieces -will be found serviceable on many occasions, and will do away with the -necessity of a large set of cup chucks.</p> - -<div class="figcenter" id="i-p023a" style="width:400px;"> - <img - class="p2" - src="images/i-p023a.png" - width="400" - height="238" - alt="" /> - <p class="center smcap">Figs. 32, 33.</p> - </div> - -<p>A few of the latter, however, are very useful and will cost but -little. The castings are sold by weight, and the turner will -experience no difficulty in fitting and finishing them for himself. -<a href="#i-p023a">Fig. 33</a> is the form of these, and needs no description. The substance -may be from ⅛ to ¼ of an inch, and need not be more, as that -thickness will stand any reasonable shock caused by driving a piece -of wood into the chuck, and it is always well not to overweight the -mandrel with chucks of undue size or substance. The addition of -three to six screws to one or two sizes of the cup chuck extends its -usefulness. This form is represented in <a href="#i-p023bs">Fig. 34</a>, A and B. In this -case, the casting may be rather more substantial (¼ to ⅜ of an -inch in thickness).<span class="pagenum"><a name="Page_24" id="Page_24">[24]</a></span> The screws <i>must be strictly radial</i>, pointing to -the centre of the circle, and their ends must be turned off or filed -flat. Their heads may be squared to enable a key or pair of pincers to -be applied, or round with a hole through them. It is better to make -this kind of chuck with six screws—three in one plane, and three -again <i>between</i> these in another plane behind them. In fitting a piece -of work into the chuck, it will not at first be found an easy matter -to make it run truly. The best way is to centre it as nearly as can -be guessed, by means of the three screws nearest to the open end of -the chuck, and then, placing the latter on the mandrel, set the lathe -in slow motion and correct the eccentricity of the piece by means of -the three inner screws. Even after this it is probable that a little -alternate slackening and tightening of the different screws may be -necessary; but a little practice will quickly enable the turner to set -a piece of work in the true axial line of the mandrel without much -difficulty, and the work will then be held very securely. Any short -piece, such as the ring of an eccentric to be bored truly inside, may -be held by the outer set of screws alone; but if such a piece of work -as a small cylinder is to be bored, the six screws must be brought -into action. Here let the hint given when speaking of projecting -screws, be repeated, <i>Beware of the knuckles</i>, which are peculiarly -liable to be damaged in making use of these chucks. The shirt sleeve -or coat, moreover, does not always enjoy perfect immunity from similar -danger, and both should be kept out of harm's way, not for their own -sake only, but because the arm may be brought into violent contact -with the rest if the sleeve should get entangled (the momentum of the -flywheel being great, and therefore not to be checked entirely at any -given moment). A single rap of the above nature is not a <i>delightful</i> -even if <i>salutary</i> lesson to the novice.</p> - -<div class="figcenter" id="i-p023bs" style="width:450px;"> - <img - class="p2" - src="images/i-p023bs.png" - width="450" - height="247" - alt="" /> - <p class="center smcap">Fig. 34.</p> - </div> - -<p>To hold rings and washers a tapering mandrel, <a href="#i-p024s">Fig. 35</a>, is used; -and of these it is necessary to keep a few different sizes to suit -different diameters. These may be made of iron or brass if for<span class="pagenum"><a name="Page_25" id="Page_25">[25]</a></span> -permanent use, but box or other hard wood is a ready substitute, and -may be turned down for smaller work when the surface gets spoiled by -use. The expanding mandrel, "Hicks' patent," which will be treated of -hereafter, is a convenient substitute for the simple conical form here -spoken of; and in manufactories where large numbers of mandrels have -to be kept of various sizes, a great saving of time, money, and labour -is effected by their use. For amateurs and artisans in a smaller -way of business the simpler form is generally sufficient. A slight -modification is here appended, by which the common form may sometimes -be made more efficient in the holding a ring tightly while undergoing -the operation of turning, and this can be made applicable to metal -mandrels, though specially intended for wooden ones. <a href="#i-p024s">Fig. 36</a>.</p> - -<div class="figcenter" id="i-p024s" style="width:500px;"> - <img - class="p2" - src="images/i-p024s.png" - width="500" - height="220" - alt="" /> - <p class="center smcap">Figs. 35, 36.</p> - </div> - -<p>The mandrel having been turned conical (N.B., the angle of the cone -must be small, so that the size will diminish very gradually from the -largest end), the wood is divided by a fine saw, just as the chuck -already described with the outside rings was sawn into segments, a -conical hole having been first made at the smallest end, as shown -in the section <i>b, b</i>. Into this a short cone of larger angle is to -be fitted, against the end of which the point of the back centre -will press, tending to drive it into the mandrel, which will thus be -made to expand. The ring to be turned will prevent the mandrel from -splitting by the wedge-like action of the plug, unless the said ring -is of light substance, in which case this form must not be used. The -work will, by the above method, be securely and centrally held and not -liable to slip towards the small end of the chuck.</p> - -<p>In the <a href="#i-p024s">Fig. 36</a>, a groove, <i>c, c</i>, is shown at the bottom of the -saw-cuts. This should also be made round the boxwood spring chucks -with rings, as it gives more freedom of expansion to the segments. -With such a groove and the chuck itself completely hollowed out, -the pressure of a <i>strong</i> india-rubber ring will be sufficient to -hold work whilst being polished: and this will, when the latter is -delicate, be even superior to the screwed rings, as the pressure -will be more gentle and equable. India-rubber rings for this purpose -must not be thin and flat, like those used for bundles of papers or -letters, but made of round material, the thickness of a quill or even -larger. They may be had of all sizes at an india-rubber warehouse -in Holborn, at the bottom of the hill on the left hand side going -eastward, and not far from Negretti and Zambra's shop. The writer is -not acquainted with the name of the proprietor.</p> - -<p>Having had occasion to speak of tapping chucks of metal to fit the -mandrel, it will be as well to speak here of the requisite tools for -effecting this.</p> - -<p>In the case of iron chucks it is not likely, as a general rule, that -the amateur or workman will obtain access to a screw-cutting<span class="pagenum"><a name="Page_26" id="Page_26">[26]</a></span> lathe, -and to cut an internal thread by hand with the chasing tool is hardly -feasible, though readily accomplished in the case of brass chucks. -When, therefore, a lathe is purchased, a set of taps of the diameter -and pitch of the screw on the mandrel should be provided. Of these -there must be three—an entering taper tap, an intermediate one -rather less tapering, and a plug tap, which is cylindrical. And here -we must enter a caution. Do not let the tapering taps be too long. -For instance, let it be required to tap the boss of a face plate in -which the hole cannot be drilled through the plate. It is first bored -out to the size of the <i>bottom</i> of the mandrel threads, or rather -less. Tap number one must then be screwed into it; but if this is too -long, so that it cannot enter to the end of the threads cut upon it, -the second tap will be too large and will not enter properly, but -will most likely start a new thread for itself and spoil the first. -<a href="#i-p026">Fig. 37</a>, <i>a</i>, <i>b</i>, <i>c</i>, shows the form required; <i>d</i>, the form to be -avoided, except in cases where, as in the cup chucks, a hole can be -made quite through the article, so that the tapering tap can be worked -to the line <i>x, y</i>, or nearly so. The long tap, <i>gradually</i> tapering -as it does from end to end, is of course the easiest to use, and for -nuts and such like is far the best; the conical tap of larger angle -requires more power, but in the case named it is a matter of necessity -to use it; and, if preferred, a set of four taps instead of three will -remedy any difficulty. The novice must take great care to place the -tap perpendicular to the face of the chuck, or the shoulder will not -fit close to that on the mandrel. If much difficulty is experienced, -such an arrangement as <a href="#i-p027s">Fig. 38</a> may be of service. A represents the -standard of an upright drill-post, of which B is the bench, C the -screw by which to depress the drill and keep it to the cut. For the -latter, and brace by which it is worked, substitute the tap, and place -a spanner or wrench round the head of it. In<span class="pagenum"><a name="Page_27" id="Page_27">[27]</a></span> the centre mark, which -is generally left from the turning, place screw point <i>c</i>. By means -of a plumb line or square, D, test the perpendicularity of the tap; -and as the latter penetrates, keep it to its work by the screw C; oil -the tap freely, and the chuck will be easily and accurately cut with -the required thread. Some kind of clamp will of course be required to -secure the chuck to B, while it is being tapped.</p> - -<div class="figcenter" id="i-p026" style="width:450px;"> - <img - class="p2" - src="images/i-p026.png" - width="450" - height="343" - alt="" /> - <p class="center smcap">Fig. 37.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p027s" style="width:350px;"> - <img - class="p2" - src="images/i-p027s.png" - width="350" - height="433" - alt="" /> - <p class="center smcap">Fig. 38.</p> - </div> - -<p>The upright drill should always have a place in the workshop. It is -much easier to drill with it than in the lathe, and the mandrel will -thus be saved considerably. The latter should never be used except -for light work. A variety of drilling apparatus will hereafter be -described in this series, so that we need not now write more upon this -part of our subject.</p> - -<p>Somewhat akin to the chuck described as the cup chuck with six screws, -is a chuck mentioned in an old French work,<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a> the purpose of which -is to turn up a cylinder, with a point at the end, so as to insure -the axial line being kept. In the ordinary course, the cylinder would -be turned up with the point and carrier, or driver, chuck already -described; the conical point would be then turned down as far as -possible, and the mark of the back centre afterwards turned off by -means of the boring collar. It is by help of a miniature lathe and -boring collar in one piece that the pivots of the balance of a watch -are finished. In both cases the work may be well done by the same -process. The chuck now to be described requires no boring collar, -but at the same time it does not seem to be well suited for any but -light work; in which latter case however it would be advantageous, -and must therefore have a place in our present paper. The body of -the chuck is shown in section, in <a href="#i-p028s">Fig. 39</a>. A is the socket with -screw to fit on the mandrel of the lathe. It will be seen that the -chuck itself is hollowed out cylindrically, and in this cylindrical -cavity slides a plug, <i>c</i>, bored conically, which can be fixed by a -thumb-screw, <i>h</i>, traversing a slot in the body of the chuck. This -cone is destined to receive one end of the cylinder to be pointed, -which will, according to its diameter,<span class="pagenum"><a name="Page_28" id="Page_28">[28]</a></span> centre itself in some part of -the conical hole in the plug. The latter is made movable, so as to be -adapted to the length of the article to be turned. At the outer end -of the chuck is a groove dovetailed to receive a slide, shown clearly -in the cross section B. The slide must be of sufficient substance to -allow a clamping screw, <i>f</i>, to be tapped into it at one end, which -screw must be long enough to reach when fully advanced nearly to the -apex of the triangular opening seen in the slide. The action of the -whole contrivance is as follows:—The cylinder to be pointed is placed -in the conical cavity of the plug—the latter slid to or fro till -the point to be turned projects a short distance beyond the mouth of -the chuck through the triangular opening in the front slide; when it -is fixed by a turn of the screw, <i>f</i>, which forms the third point of -resistance, the sides of the triangular opening forming the other -two. As the point or apex of the triangle is always in the diameter -of the cylindrical chuck, it will only be necessary to move the slide -itself in order to bring the axis of the cylinder to be turned in a -line with that of the mandrel. As soon as this is accomplished so that -the piece runs truly, the screw, <i>g</i>, is turned, and the slide fixed -in position. A good deal of ingenuity is displayed by the inventor of -this chuck, a description of which was published twenty years ago, and -there are very many cases in which it will be called into requisition -by the mechanic. With a little care, moreover, the amateur might make -one for himself—the body of brass or gun metal, the plug and sliding -part of iron or steel.</p> - -<div class="footnote"> - -<p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> Manuel de Tourneur par H. Bergeron.</p></div> - -<div class="figcenter" id="i-p028s" style="width:700px;"> - <img - class="p2" - src="images/i-p028s.png" - width="700" - height="252" - alt="" /> - <p class="center smcap">Fig. 39.</p> - </div> - -<p>Amongst the various devices connected with the lathe, many of which, -even as makeshifts, are valuable to the turner, is one not generally -known for keeping up the tension of the lathe cord in whatever groove -of the fly wheel or pulley it may be placed. The plan is not more -ingenious than practical, and the writer is acquainted with one -workman, a gasfitter by trade, who has had it in constant use for -many years. Directly over the mandrel pulley is another of larger -diameter, in which are two grooves of equal depth, fig. 40. This<span class="pagenum"><a name="Page_29" id="Page_29">[29]</a></span> -upper pulley is suspended on a movable arm, D, which is pivoted at -E, and kept up by an india-rubber spring, F, or, as in the original -plan (before these rubber cumulators were known), by a cord passing -over a pulley, and having a heavy weight attached, as shown by the -dotted lines. In the fig. A represents the fly wheel, B the mandrel, -C the upper pulley. The lathe cord is very long, and passes upwards -from A, over the upper pulley in groove 1, down again and round the -mandrel, a second time over groove 2 of the upper pulley and down to -the fly wheel. The tension of the cord is thus always the same, and is -regulated by the spring or weight. If the cord is slipped to a smaller -part of the lathe pulley, the slack is instantaneously taken up by the -descent of the weight, and rising of the arm D, which in like manner -yields to allow the cord to be slipped to the larger groove of the -mandrel pulley.</p> - -<div class="figcenter" id="i-p029s" style="width:400px;"> - <img - class="p2" - src="images/i-p029s.png" - width="400" - height="577" - alt="" /> - <p class="center smcap">Fig. 40.</p> - </div> - -<p>There are many other useful contrivances for chucking work in the -lathe, a few of which will be noticed on a future page. The main -thing<span class="pagenum"><a name="Page_30" id="Page_30">[30]</a></span> to be attended to is the holding securely as well as centrally -the object to be turned. If this is attained, the precise form of -chuck is of little importance, and it matters not whether it be -made of metal or wood. The latter has indeed, in some respects, an -advantage resulting from its elasticity and the ease with which its -form is modified.</p> - - -<h3 class="sc"><a name="HAND_TURNING" id="HAND_TURNING">Hand Turning of Wood.</a></h3> - -<p>We have now described the simple foot-lathe and chucks adapted for -hand turning, but of the latter a great number may be provided, -and will, in fact, accumulate as the turner proceeds to work upon -objects of varied form and size. No chuck once made should be thrown -away until it has become so reduced, from repeated alterations, as -to be no longer serviceable. And now, before we commence actual -turning, it will be well to offer a few concluding remarks upon the -selection of a lathe. It will be evident from our previous remarks -and illustrations that there is room for great diversity in the size -and quality of this machine, and it is astonishing what excellent -work is often turned out by an experienced hand from a lathe of the -worst description. The simple pole-lathe, which is so out of date -that we did not deem it worthy of notice in this series, with its -reciprocating motion, like the little tool of the watchmaker, has, -before now, supplied the cabinet maker with first-class work, and not -many years since we ourselves stood before just such a clumsy tool, -taking first lessons in the art. Our next step was to a lathe with -wooden poppets, and flywheel of the same material, a mandrel made by -a country blacksmith, which scarcely did even <i>him</i> credit; the value -of the whole, with stand and beechen bed complete, was £2 sterling, -and sufficiently dear at that price. Now, we do not recommend such a -tool, and in the present day a much better may be had at that price, -but, notwithstanding its evident defects, very tolerable work may -be produced from it. We state this to deter the reader from a very -common fault—namely, the purchase of an expensive tool and elaborate -fittings when the purse is shallow, and the skill shallower still. In -fact, any amount may be spent in lathes, and in fitting up a workshop, -but to gain real pleasure and satisfaction from the pursuit of the -mechanical arts, the outlay should not be more than the probable -result in work fairly warrants. A hundred pounds is often expended -in the purchase of a lathe, and a hundred shillings would more than -purchase the work done by it. We speak from our own experience in this -matter, and believe our advice proportionately valuable; and we well -know the satisfaction that ensues when good work has been produced in -spite of the defects in the appliances at command. If the means do -not admit of the purchase of a good lathe necessity must decide the -question, and an inferior one must<span class="pagenum"><a name="Page_31" id="Page_31">[31]</a></span> take its place in the workshop. -Nevertheless, we would rather counsel a certain amount of delay, and -economy and hoarding, that a good foundation may be laid and a lathe -purchased of such average excellence that future additions may convert -it into a really serviceable tool.</p> - -<p>It would be invidious and perhaps rather unfair in this little work to -send the reader to any particular lathe-maker. There are several good -and two or three first-class ones in London, and if prices range high, -the work is at any rate of undeniable excellence.</p> - -<p>There are also many cheaper firms than those alluded to, where the -work is rather of rough-and-ready style; all depends on what <i>class</i> -of work the would-be purchaser proposes to engage in, whether he -intends to confine himself to plain hand-turning in wood, to the -construction of steam engine, and other models of machinery in metal, -or to the more beautiful finished work in hard wood and ivory, which -develop the full power of the machine itself, and the skill of the -accomplished turner. In the former cases, a very plain and inexpensive -lathe will suffice. In the latter, it is absolutely necessary to -purchase one of the best construction, at a tolerably high figure.</p> - -<p>The best advice to those of slender means, and who, therefore, vastly -predominate, is to sacrifice all else to the mandrel and collar. The -latter may be bought at from twenty to thirty shillings, ready for -mounting in detached wooden headstocks, and will be far superior to -any that an ordinary smith can produce. In this case, the two poppets -that carry the mandrel and centre screw should be connected together -by a block of wood between them, which latter may be rounded off and -shaped to something near the form of a cast-iron headstock.</p> - -<p>The only care necessary in mounting such a mandrel, will be to keep -the axial line parallel to the lathe-bed, and directly over the centre -of the latter. Whether the mandrel is thus a separate purchase, as may -happen from necessity, or obtained as part of the lathe, and fitted in -a cast-iron headstock, it should certainly be hardened, and also the -collar, if of steel. Both will take a higher polish for this process, -and will run easier in consequence. The cost of such a mandrel is -rather greater, because many warp or split in the process, and have -to be thrown aside; and the labour of grinding mandrel and collar -to an exact fit, is considerably increased. The gain, however, is -greater than the loss to the purchaser, and the extra outlay must not, -therefore, be grudged. It is very annoying to find a conical mandrel -worn down by the collar after a twelvemonths' work; for a collar is -thus formed on the conical part, so that it cannot be tightened up by -the back screw.</p> - -<p>The first tool to be noticed is the gouge, the form of which is a -longitudinal section of a tube, and is shown in <a href="#i-p032s">Fig. 41</a>. Of this -tool<span class="pagenum"><a name="Page_32" id="Page_32">[32]</a></span> not less than three sizes should be selected, of the respective -diameters of one inch, half-inch, and a quarter or three-eighths. -When purchased, they require grinding, the bevel being too short. It -is essential that this tool and the turning chisel have a long bevel, -so that the cutting edge should be a very acute angle. (Fig. 41, not -like 42.) It is impossible to do good work with the latter form of -tool which is, nevertheless, of frequent occurrence in the workshops -of amateurs. Both gouge and chisel must be sharpened on an oilstone -(Arkansas or Turkey will be found the best) to a keen edge, <i>and no -pains must be spared in preserving the tools in this condition</i>. Three -sizes of chisel to match the gouges should be selected. The latter -tool is not made like that intended for carpenter's use, with the edge -at right angles to the sides, but is sloped like <a href="#i-p032s">Fig. 43</a>, so as to -present an obtuse angle A, and an acute one B, and the cutting edge -is central, the bevel being alike on both sides, so that the tool may -be<span class="pagenum"><a name="Page_33" id="Page_33">[33]</a></span> turned over, and used with either of the flat sides upwards. The -handles of gouges and chisels should be much longer than those used -by carpenters, and nicely rounded and shaped in the lathe. The most -difficult thing to turn being a cylinder of soft wood; a description -of the method of effecting this will be the best means of initiating -the novice in the art of turning. In all the most perfect work by -practised hands, there is a sharpness of edges and roundness of -mouldings, that are exceedingly agreeable to the eye, and bespeak -at once keenness in the tool with which the work has been done, -and steadiness in the hand of the operator. The novice must aim at -similar perfection, and to this end he must determine to avoid the -use of sand-paper, and trust to his management of exceedingly keen -tools to put a workmanlike finish to his work. To commence with the -proposed cylinder. Let a piece of sound beech be selected for the -first essay, as being less difficult to manage than deal, the grain -of the latter tearing up in long shreds under the action of the tool. -The first thing to be done, after sawing off the necessary quantity -of sufficient diameter for the proposed work, is to round it off -roughly by means of the hatchet and draw-knife, or spoke-shave. The -next thing is to mount it in the lathe. For this purpose the prong -chuck, or, better still, that represented as an improvement on the -latter, and shown in <a href="#i-p015bs">Fig. 23<sup>B</sup></a>, must be screwed on the mandrel, and -the work made secure by the aid of the back poppet centre. Care should -be taken that the piece runs truly between the points of support, and -that it revolves steadily without shake. There is no real necessity -for using the compasses, or other contrivance for finding the exact -centre at each end, as sometimes recommended, neither, indeed, is it -always possible thus to find the axial line. It is easy to fix it at -first lightly in its place, and ascertain by a turn or two of the -mandrel, how nearly it runs as it ought to do. If it seems tolerably -true, a turn of the back centre fixes it securely, if not, it can be -shifted in any direction at pleasure. The tyro ought, however, to -be warned that he is likely to be deceived in the size of the rough -piece, and that he may very probably think it of sufficient diameter -for the proposed work when in reality it is too small. Practice, or -the use of the callipers, which are bow-legged compasses for measuring -the diameters of work, will soon settle the question. The piece being -properly fixed in the lathe, the latter is to be set in motion by -means of the treadle, the rest having been first fixed as near as -possible without touching the piece, and the T clamped parallel to it. -If the tyro wishes to become a proficient, no pains must be spared -to acquire the knack of working the treadle without moving the body -to-and-fro. He must learn, therefore, to stand firmly on one leg, and -after the wheel has been put in motion, he must let it and the treadle -have its own way. He will thus soon <i>feel</i> when the crank has passed -the dead<span class="pagenum"><a name="Page_34" id="Page_34">[34]</a></span> point at the highest point of revolution, and the proper -moment to bear down with the foot. It is not necessary to describe the -precise movement, as a few trials will teach the method much better -than any written description. At first it is hard work, and constant -change of leg from the right to the left, and back again, will have to -be resorted to to diminish the fatigue. Practice will, however, remove -all difficulties, and allow the whole undivided attention to be given -to the management of the tool.</p> - -<div class="figcenter" id="i-p032s" style="width:500px;"> - <img - class="p2" - src="images/i-p032s.png" - width="500" - height="485" - alt="" /> - <p class="center smcap">Fig. 41, 42, 43, 44, 45, 46.</p> - </div> - -<p>The gouge must be held down firmly on the rest with the hollow side -upwards, and the bevel of the edge forming a tangent to the work, <a href="#i-p032s">Fig. 44</a>. -In this position it will cut freely and smoothly, and the edge -will be preserved. If held horizontally, as in <a href="#i-p032s">Fig. 45</a>, it is evident -that the fine edge of the tool will be immediately destroyed by the -rapid blows it will receive as the rough wood revolves in contact with -it. Its tendency in the latter position will be to scrape, instead of -cutting, and the fibres of the wood will thus be torn out in threads, -and the surface of the work be roughened. The gouge, then, being -placed in the former tangential position, the right hand grasping the -handle, the left the blade, as in <a href="#i-p032s">Fig. 46</a>, the tool is to be slowly -slid along the rest, and a series of light shavings, more or less -continuous, will be removed from end to end of the piece. Let the -workman bear in mind that the tool is to take a firm bearing on the -rest, and that it must not move to-and-fro with the inequalities of -the piece to be turned. It is not necessary to remove large chips -unless the turner has acquired from practice perfect command over the -tools, and for the adept this chapter is not written. After the most -prominent inequalities have been removed, the <i>side</i> of the gouge will -come into use instead of the extreme end, and with this the work may -be rapidly reduced to its intended size, always allowing, however, -for the final cut with the chisel. Before the latter is taken up, -the piece of work is to be rendered as level and true as can be done -by the aid of the gouge alone; indeed, if the latter is of tolerable -size, and skilfully used, a finish can be put upon the work by it -almost equal to that which the chisel can produce and if the work -in hand were a moulded pattern, with hollows and raised work, great -part would have to depend on the gouge alone. In the present case the -chisel must be used, and the method is as follows: Take a hold with -both hands, as directed for the management of the gouge, but instead -of the flat part lying evenly on the rest, the tool must be partly -raised from it, so that only the lower edge takes a firm bearing. -By this means the upper angle of the cutting edge (<i>generally</i> the -most acute) is kept clear of the wood, and the latter is cut away -only by means of the middle and lower part of the edge, as shown in -<a href="#i-p036s">Fig. 47</a>. If placed as in <a href="#i-p036s">Fig. 48</a>, the acute angle, <i>a</i>, is sure to -catch and stick into the work, spoiling in two seconds all that has -been<span class="pagenum"><a name="Page_35" id="Page_35">[35]</a></span> done. The chisel can be used with either of its flat sides -upwards, and moved along the rest from right to left, or from left to -right, or turned upside down, as <a href="#i-p036s">Fig. 49</a>, so that the acute angle is -downwards. These positions are shown in the <a href="#i-p036s">Fig. 47 to 51</a>. The only -care necessary is to keep the upper point clear, allow the chisel to -rest as flatly on the wood as the above precaution will permit, and to -take as <i>fine</i> and <i>continuous</i> shavings as possible. The chisel will -be found to draw itself along in some degree as the cut proceeds, and -when this action is felt, it is doing its work properly—still, it is -a difficult thing to use a chisel well, and the tyro will fail many -times and oft before he will succeed.</p> - -<div class="figcenter" id="i-p036s" style="width:700px;"> - <img - class="p2" - src="images/i-p036s.png" - width="700" - height="408" - alt="" /> - <p class="center smcap">Figs. 47, 48, 49, 50, 51, 52, 53, 54, 55, 56.</p> - </div> - -<p>The chances are that this initiatory lesson will result in anything -but a correct cylinder—the surface will not be true like a ruler, -but if tried by a straight edge it will be seen to be wavy. Tested by -the callipers, <a href="#i-p036s">Fig. 52</a>, one part will be larger than another, even if -the extreme portions be tolerably true to the proposed gauge. Now, -the best turner on earth found just these difficulties, and nothing -but perseverance and resolute determination will overcome them. -Never mind spoiling the first piece of work, give up making it of a -determined size, but do not give up making it a true cylinder. Keep -the callipers at work, and gently level the prominent parts (you must -work down to the size of the deepest hollow, for you cannot fill up -such valleys like a railway engineer; you must throw down the adjacent -hills instead), proceed gently, little by little; make the tool obey -you, show it (as Ruskin speaks of pencil and brush) that you will -not yield to its caprices and "henceforward it will be your most -obedient servant." Having done the best you can with the surface of -your cylinder, proceed to square up the ends, and mind the angle at -this part is a right angle, <i>square</i> and <i>sharp</i>, not rounded off. Now -this again requires care and a knowledge of the proper method. You -will work chiefly with the lower corner of the chisel, and we shall -best describe the management of the tool by supposing the cylinder -an inch too long, and that the extra piece is to be removed. Now -there are three positions in which the chisel can be placed to bring -its lower corner in contact with the cylinder. First, with the blade -perpendicular to the work; secondly, with the blade inclined to the -left, <a href="#i-p036s">Fig. 53</a>, as if to round off the end of the piece; thirdly, -inclined to the right, <a href="#i-p036s">Fig. 54</a>. Held perpendicularly it will cut a -fine line, but penetrate slightly; alternately in the other positions -it will remove a <span class="sans">V</span>-shaped piece, and thus the cutting off is to be -begun. One side of the cutting, however, has to be perpendicular, the -other may be as sloping as convenient. Now, it is to be remembered in<span class="pagenum"><a name="Page_36" id="Page_36">[36]</a></span> -cutting the upright side, which is the end of the roller, the chisel -is to incline <i>rather to the right</i>, for this reason,—if it incline -to the left a momentary inattention will cause it to take the path -<i>a, b</i>, <a href="#i-p036s">Fig. 55</a>,<span class="pagenum"><a name="Page_37" id="Page_37">[37]</a></span> the tendency being to cut a spiral track towards -the left. The experiment may be made by gently resting the edge thus -inclined on any part of the roller, when it will describe a spiral -at once. To the right, then, the chisel must <i>slightly</i> incline, and -it will cut off a thin curling shaving like <a href="#i-p036s">Fig. 56</a>, leaving the end -of the piece quite smooth and shining. When the piece is nearly cut -off, great care and lightness of hand must be used, as the central -portion will have become weak and ready to break off before the work -is finished. When it will no longer bear the chisel, take it out of -the lathe, break it off, and neatly finish with the sharp chisel the -central portion, and your first lesson is learnt. There is certainly -very little of interest in turning an imperfect cylinder, for it is -useless when done, but the alphabet of the art, though not amusing, -must be first thoroughly mastered, and the rest will follow in due -course. If, however, the work seem unreasonably dull and stupid, -the cylinder may be converted into a tool handle, which will be at -any rate a useful article, besides affording practice. No special -directions are needed in addition to the above, except in respect to -the ferrule. This is to be cut off a piece of brass tubing or an old -gun barrel, or it may be had at the tool shops ready cut to any size. -Begin by turning down the place for this ferrule, taking care not to -cut it too small or the ferrule will drop off. Take the piece out of -the lathe, and with a mallet hammer on the ferrule. Return it again, -taking care to centre it in the old marks, and finish the handle. The -brass or iron may be polished with a file for this first attempt.</p> - -<h3 class="sc"><a name="HOLLOWED_WORK" id="HOLLOWED_WORK">Hollowed Work.</a></h3> - -<p>It is now necessary to speak of hollowing out wood for the purpose -of making boxes, cup chucks, &c., and the latter, which may be made -in any quantity, and of all sizes, will afford excellent practice in -this part of the turner's art. The majority of work of this kind is -done rather by scraping or fretting out than by cutting; side tools -of the forms of <a href="#i-p036s">Figs. 51 and 56</a> being used for the purpose. These -however, are specially adapted for ivory and hard woods, the grain of -which, being very compact and close, is not torn out in shreds by the -action of such tools, as would be the case with softer woods. Where -the latter material is used in quantity, as in the manufacture of -wooden bowls, hook tools, like <a href="#i-p038">Fig. 57</a>, are made use of, which cut on -their upper edges. These are exceedingly difficult to use, though the -practised hands of those brought up to the art, make them cut with -a surprising ease and rapidity—fairly surrounding the lathe with a -ceaseless cloud of fine shavings removed in the progress of the work. -The difficulty experienced in the use of these tools is not confined -to the novice, for the majority of turners accustomed to hard<span class="pagenum"><a name="Page_38" id="Page_38">[38]</a></span> wood -often cut a sorry figure in the manipulation of softer material with -the aid of the tools in question. The hard and soft wood turners form, -in point of fact, two distinct branches of the trade. We have in part -anticipated this section, by speaking of the making a wooden chuck -when describing the use of the metal chuck with taper screw. We shall, -therefore, proceed to describe the best method of turning a plain -wooden box with cover, but not screwed; the latter being reserved for -more extended notice hereafter. The best material to work upon is -sound Turkey boxwood, and care must be taken that it is quite dry -and well seasoned, or, after it is worked up with, it may be, great -care and trouble, the box will split, or the cover become so loose -as to fall off, either fatality being sufficiently vexatious. We may -mention, in passing, that hard woods of all descriptions may be had -in large or small quantities of Messrs. Fauntleroy<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">[2]</a> and Co., 110, -Bunhill-row, Finsbury, or of Jacques and Sons, Covent-garden. Most of -the lathe-makers also supply it, especially Holtzapffel and Co., of -Charing-cross, but the first-named is a large dealer, wholesale and -retail, and his charges are moderate.</p> - -<div class="footnote"> - -<p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">[2]</span></a> Now Messrs. Mundy and Berrie.</p></div> - -<div class="figcenter" id="i-p038" style="width:550px;"> - <img - class="p2" - src="images/i-p038.png" - width="550" - height="514" - alt="" /> - <p class="center smcap">Figs. 51, 52, 53, 54, 55, 56, 57.</p> - </div> - -<p>Supposing a selection made of size proportionate to that of the<span class="pagenum"><a name="Page_39" id="Page_39">[39]</a></span> -intended box, including cover and a tolerable margin for waste and -accidents, proceed as before to rough it down between two centres -and thus to reduce it to a cylindrical form—there is, however, -no occasion to use the chisel at present, as we only need a rough -cylinder. Remove this from the lathe, and if you have no brass cup -chuck into which you can fit it, proceed to make one out of a piece -of beech, ash or, if you have plenty, boxwood. Do not hurry the -work, but cut the chuck out neatly, screw and fit it, as previously -directed, on the nose of the mandrel. We shall suppose it as yet -merely a short neat cylindrical block, quite solid. Place the rest -with the tee across the end of the piece of wood, the top edge a -little below the centre (by the thickness of the blade of the tool). -For the latter select one of the three following—either will answer -well—58, 59, 60. With one or the other drill a hole in the centre, -keeping the tool quite horizontal across the rest. Enlarge this hole -by a left side tool, working from the centre of the piece towards the -outside, not taking the whole depth at once, but a quarter or half an -inch at a time. You must hollow it out about one inch, and see how -nicely you can fit the hollow to the size of the piece you are going -to turn. You will, of course, have squared up one or both ends of the -latter, which must now be driven tightly into the hollow chuck. If you -squared the ends of the cylinder correctly and left also the bottom of -your chuck level and true, you will be gratified by seeing the piece -run evenly at once.</p> - -<div class="figcenter" id="i-p039" style="width:204px;"> - <img - class="p2" - src="images/i-p039.png" - width="204" - height="500" - alt="" /> - <p class="center smcap">Figs. 58, 59, 60.</p> - </div> - -<p><a href="#i-p040s">Fig. 61</a> shows a section of the chuck with the piece to be turned -fitted inside it. Now take the gouge and chisel and reduce the piece -to a plain cylinder, and take special care to square up the outer -end. This may be done by the aid of a carpenter's chisel held across -the rest, like the side-tool. If the end is much out of truth you had -better use first the round-ended tool, <a href="#i-p039">Fig. 60</a>, but if you have worked -carefully from the commencement this will be unnecessary.</p> - -<p>To ascertain the correctness of this part, apply a small steel square -like <a href="#i-p040s">Fig. 62</a>, the blade of which slides through the brass part and is -clamped by a small screw at the side. We show the method of applying -this tool to gauge depth, test right angles, &c., in <a href="#i-p040s">Figs. 63 and 64</a><span class="pagenum"><a name="Page_40" id="Page_40">[40]</a></span> . -It is a most convenient and necessary instrument, and should be at -once provided. Having thus ascertained that the end of your cylinder -is at right angles with the side, take the point tool, <a href="#i-p039">Fig. 58</a>, or the -acute corner of your chisel, and, setting the lathe in motion, mark -off the intended depth of the <i>cover</i>, as D, C, <a href="#i-p040s">Fig. 61</a>. (Observe, -it is the cover and not the box that first demands attention.) Now -proceed to hollow out the cover as you hollowed out the chuck, but -with greater care. You must allow in the thickness of the top rather -more material than you will eventually require, the thickness of the -sides, also, may be a trifle in excess, but take the utmost care to -make the inside rectangular, that is, the line <i>f, g</i>, perpendicular -to g, D. Upon the correctness of this the fit of the cover will -depend. This being done and tested as to truth with the square, as -before, you may cut off the cover with a parting tool, <a href="#i-p041">Fig. 65</a>. This -tool is thin, with a cutting edge at the end, and is held edgewise -upon the rest. The blade is made rather thicker near the end, so that -as the tool penetrates the work it may not bind, but allow the small -chips made by it to escape freely. The rest must be removed from -its former position and placed parallel to the side of the piece, -and the tee at such a height that the latter may, when the tool is -held horizontally, point to the axis of the work. The tool should be -occasionally withdrawn, and the point, instead of being kept precisely -in one position,<span class="pagenum"><a name="Page_41" id="Page_41">[41]</a></span> may be slightly raised and lowered from time to -time, describing a small arc. It will soon be ascertained in what -position it cuts most easily. There are different sizes of parting -tool, some very thin in the blade, for ivory and precious woods, some -thicker, for box and less valuable stuff, some with a notched end, -forming two points, for soft woods, the action of all being similar -to a saw tooth, or, in the last, to two adjacent saw teeth set out to -clear themselves in working. Care must be taken that the thin blades -do not bend and twist while cutting, especially after the cut has -become deep. To avoid this do not hurry the work, but take a little at -a time, and be careful to keep the tool with its sides perpendicular -to the rest. With these precautions the cover will soon be cut off -neatly. If care is not taken to allow for the necessary thickness of -the cover, the turner will be mortified by finding that instead of -the latter, he has merely cut off a ring, and he will have to expiate -his want of judgment by beginning a new cover and making a shallower -box. We name this to put him on his guard. Supposing the above work -satisfactorily accomplished—the top of the cover, however, being -(as will probably be the case) either convex or concave, requiring a -little touching up and finishing, it will be necessary to turn down -on the solid bit of wood left in the chuck the part A, B (<a href="#i-p041">Fig. 66</a>), -on which the cover will eventually rest. On no account, however, must -this be now turned small enough, it must be left so large as not quite -to enter the cover, because if it is now nicely fitted, and the box -subsequently hollowed out, the cover is sure to be too slack, the -wood shrinking in the process of hollowing out. This shrinking may be -accounted for by supposing the rings of woody fibre, the result of -yearly growth, naturally elastic, with a tendency to contract, each -one, like a series of india-rubber bands, embracing<span class="pagenum"><a name="Page_42" id="Page_42">[42]</a></span> that within it. -The central ones being removed by the tool, permit the outer ones -to contract, their particles approaching nearer to each other and -the structure becoming more dense. This tendency causes those radial -cracks so often seen in the ends of pieces of wood sawn from the trunk -or limbs of the tree. The outer parts becoming drier than the inner, -and prevented by the latter from shrinking, necessarily split, hence, -when it can be done, the centre of such pieces is bored out, while the -wood is yet full of sap, and the rest is thereby preserved. Where this -cannot be done the ends may be covered with glue or resin; or paper -may be glued on, to prevent access of air, and thus the drying of the -outer portion may be so retarded as only to keep pace with that nearer -the centre. The concentric rings thus shrink equally, and no radial -splitting takes place.</p> - -<div class="figcenter" id="i-p040s" style="width:700px;"> - <img - class="p2" - src="images/i-p040s.png" - width="700" - height="493" - alt="" /> - <p class="center smcap">Figs. 61, 62, 63, 64.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p041" style="width:331px;"> - <img - class="p2" - src="images/i-p041.png" - width="331" - height="550" - alt="" /> - <p class="center smcap">Figs. 65, 66, 68.</p> - </div> - -<p>We will now return from this explanatory digression to the work in -hand. Having cut down the flange for the cover to nearly the required -size, proceed to hollow out the box. Work carefully, so that the -sides shall be smooth and perpendicular to the bottom, and the latter -plane and neat. Take care, as with the cover, to leave the necessary -thickness of bottom, allowing for the cut of the parting tool, and, -if possible, half an inch or more beyond it. Now finish that part on -which the cover is to rest. Take great care, as before, to secure -right angles, and cut away the wood little by little, trying on the -cover from time to time, until at last it will just go smoothly and -stiffly into its place. It must fit rather tightly, but take especial -care not to force it on, or you will split and spoil it. We shall here -introduce to the notice of the reader another form of callipers useful -in such work as the above, and in many cases absolutely necessary. -They are called in-and-out callipers, and are made as shown in <a href="#i-p042">Fig. 67</a>. -These are so arranged that whatever interval exists between <i>a</i> -and <i>b</i>, exists also between <i>c</i> and <i>d</i>. If, therefore, the inside of -a box cover (or similar article) is measured by the latter, the other -end of the instrument will show the exact size to be given to the part -A, B, <a href="#i-p041">Fig. 66</a>. The convenience of such an arrangement for an infinity -of cases will be apparent on an inspection of the figure.</p> - -<div class="figcenter" id="i-p042" style="width:172px;"> - <img - class="p2" - src="images/i-p042.png" - width="172" - height="350" - alt="" /> - <p class="center smcap">Fig. 67.</p> - </div> - -<p>The cover of the box must now be put on, the lathe set in motion, -and the outside, and also the top of the cover, carefully turned and -finished. If the box is to be cylindrical, care should be taken that -it is truly so, and that the angle formed by the junction of the top -and sides is sharp. If sand-paper is used to finish the work, the -edges<span class="pagenum"><a name="Page_43" id="Page_43">[43]</a></span> will be rounded and the workmanlike appearance spoiled. If, -therefore, the article is made of box or other hard close-grained -wood, this finishing-off may be done with a carpenter's chisel held -so as to act as a scraper. The turning chisel will answer the same -purpose, but it is a pity to spoil the edge, which should be always -preserved keen and fit for use. If the box is made of soft wood, -scraping will not answer; the turning chisel must then be made use -of, held as previously, described. If the cylindrical form is not -proposed, the sides of the box must be left thicker, and after the -cover is fitted on the outside may be moulded by the gouge and chisel, -and tools like 60 and 68 to 70, to any desired pattern. The only thing -remaining to be done is to cut off the box with the parting tool, the -same precautions being observed which we spoke of in separating the -cover. If there should be any defect in the bottom after the work is -detached, the box must be placed in a cup chuck turned to receive it, -and the above defects removed.</p> - -<div class="figcenter" id="i-p043" style="width:339px;"> - <img - class="p2" - src="images/i-p043.png" - width="339" - height="550" - alt="" /> - <p class="center smcap">Figs. 69, 70, 71, 72, 73.</p> - </div> - -<p>In hollowing out a piece of solid ivory or similar costly material, it -would be exceedingly wasteful if the central part were removed as in a -common box, by being reduced to small chips. It is possible to remove -the whole interior in a solid block, and with exceedingly trifling -loss of material. This is effected by means of side parting tools, -71, 72, 73. A common parting tool is first used and a groove cut -therewith in the face of the block to be turned. <a href="#i-p044s">Fig. 74</a> represents -this face 75; the section after the groove is cut the depth of the -box required. The shaded part in the centre represents the part to be -removed. The smallest parting tool, <a href="#i-p043">Fig. 73</a>, is now introduced, the -back of the tool being laid across the rest, so that the crook takes -a<span class="pagenum"><a name="Page_44" id="Page_44">[44]</a></span> perpendicular position, A, B, <a href="#i-p044s">Fig. 74</a>. When at the bottom of the -groove the hook is turned to the left, so that it may cut a groove -underneath the block, until stopped by its shank. It is then withdrawn -and <a href="#i-p043">Fig. 72</a>, and subsequently <a href="#i-p043">Fig. 71</a> introduced, and used in a -similar way. In <a href="#i-p044s">Fig. 76</a> the black line shows the tool in position, -with the under cutting done by it. The sizes are thus increased until -the last tool removes the block entire.<a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">[3]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">[3]</span></a> The side parting tools are sometimes inserted in the -centre of the work, a hole being made for their introduction, they -then cut from within outwards. In this case, however, instead of a -solid piece a thick ring of the material is detached.</p></div> - -<div class="figcenter" id="i-p044s" style="width:448px;"> - <img - class="p2" - src="images/i-p044s.png" - width="448" - height="550" - alt="" /> - <p class="center smcap">Figs. 74, 75, 76, 77.</p> - </div> - -<p>We now propose to describe the method of turning a round ball or -globe, and, to make the work more interesting, it shall contain a -small box. The first thing necessary is to decide upon the diameter. -In the present case let it be an inch and a half. Turn a cylinder of -boxwood a little exceeding this, and cut off from it rather more<span class="pagenum"><a name="Page_45" id="Page_45">[45]</a></span> -than an inch and a half in length. The excess is merely to allow for -waste. You will thus have a cylinder whose diameter equals its length. -Before removing it from the lathe, mark its centre by a groove with a -point tool—subdivide the outer spaces with five lines, and from the -latter remove the corners of the piece, thus reducing it to the form -77. Test the length and breadth by the callipers and take care that -the ends of the cylinder are at right angles to the sides. Now place -the piece in the chuck in the position shown in the figure, that is, -at right angles to its original position in the lathe. It must be -tested as to truth by holding a point tool on the central line E, F. -If correctly placed this will only make a dot when the lathe is put in -motion. If the piece does not lie evenly the point of the tool will -make a small circle—it must then be corrected with a light tap or -two, until it runs evenly.</p> - -<p>If the inside of the chuck is rubbed with chalk the work will be less -liable to slip. The following operation, however, must be conducted -very gently and with exceeding care, or a satisfactory result will not -be produced. It will be observed that the central line having been -marked or cut upon the side of the cylinder is necessarily a circle, -and its revolution on its axis forms a sphere.</p> - -<p>We have therefore only to cut away the piece truly down to this line -to finish what <i>ought</i> to be a perfect globe. Bergeron, however, -justly remarks that although the theory is correct it is next to -impossible to manage the tools with sufficient skill to complete in -this way a true sphere. One great cause of this difficulty, is that -as the work revolves in its new position the central line is not -visible as a line, but simply becomes the boundary of the sphere. This -may be in part done away by making a <i>red</i> line or black one (red is -the best) instead of a mark with the tool. The work will then appear -red as it revolves, and the gouge and chisel must be used to cut -away this red part, great care being taken only just to remove what -appears coloured. Thus you will in the end have cut the work away so -as <i>barely</i> to remove the line. Work from the central part outwards, -and always with exceeding care, and you will eventually succeed to -your satisfaction. It is, nevertheless, a very difficult bit of work -to finish even fairly well—mainly on account of the great obscurity -of your landmark, the red line. For the more perfect finishing of the -above a template of steel may be made like <a href="#i-p045">Fig. 78</a>, with which to -test the work—its diameter is equal to that of the sphere, and it -will serve as a gauge or scraper. It should be made of saw plate if -intended for the latter purpose, otherwise sheet brass will answer as -well. After the semi-globe has been turned in the first chuck, it will -be necessary to<span class="pagenum"><a name="Page_46" id="Page_46">[46]</a></span> turn another to receive the finished part, and for -the more perfect formation of the same a semicircular template of the -same gauge as the concave one first made may be provided, as the more -nicely the ball fits the chuck, the less chance there will be of the -work shifting during the turning of the latter half of the sphere.</p> - -<div class="figcenter" id="i-p045" style="width:358px;"> - <img - class="p2" - src="images/i-p045.png" - width="358" - height="204" - alt="" /> - <p class="center smcap">Fig. 78.</p> - </div> - -<p>In order to obviate the difficulty of following the diametrical line -with the cutting tool, the following contrivance has been suggested -to the author by one who has followed lathe work as a profession -for many years, and is an adept at the art. The lathe band is to be -slightly slackened by partial untwisting (a turn or two will suffice), -if of catgut, so that it will carry round the pulley, if desired, but -will slip if the hand is placed on the latter. Thus, the tool may be -applied, and a light cut taken, and the work instantly stopped for -examination without stopping the lathe, as the flywheel continues to -revolve all the time. This examination can be repeated, if necessary, -every few seconds, by merely placing the hand on the pulley, and in -this way the work being carried on little by little, a good result is -attainable with comparatively little difficulty.</p> - -<p>The best position for the rest during the above operations will be -across the face of the work, as in hollowing out boxes, working -carefully, little by little, from centre to circumference. Towards the -finish a scraper should be used, the common carpenter's chisel being -as good a tool as any. Now to proceed with the box. Before removing -the finished ball from the chuck, bore it through with tool <a href="#i-p039">Fig. 59</a>, -enlarge with <a href="#i-p038">Fig. 51</a>, and make the hole conical, unscrew the chuck, -with the ball remaining in it, and put on another with a piece of -boxwood large enough to make a plug to fit this hole. This plug, when -fitted, is to be hollowed out, and converted into a box, like <a href="#i-p046">Fig. 79</a>. -The latter, when put in place, must fit so neatly that only a light -circle shows its position. To conceal it still more completely, a -series of circles are to be set at each of the six sides of the ball, -as shown at <a href="#i-p046">Fig. 80</a>. To remove the box, the thumb is placed<span class="pagenum"><a name="Page_47" id="Page_47">[47]</a></span> at the -small end, and pressure made. This forms a neat pocket needle-case, -and may be made of ivory as a present to your lady-love.</p> - -<div class="figcenter" id="i-p046" style="width:428px;"> - <img - class="p2" - src="images/i-p046.png" - width="428" - height="300" - alt="" /> - <p class="center smcap">Figs. 79, 80.</p> - </div> - -<p>There is no practical difficulty likely to be met with in the above -after the round ball is itself made, unless it may arise in respect -of the conical hole. Let this be turned out as directed, until at the -furthest (smallest) end it will just allow a gauge, like the annexed -figure, 80<sup>A</sup>, to pass through it.</p> - -<div class="figcenter" id="i-p047a" style="width:300px;"> - <img - class="p2" - src="images/i-p047a.png" - width="300" - height="110" - alt="" /> - <p class="center smcap">Fig. 80A.</p> - </div> - -<p>Having also gauged the large end of the hole to the desired size, -take care to finish the side evenly from one to the other. The gauge -may be a disc of tin on a wire, or, still better, a short cylinder of -box wood, on a similar handle, as there will be a little difficulty -in feeling whether the disc is placed at right angles to the axis -of the hole. Unless, however, you desire to work to a pre-arranged -exact measurement, the above precautions will scarcely be necessary, -inasmuch as the hole is first bored, and the conical plug afterwards -fitted to it. The ball may, therefore, be taken from the chuck, each -end of the bore measured, and the plug gauged at each end by the -callipers, and turned to an exact fit.</p> - -<p>In the above account the unmathematical phrase of "<i>six sides</i> of the -<i>ball</i>" is used for want of a better; the <i>meaning</i> of the author -will, however, be evident.</p> - -<p><span class="pagenum"><a name="Page_48" id="Page_48">[48]</a></span></p> - - -<h3 class="sc"><a name="CUTTING_SCREWS" id="CUTTING_SCREWS">Cutting Screws.</a></h3> - -<p>The ambition of amateurs, especially, is very commonly centered in -a desire to cut screws in the lathe, and there is good reason for -this, because in the first place there is a difficulty presented -which it is pleasant to overcome, and in the next place, a screw is -of absolute necessity in the greater number of turned works. There -is an apparatus of simple but ingenious construction called a screw -box, which is commonly used by carpenters and others who have not -attained the skill necessary for chasing screws in the lathe, and -which is very convenient even for those who have obtained this power. -A sketch of this is given in <a href="#i-p047bs">Fig. 81</a>. A, shows the tool complete, B -is a view after the top plate has been removed, showing the knife or -cutting tool, the latter being delineated alone at D on a large scale, -C is a section. To make this tool, which is within the power of any -person of average skill, a block of hard wood is first selected, and -drilled with a hole corresponding to the proposed size of the screw -to be cut. If no tap is at hand of the desired diameter and pitch, -this block must be mounted in the lathe, and the thread chased as we -shall presently describe. It is absolutely necessary that the block be -nicely squared up and level on the face. A small place must then be -cut to receive the knife, the edge of which is so constructed as to -form part of the thread cut away to make room for it. It is <span class="sans">V</span> shaped -like <a href="#i-p047bs">Fig. D</a>, and very keenly sharpened. The method used to clamp the -knife in position, which is shown in <a href="#i-p047bs">Fig. D</a>, permits the cutter to be -advanced or withdrawn until its position is accurately determined as -above. The top plate of wood is now fitted, and adjusted—the central -hole, <i>which is not tapped</i>, but as large as the <i>outside</i> of the -screw-thread to be cut, forming a continuation of that which is tapped -in the lower block. A slot <i>b</i>, <a href="#i-p047bs">Fig. A</a>, forms a passage from the -knife, to allow of the escape of the chips. The piece to be cut into a -screw should be shaped like <a href="#i-p049s">Fig. 82</a>. The part <i>a</i>, will be left plain, -<i>b</i>, is that on which the thread is to be cut, and must be truly -cylindrical, and of such size as to just enter the hole in the top -plate of the screw box. The part <i>c</i> must pass through the threaded -part of the screw box, not loosely, but just so as not to damage the -threads in the least. The lower part of the central division is sloped -off as seen in the sketch. To cut the thread the screw blank is fixed -in the vice by its head, which, after being turned, should be planed -off at each side. The screw box being then placed upon it the lowest -and smallest part of the blank should just project, as in <a href="#i-p049s">Fig. 83</a>. -This part is intended to insure the perpendicular position of the -blank in respect of the screw box. The latter is then turned from left -to right until the screw is cut, which ought to come from the tool -clean and smooth. Box wood is especially suitable for this purpose. -This<span class="pagenum"><a name="Page_49" id="Page_49">[49]</a></span> method is, of course, wholly inapplicable to anything but wooden -screw bolts, and for practice the tyro may set to work and make three -or four of the following screw clamps, which are useful to hold pieces -of wood that have been glued together. The tap for screwing nuts and -the jaws of these clamps, is similar to that used for metal, but, the -teeth, or cutting threads, are deeper and more pointed. The jaws of -the clamps shown in <a href="#i-p049s">Figs. 84, 85</a>, are usually made of beech, which -will take a very fair thread; or of birch, which is still better; and -the screws may be made of the same material, box being too costly and -scarce for such purposes. In making these clamps, there is to be no -thread cut on that part at which the handle of the screws project, -nor is there any thread on this part of the bolts, which pass through -a smooth hole in one jaw and lay hold of the other only. Other forms -will suggest themselves, but the two given will be found serviceable -patterns.</p> - -<div class="figcenter" id="i-p047bs" style="width:700px;"> - <img - class="p2" - src="images/i-p047bs.png" - width="700" - height="455" - alt="" /> - <p class="center smcap">Fig. 81.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p049s" style="width:680px;"> - <img - class="p2" - src="images/i-p049s.png" - width="680" - height="550" - alt="" /> - <p class="center smcap">Figs. 82, 83, 84, 85.</p> - </div> - -<p>The above method of cutting screws is not of anything like universal -application, nor specially the work of the turner; we shall now, -therefore, speak of cutting them by the chasing tool in the lathe. To -effect this with certainty requires much care and long practice, and -at first the attempt should never be made on a box or ornamental piece -of work, otherwise finished, but on a plain cylindrical bolt, such as -those of the clamps just described. For the inside, or female screw, -the making of chucks will afford endless practice, and a failure in -either of these will be of little importance. The<span class="pagenum"><a name="Page_50" id="Page_50">[50]</a></span> screw tool for male -and female threads is represented in <a href="#i-p050">Figs. 86 and 87</a>. It is of steel, -and as each tooth inclines in the direction and with the pitch of the -screw, it cannot be made with a file, but is cut by being held against -a revolving tap (or screw hob, which is of similar form.) There is -certainly a defect in the above common form of screw chaser, and a -slight modification, to be presently described, will be found easier -to use, and, in many respects, easier to make. To cut a thread with -the chasing tool, the top of the rest must be quite level and smooth, -so that the tool may readily slip along it. Suppose an outside thread -to be required on a cylinder of box or other close grained wood. The -rest being firmly fixed so that the upper edge is level with the axis -of the piece, and about half an inch from it, as <a href="#i-p050">Fig. 88</a>, the tool is -advanced to touch the work, not in a line with the axis, but so as -to bring the part, <i>a</i>, in contact with it first, and the moment the -tool is felt to run along, which it will do as soon as this part of it -indents the wood, the handle is raised a little so that the points of -the teeth come into work. The tool in fact must describe the segment -of a circle, as shown by the dotted line. If this is done cleverly -the tool will not hitch, nor produce a drunken thread, but the latter -will come out clean and sharp. It is, nevertheless, necessary to -practise till the knack of thus chasing a thread<span class="pagenum"><a name="Page_51" id="Page_51">[51]</a></span> is attained, and, -considering that once acquired, the necessity of traversing mandrel or -other expensive (and yet more or less defective) apparatus, no longer -exists, it is evident that the young aspirant should spare neither -time nor patience in becoming an adept in this useful art.</p> - -<div class="figcenter" id="i-p050" style="width:508px;"> - <img - class="p2" - src="images/i-p050.png" - width="508" - height="550" - alt="" /> - <p class="center smcap">Figs. 86, 87, 88.</p> - </div> - -<p>One great difficulty in cutting the screw-threads to the top of a box, -or the inside of its cover, arises from the necessity for stopping -short, and removing the tool instantly as soon as it touches the -shoulder, or the top of the cover. The latter should be made rather -deeper than is necessary, so that there may be a turn or two of screw -to spare. This will give more room for the play and removal of the -inside chasing tool.</p> - -<p>The ordinary form of the latter is as shown in <a href="#i-p050">Fig. 87</a>, the part under -the plane upper surface (<i>a</i>) being either slightly hollowed or flat, -generally the former, from having been cut by a revolving cylindrical -hub.</p> - -<p>Now, although this form may be suitable for outside screw tools, -which have to work on cylindrical pieces, it does not appear equally -suitable for inside tools, which are to act on concave work. The -writer of this article has experimented upon many patterns of chasing -tool, and has found it perfectly easy to chase an inside thread with -an ordinary grooved tap, which seldom makes a false cut, or crosses -the threads. From this the idea naturally arose of a convex edged tool -for inside chasing, and a concave one for outside work, as <a href="#i-p051">Fig. 89</a>.</p> - -<div class="figcenter" id="i-p051" style="width:524px;"> - <img - class="p2" - src="images/i-p051.png" - width="524" - height="550" - alt="" /> - <p class="center smcap">Figs. 89, 90.</p> - </div> - -<p>Practically, however, the convex edge, <a href="#i-p051">Fig. 90</a>, will answer -satisfactorily for an outside cylinder. In order to obtain an -efficient cutting edge from this form, the rounding must be very -slight. The out or inside tool is used with a rolling movement on -the rest as it advances. If for hard wood, a notch cut across in the -line <i>e, f</i>, <a href="#i-p051">Fig. 90</a>, with a saw-file, will, by making a partially -cutting edge on the convex part, cause the tool to enter more readily -at starting. Tools like the above must be necessarily the work of -the amateur himself. The regular makers have a great objection to -make any tool or machine out of the ordinary routine. Hence the same -patterns are<span class="pagenum"><a name="Page_52" id="Page_52">[52]</a></span> constantly reproduced year after year, until some one -connected with the manufacture invents an improved form, or some one -else of mechanical genius, and possessed of means, registers a new -design. Amateurs are apt to cavil at this system, and in some cases -it no doubt interferes with, and checks improvement in tools and -machines, but the evil is almost a matter of necessity. Tools are made -not singly, one of each pattern, but so many score or hundreds of one -form are forged out, and handed over to the grinding and finishing -department, and it would sadly interfere with the system and order -of the manufacturer to make a single tool or two for individual -purchasers of different pattern to those ordinarily used. If a design -is sent in by a retail dealer who can order a hundred or so at his -own risk, the above objection is obviated, and the new pattern of -tool or machine is at once introduced. If, however, any new design by -an amateur, being submitted to such men as Holtzapffel, Buck, Fenn, -or Whitworth, appears to <i>them</i> good and saleable, they will not -only not object to introduce it, but may possibly give a premium to -the inventor. We have thought it necessary to make these remarks to -obviate the possible disappointment of amateurs in this respect. It -is but natural to suppose that some ingenious device must have long -since arisen to obviate the difficulty of thus cutting screws by hand. -Every turner finds the difficulty, and few perhaps have failed to try -some plan or other to counteract it. There are two methods whereby -this can be done: one by causing the tool to traverse at a given rate -according to the proposed pitch of the screw, the other by giving -similar movement to the mandrel, while the tool remains still. For -such work as screwing the lids of boxes, the traversing mandrel is -commonly used, but for cutting long screws in metal, the tool is fixed -in a slide rest, and the latter is made to traverse, if necessary, the -whole length of the lathe bed, by means of a guide screw driven by -suitable gearing put in motion by the mandrel itself, the speed being -adjusted by a series of cog wheels which can be interchanged to cause -various rates of motion. The latter method belongs to machine lathes, -and will be treated of hereafter in this series.</p> - -<p>The author has great pleasure in here introducing a device, not -exactly for <i>cutting</i>, but for starting the threads of a single, or -double screw, or, indeed, a quadruple one. It is the invention of a -gentleman whose <i>nom de plume</i> is East Norfolk Amateur, and was by him -kindly communicated to the <i>English Mechanic</i>, of June 21, 1867. The -description is here given in his own words:—</p> - -<p>"I think the plan to be described will produce to a certainty any -required number of screws and turns to the inch. The screws are -entirely cut with a common comb tool, but started by a revolving -cutter set to the required angle, and applied firmly to the work, on -the T-rest. I call it 'the universal screw guide tool,' contrived -and<span class="pagenum"><a name="Page_53" id="Page_53">[53]</a></span> made by myself, and I believe will prove as useful to others as -it has to me: the <a href="#i-p053">drawing</a> will almost explain the tool. The cutter, -A, is <sup>9</sup>/<sub>16</sub>ths of an inch in diameter, turned to a cutting edge, and -finely tempered. The stem, B, in which it revolves, is round, and fits -into the shoe, C, having a graduated collar, D, in front of C, to set -the cutter to the required pitch or angle, the set screw, E, makes it -fast; having turned a piece of rod, of brass, iron, or steel, a little -above the size necessary, and supposing a quadruple screw is to be -cut having ten turns to the inch, there would, of course, be forty -threads when complete; if one of these four can be truly traced, the -comb tool will easily follow by inserting the outside tooth, either -right or left hand, as found convenient, in the line traced, when the -other three will soon appear with perfect accuracy, provided the first -one exactly corresponded to five points of the comb, which is easily -accomplished after a few trials, and if not successful at first,<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">[4]</a> -can be removed by a dead flat file several times, without reducing the -rod too much. When found to exactly fit the five points, the cutter -may be applied with more force to leave a good chase for the comb. The -T-rest requires a smooth surface for the shoe, C, to slide freely on, -and to be set parallel with the work, and the tool held at a right -angle as it proceeds along the rest, or the lines formed would be -of unequal distance. After a little experience it will be found to -work with beautiful accuracy, and for those who have not screw-guide -mandrels, and are not practised hands at flying common screws, it -will be found a great assistance, as it sets to anything. I described -only the quadruple, but the same rule applies to all quick screws; -for a double the chase must correspond to three points, and so on for -any number, that is, one more point of the comb than the number of -screws to be cut, and for a common one the chase must fit the comb -altogether."</p> - -<div class="footnote"> - -<p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">[4]</span></a> This doubt seems to mar the invention. It is, however, on -the whole a good design.</p></div> - -<div class="figcenter" id="i-p053" style="width:580px;"> - <img - class="p2" - src="images/i-p053.png" - width="580" - height="321" - alt="" /> - <p class="center smcap">Figs. A, B, C, D.</p> - </div> - -<p>The above simple apparatus will, it is believed, be of great service -to those who find difficulty in hand chasing of screws; it is, -however, necessary to speak of other methods, and especially of that -so universally used by the turners of "Tunbridge ware"—viz., the -traversing mandrel. This is represented in <a href="#i-p054s">Fig. 91</a>. A is the poppet; -B, the mandrel, no longer conical at the place where it traverses -the collar, but cylindrical, and passing through <i>two</i> cylindrical -collars. It is prevented from advancing towards the left in its -bearings by the shoulder, K, and in the other direction by a plain<span class="pagenum"><a name="Page_54" id="Page_54">[54]</a></span> -cylindrical collar, or ferrule, C, which slips over the end, and is -secured by a nut, D. The whole is thus ready for use, as an ordinary -mandrel. To cause it to traverse from left to right, as it revolves, -the nut and collar, C, D, are removed, and a ferrule, or guide, F, -which has a screw of the desired pitch cut on its edge, is slipped -on the mandrel over a short feather against a shoulder, where it -is retained by a nut or pin. There are several such guide-ferrules -supplied with the mandrel of different pitches of screws. The nut G -is then removed and the piece E, which is of brass or gun metal ⅜ -or ½ inch in thickness, with similar screw threads in each of the -hollows is attached. This guide is slipped on at H, and secured by -replacing the nut. The pin, which carries the guide, is frequently -made to slide up and down the face of the poppet, by the action of a -screw, M, working through a brass piece attached to that which carries -the pin. It is thus readily lowered out of gear or drawn up again -to touch the screw ferule. This is better than a pin screwed to the -head of the poppet, and is always adopted in the best lathes. In the -frontispiece is a <a href="#frontispiece_s">photograph</a> of this arrangement. -This guidepiece acts like a half nut, and as the mandrel revolves -it gears into the ferule and causes the required traverse. A single -point tool, therefore, held against the work will trace a screw of -the same pitch as that of the guides, and of a length equal to that -of the ferule. The above is not intended for cutting long screws, -which would have to be done in successive short lengths, but for -screws of box lids, chucks, and similar work it is a most excellent -contrivance, and peculiarly adapted for the use of the amateur. The -guide threads in the commoner patterns of these lathes are cut on -the mandrel itself, which is made of greater length than usual, and -these several guides are cut upon the part within the poppet heads, -as <a href="#i-p054s">Fig. 92</a>,<span class="pagenum"><a name="Page_55" id="Page_55">[55]</a></span> which represents such a lathe as is sometimes used by -gasfitters and brass workers in general.<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">[5]</a> In the latter it will -be noticed that there is added a sustaining screw at the back of -the mandrel. This is a good addition, and indeed almost a necessary -one if the lathe is to be used for ordinary rough work, especially -drilling, as it takes off the pressure which must otherwise come -against the shoulder, K, <a href="#i-p054s">Fig. 91</a>, and it must be remembered that these -lathes are expensive, and, therefore, ought to be taken care of. The -amateur may also be warned against bad work; none but the first-class -makers can turn out a reliable lathe of this description. The collars -and mandrel require <i>perfect</i> fitting, and they must be quite hard, -because there is no possibility of tightening them when worn. They -must be kept well oiled, therefore, when in use, and the oil holes in -the top of the poppet should be fitted with brass covers, to prevent -any particles of metal, and especially emery dust, from working in -between collars and mandrel. Be sure to have one guide screw of -the same pitch as that on the nose of the mandrel, for the purpose -of tapping chucks to fit thereon. In using the traversing mandrel, -either the cord should be slackened so that the pressure of the hand -on the pulley may stop the revolution of the work in a moment, or -the flywheel should not be brought into use, the cord being instead -grasped by the left hand, because it is generally necessary to cut -to a shoulder or given point. It is, however, possible sometimes so -to arrange the guides by insertion of a washer or other expedient as -to cause the action to cease of itself at the required point. In a -future chapter, the cutting of long metal screws will be treated in -detail, but before concluding the present chapter, it may be useful -to say a few words concerning the nature of the screw itself as a -mechanical expedient. A screw may be defined as a continuous inclined -plane—or an inclined plane wound round a cylinder—the pitch being -the inclination of the plane, that is, the ratio of its height to the -length of its base. From the mechanical principle of the inclined -plane it follows that the greater number of threads in a given space -the greater is the power of the screw when used as in a press, or to -draw along its nut, as in the slide rest, in which endlong motion -in the screw itself is prevented. It seems, at first sight, easy to -devise a method for cutting screws of any desired pitch, but this is -far from being the case, and when it becomes necessary to increase the -number of threads to fifty, sixty, eighty, or even more to the inch, -with such accuracy that one turn of the screw shall always produce an -<i>equal</i> longitudinal movement of the nut, the most delicate machinery -scarcely suffices for the purpose. The microscope detects and shows -errors even in the best work, and it is questionable whether a perfect -screw of any length <i>can</i> be cut by machinery, as every imperfection -in the latter is communicated to<span class="pagenum"><a name="Page_56" id="Page_56">[56]</a></span> the work done by it. If the amateur, -therefore, requires a screw for a slide rest, eccentric chuck, -microscope, or other delicate piece of machinery, or philosophical -instrument, he had better get it cut by some practical mechanician, in -the possession of the necessary apparatus.</p> - -<div class="footnote"> - -<p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">[5]</span></a> There should be a collar or shoulder to this mandrel, the -same as at K in the other figure.</p></div> - -<div class="figcenter" id="i-p054s" style="width:700px;"> - <img - class="p2" - src="images/i-p054s.png" - width="700" - height="421" - alt="" /> - <p class="center smcap">Figs. 91, 92.</p> - </div> - -<p>In the "Manual Bergeron" is an ingenious contrivance, by an amateur, -which is worth notice, although unsuited for any work where extreme -accuracy of pitch is required in the screw. The following, <a href="#i-p056s">Fig. 93</a>, -is a description:—The mandrel is made to traverse in its bearings, -as before detailed in this series, but instead of its motion being -governed by guide hubs, it is dependent on the action of a pair of -differential pulleys, B. A bent lever, C, is pivoted at E to the -face of the poppet, having a bit of hardened steel fitted to work in -a semicircular groove in the mandrel itself, and so arranged that -on raising the tail or long arm of the lever the mandrel is thrust -forward from left to right, while a reverse action of this lever -causes a similar movement in the opposite direction. The movement of -the lever is thus regulated:—At the extreme end of the long arm is a -pulley and hook, as shown in the drawing; the double, or differential -pulley, is fixed to the end of the mandrel, and from the smaller -part depends a cord which passes thence through the pulley on the -lever, and is wound round the larger one on the mandrel when its end -is secured. On the hook is hung a weight. It will be evident, on an -inspection of the drawing, that on putting the lathe in motion the -cord on the differential pulley will coil itself round the largest -part of the same, and will draw up the end of the lever with a speed -proportionate to the difference of diameter between the larger and -smaller parts of the double pulley. The short end of the lever will -at the same time with similar proportionate motion move the mandrel -and work, and cause the fixed tool to cut a spiral or screw thread on -the latter—a good deal of ingenuity is displayed in the above, and it -has the advantage of being easily fitted up, but it is evident that -some alterations and additions would be required to adapt it to any -other use but that specified. A contrivance similar to <a href="#i-p057a">Fig. 94</a>, may -in some cases be a sufficient makeshift, when a more perfect one is -not at hand. A screw is here cut on the outside of the chuck, and a<span class="pagenum"><a name="Page_57" id="Page_57">[57]</a></span> -kind of double tool is used, the tracer which is in contact with the -guide thread being adjustable as to its length, and the cutting tool -having a sidelong adjustment as well. The rest being placed between -the connecting bar of the tool and the work, the former will be held -with sufficient steadiness to enable the workman to traverse the -whole easily by hand. The use of this tool is of course limited, but -the plan is simple and fairly effective. The only really serviceable -plan is the slide rest, to be hereafter described. But one other plan -is here added, which is called "Healey's chuck." The description and -sketch are from Holtzapffel's work, in which it was however copied -from an older treatise. The author, it must be understood, has never -seen the contrivance himself, and there is a fault in its principle -of construction which must militate against its use except in a very -limited degree. Since, however, Holtzapffel has considered it worthy -of a place in his work, it is at any rate well to introduce it to the -reader, especially as its defects will not be of great importance -in tracing screws of half a dozen threads or so. The apparatus is -represented in <a href="#i-p057b">Fig. 95</a>. in plan. C is the chuck which carries the work -to be screwed, and T is the tool which lies upon R, R, the lathe rest, -that is placed at right angles to the bearers and is always free to -move in its socket S, as on a centre, because the binding screw is -either loosened or removed. On the outside of the chuck C is cut a -coarse guide screw which we will suppose to be right handed. The nut -N, N, which fits the screw of the chuck is extended into a long arm, -and the latter communicates with the lathe rest by the connecting rod -C, C. As the lathe revolves backwards and forwards, the arm, N (which -is retained horizontally by a guide pin, G), traverses to and fro, -as regards the chuck and work, and causes the lathe rest R, R, to -oscillate in its socket S. The distance S, T being half S, R, a right -hand<span class="pagenum"><a name="Page_58" id="Page_58">[58]</a></span> screw of half the coarseness of the guide will be cut, or the -tool being nearer to and on the other side of the centre, S, as in the -dotted position T, a finer and left hand screw will be cut. The rod C, -C, may be attached indifferently to any part of N, N, but the smallest -change of the relation of S, T to S, R would mar the correspondence -of screws cut at different periods, and therefore T and R should be -united by a swiveljoint capable of being fixed at any part of the -lathe rest R, R, which is omitted in Mr. Healey's perspective drawing -of the apparatus.</p> - -<div class="figcenter" id="i-p056s" style="width:700px;"> - <img - class="p2" - src="images/i-p056s.png" - width="700" - height="294" - alt="" /> - <p class="center smcap">Fig. 93.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p057a" style="width:331px;"> - <img - class="p2" - src="images/i-p057a.png" - width="331" - height="433" - alt="" /> - <p class="center smcap">Fig. 94.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p057b" style="width:450px;"> - <img - class="p2" - src="images/i-p057b.png" - width="450" - height="515" - alt="" /> - <p class="center smcap">Fig. 95.</p> - </div> - -<p>This is one of the least perfect modes of originating screws, it -should, therefore, be only applied to such as are very short, as, -owing to the variation in the angular relation of the parts the motion -given to the tool is not strictly constant nor equable. When in the -midway position the several parts should lie exactly at right angles -to each other in order as far as possible to avoid the error. The -inequality of the threads is imperceptible in a short screw. A little -modification of the screw-chuck of Healey would result in a more -correct and serviceable arrangement.</p> - -<p>The disadvantage, for instance, of being obliged to set the T of -the rest across the face of the work is apparent at once, and it is -difficult to understand how such an arrangement could be made to -answer when the work might be of a length to require the support of -the back poppet. The following plan, <a href="#i-p058s">Fig. 96</a>, would obviate this and -the other disadvantages, and make a more efficient apparatus. B is the -chuck with screw chased on the outside, A the nut travelling upon the -same. To this is attached a bar H, which<span class="pagenum"><a name="Page_59" id="Page_59">[59]</a></span> passes through the bar K, -to which it is clamped by the binding screw visible at H. Two short -pillars, F, F, are screwed into the bed of the lathe, in which there -might be more than one hole for each to permit the pillars to be fixed -at different distances from the line of centre. Through slots in these -passes the square bar of polished iron or steel E, supporting the -traversing rest socket, D, of which two other views are given at <a href="#i-p058s">Figs. 97 and 98</a>. -It will be evident on inspecting the drawing that as the -nut A travels to and fro, it carries with it in a line parallel to -the lathe bed the rest socket and T. To enable the workman to steady -the tool, the latter should rest against two short pins fixed in the -top surface of the rest in holes made for the purpose; with the aid -of these the tool will be made to traverse the work with great ease -and regularity. In chasing a right-handed screw, the tool would have -to lie on the left side of the pins, and the latter would insure its -traversing with the rest. A longer T (or half T) being turned in its -socket to stand across the face of the work will enable an inside -thread to be cut with the ordinary tool either of one or more points. -Of course, in this modification of Healey's chuck, the screw cut will -be of the same pitch as that of the chuck itself; but as the latter -may be of boxwood, there would be no difficulty in having from three -to six with the most generally useful pitches of screws, as the arm -may be screwed into the near side of the nut, and, therefore, it, -and all the other parts of the apparatus, would answer for the whole -set of chucks. If the work to be screwed is merely a box cover, or -some such work where great length of screw is not required, it is -evident that to rig up this kind of contrivance, or Healey's, or -indeed anything of similar elaboration, would appear like summoning -a gang of navvies to remove a mole-hill. Hence, if a traversing -mandrel cannot be obtained, by far the simplest plan is the chasing -tool used by hand; it is therefore well worth while to get into the -knack of using this tool. To give confidence (which is essential to -success, the least nervousness generally proving fatal to such work) -the part on which the screw is to be cut may be left larger than will -finally be necessary. The screw is then commenced, and if a failure -takes place it is again levelled, but if, as is more probable, the -attempt is successful, the chisel and chase are alternately used, the -cuts of the latter not being obliterated by the former but always -left sufficiently deep to form a guide until the desired object is -satisfactorily accomplished.</p> - -<div class="figcenter" id="i-p058s" style="width:619px;"> - <img - class="p2" - src="images/i-p058s.png" - width="619" - height="550" - alt="" /> - <p class="center smcap">Figs. 96, 97, 98.</p> - </div> - -<p>Having treated of screw cutting so far as we are able without -trespassing on that section of the present series which is to be -devoted to machine work with slide rest and change wheels, we shall -enter on the matter of spirals, or Elizabethan twists, the method of -making which was long kept a secret by the trade. These twists are<span class="pagenum"><a name="Page_60" id="Page_60">[60]</a></span> -essentially screws of very extended pitch, and generally rounded -threads. The latter sometimes embrace the central cylinder or core, -and sometimes are detached so as to assume a more open form like a -corkscrew, and in the latter case two, three, or more threads can be -cut, so that the spirals appear to intertwine. These spirals, too, -are frequently ornamented with the aid of the eccentric chuck, and -thus the work becomes fit for the adornment of the drawing-rooms -of the highest in the land. No turned work can in short exceed in -beauty these delicate and elaborate specimens of the turner's art. -To commence with a single twist of one thread. A cylinder of the -requisite length must first be turned. The number of turns the -thread or cord of the spiral is to make in a given space must next -be determined. We will suppose the cylinder one foot long, exclusive -of any mouldings or tenons at the ends, and that the spiral is to -make three turns round it, that is, one turn in four inches of its -length. Divide the cylinder into three equal parts by the lines B, C, -<a href="#i-p060">Fig. 99</a>. Next rule equidistant lines D, E, F, along the cylinder in -the direction of its length; in the present case let there be <i>four</i> -such lines. The three divisions first made must be subdivided each -into four (always the number of the longitudinal lines). The angles -of the parallelograms thus formed must then be connected diagonally -as shown in the figure, which diagonals being continued, will be -found to describe a spiral line. A second similarly constructed -spiral determines the thickness of the thread or cord of the twist. -These spirals may now be cut with a tenon saw, and all the material -outside the cord carefully removed with the gouge, so as to form -a semicircular hollow between the threads. This cannot be done by -putting the treadle and flywheel in motion, but the work itself must -be grasped with the left hand, while the right holds the gouge upon -the rest and guides its edge. After the work has thus been roughed -out, it must be finished by rasps and files, or by a kind of plane -with a semicircular cutting edge. While the latter is being used, the -flywheel must be brought into action, so that the work may be made to -revolve with sufficient rapidity to ensure a clean and smooth cut. A -hollow plane may be used to round the cord of the twist, and the whole -finished with glass paper and polished.</p> - -<div class="figcenter" id="i-p060" style="width:450px;"> - <img - class="p2" - src="images/i-p060.png" - width="450" - height="114" - alt="" /> - <p class="center smcap ">Fig. 99.</p> - </div> - -<p>The "kind of plane" named was designed by a regular workman for his -own use, and was made thus and grasped in the fist, or rather hollow -of the hand. The iron was like <i>c</i>, sharp at one edge,<span class="pagenum"><a name="Page_61" id="Page_61">[61]</a></span> the block of -wood being slightly bevelled off in front of the cutting edge. The -workman, who made scores of these twisted works for the trade, of all -dimensions, would run this along the hollows, while the lathe was -in motion, with great speed and accuracy. He marked the spirals as -described, and then grasping the work in the left hand, and the gouge -in the right, turning the work round with the former (the cord thrown -off the wheel), he cut out the wood boldly in large pieces with little -apparent care, and perfect ease. Then came the plane described above.</p> - -<p><a href="#i-p061">Fig. 100</a> shows a simple spiral thus made. If the piece to be turned -is dark it is not easy thus to mark out the divisions. In that case -the following method will answer equally well. It is the plan used -and contrived by the writer,<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">[6]</a> and specially handy when a number of -similar twists are to be cut, as in ornamented pieces of furniture. -A, <a href="#i-p061">Fig. 101</a>, is a straight edge of hard wood, through which, at any -given angle (regulated by the number of turns the cord is desired to -make in a given length of cylinder), a knife edge is fixed. If this is -held as in the figure, and the blade is pressed down upon the cylinder -to be cut, the lathe being put in motion, a very correct spiral will -be traced, which can be at once deepened by a tenon saw as before. -The thickness of the cord being determined it only remains to place -this tool again upon the work so that the second line shall be traced -at the required distance from the first. A second, or any number of -cords, may be thus traced in succession parallel to each other by this -simple method. By a slight modification of this instrument, which -allows the knife to be clamped at<span class="pagenum"><a name="Page_62" id="Page_62">[62]</a></span> any desired angle with the straight -edge, the inclination of the cords, and, consequently, the pitch of -the spiral can be varied at pleasure, and a second blade can be added -to trace the second line, determining the thickness of the cord with -one movement of the tool along the cylinder. The edge of the knife may -be across the rest, the piece of wood just overlapping the T on the -side next the workman, if the blade is long enough to reach across the -work when thus held. The tool will be steadier and perhaps more easy -of management in this position. One hand should then lightly press the -back of the knife, while the other retains the wood against the rest -as a straight edge. East Norfolk Amateur's design of a screw guide is -on the same principle, the only difference being the substitution of a -revolving instead of a fixed knife edge. In using either it requires -some care to allow the tool free traverse, as the least check would -spoil the thread.</p> - -<div class="footnote"> - -<p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">[6]</span></a> A similar plan is noticed in Holtzapffel's mechanical -manipulation, which the writer had not seen. It is satisfactory to him -to find the method thus authorised.</p></div> - -<div class="figcenter" id="i-p061" style="width:550px;"> - <img - class="p2" - src="images/i-p061.png" - width="550" - height="412" - alt="" /> - <p class="center smcap">Figs. 100, 101.</p> - </div> - -<p>The next class of spirals is that in which no central core exists, -but the coils stand separate and distinct, two or more rising from -the same base. The coils are sometimes flat, sometimes rounded, and -still more frequently, in the best work, exquisitely, and (as a -casual spectator would say) <i>impossibly</i> carved. The process is as -follows:—Turn a cylinder of ivory or hard wood, forming at the end -any required mouldings as a base and capital. Determine the number of -coils and the pitch, and by one of the previous methods mark out the -same. The cylinder is now to be bored out from end to end, leaving -sufficient for the thickness of the required cords. This bore may -with advantage be slightly larger at one end than at the other, so -that a mandrel of wood may be fitted into it, to be afterwards easily -withdrawn. This will certainly be necessary if the ivory cords are -to be of light substance, as they require support to enable them to -bear the action of the tool. After the cylinder has been bored as -above directed, let a mandrel of common wood be inserted, and the -lines, marked as shown, be cut quite through. The intermediate parts -between the intended threads must then be removed carefully (with a -round rasp, if of ivory) with any convenient tool if of wood. The -cords must then in a similar way be rounded or otherwise moulded, and -afterwards the common and now damaged mandrel removed. In the case of -ivory the piece of work will not only be strengthened by the insertion -of a polished mandrel of ebony, but its appearance will be improved. -Sometimes, however, it may be preferable to line it with red velvet or -silk, or it may be left entirely open. The further ornamentation of -the cords, depending on the eccentric chuck or eccentric cutters, will -not be described in the present paper. These open spirals are worth a -vast amount of patience and trouble, which their elegant appearance -when finished will amply repay.</p> - -<p><span class="pagenum"><a name="Page_63" id="Page_63">[63]</a></span></p> - -<p>The reader is not to suppose that this method of cutting spirals by -rasp and file is the only or best method, especially when ivory is -the substance operated upon. Further on will be described various -modes of accomplishing the same ends by self-acting machinery, and -by the spiral apparatus designed for use with the ordinary lathe, -but all these need the slide rest, whereas it is quite possible in -the foregoing manner to make spirals by hand tools alone, which for -correctness and finish may vie with those which may have been worked -with more elaborate and costly apparatus.</p> - -<p>Before quitting the subject of plain hand turning in wood, a few -more words may be necessary in respect of certain details of lathe -manipulation, foremost among which comes Chucking work. This is often -carelessly done, especially by amateurs, who, in consequence, are -frequently annoyed by the shifting of the material under the influence -of the cutting tool. If this is hard and valuable—as are many of -the best woods for ornamental turning—the fork or prong chuck will -not enter sufficiently to sustain the piece, and at the same time -the stuff is too valuable to allow of the waste incurred in screwing -it direct to the mandrel, or inserting it sufficiently far into a -brass cup chuck. In such cases the best plan is to screw a piece of -common wood upon the mandrel, face it truly, and cut a few shallow -concentric circles upon the end thus levelled, both for the purpose of -a guide to centrality, and also to give a hold to the glue by which -the more precious material is to be attached to it. For this purpose, -both chuck and work are to be well warmed, and the glue—boiling -hot—brushed upon the parts to be united. The latter are then to be -rubbed together a few seconds, and when the piece to be turned runs -truly, the back poppet with boring flange attached—if the right hand -end of the piece is level, otherwise, the point allowed to remain—is -to be brought up and screwed as a clamp against it till dry. This -process requires time, but is well worth the trouble, as the material -will be securely held, and can be safely operated on. None but those -who have had to contend personally with a tyro's difficulties, and -have, in consequence, seen the work shift in the chuck when nearly -completed, can truly appreciate the advantages of efficient chucking. -In the case detailed, there is absolutely no waste of material, no -possibility of the work becoming loose or out of truth; and the -ornamentation by eccentric cutters, drills, and so forth, can be -proceeded with, and carried out with that confidence which never fails -to promote good workmanship. Even with the above arrangement the back -poppet should be used while the excrescences are turned down, and -retained as long as the gouge has to be used in bringing the design -into an approximation to its intended form. This should be removed, -however, before taking the final cut, as the work will generally seem -to drop a little when the support is taken away,<span class="pagenum"><a name="Page_64" id="Page_64">[64]</a></span> in consequence of -the mandrel, which has been forced against the back centre, returning -to its place in the collar.</p> - -<p>Pieces of six or seven inches in length, and of one or two inches -diameter, requiring to be hollowed out, may frequently be turned by -reversing the usual method and boring out the interior, previous to -shaping the outside. A case for pencils, for instance, or a bodkin -case, may be thus worked:—Mount in the square hole chuck, an American -screw auger, sets of which are now to be had beautifully finished and -polished. The kind meant has a scooping kind of edge above the screw, -<a href="#i-p064a">Fig. 102</a>, and cuts cleanly and rapidly. The piece of wood—soft wood -alone is meant—is brought against the tool, being grasped by the -left hand, while the back centre, with flange, is steadily advanced -with the right hand against the opposite end. This auger will run -straight through several inches without requiring to be withdrawn, as -the borings pass freely along the polished threads of the instrument -and escape. If necessary, however, it can be readily withdrawn by -reversing the action of the lathe, and replaced without difficulty. -The piece thus bored may then be mounted in the lathe and finished on -the outside. To do this satisfactorily, an arrangement is requisite -by which the centrality of bore is insured, else in the process of<span class="pagenum"><a name="Page_65" id="Page_65">[65]</a></span> -cutting the external surface, the material will, in all probability, -be cut through in one part, while in another it will remain of -considerable thickness. If the piece is bored quite through, so as to -become a tube, <a href="#i-p064bs">Fig. 103</a> will be satisfactory, as the cones preserve -centrality, whilst the use of the carrier will prevent the necessity -of screwing the cones up so tightly as to endanger splitting the wood. -This is the best way to chuck small cylinders and brass tubes. The -more obtuse the angle of the cones the better.</p> - -<div class="figcenter" id="i-p064a" style="width:173px;"> - <img - class="p2" - src="images/i-p064a.png" - width="173" - height="350" - alt="" /> - <p class="center smcap">Fig. 102.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p064bs" style="width:638px;"> - <img - class="p2" - src="images/i-p064bs.png" - width="638" - height="550" - alt="" /> - <p class="center smcap">Figs. 103, 104.</p> - </div> - -<p>In this method the bottom of the case must be turned as a plug and -glued into its place. If the bottom of the case is left solid, an -arrangement like <a href="#i-p064bs">Fig. 104</a> will answer well. The plug chuck, A, must -not be at all conical, and the part that enters the work must be at -least an inch long. If this is attended to, and the face of the work -and of the chuck is square, the tube will be truly centred, only -requiring the back poppet to take off the strain upon A, when the -tool is applied. If A is chalked, there will be no slipping, provided -it has been accurately fitted. Observe, nevertheless, that as a -general rule, hollow work should be placed <i>inside</i> and not <i>upon</i> a -chuck, unless you have to work upon the <i>whole</i> exterior surface. By -this plan, there will be no likelihood of splitting the object, an -undesirable consummation which not unfrequently takes place when the -contrary method is pursued.</p> - -<p>Thin discs of wood or brass are most conveniently turned upon a -face-plate, to which they can be attached by turners' cement, already -described. If, however, one surface only has to be worked, and the -plate is not of less thickness than ⅛th of an inch, it may be -mounted on a flat chuck with small projecting points, the back poppet -being used to keep it firmly against the face of the chuck. Even a -plate of brass may be thus turned if placed first of all against the -chuck and gently tapped so as to mark the position of the points, and -then drilled to suit them. Bread-platters are thus easily chucked, -first of all <i>face downwards</i>, and then reversed with the bottom -against the points, so that in the latter position, the chisel or -broad may be applied to the face and the marks removed. The larger -designs on these platters are carved by hand after their removal from -the lathe, and the small figures forming the ground, which often -appear round the main design, are made by figured punches.</p> - -<p><i>Chucking Egg Shells</i>:—The method of doing this so as to enable the -turner to cut the shell evenly in two parts, is given by Holtzapffel, -in his "Mechanical Manipulation," and has been copied elsewhere. It -is ingenious and effective. The object is simply to obtain a pair of -delicate vases, to be edged with ivory, and mounted on a pedestal, as -a curiosity. The following account is from the pen of the inventor, -Mr. G. D. Kittoe, as communicated to Mr. Holtzapffel:—"In the -accompanying figure—<a href="#i-p066s">Fig. 105</a>—is represented the nose of a lathe,<span class="pagenum"><a name="Page_66" id="Page_66">[66]</a></span> -with an egg chucked ready for cutting." <a href="#i-p066s">Fig. 106</a> is the chuck used -first "to prepare the egg, to be mounted in the above way. The latter -is generally termed a spring chuck, and is made by rolling stout paper -with glue upon a metal or hardwood cylinder, the surface of which -has been greased to prevent the paper sticking to it, and upon which -it must remain until perfectly dry, when it may be removed and cut or -turned in the lathe as occasion may require." [N.B. Nothing is said -in the above account of the evident necessity of fixing the paper -cylinder to a wooden block, in which a screw must be cut to mount it -on the nose of the lathe.] "This sort of chuck is very light—easily -made and well adapted for the brittle material it is intended to hold. -Before fixing the egg in it, the inner surface should be rubbed with -some adhesive substance (common diachylon answers exceedingly well); -when this is done the egg should be carefully placed in the chuck, -the lathe being slowly kept in motion by one hand whilst with the -other the operator must adjust its position until he observes that -it runs perfectly true, then, with a sharp pointed tool he must mark -the centre and drill a hole sufficiently large for the wire in the -chuck, <a href="#i-p066s">Fig. 105</a>, to pass freely through. When this is done the egg -must be reversed, and the same operation repeated on the opposite end, -its contents must then be removed by blowing carefully through it. -It is now ready for cutting, for which purpose it must be fixed in -the chuck, <a href="#i-p066s">Fig. 105</a>. A is a chuck of box or hard wood having a recess -turned in it at <i>a, b</i>, into which is fitted a piece of cork as a soft -substance for the egg to rest against. B is a small cup of wood with -a piece of cork fitted into it serving the<span class="pagenum"><a name="Page_67" id="Page_67">[67]</a></span> same purpose as that in -A. A piece of brass, <i>d</i>, is to be firmly screwed into the chuck A, -and into this a steel wire screwed on the outer end, on which a small -brass nut <i>e</i> is fitted to work freely in a recess in the piece B. -When the egg is threaded on the wire through the holes previously made -in it, this nut is to be gradually tightened up until it presses the -cup B against the egg sufficiently to hold it steady and firm enough -to resist the action of a finely-pointed graver used to cut it. The -tool requires to be held very lightly, as a little undue violence -would crush the shell. Neither should the latter be pinched unduly -tight in the chuck, as otherwise when the point of the tool divides -the shell the two parts might spring together, and be destroyed by -the pressure. It requires some delicacy of hand to attach the rings -to the edges of the shell to constitute the fitting. The foot and top -ornaments are fixed by very fine ivory screws, the heads of which are -inserted within the shell."</p> - -<div class="figcenter" id="i-p066s" style="width:550px;"> - <img - class="p2" - src="images/i-p066s.png" - width="550" - height="460" - alt="" /> - <p class="center smcap">Figs. 105, 106.</p> - </div> - -<p>Box wood is decidedly the best material for ordinary chucks, as it -takes a screw almost as well as brass, is pleasant to work, holds -the material firmly, and is of good appearance, which last is not -unimportant to those who possess good lathes, and like to see -everything in decent order about the workshop, and it is certain -that a disorderly workman will commonly produce slovenly work. This -wood, however, though tolerably plentiful, is sufficiently costly to -be worth preserving, and by a little management chucks may be made -to answer for a longer period than might be at first supposed. A -chuck, for instance, too large to hold the work, may be plugged with -a worn-out chuck of smaller bore, or with wood of inferior character, -to save the necessity for hollowing out a new piece of box wood. The -latter material, moreover, excellent as it is, may be replaced by -other kinds of wood, provided the latter will bear a good screw.</p> - -<p><i>Beech</i>, if dry, will answer very well for the purpose.</p> - -<p><i>Pear</i> is tough and screws well.</p> - -<p><i>Apple</i> is little inferior.</p> - -<p><i>Ilex</i> or <i>evergreen oak</i> is sufficiently hard and tough and will be -found quite satisfactory. Elder of large size is good, and screws well.</p> - -<p><i>Sycamore</i> screws well, but is not always equally tough.</p> - -<p>All hollow or cup chucks should be furnished with rings of iron or -brass to prevent splitting. About six sizes of rings will suffice -for a great number of chucks. Bergeron, speaking of the barrel stave -chucks already alluded to, prefers the encircling rings plain and not -screwed. He gives the following reason:—"If a piece of work entered -in such a chuck does not run quite truly, a tap on the ring in the -proper place will, by closing the sawgates more in that part, rectify -the error, whereas with a screwed ring this is impossible." There is -reason in this, but at the same time it would be easy to unscrew the -ring a turn or so, give a light tap to the work, test its position -by<span class="pagenum"><a name="Page_68" id="Page_68">[68]</a></span> putting the lathe in motion, and when true fix it securely by -screwing up the ring. There is, however, one precaution to be taken -in making these useful chucks—namely, to cut the staves of equal -width, else they will not yield equally to pressure, and the work -will not be so readily centred truly. A grip chuck of inexpensive -make (one additional pattern of which is introduced from a design by -contributors to the <i>English Mechanic</i>) should always be provided. A -rough block of ivory for instance may be seized in its jaws, and the -exterior useless part cut off by a parting tool as a ring, leaving the -nicely rounded material ready for chucking. Ivory nuts or <i>corosos</i> -which are peculiarly awkwardly shaped for mounting in the lathe, may -also be thus seized, and one portion faced up and rounded so as to -allow of being fixed on a face chuck by glue or cement, or fitted into -a cup chuck. Rough pieces, too, thus mounted may be faced up, bored -and tapped to fit the mandrel as chucks, and a thousand similar works -may thus be handled. The simple grip chuck in question is important -as having the very useful addition of a centre point which the writer -would, if he did not abominate and eschew puns, direct attention to, -as the chief "point" of interest—"I call it," says the inventor, -a "Universal Self-Centering Grip Chuck." The drawings 1, 2, and 3, -almost speak for themselves, to practical turners.</p> - -<div class="figcenter" id="i-p068s" style="width:428px;"> - <img - class="p2" - src="images/i-p068s.png" - width="428" - height="550" - alt="" /> - <p class="center smcap">Figs. 1, 2, 3.</p> - </div> - -<p><a href="#i-p068s">1</a>, is an elevation of one of the grips. <a href="#i-p068s">2</a>, a section through centre -of chuck. <a href="#i-p068s">3</a>, a side section of ditto. The body of the chuck is made -of cast iron, to screw on to the mandrel; and the grips, 1, are moved -simultaneously by a right and left-handed screw acting in a circular -groove. The jaws of the grip are serrated and tempered, the same -as in ordinary vices. In the centre of the grips, when closed, a -three-sixteenth hole is bored true to the centre of the lathe. Behind -this there is a true centre point screwed into the body of the chuck, -as marked at <i>a</i>. The above hole and this centre point are to be -particularly attended to, as on their truism depends the correctness -of your work.</p> - -<p>If I want to turn a solid cylinder I make the usual centre at each<span class="pagenum"><a name="Page_69" id="Page_69">[69]</a></span> -end; put one on the above centre point and the other on the back -centre of lathe, and then screw up the grips tight; but if the work is -short you need not apply the above centre point or the back centre, -as the grips are alone sufficient. The hole in the jaws of the grips -admit of any kind of drill or other tool being put into them without -using any centres, and the grips will admit anything up to two inches. -In fact, I do almost every sort of thing with this chuck, and I think -amateurs, if not others, will find it a most valuable and handy -contrivance.</p> - -<p><a href="#i-p069s">Fig. 108</a>, A and B, represents a modified form—a chuck already spoken -of and recommended for ordinary plain turning, in which the work -is supported at both ends. The present form is to a great extent -self-centering and will hold the work also without the saw-cuts -otherwise needed, the sharp edges of the double fork entering the work -with the pressure caused by the back centre. The chuck is useful not -only for ordinary work, but for re-mounting pieces centrally, which -it may have been necessary to remove when partly finished, and to -return to the lathe for completion. A still further addition to this -chuck of a steel point sliding through the centre, as in the section, -<a href="#i-p069s">Fig. 109</a>, makes it a very complete and serviceable apparatus, as by -this means it is easy to reverse the work without destroying its -centrality. The point is intended, as in the chuck of Wilcox, to slide -back stiffly (being if necessary kept up by a spiral spring as shown), -as it is only intended as a guide to assist in mounting the piece. If -the mandrel is not bored the chuck must be long enough to receive the -pointed wire within its substance. This will be found in every way a -most serviceable chuck. It may be of iron or brass, or even of wood, -if a round plate of brass is mounted on its face, to which the holding -pieces can be soldered or brazed.</p> - -<div class="figcenter" id="i-p069s" style="width:277px;"> - <img - class="p2" - src="images/i-p069s.png" - width="277" - height="450" - alt="" /> - <p class="center smcap">Figs. 108, 109.</p> - </div> - -<h3 class="sc"><a name="HOLLOWING" id="HOLLOWING">Hollowing Out Soft Wood.</a></h3> - -<p>This is done, as already described, by the regular soft wood<span class="pagenum"><a name="Page_70" id="Page_70">[70]</a></span> turners -in Tunbridge and elsewhere, by means of hook tools. A great number -of workmen, however, use only the gouge, and for boring out chucks, -hollowing boxes, small bowls, and similar work, the latter tool will -be found effectual if rightly held and carefully managed. It must not, -however, be applied to the inner surface of the work at the point -usual with scraping tools, but beyond the centre, <a href="#i-p070">Fig. 109<sup>A</sup></a>. The -rest, B, does not require to be turned across the face of the work, -but remains parallel to the bed of the lathe. The blade of the gouge -is to press against the near side of the hollow as the work proceeds, -which considerably aids in securing the position of the tool. The back -of the gouge is to face the bottom of the hollow (next the mandrel), -but the tool is generally rolled on the rest a little, so that its -hollow side is often more or less below, towards the lathe bed, and -the point is also lightly raised as it approaches the finish of the -cut. Begin with the tool almost horizontal, and at the centre of the -piece, the back against the wood, and, depressing the handle as the -shaving is removed, finish at the top <i>outer</i> edge of the hollow, -rolling over the tool, so that it shall leave the work with its back -upwards and hollow downwards. Thus used it will not stick in its -course, and, after a few trials, will be found to cut out the wood -cleanly and rapidly.</p> - -<div class="figcenter" id="i-p070" style="width:532px;"> - <img - class="p2" - src="images/i-p070.png" - width="532" - height="376" - alt="" /> - <p class="center smcap">Fig. 109A.</p> - </div> - -<p>Another grip chuck, or self-centering scroll chuck may here be -introduced, from the source of information previously alluded to. The -writer thus describes it—</p> - - -<h3 class="sc"><a name="AMERICAN_SCROLL" id="AMERICAN_SCROLL">American Scroll Chuck.</a></h3> - -<p>This chuck is made upon the same principle as the Warwick Drill -Chuck—namely, a flat spiral so acting on three jaws sliding in radial -grooves as to make them recede from the centre to admit any object -between certain sizes, and then to be tightened upon it. <a href="#i-p071s">Fig. 1</a> is -a plan of a 4-inch chuck. <a href="#i-p071s">Fig. 2</a> is a vertical section of the same. -<a href="#i-p071s">Fig. 3</a> is a view of the outside of the chuck, and <a href="#i-p071s">Fig. 4</a> is a separate -section of the principal part <i>a, a</i>, taken through the line <i>z, z</i> -(<a href="#i-p071s">Fig. 1</a>).</p> - -<p>In <a href="#i-p071s">Fig. 2</a>, <i>a, a</i> is this piece, <i>b, b</i>, has the spiral cut on it -which actuates the jaws 1, 2, 3 (<a href="#i-p071s">Fig. 1</a>), <i>c, c</i> screws on the piece -<i>a, a</i> to keep <i>b, b</i> in its place and <i>d, d</i> is the plate which -screws on the mandrel, and<span class="pagenum"><a name="Page_71" id="Page_71">[71]</a></span> which is fixed to <i>c, c</i>, by three -countersunk screws, one of which is shown in section.</p> - -<div class="figcenter" id="i-p071s" style="width:566px;"> - <img - class="p2" - src="images/i-p071s.png" - width="566" - height="550" - alt="" /> - <p class="center smcap">Figs. 1, 2, 3, 4.</p> - </div> - -<p>If the foregoing observations are carefully studied the further -practice of plain hand-turning in wood will not be difficult, and -we shall proceed to speak of metal turning, before passing to a -description of the Slide Rest and other apparatus usually added to -the lathe. We may, however, observe here, that, for ivory and hard -wood—especially the former, the first roughing down cannot be done -with the gouge. A point or small round-ended tool must in these cases -take its place, to be succeeded by one or more of those tools which<span class="pagenum"><a name="Page_72" id="Page_72">[72]</a></span> -rather scrape than cut, as described in detailing the process of -hollowing out boxes and similar work.</p> - - -<h3 class="sc"><a name="METAL_TURNING" id="METAL_TURNING">Metal Turning by Hand Tools.</a></h3> - -<p>The first requisite for the above work is a well made and sharp tool, -for, strange as it may appear, a keen edge is as necessary for making -good work in metal as in turning wood. The principle of this cutting -edge must be well understood, and this has been well explained by -Nasmyth and others.</p> - -<p>The remarks of the above eminent mechanic upon this subject, as also -those of Professor Willis and Mr. Babbage have been embodied in a -very excellent paper by Dodsworth Haydon, Esq., an amateur, and will -be found in the Appendix to this work. The whole principle of the -formation and application of cutting tools is explained in that paper, -so that it only remains to treat briefly of a few special <i>forms</i> of -tools which are required for metal-turning in the lathe, whether by -hand or by the aid of the slide-rest. In the first place, however, -a word or two may be necessary as to the kind or quality of steel -required for such tools. What is called Blister steel may be at once -passed over as unfit for the formation of tools—it is, however, the -raw material (so to speak) from which, by the process of reheating -and welding, the next quality, called Shear steel, is made. When bars -of this are similarly heated and again welded into a homogeneous mass -under the tilt-hammer or between rollers, double shear-steel is made, -which is of extensive use for cutting tools, and must, moreover, of -necessity be used in almost every case where there is to be an iron -shank, for economy's sake, the steel being then welded to the iron, -and forming that part of the tool intended for the edge. The third -and best kind of all is Cast-steel, formed of blister steel, melted -at an intense heat and run into iron moulds. This, however, can be -welded only with great difficulty, and hence the whole tool, whatever -its length, must be of the same material. This can be purchased in -bars of a convenient size of round, triangular, square, or other -section, and needs only the careful use of the hammer, file, and -grindstone to become a tool of any required pattern. It would be very -advantageous to an amateur to master the art of forging in a small -way to enable him to make his own tools, for he may sometimes require -them of unusual form, and if he lives far from a manufacturing town -he will find it very difficult to get them fashioned to his liking. -Cast-steel will not allow of the welding heat applied to iron—it will -burn, and cannot then be made to recover its proper consistency, and -is for ever useless for the purpose in question. Double shear will -take a moderate white heat, while cast-steel must not be<span class="pagenum"><a name="Page_73" id="Page_73">[73]</a></span> brought to -a higher temperature than that indicated by bright red—a point never -to be forgotten when shaping a tool at the forge. There are in every -workshop a number of files laid aside as worn out. These being made of -the best cast-steel, are invaluable to the turner in metal, as they -supply the best material for his tools at no cost whatever. To begin -with the saw files (called, by a horrible perversion of mathematical -definition, "three square"). Here you possess a tool at once for the -mere trouble of grinding off the teeth and reducing the sides to a -smooth surface. Each angle is equally useful—each 60°, which, as the -paper above alluded to demonstrates, is the best angle for cutting -iron. On brass, however, its use is by no means to be recommended, -being, as Holtzapffel remarks, "too penetrative and disposed to dig -into the work." It is to be used upon iron in the position shown in -<a href="#i-p076as">Fig. 110</a>, where A is the rest, B the cross section of the tool, C the -diametrical line. The side, of which D is a continuation, is to form -very nearly a tangent to the circumference of the work, being, as -explained in the Appendix, only 3° from that position. Worn out square -files being of rectangular section, are exactly suited for brass -turning, for which metal a cutting edge is required of 80° to 90°, the -former for the first or roughing down cut, the latter for finishing. -The position of such tool is shown in <a href="#i-p076as">Fig. 111</a>.</p> - -<div class="figcenter" id="i-p076as" style="width:700px;"> - <img - class="p2" - src="images/i-p076as.png" - width="700" - height="287" - alt="" /> - <p class="center smcap">Figs. 110, 111.</p> - </div> - -<p>The flat files are not altogether so useful for making turning tools -as those alluded to; they are too thin in proportion to their breadth. -Their sides, moreover, generally speaking, are not rectilineal, but -curved, so that they are more fit for grinding off at the ends to -form brass-turning tools with rectangular edges. They may, however, -by careful forging, be made to assume a square section, and thence -be formed as desired; but a rectangular bar of steel, ready-made, is -then to be preferred. A round or rat's tail file is of far greater -service than the last-named—not, indeed, in its own shape, for the -reasons stated by Mr. Haydon, but as being capable, with very little -labour at the forge, of being converted into a bar of square section. -The first tool to be made from such a bar is the graver, <i>the</i> tool -of the watchmaker, and not less useful to the general mechanician. -This is formed by grinding the end of a square bar diagonally, so as -to produce a lozenge-shaped face. The angle to be preferred in this -operation is 45°, which will give two cutting edges of 60°. The latter -may be varied at pleasure by varying the angle at which this face is -ground, as explained in the chapter which treats upon this question. -The graver will do all kinds of outside work, light or heavy, as it -may be made of any size. It is represented in <a href="#i-p076bs">Fig. 112</a>. <a href="#i-p076bs">Fig. 113</a> is -the heel-tool shown in position for work; <a href="#i-p076bs">114 and 115</a>, two forms of -nail-head tool very commonly used, but both requiring great attention -to the angles of the cutting edge to become effective. All the above -are for outside work, and are to be so held that the side<span class="pagenum"><a name="Page_74" id="Page_74">[74]</a></span> next to -the work—the <i>sole</i> of the tool in <a href="#i-p076bs">Fig. 113</a>—forms very nearly a -tangent to the work—a position, as Holtzapffel remarks, strangely -similar to that required by the soft wood chisel and similar tools. -The heel-tool, indeed, if more keenly sharpened, will cut soft wood -(on the face) with great rapidity, and is in principle similar to the -broads used for that purpose. It is, however, an unsafe tool, owing -to its great tendency to dig into the work. It is a good plan to make -extensive use of various shapes of hand-tool before passing to the -slide-rest, because the hand feels exactly the <i>resistance</i> which the -tool meets with, and the best form and position is thus <i>practically -tested</i>, and will be found to bear out to the utmost the theory -advanced in this work, and founded on mathematical truths worked out -and applied by Willis, Babbage, and others.</p> - -<div class="figcenter" id="i-p076bs" style="width:373px;"> - <img - class="p2" - src="images/i-p076bs.png" - width="373" - height="550" - alt="" /> - <p class="center smcap">Figs. 112, 113, 114, 115.</p> - </div> - -<p>Inside tools must of course be made upon the same principles as the -last, the particular form alone being modified to enable the cutting -edges to penetrate into the various nooks and corners that may occur -in such work. The inside tool for iron (<a href="#i-p076c">Fig. 116</a>), with cutting angles -of 60°, is of a general and useful pattern. It must be so curved and -so placed that <i>both</i> cutting edges come into action, one on the -face and one on the side of the cut, a condition explained in the -Appendix as <i>essential</i> to all good work. It being quite impossible -to cut metal like wood, and necessary to allow sufficient time for -such work, a pointed tool is in most cases preferable to one of a -semicircular or rectangular form of edge, and the greater part of -the heavy work done in large factories is thus executed. Inasmuch, -however, as such a tool, well formed on correct principles, may be -made to take a tolerably deep cut, the shaving detached will be of -sufficient <i>thickness</i>, and consequently sufficient width to reduce -work a satisfactory quantity at each cut. The cut, too, must be -continuous wherever possible, the tool being slowly and steadily -advanced the whole of the acquired distance without being removed, -and then re-entered for a second cut. The result should be a smooth, -even surface, and that great exertion is not required when thus -working with hand-tools is sufficiently evidenced by a remark of Mr. -Haydon to the writer, "I have often detached, with a graver alone, a -tolerably thick shaving of iron, two feet and more in length." From -what has been said, it will be understood that in hollowing out a -piece of metal such as a chuck, the tool should not be made with a -<i>long</i> cutting edge, such as would be used if it were intended to -scrape the whole depth of the side. A <i>broad</i> shaving is not to be -thus aimed at, nor is the <i>inside only</i> to be thus attacked, but -the tool advanced gradually inwards from the face of the work till -it reaches the bottom, thus (to repeat the important point again) -cutting at the same time the front and side of the shaving. The -half-round or cylinder-boring bit already described is, of course, an -inside turning<span class="pagenum"><a name="Page_75" id="Page_75">[75]</a></span> tool, but is used with the aid of the back centre. In -principle it follows other inside tools, the end being bevelled or -sloped off 3°, and the side being 90°. The latter is to be regarded -as a blunt cutting tool, being the largest angle that can be used; -but, nevertheless, this bit must be regarded as cutting in the two -required directions—forward and sideways. If a regular Goniometer for -measuring angles is not to be obtained, nor any apparatus for grinding -a tool to the required bevel, an addition to Nasmyth's tool-gauge, -described in the Appendix, may be made by constructing in tin a set -of templates, with the angles marked upon them. The easiest way is to -mount on the lathe a few round sheets of tin, and mark the degrees -by the division-plate, the outer circle of which contains 360°. -The tin may then have pieces cut out, as shown in <a href="#i-p076c">Fig. 117</a>, to be -applied as gauges over the ends of the tool, or <i>solid</i> pieces of the -required sections (those which are removed in forming the above) may -be retained. It will, perhaps, be as well to finish up both neatly, -taking care to mark the angles on each. The degrees most required are, -as explained, 90°, 60°, 80°, and 3°; but intermediate numbers may be -prepared, and will often be found convenient. An inside tool for brass -must retain the angles 80° to 90°, the latter acting as a scraping -tool to put a finish to the interior of work roughed out by a tool -of the lesser angle. There are not many forms in general vogue, for -brass work, whether internal or external. The round, the flat, and the -point tools (<a href="#i-p076d">Figs. 118 to 121</a>) are more or less capable of hollowing -out work, as well as surfacing. With the first ground to an angle -of 80°, brass chucks can be hollowed, and, with the second at 90°, -finished; and if there chance to be any internal angles out of reach -by the point-tool, it is only necessary to use a similar one bent -round at the end towards the left. Much of the turner's success in -brass work depends upon the quality of the metal, which is often very -hard and unequal in texture and perhaps blown and honey-combed. It is -always the best plan to send patterns of any work of importance to -some well-known firm, instead of trusting to a country foundry, whose -business, if worthy the name, is generally iron work, and who only run -brass once in a way, and make a terrible mess of it, too. The same may -be said respecting iron castings. It is worth while, as an experiment, -to test with turning tools the quality of a country casting, pulley, -or what not, by the side of a similar work really made of malleable -iron, such as is now so extensively used by the sewing-machine makers. -Tools that will stand the first and make good work deserve a place in -the British Museum, with a portrait of the turner!</p> - -<div class="figcenter" id="i-p076c" style="width:450px;"> - <img - class="p2" - src="images/i-p076c.png" - width="500" - height="301" - alt="" /> - <p class="center smcap">Figs. 116, 117.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p076d" style="width:500px;"> - <img - class="p2" - src="images/i-p076d.png" - width="500" - height="206" - alt="" /> - <p class="center smcap">Figs. 118, 119, 120, 121.</p> - </div> - -<p>For light brass work, such as small model engines now so generally<span class="pagenum"><a name="Page_76" id="Page_76">[76]</a></span> -sold, a description of lathe may be used of which no mention has yet -been made—namely, a bar lathe <a href="#i-p077">Fig. 122</a>. Such a tool may be made for -£3 or £4, and will be found sufficient for such work<span class="pagenum"><a name="Page_77" id="Page_77">[77]</a></span> as specified.</p> - -<div class="figcenter" id="i-p077" style="width:602px;"> - <img - class="p2" - src="images/i-p077.png" - width="602" - height="399" - alt="" /> - <p class="center smcap">Fig. 122.</p> - </div> - -<p>In place of the double bed a triangular bar of cast iron is used, on -which the poppets slide, and are clamped. D shows one of two sockets -with feet which hold the ends of the bar, and by which the lathe can -be mounted on any stout plank or on the window sill. The pulley A is -made for a strap, because this allows of a plain flywheel, which is -much cheaper than those which are bevelled and turned. The rest is -shown at E and F. The part E slides upon the bar like the poppet—at -the top is a dovetailed groove to receive the slide F, which carries -the socket for the tee, and is fixed by a turn of the screw seen on -the top of it. There is much to be said in favour of triangle bar -lathes, they are very stiff, and can be fixed anywhere. The flywheel -can be supported on a separate frame, which is an excellent plan, for -the jerk of the treadle and crank is not communicated to the poppets -and mandrel. In Maudslay's triangle bar lathe, which was made for -amateurs, a slide rest was attached, and the whole work was first -class—of late they have gone out of fashion, but are nevertheless -good tools.</p> - -<p><a href="#i-p078s">Fig. 123</a> represents another very simple form of lathe for turning -small articles of brass. It may be said to be one remove from the -watchmaker's bow lathe, as it has no true mandrel or treadle; the -small flywheel being attached to an arm at the back and worked by -hand. The left hand is used for the latter purpose while the tool -is held in the right. Through a tapped hole in the left hand poppet -passes a steel pin shown at E, on a larger scale; this screws into -the poppet after passing through a brass pulley B; this bolt ends -in a point, and an arm fixed into the pulley becomes a dog to act -against a carrier screwed on to the work as in turning iron. Thus -the mandrel and point are fixtures, and the pulley only turns when -motion is communicated to it by a catgut from the flywheel behind -it. The back poppet and rest, which last is shown separately, slide -on the<span class="pagenum"><a name="Page_78" id="Page_78">[78]</a></span> rectangular bar; the latter is about two inches wide, and -three eighths thick, and is made with feet to screw to any convenient -support. This lathe is especially adapted for work of small size which -can be centred at both ends, and on which a carrier can be fixed -to bear against the pin, E, of the pulley; nevertheless it is even -possible to use chucks, if cast in metal with a pulley to each like G. -A spindle must in this case be made like H, on which the chuck must -be slipped, and fixed by the nut in the hollow of the chuck. Although -however this form of lathe is sometimes met with, and may be used as a -makeshift, a small triangle bar or 3in. lathe of the usual form is far -preferable.</p> - -<div class="figcenter" id="i-p078s" style="width:700px;"> - <img - class="p2" - src="images/i-p078s.png" - width="700" - height="422" - alt="" /> - <p class="center smcap">Fig. 123.</p> - </div> - -<p>In centering a bar of iron in the lathe too much care cannot be -exercised in causing it to run evenly. The ends should be drilled, -first with a small, and afterwards with a larger drill, so that a -countersunk hole may be obtained in order <i>to keep the point of the -lathe-centre from touching the bottom of the hole</i>. If this is not -done the friction of the work upon its bearing will soon spoil the -lathe-centre, and the work itself will speedily get out of truth, and -it will not be possible to screw up the spindle of the back poppet -so as to correct this. Of course in turning up very small work this -drilling cannot be done. A simple hole must then be made, sufficient -for the safe support of the work while being turned, but even in this -case the angle of the drill point should be less than that of the -conical centre of the lathe, the point of which will then run free. -To mark the true centres of a round bar of metal a punch has been -devised like <a href="#i-p079a">Fig. 124</a>. This is figured in Bergeron's work, and is -very<span class="pagenum"><a name="Page_79" id="Page_79">[79]</a></span> serviceable. To insure its working truly be careful that the bar -of metal is filed flat on the ends, and that the surface of the latter -is at right angles to the length of the bar. It is then only necessary -to place the end of the piece in the conical part of the cup (which -will be best effected by fixing the bar in a vice) and by raising the -spring and letting it go sudden by a sufficient mark will be made to -guide the point of the drill.</p> - -<div class="figcenter" id="i-p079a" style="width:299px;"> - <img - class="p2" - src="images/i-p079a.png" - width="299" - height="400" - alt="" /> - <p class="center smcap">Fig. 124.</p> - </div> - -<p>The proper place at which to commence turning an iron bar is at one -end, the rest being placed so as to bring the tool just upon the line -of centres; if applied lower the tool would take too deep a hold, and -would either be broken or lift the bar out of the lathe, damaging the -centre points. The ends of the bar should be squared up before the -circumference is turned, and on no account must a file be used after -the turning tool has done its work. It is only at the commencement -before a cutting tool has been applied, that an old file may be made -use of to take off the scale and roughness left from the forging or -casting.</p> - -<p>Brass may be attacked upon or just below the line of centres, because -the form of tool is such as cannot penetrate deeply. This metal is -perhaps easier in some respects to turn, but the tool is apt to form -undulations on its surface (is apt to chatter). This is due, partly -to the impos<span class="pagenum"><a name="Page_80" id="Page_80">[80]</a></span>sibility of obtaining continuous shavings, and partly to -the vibration of the tool, and when once this has taken place there -is a tendency to deepen these channels, which makes it difficult to -produce a plane and even surface. If a rectangular tool is used in -the position already shown and described under the head of tools for -metal turning, this chattering will be avoided. If it takes place, the -undulations should be worked off by gentle usage of the angle of the -tool, the rest being placed close to the work, and only a light cut -taken.</p> - -<p>With regard to the method of mounting a piece of brass in the lathe, -any convenient chuck may be used, but sometimes the piece is short -or irregular and requires to be bored out. In this case use solder -and firmly attach the piece to a face plate of brass. The easiest way -is to smear the two faces to be joined with sal-ammoniac made into a -paste with water, and laying a piece of tin-foil between the surfaces, -which must be quite clean and bright, apply heat. The tin will melt -and a perfect union will be effected. When the piece is finished it -is re-heated and detached. This may be considered a wrinkle worth -knowing. The flat flanges of brass spoken of under the head of chucks -are just suited for this method of working, and they are not damaged -by the process, as the solder can be wiped off quite clean when -the chuck is made hot. This is a good way to mount small cylinders -of brass for model engines, as they can be bored and turned on the -outside at one operation with great ease and certainty. If a piece is -to be drilled or bored in the lathe, the following is the arrangement -to be adopted. <a href="#i-p079bs">Fig. 125</a>, A is the face plate, B, the piece to be -drilled, C the drill, which is advanced by screwing up the point, E, -of the back centre; D is a hand vice or similar article to prevent the -drill from revolving with the work. If it is more convenient to fix -the drill itself in a chuck, the point of the back centre is to be -removed, and a flange of brass or iron substituted, as A, <a href="#i-p079bs">Fig. 126</a>. If -the drill is to penetrate quite through the work a piece of wood must -be interposed between the latter and<span class="pagenum"><a name="Page_81" id="Page_81">[81]</a></span> the flange to receive the point -of the drill and protect it from injury. The pressure should be so -regulated as to be constant and equal without being excessive, or the -drill will be bent or broken. Boring is simply drilling on a larger -scale, and is of such general use as to require detailed notice. -In the first place there are several tools used for the purpose, -according to the size of the work. The first is the cylinder bit, -<a href="#i-p080">Fig. 127</a>. This is a most excellent tool, as it will work very truly, -and can hardly get out of place if properly directed at starting. The -cutting part A is half a cylinder, the centre being just left visible, -the end is not quite at right angles with the length of the tool, -but is sloped off a little and bevelled also slightly below.<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">[7]</a> This -forms the cutting edge. The other end of the tool has a central hole, -drilled to receive the point of the back centre by which it is kept to -its work. To use this tool, let the piece to be drilled be placed in a -chuck, and a recess turned in it of the same diameter as the cylinder -bit, the latter is then placed in this recess B, and when screwed up -it cannot possibly rise or shift its position; a hand-vice or spanner -is then fixed as shown in <a href="#i-p079bs">Fig. 125</a>, and the lathe put in slow motion, -oil or soap and water being freely used to lubricate the tool. Either -a solid piece of metal, or a hollow casting can be thus bored.</p> - -<div class="footnote"> - -<p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">[7]</span></a> To an angle of 3°. See Appendix.</p></div> - -<div class="figcenter" id="i-p079bs" style="width:700px;"> - <img - class="p2" - src="images/i-p079bs.png" - width="700" - height="490" - alt="" /> - <p class="center smcap">Figs. 125, 126.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p080" style="width:550px;"> - <img - class="p2" - src="images/i-p080.png" - width="550" - height="312" - alt="" /> - <p class="center smcap">Fig. 127.</p> - </div> - -<p>These cylinder bits can be had of all sizes, from one-eighth of an -inch upwards.</p> - -<p>Pipe stems are bored with the smallest of these tools. For this -purpose they are made of round steel wire, which is sometimes merely -flattened with a hammer at one end to spread and enlarge it, this -part being afterwards rounded on the underside with a file, and with -the same tool finished on the upper flat face. These slender drills -require to be delicately used, and are conveniently held in a pin vice -or pair of pin pliers, the handle of which being hollow, allows the -greater part of the drill shank to lie within it, a small part only -being drawn out at a time for use; thus the drill will be kept from -bending, and will work quickly and well.</p> - -<p>Of recent inventions in the matter of drills, the most important is -the Morse American twist drills sold, in sets, at 30s. on a neat stand -with a self-centering chuck, complete. The form is that of a cylinder -with spiral grooves cut round it of extended pitch. The cutting edge -is as difficult to draw as it is to describe, and must be seen to be -understood. It is chiefly formed by the meeting of the spiral grooves -and the solid end, the latter forming a blunt angular point rendered -cutting by the edge of the grooves. They should have a place in every -workshop.</p> - -<p><span class="pagenum"><a name="Page_82" id="Page_82">[82]</a></span></p> - -<p>The next tool to be described is also much used, especially in -agricultural implement manufactories, for boring out the brasses, -or bearings. It is called a rose bit, or grinder, and is shown in -<a href="#i-p082a">Fig. 128</a> A and B. In this case also a recess is cut in the work as a -guide, and as the tool fills up the whole interior as it proceeds, no -change of position can occur. The rose bit is used as shown in <a href="#i-p079bs">125</a>. A -bit of this pattern is very useful for brass work of all kinds, such -as the cylinders of small engines, bosses of wheels, bearings and -collars, and one of these tools of the exact size for hollowing out -the sockets of brass chucks, previously to their being tapped, will be -found serviceable. The third kind of boring tool is made with movable -cutters, which can be removed at pleasure, to be sharpened or replaced -by more convenient ones. The simplest consists of a cutter bar, A, -<a href="#i-p082b">Fig. 129</a>, with a slot in it to hold the tool, which is fixed by -driving a wedge at the back of it. The tool here shown has two cutting -edges, <i>b</i> and <i>c</i> which should be shaped according to the principles -already enunciated respecting hand tools for iron and brass. The -cutter bar is usually fixed between the lathe centres, and turned by -a driver chuck and carrier, while the cylinder to be bored is clamped -to the slide rest, and thereby advanced against the cutting edge. This -form is chiefly used upon work that has been cast hollow, or drilled.</p> - -<div class="figcenter" id="i-p082a" style="width:658px;"> - <img - class="p2" - src="images/i-p082a.png" - width="658" - height="156" - alt="" /> - <p class="center smcap">Fig. 128.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p082b" style="width:500px;"> - <img - class="p2" - src="images/i-p082b.png" - width="500" - height="309" - alt="" /> - <p class="center smcap">Figs. 129, 130.</p> - </div> - -<p><a href="#i-p082b">Fig. 130</a> is another form of boring tool for large and heavy work. A -boss, A, is fixed to the cutter bar, having a series of dovetailed -grooves, or slots, on its surface, in which cutters are fixed by -wedges. In this and every similar form, it is expedient always to -complete the circle, or, at any rate, two-thirds or three-quarters -of it, by driving in blocks of wood in the slots not occupied by the -cutters. This preserves the concentricity of the tool. One edge of -these movable cutters should be radial to the centre of the bar, or -boss, the other rather less than a right angle, which will ensure a -good cutting edge. The best lubricant is oil for the first cut, and -soap and water, or pure water, for the finishing cut. The surface will -thus be left bright. It<span class="pagenum"><a name="Page_83" id="Page_83">[83]</a></span> is not well to finish with emery any collar -in which an axle is to work (as the collar in which the mandrel of -the lathe runs). This substance imbeds itself in the pores of the -metal, and by forming a grinding surface, considerably increases -the friction and wear and tear of the parts.<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">[8]</a> Although boring and -drilling are capable of being done in the lathe, a far superior plan -is to employ an upright boring apparatus, as is now generally used in -making steam cylinders. The work is not then suspended between two -points, or carried on the slide rest, but takes up a firm bearing on -a fixed support, and the boring tool descends by a pressure screw, or -self-adjusting contrivance, as the work proceeds.</p> - -<div class="footnote"> - -<p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">[8]</span></a> Oilstone powder may be substituted, especially for the -best brass work.</p></div> - -<p>We have spoken of the slow motion as necessary for turning metal work. -This is represented in <a href="#i-p083s">Fig. 131</a> A B C D. The first is a plan seen from -above. The poppet is cast double like F, so as to afford a bearing -for the mandrel, and a second for the back spindle seen at A. This -back spindle, it will be observed, passes through its two collars or -bearings, and can slide freely in them from side to side. This can, -however, be prevented by dropping a pin through a hole in the top of -the poppet, which falls into a semicircular groove in the spindle. The -pulley is securely attached to a small cog wheel, and can be firmly -united to a larger one, as seen at A<sup>2</sup>, and separately at C and D. -This pulley and small cog wheel run loosely on the mandrel, and do -not revolve with it until clamped to the wheel, C, which is itself -keyed to the mandrel. Suppose them to be thus free to revolve, and the -wheels in position shown in the plan, A. On putting the fly wheel in -motion, the pulley will revolve on the mandrel, carrying with it<span class="pagenum"><a name="Page_84" id="Page_84">[84]</a></span> the -small cog wheel, which in turn will act on the large wheel on the back -spindle. The small cog wheel on the latter will thus put in motion the -large one geared with it, the which being keyed to the mandrel, will -put the latter in motion. There are many ways of clamping the pulley -to the large cog wheel, perhaps the following is as good as any. It -must be so clamped for wood turning when the back spindle is to be -slipped on one side out of gear.</p> - -<div class="figcenter" id="i-p083s" style="width:550px;"> - <img - class="p2" - src="images/i-p083s.png" - width="550" - height="382" - alt="" /> - <p class="center smcap">Fig. 131.</p> - </div> - -<p>In the face of the pulley, which is concave, is a piece of brass flush -with the rim, and which forms a dovetailed groove, into which the head -of a clamping screw, E, fits. This screw projects through a slot in -the wheel D. When it is required to fix the pulley, this screw is slid -up towards the rim till the head rests in the dovetailed projection, -and it is clamped in that position by a nut. When it is desired to -put the back action into gear, this nut is loosened, the screw-bolt -dropped towards the axle (thus freeing the head from the dovetail), -and again fixed by the nut. The wheel and pulley are thus independent -of each other, the back spindle is slipped sideways into gear, and -held by the pin, and the slow motion will be obtained.</p> - -<p>There is one fault in the arrangement of the back geared lathe that -with amateurs in a private house is especially disagreeable, and it is -questionable whether in large machinery establishments it might not -with great advantage be corrected. In the action of toothed wheels, -nuts and screws, and similar gearing, there occurs what is called -<i>back lash</i>. If, for instance, the tool holder of a slide rest is -advanced, and then the action is to be reversed, the movement of the -nut and tool holder does not commence simultaneously with the movement -of the screw. This is due to the play, or necessary looseness of the -working parts, the pressure coming on one side of the thread when the -screw is turned in one direction, and on the contrary side when the -motion is reversed. In toothed wheels a similar defect exists, and -gives rise to that disagreeable and ceaseless noise which assails the -ear on entering a building where machinery is in motion. This may -be avoided by the use of frictional gearing, a simple but excellent -mechanical contrivance which deserves far more extensive notice than -it has yet received. It is the invention of a Mr. Robertson, and -is patented. A lathe fitted with it would be almost noiseless, and -would work with a delicious smoothness, very conducive to the comfort -of the workman. This gearing, represented in <a href="#i-p085">Fig. 132</a>, is merely -the substitution of <span class="sans">V</span> shaped or semicircular grooves for cogs, the -former running round the periphery of the wheel like the grooves in -an ordinary lathe pulley. In this method of gearing, it would be -necessary to move the back spindle to-and-fro, the usual horizontal -movement not being possible. This is easily effected by a screw or a -cam, either of which might be made to act on the frame which carries -the back spindle, and which may then work on a centre, as<span class="pagenum"><a name="Page_85" id="Page_85">[85]</a></span> <a href="#i-p085">Fig. 133</a>, -where A is the poppet, B, the support of the spindle, D, a cam; when -the handle of the latter is raised, the standard, B, is allowed to -fall back out of gear into the position shown by the dotted line, C. -A screw movement would have the advantage of enabling the workman to -regulate with greater precision the pressure of the friction pulleys -against each other. The drawing shows the grooves of these pulleys -larger and deeper than usually made. They are generally rather shallow -and numerous, and it is astonishing with what firm hold they grip each -other without that violent pressure which it might be imagined would -be necessary to prevent slipping when in use.</p> - -<div class="figcenter" id="i-p085" style="width:550px;"> - <img - class="p2" - src="images/i-p085.png" - width="550" - height="327" - alt="" /> - <p class="center smcap">Figs. 132, 133.</p> - </div> - -<p>The ordinary slide rest for hand lathes is made as follows:—That for -ornamental turning will have a separate notice. <a href="#i-p086s">Fig. 134</a>, shows the -slide rest viewed from above, and it is evident if the tool is clamped -to the holder F on the top plate, it can be advanced from end to end -of the top slide B, and also (with the upper frame itself) along the -lower frame A, A, these movements being at right angles the one to the -other. For parallel work this is sufficient. In this compound rest a -third motion is arranged for turning cones or taper plugs like those -of stop cocks, taps for screw plates and such like articles. For this -purpose the upper frame is cast like <a href="#i-p086s">Fig. 135</a>, with a flat surface, -but with two ribs underneath, uniting the frame to a circular plate -with two concentric slots in it. This plate revolves on the plate G -G, turning on a central pin, and it can be clamped by the two screws -which pass through the slots into the plate in any desired position; -once clamped at the required angle a piece of metal can be bored -with a conical hole and a plug turned to fit it without possibility -of failure. The details of construction allow of considerable -variety, and different makers keep to their respective patterns; the -main desideratum is strength and solidity, combined with accurate -adjustment of the moving parts. The <span class="sans">V</span>'s, underneath the frames, -and the edges of the latter, must fit, so as not to be tighter in one -place than<span class="pagenum"><a name="Page_86" id="Page_86">[86]</a></span> another, and the upper and lower frames must cross each -other accurately at right angles. It is likewise essential that the -tool traverse the work in a perfectly horizontal line. Every part -must, therefore, be accurately made by means of the lathe and planing -machine, and the whole carefully put together. Notwithstanding the -above desiderata, a slide rest is not necessarily beyond the skill of -the amateur. We have, indeed, seen one thus made quite equal to the -work of a professed mechanic, though the file and scraper had to take -the place of the planing machine. The rough castings can be bought -for about half-a-crown, suitable for a five-inch centre lathe, and it -would be much better to try and fit up a set of these castings than<span class="pagenum"><a name="Page_87" id="Page_87">[87]</a></span> -to attempt such a substitute as a wooden slide rest. The latter has -nevertheless been made, and we remember seeing one of mahogany edged -with brass, the work of a cabinet maker, which did good service in -turning and ornamenting wood.<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">[9]</a> This, however, was upwards of twenty -years ago, since which time the facilities for obtaining slide rests -of metal, properly constructed, have materially increased. As the -dovetailed edges of the slides wear away by use, it is necessary to -provide means for tightening up the <span class="sans">V</span>-pieces. This is shown -in <a href="#i-p087a">Fig. 136</a>. The holes in the <span class="sans">V</span>-pieces through which the -top screws pass are not round, but oval, so as to admit of lateral -movement.</p> - -<div class="footnote"> - -<p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">[9]</span></a> In the Paris Exhibition of this year (1867) are some -slide-rests made of hardwood and metal.</p></div> - -<div class="figcenter" id="i-p086s" style="width:505px;"> - <img - class="p2" - src="images/i-p086s.png" - width="505" - height="550" - alt="" /> - <p class="center smcap">Figs. 134, 135.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p087a" style="width:400px;"> - <img - class="p2" - src="images/i-p087a.png" - width="400" - height="241" - alt="" /> - <p class="center smcap">Fig. 136.</p> - </div> - -<p>Two large headed screws, E, E, are tapped into the place on which -the <span class="sans">V</span>-pieces rest, and when these are screwed up, their -heads (which are sunk for the purpose in two recesses in the lower -plate) press against the <span class="sans">V</span>-pieces, driving them closer to the -dovetailed slide. When thus adjusted the top screws are made use of -to fix the strips <i>c</i>, <i>c</i>. By this method the slides can be adjusted -to work with the utmost ease and accuracy, without shake or side -play. The edge of the circular plate and the heads of the leading -screws are very frequently marked in graduated divisions, so that -the advance of the tool or the angle to be made with the work by the -tool can be accurately measured and preserved. There should at any -rate be a mark on the circular plate to show when the rest is set for -parallel work.<span class="pagenum"><a name="Page_88" id="Page_88">[88]</a></span> There are several patterns of tool holder, of which -the forms shewn are convenient for light work. The one shown in <a href="#i-p087b">138</a> -& <a href="#i-p087c">139</a> on the rest is somewhat different. The plate F, <a href="#i-p086s">Fig. 134</a>, is -cast with a boss and socket, like that of an ordinary rest. In this -socket the tool holder fits, and can be not only turned round so as -to set the tool at any angle, but also slightly adjusted in height, -which is a great advantage. The tool is clamped by a single screw -as shown in the sketch. The drawback to this form, and that on the -rest, is this single screw, which will indeed hold the tool when the -work is easy, but will not always retain it with sufficient firmness -when the work is rough, or of tolerable size. In large workshops one -usually meets with the holder represented in <a href="#i-p087d">Fig. 140</a>. A plate, A, -with central block B, and slide C, are in one casting. Through A pass -eight screws. The tool lies on either side of the central square block -and is clamped with three screws, it has thus a fair bearing on two -sides, and the screws form a third above, so that accidental shifting -of the tool during the progress of the work is hardly possible. The -tool holder of Professor Willis, which is described in the Appendix, -is perhaps the best of all at present in use. It holds the tool firmly -at any desired angle.</p> - -<div class="figcenter" id="i-p087b" style="width:145px;"> - <img - class="p2" - src="images/i-p087b.png" - width="145" - height="200" - alt="" /> - <p class="center smcap">Fig. 138.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p087c" style="width:296px;"> - <img - class="p2" - src="images/i-p087c.png" - width="296" - height="267" - alt="" /> - <p class="center smcap">Fig. 139.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p087d" style="width:450px;"> - <img - class="p2" - src="images/i-p087d.png" - width="450" - height="203" - alt="" /> - <p class="center smcap">Fig. 140.</p> - </div> - -<p>It is quite possible that the novice who has seen mere boys working -with slide rests at manufactories will be disappointed at his own -first attempts to use this piece of machinery. All the difficulty lies -in the shape and set of the tool. When turning metal with hand-tools -it is easy to feel one's way. If the cut is not satisfactory, the hand -at once modifies the angle of the tool, and regulates its direction -to a nicety, but the slide rest cannot thus adapt itself to its -work. It must be set with its slides in position, and the tool once -fixed must pursue its own course. Hence it requires a very accurate -knowledge of the nature of cutting tools, such as we have given in the -Appendix to this work. If the tool is well placed upon the axis of -the work for iron, a little below it for brass—it will cut cleanly -and easily, without rubbing or jarring, both of which are proofs of -either a wrong angle of edge, or a wrong form of tool. The work should -proceed with as much apparent ease as if the metal were an apple, and -the shaving should curl off like its peel. Moreover, this case is not -merely apparent, it is perfectly easy to cut iron, and the strain on -the tool, whether held by the hand or by slide rest, is comparatively -slight, if the tool is properly made and held. <a href="#i-p088">Fig. 141</a> is quite the -best form<span class="pagenum"><a name="Page_89" id="Page_89">[89]</a></span> of tool for surfacing cylinders with the slide rest. It -is to be so placed that both edges are made to cut near the point; -hence the crank should slightly curve away to the left. It is not -possible to cut metal quickly, be content with fine clean shavings -curling off freely. You will soon see whether you can take a deeper -cut with safety. The tool here sketched is not at all likely to dig -in and hitch in the work; if it is not properly placed it will spring -and jump, or its side will rub against it, and no cut will be made. -To describe the exact position is very difficult, but the principle -once grasped, little difficulty should be experienced in making and -setting to work any tool, whether for inside or outside work. The -<i>rule of thumb</i> was all well enough in olden days and in the infancy -of the art of metal working, but it is time to discard it; to master -and man it is equally advantageous to do so. Indeed, in some of our -leading firms, the old system of follow-my-leader, when the leader -was as ignorant of his work as the follower, is waning, and the "how" -is now, as it ought to be, coupled with the "reason why." One of the -best papers ever written on this subject is to be found in Weale's -series, "Mechanism and Construction of Machines," by T. Baker, and -"Tools and Machines," by J. Nasmyth, 2s. 6d. The latter part is that -specially referred to, and is well worth the whole price of the work. -The remarks, however, of that eminent mechanic are embodied in the -paper in the Appendix, and therefore, after the reader has studied the -latter, he should make trial for himself of the principles laid down. -Expend a quarter or a half an hour experimenting thus, with keen and -obtuse tools, held at divers angles, and you will see and understand -what is meant by setting a slide rest, or hand tool to cut metal as it -ought to do.</p> - -<div class="figcenter" id="i-p088" style="width:450px;"> - <img - class="p2" - src="images/i-p088.png" - width="450" - height="187" - alt="" /> - <p class="center smcap">Fig. 141.</p> - </div> - -<p><a href="#i-p088">Fig. 141</a> is too much cranked; half the length of the -hanging part would amply suffice.</p> - -<p>Supposing the tool fixed in the tool holder in the position indicated, -and just overlapping the circumference at one end (the right). Take -hold of the handles, one in each hand, and with that which advances -the tool from end to end of the bar try very carefully whether the -tool will cut cleanly by making a turn or two while the lathe is in -slow motion. If the tool bites too deeply, turn the other handle -and ease it. If you still find the tool sticking into or scraping -the work, instead of bringing off a fine shaving, look well to its -position, and observe whether the edge is well placed on the axis of -the piece. If it has been hitching in the work it is probably too low, -if rubbing it, too high, and touches at some point below its edge. -It is presupposed, of course, that the tool is made correctly as to -angle of cutting edge. Do not lower the point by packing the end of -the shank; <i>pack the whole length</i> or none. It is astonishing what -a great difference is made to the cutting power of a tool by slight -adjustments of this kind, and how smoothly a tool will work with -proper attention to these details, which would otherwise be probably -cast aside as unfit for the<span class="pagenum"><a name="Page_90" id="Page_90">[90]</a></span> work. Hence the greater ease in managing -a hand-tool. The hand <i>feels</i> the error, and at once, if experienced, -corrects it by an almost imperceptible movement—slightly raising or -depressing the handle or gently varying the angle sideways on the -rest. When once the tool is found to cut as it ought to do, nothing -remains but to turn the handle in the right hand, and thus cause the -tool to progress steadily along the work from end to end. Then free -it by a half turn of the other handle, reverse the movement until the -tool has arrived at its old place, and having slightly advanced it to -take a fresh bite, repeat the process until the whole bar is reduced -to the required size. If the piece is slender and bends away from the -tool, add to the slide rest a support; let it be fixed opposite to -the tool, and it will keep the work steadily up against the cutting -edge. It can be fixed (if a hole is made for the purpose) anywhere -about the slide which traverses in the direction of the length of -the work. It is well to drill and tap a few holes about the slide -rest, and some along the side of the bed of the lathe. These will be -found very useful at various times for fixing apparatus. For, be it -observed, (and we shall recur to this with some practical hints by and -by) the lathe may and ought to do many kinds of work beyond ordinary -turning. It may become a machine for planing, slotting, drilling, -wheel cutting, &c., and is to be pressed into the service of the -jack-of-all-trades, without compunction.</p> - -<p>When ordering a slide rest let steel screws and nuts be specified, and -gun metal <span class="sans">V</span>-pieces, and let the parts be strongly made (too strong -for the supposed work); for the latter may unexpectedly turn out to -be sometimes rather heavy. We have found the top plate of a 3in. -slide-rest so weak that when the tool was clamped on the top of it, -by the screw of the tool holder, the slide itself became jammed; a -defect quite beyond remedy, except by the substitution of a new and -stiffer plate. The same advice may be given respecting the tools. Let -these also be strong; neat and pretty tools are all very well, but -you seldom see them in a workshop; you don't require pretty tools, -but good and serviceable ones. Nevertheless, let the material be of -the best quality possible; and that you may not be ever at a loss, -you should learn to make tools yourself. Procure some small square -and round steel bars; save up as directed your old files, and you -need but heat them red hot (not on any account white hot), and with -hammer and file shape them to your mind. Then temper to a deep straw -colour, and after being accurately ground and finished on the stone, -they will be fit to use upon any metal. The form of tool given as the -best for slide rest work may be exchanged, when the bar is nearly -turned, to the required size, for a fresh one, keen, sharp, and of -an almost flat edge instead of point. A tool, of which the edge is a -segment of a very large circle, will serve the best as a finish<span class="pagenum"><a name="Page_91" id="Page_91">[91]</a></span>ing -tool, just to take off the lines left by the pointed tool. With -regard to lubricating the work, we may observe that the chief object -is to prevent the point or edge of the tool from heating and losing -temper; oil, water, or soap and water will therefore answer, but it -is a curious fact that oil will not produce so polished a surface as -water will. We should advise in all cases soap and water. Soft soap -is best, boiled in water, and allowed to cool. The drills with which -the huge armour plates of ships six inches thick are drilled are thus -lubricated, and instead of throwing out dust in a wet state as usual, -these large drills fairly turn out curled shavings similar to those -produced by the planing tool. It is by no means a bad plan to lay the -shank of the tool which falls upon the top plate of the rest, upon a -piece of leather, wood, or sheet lead. The surface of the iron, when -planed and finished, is often too smooth, and the tool will sometimes -slip from this cause, unless screwed unduly tight, to the detriment of -the rest. By the above plan this annoyance will cease at once.</p> - -<p>We will now say a word about hollowed work. Finishing a chuck will -serve our purpose, and here be it advised not to go to much expense -about chucks—get those which must be of brass in the rough, and -practice metal turning by finishing them yourself. If no slide rest -is available do it by hand. However, we are supposing the slide rest -to have been procured, and may therefore proceed to use it. First -you must drill the back part of your chuck as directed in a previous -chapter. The drill is to be the size of the diameter of the hollows -in the mandrel screw, that is, smaller by the depth of a thread, than -the full size of the nose. Having drilled it, proceed with the most -tapering of your taps, which we suppose to be provided to form the -internal thread (external if your mandrel has female screw, in which -case, instead of a drilled hole, the chuck will have a projection to -be turned truly cylindrical, and a screw cut outside with stock and -dies or chasing tool).</p> - -<p>Follow up with the intermediate and finish with the plug tap. If you -were careful to square up the shoulder, the drill having been likewise -placed perpendicularly to the face of the chuck, the latter will fit -truly up to the collar or shoulder on the mandrel. If not, you must go -to work again, and square up the back of the chuck till a good fit is -produced.</p> - -<p>Now, if you have a compound slide rest—that is, one in which the -slides turn on a centre pin—you can loosen the screws and turn it -a quarter of a circle. If not, you simply put the tool into the -holder, at right angles to its former position, so that the movement -of that slide which is parallel to the lathe bed will become that -requisite to advance the tool into the hollow of the chuck. Whichever -way you set to work put in a side tool, like <a href="#i-p092">Fig. 142</a>, and, as it<span class="pagenum"><a name="Page_92" id="Page_92">[92]</a></span> -is a brass chuck, remember that the bevel underneath is to be very -slight. Introduce the tool so as to take a light cut at first, until -the roughness is taken off, after which you may cause it to bite more -freely. Repeat this until the chuck is sufficiently hollowed out, when -you may substitute a similar shaped tool, but with a flat or slightly -rounded edge, to take off the marks left by the point tool. To finish -the bottom of the inside you will require a tool which cuts on the -end, but it should not have a perfectly flat end—at any rate, not -until, by means of a pointed or small round-ended tool, you have cut -away the roughness left from the process of casting. This has always -in its interstices a number of grains of sand fused, and very hard and -detrimental to cutting edges of all kinds. The point tools dig these -out very effectually, and should always precede those of other forms.</p> - -<div class="figcenter" id="i-p092" style="width:302px;"> - <img - class="p2" - src="images/i-p092.png" - width="302" - height="247" - alt="" /> - <p class="center smcap">Fig. 142.</p> - </div> - -<p>The outside must be turned in a similar manner, and a hole drilled -to receive a pointed bar or wrench, for the purpose of unscrewing it -when screwed up tightly. To turn up a face plate of iron or brass -proceed in a similar way, but commence from the centre with a point -tool. This tool is the best for taking off the rough outside of hard -wood, instead of the gouge, as well as for removing the roughness of a -fresh casting. It is absolutely necessary that the faces of these flat -chucks, or surface chucks, be truly at right angles with the mandrel; -hence it is very difficult to turn and finish them by hand. We may -here also state the necessity of knowing when the slides of the rest -are at right angles to each other, without which no work can be turned -correctly. It is necessary to ascertain this by help of a small steel -square. Once fixed truly, it is only necessary to make a mark on the -quadrant (which should be marked in true degrees), by which the same -position can be found again at any time. We have spoken here of the -quadrant—we mean the arc, or arcs with slot—allowing the circular -movement of the compound slide rest. The chief use of these is to -enable the workman to turn true cones instead of cylinders, which -latter will only be produced when one slide is parallel to the lathe -bed. Such is the common use of the slide rest; and it will be evident -from these few remarks that there is an infinity of work, not only -produced with ease by its aid, but which cannot, even with expenditure -of time and labour, be produced without it; hence we advise this to be -the chief ambition of the tyro after he has mastered the difficulties -of ordinary hand turning (and not before). The cost of a fair one -for 5-in. lathe will be £5, or thereabout. At Munro's, £7 or £8; at -Holtzapffel's, £10 or £12. Both the latter are of course perfect.</p> - -<p><span class="pagenum"><a name="Page_93" id="Page_93">[93]</a></span></p> - -<p>We have directed to tap the chuck where it is to be screwed to -the mandrel with a set of three taps, or to cut it with stock and -dies if an outside thread is required. In both cases more true and -satisfactory work may be produced by the chasing tool. We speak of -the latter as used by hand; an account of cutting the threads by -help of the slide rest we reserve for the present. Mount the work -in any convenient way, either driving it into a wooden chuck, or by -clamping it to the face plate if you have one. Now in this way you -have advantages. In the first place you need not have a drill the -exact size, though it is convenient to have such a one, and also a -cylinder bit. You can drill and enlarge the hole by the slide rest -tools, and you can also with the slide rest ensure the perpendicular -position of the hole with respect to the end. Thus it is sure to fit -up close and snug to the shoulder of the mandrel. When bored thus -it will be in position for chasing. It is not difficult to chase a -thread in brass, as it does not chip away like wood, but cuts clean -and sharp. Follow the directions already given and you will succeed in -a few turns in getting the tool to run. Then let it have its own way; -hold it lightly, but steadily, and do not force it either to cut too -deeply, or to advance too quickly; it will run along of itself after -the faintest thread is cut or scratched, and the lathe can be worked -by means of the treadle all the time as soon as you have attained the -knack of dropping the chaser into its place at the commencement of its -cut, and suddenly withdrawing it when it has reached the bottom of the -hole. A chuck thus turned and screwed entirely in the lathe is sure -to prove a good fit, and there can be no better practice than to cut -screws in all your brass and boxwood chucks in this way. A very good -chuck to hold flat plates of brass was invented by a Mr. Wilcox, of -Bishop's Stortford, some years ago—an amateur of rare ingenuity and -mechanical knowledge, and who made all his own apparatus for plain and -eccentric turning. The chuck, <a href="#i-p093">Fig. 143</a>, as described by him in some -unpublished manuscript, is made of boxwood, or may be of metal. It -is a plain disc or surface chuck with three slots A B C. and a steel -centre. This last must penetrate rather deeply into the wood of the -chuck, but is only kept up so as to project from the surface by a -spiral spring below it. Hence, when pressure is made upon its point by -the application of the object to be turned, the pin recedes into the -body of the chuck, suffering the work to lie flat on its surface. In<span class="pagenum"><a name="Page_94" id="Page_94">[94]</a></span> -the three slots are three screws, with nuts at the back of the chuck -the screws pass through two pieces of brass, forming a pair of jaws, -one of which is shown separately.</p> - -<div class="figcenter" id="i-p093" style="width:478px;"> - <img - class="p2" - src="images/i-p093.png" - width="478" - height="380" - alt="" /> - <p class="center smcap">Fig. 143.</p> - </div> - -<p><a href="#i-p093">Fig. 143</a> shows the chuck complete. Suppose we have to face up a round -disc in its central part, or to perform any surface work in which the -jaws will not be in the way of the tool, the centre of the plate is -marked at the back of it, and this mark laid on the central pin. The -work can be clamped down by the three jaws, and the necessary work may -be done. Now so far the chuck is but a simple affair, and the receding -pin does not show itself to such great advantage; we will therefore -suppose a plate is to be drilled at several spots; let these be marked -at the back by a centre punch. It is now only necessary to bring these -marks in turn upon the central point, and clamp the plate in position. -Bring the point of the drill against the work and keep it up to cut by -the back poppet screw. In the same way eccentric work or any operation -may be done to such a plate, with the certainty that the point to be -thus worked upon is precisely central with the axis of the pulley, -or mandrel. Many similar applications of this chuck will present -themselves to the reader upon due consideration. We present the chuck -in this place because we have had occasion to speak of drilling as -connected with the slide rest, and there are many pieces of work that -could not otherwise be conveniently held in the desired position.<a name="FNanchor_10_10" id="FNanchor_10_10"></a><a href="#Footnote_10_10" class="fnanchor">[10]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">[10]</span></a> The MS. book containing the above was kindly lent to the -author of the present work by Mr. Hoblyn, of Bishop's Stortford, who -is the inventor of a new form of slide rest, which will be introduced -in a later page. The chuck in question is, however, commonly attached -to the watchmakers' lathes of the present day, and therefore may not, -as the writer supposed, be actually the invention of the late Mr. -Wilcox.</p></div> - -<h3 class="sc"><a name="OVERHEAD" id="OVERHEAD">Overhead Apparatus.</a></h3> - -<p>It now becomes necessary to speak of another addition to the lathe, -by means of which the use of the slide rest is considerably extended. -We mean the overhead motion. Of this there are several patterns, and -we have sketched three of these. As to their respective merits we can -hardly venture to speak. They all answer equally well the purpose for -which they have been designed, and the turner must select according to -his fancy, or, if he please, design a better for himself. A, <a href="#i-p095s">Fig. 144</a>, -represents the lathe bed. From the left-hand standard rises a round -iron rod, not less than one inch in diameter. This is not generally -fixed, but is attached to the standard by two staples, <i>a, b</i>, which -hold it securely in an upright position, but allow it to turn with -its projecting bar F, F,<span class="pagenum"><a name="Page_95" id="Page_95">[95]</a></span> after the manner of a crane. It may thus be -turned back, out of the way, or brought into any desired position. The -part F, F is made to slide up and down on the part B, and is fixed by -a clamping screw D. Thus, if the cord should break and require to be -shortened, the arm can be brought nearer to the bed of the lathe. Upon -F, F slide two rings, or rather short pieces of tube, from which depend -two India rubber springs (door springs), E, E, now procurable at any -ironmonger's at one shilling each. From these hang double pulleys, or -better still two single ones. These pulleys, with their attachments, -are adjustable at any position on the arm F, F, which may be round or -square. If considered desirable, a second standard can be added, so as -to uphold both ends of this bar; but it is hardly necessary, as the -latter is seldom required of greater length than half that of this -lathe-bed. It is evident that the above addition to the lathe can be -made complete for a few shillings. The following are more expensive, -but more general, the writer having devised the above to suit his own -fancy, and for his own use. In <a href="#i-p096s">Fig. 145</a> A represents the standard as -before, the top<span class="pagenum"><a name="Page_96" id="Page_96">[96]</a></span> of which is forked, as shown at E, and sustains the -ring, free to revolve in its arms, as seen in the sketch. Through -this passes a bar, B B, with a heavy ball C cast on its end to act -as a counterbalance to the longer arm and its connections, and to -keep the cord stretched. By sliding this bar either way through the -ring which supports it, the tension of the cord can be increased or -lessened.<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">[11]</a> When in position it must be very securely fixed by the -screw T, which should not simply press against it, but enter one of a -row of depressions made for the purpose. The pulleys C, D are double, -as in the previous plan of overhead, and are likewise adjustable at -any position on the bar B, B. The only drawback to this pattern is the -danger of the heavy ball slipping out and falling. We prefer to hang -a weight from the end of the lever, as shown by the dotted line. This -may be within a few inches of the floor, and if it should fall no -harm can ensue. The third pattern, <a href="#i-p097s">Fig. 146</a>, is the most expensive, -but although it is of a more finished appearance, and wears an aspect -more stiff and stable, it is not practically any better than the last. -From a standard A, with overhanging bar F, F, is suspended a frame H, -by means of two coiled springs in brass boxes B, B, which keeps up the -necessary tension on the cord, or rather cords, for in this case two -are needed—one from the flywheel to the small pulley, and a second -from the roller to the slide rest.</p> - -<div class="footnote"> - -<p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">[11]</span></a> Sometimes the bar is merely hung on pivots, and the -weight is made to slide upon it.</p></div> - -<div class="figcenter" id="i-p095s" style="width:496px;"> - <img - class="p2" - src="images/i-p095s.png" - width="496" - height="550" - alt="" /> - <p class="center smcap">Fig. 144.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p096s" style="width:403px;"> - <img - class="p2" - src="images/i-p096s.png" - width="403" - height="550" - alt="" /> - <p class="center smcap">Fig. 145.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p097s" style="width:654px;"> - <img - class="p2" - src="images/i-p097s.png" - width="654" - height="550" - alt="" /> - <p class="center smcap">Figs. 143, 146, 148.</p> - </div> - -<p>This roller, which may be grooved or plain, may be replaced by a -second small pulley, which is capable of being slid along the round -bar which forms its axle and turns with it between the centre screws. -In this case the bar is made with a groove or channel along its -length, <a href="#i-p098">Fig. 147</a>, and a pin projecting from the central hole in the -pulley enters this groove. Thus the two will turn together, and at -the same time the position of the pulley is adjustable at pleasure. -The tension of the springs B, B, is increased or lessened by a turn -or two<span class="pagenum"><a name="Page_97" id="Page_97">[97]</a></span> of the nuts C, C, just in the same manner as the spring of -the safety valve is adjusted on the boiler of a locomotive.<a name="FNanchor_12_12" id="FNanchor_12_12"></a><a href="#Footnote_12_12" class="fnanchor">[12]</a> The -application of the overhead motion is plainly shown in Figs.<a href="#i-p093">143</a> and <a href="#i-p095s">144</a>. -The work is fixed in the lathe, and the mandrel kept stationary. -The cord passes to the overhead directly from the fly wheel, and -thence to a pulley on the screw of the slide rest, as in <a href="#i-p093">143</a>, to a -drill, as in 144, or to any other apparatus at pleasure. To fit the -work in the lathe in such a manner as to enable any point in the face -or side to be operated upon, a division plate and index are required. -The first is a round plate of brass or gun metal, <sup>1</sup>/<sub>16th</sub> of an inch -thick, drilled with holes in concentric circles. The index is a steel -spring with a projecting point, which, entering any one of the holes, -retains the plate, and with it the pulley, on the face of which it is -fixed immovable. There are generally four circles of holes, the number -in each selected with reference to its divisibility by the greatest -possible number of divisions—thus 360, which is usually on the -outside or largest circle, can be divided without a remainder by 2, 3, -4, 5, 6, 8, or 9—144 is a good number for the second circle, being -divisible by 2, 3, 4, 6, 8, 9. The other two may be 112 and 96. The -uses of the division plate are many. Eccentric cutting and drilling -could not be<span class="pagenum"><a name="Page_98" id="Page_98">[98]</a></span> done without its aid, and wheel cutting for clocks, or -for making cycloidal and other chucks, is entirely dependent on this -contrivance.</p> - -<div class="footnote"> - -<p><a name="Footnote_12_12" id="Footnote_12_12"></a><a href="#FNanchor_12_12"><span class="label">[12]</span></a> The frontispiece shows another superior form of -overhead, with balance-weights hanging close to the ground behind the -lathe.</p></div> - -<div class="figcenter" id="i-p098" style="width:485px;"> - <img - class="p2" - src="images/i-p098.png" - width="485" - height="506" - alt="" /> - <p class="center smcap">Fig. 147.</p> - </div> - -<p>The division plate and index are shown in <a href="#i-p098">Figs. 147, A, B, C</a>. The part -B is a knob with a round hole through it, to take the tail of the -spring C. This is shown again at C on a larger scale, to bring to view -a slot which allows of some slight adjustment of the point, to suit -the different-sized circles. The milled-headed screw clamps the point -at any desired part of this slot. When not in use, the spring is drawn -back so as to release it from the division plate, and turned down in -the position shown by the dotted line.</p> - -<p>The overhead apparatus is applicable not only to revolving cutters in -the slide rest, but to other contrivances available where the latter -is not possessed. There are many cases in which the back poppet may be -brought into use to hold revolving drills, or stationary tools, if the -resistance to their action is not too great. The only damage that can -well happen in this method is to the pin working in the slot on the -outside of the spindle. If this is of steel and tolerably stout and -strong (being very short it cannot be subject to any very injurious -strain), no harm is likely to result. With this it is possible to -drill very neatly, and also to do a little eccentric cutter work, -under certain conditions to be described. Screwing, or rather chasing, -may likewise be done very passably. We do not, of course, advise this -course when the more perfect slide rest is at hand, but there are many -who are obliged to put up with all sorts of homemade contrivances, and -to press into service for divers operations apparatus and tools not -precisely meant to be thus used, and it is as well to learn how to act -under an emergency, even if the practice is not intended to be carried -out generally. The drill stock is shown in <a href="#i-p097s">Fig. 148</a>, in which the -screw A fits into the spindle of the back poppet. If the hole in the -latter is conical instead of cut with a screw thread, the drill must -be made accordingly.</p> - -<p>The pulley of brass has a hole drilled through it, and the screw is -also drilled, the hole in the latter being rather larger than that -in the pulley (which is tapped). The steel pin H, shown white in -the sectional drawing, passes truly through the centre of the screw -in which it revolves, and is screwed into the pulley. The socket -of<span class="pagenum"><a name="Page_99" id="Page_99">[99]</a></span> steel to hold the drill is then screwed or soldered into the -opposite face of the pulley. The black part shows a flange on the -screw which abuts against the cylinder of the poppet into which it is -screwed. Thus the pulley, being attached to the cord from the overhead -apparatus, is free to revolve upon the steel pin with great rapidity, -and will carry round any drills or cutters placed in the socket B. The -simple straight drill being thus worked and advanced by the leading -screw of the poppet, will suffice for holes in any work held on the -mandrel. On page 335, vol. ii., of the <i>English Mechanic</i>, this method -is mentioned, and also a similar pattern of slide tool to be used for -boring, being, in fact, the head and spindle of the back poppet, but -instead of the standard and sole, a pin, like that of a <span class="sans">T</span>, to -fit the socket of the rest. This has the advantage of the back poppet, -but must be made on purpose, and if any special slide tool is added, -a proper slide rest is by far the best. Our present purpose is to -describe the use of the back poppet as a substitute for a better tool.</p> - -<p>With the following modification of the eccentric cutter, a fair amount -of good ornamental work may be done. <a href="#i-p099s">Fig. 149</a> represents the back -poppet with the apparatus in position. The various parts are shown -separately in A, B, C, D. A is a small frame, two or three inches -long, and ¾ to 1 inch wide, cast in iron, with a circular piece -at the back, 1½ or 2 inches diameter. This circular piece is to -be accurately divided on the edge with any even number, which is -divisible as above explained. This is turned and drilled through the<span class="pagenum"><a name="Page_100" id="Page_100">[100]</a></span> -centre. B is a flange-shaped piece to screw to the poppet as before, -and this is also accurately drilled, and the two are attached by a -central steel pin, so that the two flanges can turn face to face, the -outer one with frame revolving against the other. The pin must be -put in its place in B, and turned at the same time as the face of B, -that it may be truly central. The divisions on the edge of the outer -flange are to be drilled like the division plate of the lathe, or cut -into cogs, and in either case can be held at any point by a spring -detent or index attached. C shows the front of the frame, with a screw -down its centre and traversing slide <i>f</i>. The head of this screw is -divided, and a small brass index marks its position; one side of the -frame may likewise be divided. The small brass pulley and drill socket -are fixed to revolve in the traversing nut or slide <i>f</i>, as shown in a -side view at D. Drills of all shapes, as E 1, 2, 3, 4, may be fixed in -the socket at pleasure.</p> - -<div class="figcenter" id="i-p099s" style="width:700px;"> - <img - class="p2" - src="images/i-p099s.png" - width="700" - height="527" - alt="" /> - <p class="center smcap">Fig. 149.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p100a" style="width:301px;"> - <img - class="p2" - src="images/i-p100a.png" - width="301" - height="327" - alt="" /> - <p class="center smcap">Fig. 149E.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p100b" style="width:450px;"> - <img - class="p2" - src="images/i-p100b.png" - width="450" - height="233" - alt="" /> - <p class="center smcap">Figs. 150, 151.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p101" style="width:450px;"> - <img - class="p2" - src="images/i-p101.png" - width="450" - height="250" - alt="" /> - <p class="center smcap">Figs. 152, 153.</p> - </div> - -<p>It is evident that the cutter frame last described having a division -plate of its own dispenses with the necessity of one on the pulley of -the mandrel. Indeed it was the impossibility of supplying the latter -on the face of the cogwheel of the author's back-geared lathe that -necessitated the substitution of that alluded to. The latter may -consequently be omitted if applied to a lathe already fitted with -division plate and index. With crank-form drills the cutting edges -of which may be as E 1, 2, 3, 4, or other form, such patterns can be -cut, as shown in Figs. 149, <a href="#i-p100b">150</a>, <a href="#i-p100b">151</a>, <a href="#i-p101">152</a>, which are merely samples -of the simplest combinations of circles intersecting in straight, -spiral, or other lines. Although not now treating of eccentric work, -we may state in passing that to produce the pattern round the edge -of <a href="#i-p100b">150</a> the division plate of the instrument only is required. Select -a crank-form drill which by its revolution will produce the required -size of circle. Turn the divided screw head until you find upon trial -that the circle will come at the required distance from the edge, -and putting the lathe in motion cut the first circle. The work on -the mandrel is understood to be stationary, the mandrel being fixed -so as not to turn. The cutter frame is now turned on its axis, one, -two, or more of its divisions, and fixed by its detent, and a second -circle cut intersecting the first. This is repeated till the whole -circle is<span class="pagenum"><a name="Page_101" id="Page_101">[101]</a></span> completed. The straight line of circles in <a href="#i-p100b">Fig. 151</a> is cut -as follows:—The first circle is made as before, but the cutter-frame -should be placed so as to stand either horizontally or vertically. -Between each cut the divided screw-head is moved so many points -according to the proposed fineness of the pattern, and no movement -of the cutter frame on its axis is to be made. The spiral, <a href="#i-p101">152</a>, is -simply the result of a combination of the two movements. Start from -the centre by turning the screw head until the shank of the crank-form -drill is coincident with the axis of the mandrel. Cut the central -circle. Thence for each successive circle turn the screw head and the -frame an equal number of points, and the pattern will be formed. If -the divided screw head is made to take off and a handle substituted, -stars formed of channelled lines, or radial flutes can be made as Fig -153, but in this case the crank form drill is replaced by a plain -straight tool with a rounded end like <a href="#i-p100a">149 E 4</a>. Set the tool as for -pattern 150 straight across the face of the work, put the drill in -rapid motion, let it be advanced by the leading screw of the poppet so -as to penetrate slightly, and with the handle that has been attached -to the screw of the cutter frame cause it to traverse the face of the -work as it revolves. When one flute is thus cut, turn the frame on its -axis as many points as required, and proceed with number two, and so -on to the completion of the star. It is not necessary at present to -describe other patterns. <a href="#i-p101">Fig. 153</a> is therefore merely given without -special details of the method of producing it.</p> - -<p>We must now return from this digression to speak of other applications -of the slide rest. It is evident that when connection is made between -the overhead and a pulley on the screw of the slide rest, the latter -becomes self-acting. The speed is, however, far too great, and in -addition, the mandrel is stationary. The above connection, therefore, -is not practically possible, and the overhead is only connected with -the pulleys of revolving drills and cutters fixed in the tool-holders -of the rest. It is, however, very important to be able to form some -such connection between the lathe mandrel and the screw of the rest, -for the purpose of cutting screws or spirals. A little consideration -will show the principle of this arrangement, from which some practical -plan is not difficult to design. If, for instance, the tool simply -remains in contact with a cylinder while the latter revolves with the -mandrel, a simple line will be cut round its circumference; but if, -while the mandrel revolves once, motion is given to the screw of the -rest by which the tool is made to traverse a distance of one-eighth -of<span class="pagenum"><a name="Page_102" id="Page_102">[102]</a></span> an inch, the commencement of a spiral having that pitch will be -made. A perfectly smooth surface, as it leaves the lathe, in which a -slide rest has been used with a point tool, is in reality cut with a -very fine screw thread readily discernable under the microscope. We -have, therefore, only to devise some method of giving regular motion -to the screw of the rest while the work revolves as usual, in order -to turn plain surfaces, screws, or spirals. For the purpose of plain -turning a plan is sketched by Nasmyth in the last chapter of "Baker's -Mechanics," in Weale's series. A spur wheel is represented fixed to -the slide rest screw, the teeth of which are alternately caught at -every turn of the work, by an arm fixed to the latter, after the -manner of a lathe carrier. This plan is simple, and might be to some -extent used, but for one defect, due to the fact that the slides -of ordinary rests are the reverse of what is required to make this -plan available. The screw which advances the tool towards the work -is generally underneath that which moves the tool along the surface -of the work. The result is that, when the tool-holder is advanced -to take the deeper cut the spur wheel is brought nearer to the arm -which acts upon it, and greater traverse is thus given to the screw. -This is shown in <a href="#i-p102">Fig. 154</a>. A is the spur wheel, B the cylinder to be -turned, C the arm or carrier. The arrow shows the direction of the -movement. Now, if the lathe is put in motion, the arm will remain -in contact with one tooth of the wheel until both arrive at <i>b</i>, -giving a certain amount of motion to the screw, and thence to the -tool-holder. After one cut is thus taken, the lower screw of the rest -is turned to advance the tool nearer to the work, the effect of which -is to cause the arm to extend further over the wheel. Suppose its -position represented by the dotted line, it will remain in contact -with the tooth till both arrive at <i>c</i>, having thus traversed a -larger arc, and given more movement to the tool. Now if the frames -of the slide rest were made to cross in the contrary direction so -that the screw to advance the tool towards the work was above that -which gave the traverse in the direction of the bed, this objection -would no longer hold, and the above gearing would answer very well, -since the necessary advance of the tool would not affect the relative -position of the spur-wheel and carrier. In Fig. 5 of the same book, -in which the gearing is effected by two cogwheels, this alteration -in the rest appears in the drawing. In this case the work and rest -are connected for screw cutting, and the arrangement is satisfactory -and<span class="pagenum"><a name="Page_103" id="Page_103">[103]</a></span> simple, and for the amateur especially is the simplest and best -that can be devised. The range of screw pitches is however limited, -and the rest must have a left-handed screw, or the result will be a -left-hand thread to that which is cut. Hence another device has been -arranged, represented in <a href="#i-p103s">Fig. 155</a>, A, B, C. A shows the apparatus -complete. B is an arm of iron or brass which is about ¼ inch thick -or rather more. This is first slipped over the mandrel screw in front -of the poppet and fixed in any desired position by a screw passing -through the slot <i>a</i>, into the face of the poppet. This slot allows -the arm to be raised or lowered at pleasure and adjusted, as will be -presently described. In the slot formed in the long arm B, pins D with -nuts, fit, on the rounded part of which cogwheels, <i>b</i>, <i>c</i>, <i>d</i>, -are made to revolve and to gear with each other, and with a similar -wheel attached to the back of the chuck, C. The centre of the outside -wheel, whether one, two, or three are used, is connected to the screw -of the slide-rest. For the production of a right-handed screw, the -intermediate wheel comes into play, simply to reverse the direction -of the motion imparted to the screw of the slide rest. The number of -teeth which it may contain is of no importance, the calculation of -the change wheel teeth being only necessary with the first and last. -The central one is called an idle wheel, though its work is equal to -that of the rest. Thus, suppose the wheel on the chuck to contain 40 -teeth, and the third wheel 20, while the former revolves once, the -third will, if in immediate contact with it, revolve twice, introduce -an idle wheel with 10 teeth between these two. The wheel, with 40 -teeth, revolving once, the idle wheel will revolve 4 times—the third -wheel twice, just as if the idle wheel was not in use. In any train of -wheels, if we regard relative speed, any number between the first and -last become similarly idle wheels, and the ultimate result is the same -as if the first and last were in immediate contact.</p> - -<div class="figcenter" id="i-p102" style="width:500px;"> - <img - class="p2" - src="images/i-p102.png" - width="500" - height="292" - alt="" /> - <p class="center smcap">Fig. 154.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p103s" style="width:700px;"> - <img - class="p2" - src="images/i-p103s.png" - width="700" - height="301" - alt="" /> - <p class="center smcap">Fig. 155.</p> - </div> - -<p>Take, for example, the following train of five wheels, even -numbers being given for the sake of clearness, to represent the -circum<span class="pagenum"><a name="Page_104" id="Page_104">[104]</a></span>ferences or number of cogs in each, <a href="#i-p104">Fig. 156</a>. We have here, as -the first and last, 6 in. and 120 in., and, if in contact, the first -must revolve 20 times, while the latter revolves once. Interpose the -three idle wheels of 10, 30, and 60 in. respectively. During one -revolution of the largest wheel, the second will revolve twice, the -third four times, the fourth twelve times, the fifth twenty times, the -same precisely as if the first and last had been in immediate contact. -The range of a slide rest-screw is quite long enough for many purposes -of the amateur, and a connection thus made between the mandrel and -such screw is what may be termed a miniature of the arrangement -adopted in the large self-acting lathes. In the latter, however, a -leading screw is added the full length of the bed along which the -slide rest travels bodily. We may, therefore, consider the screw of -the slide-rest a leading screw, and make use of the rules applied in -the case of large lathes to decide the proportions of wheels required -to cut a given screw. It is plain that when the pitch of the required -screw is greater than that of the leading screw, the revolution of the -latter must be at a quicker rate than the former. If, for instance, -a spiral is to be cut, like the Elizabethan twist, containing but -one perfect thread in two inches, while the leading screw contains -twenty threads in the inch, or forty in the 2 in., the latter must be -arranged to make forty revolutions while the former makes one, because -it takes 40 revolutions to carry the tool along 2 in., which is the -pitch of the required spiral. The two outside wheels must therefore -bear that proportion to one another. Forty to one, however, would be -a practically difficult ratio, to place as described, even a pinion -of ten teeth on the leading screw requiring 400 teeth on the chuck. -Hence a different arrangement would be necessary if such very great -difference exist between the pitch of the leading or rest screw and -that to be cut. The same obvious difficulty would occur where a very -fine screw is required, and the pitch of the leading screw is coarse. -This will have to be referred to again. One example, therefore, of the -method of overcoming this difficulty will suffice. A train of wheels -is shown in <a href="#i-p105">Fig. 157</a>, of which A has 60 teeth, B 10 teeth, C, <i>on the -same axle and united to</i> C, 30 teeth, D 20 teeth. While A turns once, -B will turn six times, C necessarily six times also, D nine times. In -this case, if the first and last had geared together D would have made -but three turns, while A made one.</p> - -<div class="figcenter" id="i-p104" style="width:242px;"> - <img - class="p2" - src="images/i-p104.png" - width="242" - height="500" - alt="" /> - <p class="center smcap">Fig. 156.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p105" style="width:203px;"> - <img - class="p2" - src="images/i-p105.png" - width="203" - height="429" - alt="" /> - <p class="center smcap">Fig. 157.</p> - </div> - -<p><span class="pagenum"><a name="Page_105" id="Page_105">[105]</a></span></p> - -<p>The following is an easy method of calculating a series of such change -wheels:—</p> - -<p class="p1">Write down the number of threads in the screw to be cut, and also -the number of threads in the leading screw; multiply both by any -convenient number likely to give such results as to tally with the -cogs in the set of change wheels. Suppose it is desired to cut eight -threads to the inch, and that the leading screw has two threads in -that length. Then:</p> - -<table class="fraction center" summary="" cellpadding="0" cellspacing="0"> - <tr> - <td class="tab6">8</td> - <td rowspan="2">×10</td> - <td></td> - <td class="tab6">80</td> - <td rowspan="2" class="tab6">or</td> - <td class="tab6">8</td> - <td rowspan="2">×15</td> - <td></td> - <td class="tab6">120</td> - <td rowspan="2" class="tab6">or</td> - <td class="tab6">8</td> - <td rowspan="2">×20=</td> - <td class="tab6">160</td> - <td rowspan="2">&c.</td> - </tr> - <tr> - <td class="upper_line tab6">2</td> - <td></td> - <td class="upper_line tab6">20</td> - <td class="upper_line tab6">2</td> - <td></td> - <td class="upper_line tab6">30</td> - <td class="upper_line tab6">2</td> - <td class="upper_line tab6">40</td> - - </tr> -</table> - -<p>If you have either couple of these wheels, you can put one on -the leading screw, and another on the mandrel, and fill up the -intermediate space with dummies.</p> - -<p>If the above is inconvenient, or the wheels are not to hand exactly -as required, proceed thus. If you have the wheel for the mandrel, and -the one you wish to use for the leading screw has only half the proper -amount of teeth, it is evident that the leading screw would revolve -twice as fast as required, for they are proportioned as two to one—or -if I have the proper wheel for the leading screw, and the wheel I -wish to use for the mandrel has twice the proper number of teeth, it -amounts to the same thing. You can get over the difficulty by using -any two wheels which are in the proportion of two to one (say 20 and -40, 30 and 60, 40 and 80, &c.), and coupling the two firmly together, -so that the larger wheel of the two works into the mandrel wheel (or -dummy working into the mandrel wheel) and the smallest into the screw -wheel (or its dummy); if the speed is wrong in the contrary way, so -that the case is reversed, the coupled wheels are made to gear in a -reversed direction; and whatever may be the amount of error, whether -such as to cause either mandrel or screw to revolve ⅛, ¼, or -¾ too slow or too fast, the same arrangement may be pursued, the -coupled wheels bearing that proportion to each other. The above method -was communicated to the <i>English Mechanic</i> by a working man, James -Connor, and is perhaps as easy as any; but tables are published of -change wheels for any pitch, with any thread of leading screw. Where -it is not possible or inconvenient to apply the above arrangement, -and where only a few pitches are likely to be needed, another method -can be arranged by connecting the lathe pulley to the overhead motion -and thence to the screw of the rest. Such an arrangement is shown -in <a href="#i-p106s">Fig. 158</a>. A is the fly wheel, B mandrel pulley, C, D, pulleys on -the overhead, E pulley and screw of the slide rest. To facilitate -calculation, let diameter of C equal that of the part of the mandrel -pulley that drives it, by which it will<span class="pagenum"><a name="Page_106" id="Page_106">[106]</a></span> revolve in the same time. The -calculation of the sizes of pulleys, D and E, will be the same as for -the cogwheels of the screw-cutting lathe, circumference and number -of cogs being, so far as calculation is concerned, the same thing. -Let the leading screw have eight threads to the inch, and let it be -required to cut a spiral of two threads to the inch. Proceed as before -by dividing the required number of threads to be cut by the number -on the leading screw 2-8 = ·25. The pulley on the leading screw will -be therefore one quarter the size of that on the overhead (which is -virtually that on the mandrel as it revolves at an equal speed with -the latter). The overhead pulley may be conveniently twelve inches -diameter, and that on the screw three inches. While the mandrel makes -one revolution the screw will make four, advancing the tool half an -inch, and cutting one thread of a spiral in that distance. The next -revolution will advance the cutter a second half inch, cutting a -second complete thread of spiral. Two threads will, therefore, have -been cut in the space of one inch as desired. By the above method -short screws and spirals of divers pitches may be cut at pleasure. -<i>The practical difficulty in this plan is due regulation of the -various speeds.</i></p> - -<div class="figcenter" id="i-p106s" style="width:285px;"> - <img - class="p2" - src="images/i-p106s.png" - width="285" - height="500" - alt="" /> - <p class="center smcap">Fig. 158.</p> - </div> - -<p>We here introduce a modification of self-acting lathe for cutting -Elizabethan twist described by Mr. Wilcox in his MS. before alluded -to. The work is here done by a leading screw and toothed gearing, the -principle being that of the ordinary machine lathe. A chuck, A, with -cogwheel attached holds the work as usual, the back centre being also -required. The cogwheel gears with one of less diameter attached to the -end of the guide-screw B. On the latter works the rest C, in which -is a nut of the same thread as that on the guide screw, and which -holds the tool in a notch or hollow upon its upper part. The tool is -then used by hand, but is guided in its course along the surface of -the work to be turned. This guide screw, with the rest and cogwheel, -is mounted on a board as a separate piece of apparatus, and is, when -used, clamped on the lathe bed. As the rest is after all little else -than a large nut, it must be prevented from turning round, and must be -arranged to bear the pressure of the tool, relieving the long screw -from the strain that would be thus caused. This is effected by a long -flat bar—like the rest of a chair maker's lathe—extending the full -length of the bed shown here at<span class="pagenum"><a name="Page_107" id="Page_107">[107]</a></span> E, and supported by standards F, F. A -projecting part of the rest bears upon this, and slides along it with -the tool. The work is begun with the rest on the right hand, and some -care is necessary as it nears the cogwheel on the left, when the work -must be stopped and the whole run back by hand to its starting-place. -This is one chief defect in this apparatus, for the rest very quickly -traverses the length of the screw, and great delay is caused by having -thus constantly to stop the lathe and reverse the motion. The closest -attention is also necessary to prevent the rest from overrunning its -mark and striking the cogwheel. It is evident that by using different -pitches of cogwheels, many screws of varied threads can be cut in the -above lathe. There is, however, another defect in the above tool not -noticed by the writer of the MS. from which the description is taken, -namely, the difficulty (common to all such contrivances for turning -wood), of obtaining the requisite speed. If the work is put in rapid -motion, without which wood will not be cut clean, the movement of the -rest will be so rapid also, from the effect of the multiplying wheel, -that the tool will be carried from end to end in a few seconds. We -will therefore proceed to describe a modification of this and similar -apparatus, which allows the tool a slow traverse lengthwise of the -work, but gives it immense rapidity in the necessary direction. The -following is applicable to the lathe described above, to the ordinary -slide rest worked by hand, or to the large self-acting screw-cutting -lathes used in manufactories, and is specially adapted for cutting -spirals or other patterns in wood. In the <a href="#i-p107bs">Fig. 160</a>, A represents a -shank,<span class="pagenum"><a name="Page_108" id="Page_108">[108]</a></span> which may be made of any shape to fit particular patterns of -tool holder. This shank is turned up and becomes a cylinder at B, like -that of the ordinary revolving cutter. This part is bored, and fitted -with a steel spindle, which should be of strength proportionate to -the size of stuff likely to be operated on. One end of the spindle is -fitted with a brass pulley, from which a cord is to be attached to the -overhead apparatus, the other end terminates in a round or hexagonal -boss, D, round the margin of which are securely held, by means of -bridles B<sup>1</sup> or other simple contrivance, a pair or more of small sharp -gouges. This apparatus is put in the tool holder of the slide rest, -set to the angle that corresponds with that of the screw or twist, -and put in rapid revolution by means of the overhead apparatus. The -whole rest, or merely the upper part, is then put in motion by one of -the before-named means, and the tool advanced to make a cut. However -slow the movement of the rest may be, the cutters move with such -velocity as to make clean and beautiful work.<a name="FNanchor_13_13" id="FNanchor_13_13"></a><a href="#Footnote_13_13" class="fnanchor">[13]</a> This may be applied -to the slide-rest of the twist lathe, just described, or any similar -apparatus. In the overhead, a roller, supplying the place of the -second pulley, as described in a previous page, will allow the second -cord sufficient power of traverse to keep up a proper position in -reference to the pulley C. Revolving cutters on the same principle as -the above, have of late years come into extensive use in wood-cutting -and carving machinery. The steam planes now used in the preparation -of flooring boards, the spoke turning lathe, moulding and shaping -machines for wood are all thus fitted. The gouges or other cutters -used must not be placed radially, but as tangents to the circumference -of the boss in which they are fixed. An improvement upon the simple -bridle to hold the cutters would be the substitution of Babbage's -tool holder, four radial arms being substituted for the metal boss -above alluded to. This tool is described and figured in Holtzapffel's -"Mechanical Manipulation," to which the reader is referred for an -accurate description. It chiefly consists of a shank turned up at the -end like <a href="#i-p107bs">Fig. 161</a>, the outside, at B, being rounded to fit hollow -gouges such as <a href="#i-p107bs">Fig. 161<sub>H</sub></a>; against this the hollow of the gouge is laid, -and opposite to it, at C, a small piece like D. A band or hoop, E, is -now placed over both the above, and between the two a wedge-shaped -piece, F, which is intended to bring a strain upon the hoop and -tighten it round the gouge. This last piece is attached to the shank -or holder by a screw passing through it into the shank. The tighter -this screw is worked the lower the central wedge is drawn down, and -the tighter the hoop is made to embrace the tool. This holder is also -modified to suit flat chisels. The tool cannot possibly slip, but -can be released in a few seconds if desired. Such a termin<span class="pagenum"><a name="Page_109" id="Page_109">[109]</a></span>ation of -two, three, or four arms revolving on a spindle in place of the boss -would form the best possible circular cutter for shaping lathes. The -above lathe for producing Elizabethan twist introduces the reader -to self-acting, screw-cutting, and machine lathes, such as are used -in all large manufactories. Hand-turning, indeed, except in such -light work as turning up the heads of small bolts, and finishing up -work which, from peculiarities of form, cannot easily be done by -self-acting tools, has become a thing of the past in factories of any -pretensions; hand labour, in fact, not only no longer pays, but is -quite insufficient to meet the requirements of the present age. Take, -for example, a piston-rod requiring to be as "true as a hair," to use -a common expression, from end to end. The traverse of an ordinary -slide-rest would only enable us to turn a short length at a time, -and the result, when accomplished, would not be satisfactory. With a -self-acting lathe the tool traverses in a perfectly straight line from -end to end, is returned to its starting-point by a quick traverse, and -the movement repeated until the proper dimensions are attained. The -process is not absolutely rapid, because time is requisite in cutting -iron and steel, but the work is executed as speedily as the nature of -the metal to be cut will allow, and the execution is perfect. Of late, -however, even the above has been improved upon, for two cutters are -used at once—one on each side of the bar, so that by one traverse -of the rest a cut of double depth is taken, and the tendency of the -work to spring away from one tool is counteracted by the operation of -the other. But we require something more than speed in the present -day. We must have work of absolute truth of measurement. What would -our ancestors, or the immortal Watt himself, think of measuring work -to the hundredth part of an inch, yet it can be and is done to the -thousandth part. I believe I am correct in saying that Whitworth -constantly gauges work to that or even a higher degree of nicety. It -is not too much to assert that the best engines of the present day -really work with the precision of clockwork, and even the bore of -an Armstrong or Whitworth gun is executed with no less accuracy and -precision. Look again at that ponderous affair, the steam hammer, -so ponderous as to require a depth of solid masonry and timbers to -sustain the force of its terrific blows. In a few minutes a solid -mass of metal is reduced to a flat plate such as would have taken the -united strength of a dozen men wielding the heaviest sledge-hammers -for an hour at least. The ground beneath the feet of the spectator -trembles at every blow of the machine. The work is done, and behold! -with a touch the same ponderous concern becomes a nutcracker, not even -injuring the kernel when it breaks the shell. Such is one of a hundred -specimens of accurate workmanship carrying out in practice the clever -designs of the mechanical engineer. Sweep away self-acting machinery, -and such work would become a simple impossibility. Again, so long as -turning, boring, planing, and such<span class="pagenum"><a name="Page_110" id="Page_110">[110]</a></span> work was performed by hand alone -(even after the introduction of the slide principle), an attendant was -required at each machine. Now that the latter is contrived to regulate -its own movements, one man at two or three lathes is sufficient. Thus -the same article that was once imperfect and costly, owing to the -demand on skilled labour, which was difficult to procure and at best -inefficient when procured, has now become cheap, and to all intents -and purposes perfect; and although the demand for such work increases -year by year, self-acting machinery being constantly improved and -simplified, enables the manufacturer to keep pace with the demand.</p> - -<div class="footnote"> - -<p><a name="Footnote_13_13" id="Footnote_13_13"></a><a href="#FNanchor_13_13"><span class="label">[13]</span></a> The spiral chuck for fine work in ivory and costly woods -is described in a later page.</p></div> - -<div class="figcenter" id="i-p107as" style="width:700px;"> - <img - class="p2" - src="images/i-p107as.png" - width="700" - height="235" - alt="" /> - <p class="center smcap">Fig. 159.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p107bs" style="width:700px;"> - <img - class="p2" - src="images/i-p107bs.png" - width="700" - height="215" - alt="" /> - <p class="center smcap">Figs. 160, 161.</p> - </div> - -<p>The advantages of self-acting machinery are of course chiefly confined -to the trade, and it is not often that the mere amateur requires such -aid. Indeed, the expense necessarily attendant on the fabrication of -these machines deters the great majority from making such a purchase.</p> - - -<h3 class="sc"><a name="SELF_ACTING" id="SELF_ACTING">Self-acting and Screw-cutting Lathes.</a></h3> - -<p>The first requisite for fitting up a lathe for screw-cutting and -plain turning is the fitting a guide-screw, and adding a saddle to -the slide-rest. But it must be observed that the ordinary mandrel of -small foot-lathes, which works in a collar and back centre, is not -convertible, and must be replaced by one working through two collars, -so that a part may project at the opposite end to that intended for -the chucks. On this projection various cogwheels have to be fitted. -Now there are divers patterns of mandrel suitable for the above -purpose; some are perfectly cylindrical, some have one conical part, -some are fitted with a second cone, independent of the mandrel, and -which slides upon it, and can be adjusted by means of regulating -nuts. This latter being a good pattern, when well constructed, we -shall first describe in detail. In <a href="#i-p110">Fig. 162</a> is shown A, the mandrel -complete, with fittings in section, but without any of the change -wheels. The cone <i>a</i> is forged on the mandrel, which then becomes -cylindrical. The cone is figured too large in proportion to size of -mandrel; the latter should be represented as much more substantial. -At <i>b</i> the second cone slides on, the latter shown again at B. It is -bored truly, and a slot cut to fit a feather on the mandrel. Thus it -will slide along it, but must necessarily turn with it. Beyond D on -the left are two screwed parts, one slightly larger than the other, -one being made with a left-handed, the other with<span class="pagenum"><a name="Page_111" id="Page_111">[111]</a></span> a right-handed -thread. On these screw the two nuts, <i>d, e</i>, which drive the movable -cone towards the right, causing it to fit more tightly into its -collar, and also by the same movement tightening the fixed cone in -its bearings. The mandrel is thus readily adjustable in the collars, -and can be made to run very truly and easily without shake or endlong -movement. Any pressure, however, against the front, such as would -be caused by drilling, would jam the front cone in its collar, and -tend to loosen the other. This is counteracted by the part <i>f, g</i>, -with its screw, <i>h</i>, against which the end of the mandrel bears. That -this form requires good workmanship is evident, for there are three -points, or bearing surfaces, to be brought into a correct line, and -the slightest deviation will cause the mandrel to jam in some part of -its revolution. The nuts screw up in opposite directions to counteract -the tendency in either to screw up more tightly, or to become looser -by the revolution of the mandrel. On the whole the above is a good -form of mandrel; if it has a fault, it is a slight tendency to work -heavily. The next form is that of the ordinary mandrel, with single -cone, but a second collar is added, which is cylindrical, through -which the mandrel passes, and it then abuts on the sustaining screw -as before. This is shown in <a href="#i-p111a">Fig. 163</a>, with the addition of the wheel, -which is to be connected by intermediate wheels and pinions with the -leading screw. If the conical collar is replaced by a cylindrical -one, so that two similar bearings are made use of, a shoulder becomes -necessary to prevent the mandrel from slipping endwise. The collars -must also be split as in <a href="#i-p111a">Fig. 164</a>, so that they can be tightened up as -they become worn. Either of the above forms of mandrel can be used; -each has its advocates, and not unfrequently all may be found in -different machines in the same manufactory. The bed of a self-acting -lathe requires to be accurately surfaced, and formed by the planing -machine with two <span class="sans">V</span>'s or edges bevelled underneath, as <a href="#i-p111b">165</a> <i>b, b</i>. The -saddle of which we have spoken is a flat plate of cast iron fitted -with <span class="sans">V</span> pieces to match the bevelled edges of the lathe bed, along -which it slides truly, its under-edge being planed.<span class="pagenum"><a name="Page_112" id="Page_112">[112]</a></span> To this plate the -slide rest is attached securely, either turning when required on a -central pin, and being clamped at any desired angle, as before stated -when treating of the compound slide rest, or, when this movement -is preferred to be given to the upper slide, fixed permanently by -nuts and screws. The saddle is represented detached in <a href="#i-p112a">Fig. 166</a>. The -principle of the self-acting lathe is very simple. Motion is given -to the screw by means of cog wheels geared with the mandrel, a nut -fitting the screw is attached to a hanging bracket of the saddle, and -this with the rest is thereby carried along the bed. It is necessary, -however, to add some contrivance for instantly throwing the screw out -of gear, without the necessity of stopping the lathe itself. There -are many ways of effecting this, the most common being the use of a -split nut, which embraces the leading screw when the two halves are -brought together upon it, but which is instantly freed by separating -them through the action of levers and cams, or other simple mechanical -contrivance. In <a href="#i-p112b">Fig. 167</a>, <i>a</i> is the bottom of the saddle from which -depend the brackets E, E. The nut B, B, which is divided across the -middle, slides up and down between these brackets, D being the leading -screw which they embrace when closed. The movement of the halves of -the nut is effected by the lever <i>c</i>, in the form of the letter T -moving on a centre pin at K, and having two links, D, D, attached to -the halves of the nut at one end, and to the ends of the cross lever -at the other. A connecting bar pivoted to the part, L, is attached -to a lever and handle, by which motion is communicated to the lever. -When this rod is moved in the direction of the arrow the links will -cause the nut to close and <i>vice versa</i>. The next form, <a href="#i-p113as">168 and 169</a>, -represents the split nut attached to two arms, A, A, hinged together -at E. B, B, are slots in which work the pins attached to the cross -head of the levers C, C. A heavy knob of iron keeps the latter in -the position to which it may be moved. In <a href="#i-p113as">168</a> the pins keep the arms -and nuts apart. When the lever is thrown over, as in <a href="#i-p113as">169</a>, the nut -is securely closed and held in gear. This form requires to be fixed -to the lower part of a bracket attached to the saddle of the slide -rest, such as is shown at B, C, <a href="#i-p113bs">Fig. 170</a>. In this figure, A is the -bottom of the saddle E, E, the <span class="sans">V</span> piece, that on the left, having an -adjusting screw to tighten it on the lathe bed when necessary. At<span class="pagenum"><a name="Page_113" id="Page_113">[113]</a></span> F -is a projecting piece of the saddle fitting accurately between the -lathe bed, and kept down by a screw with bed plate underneath. This -serves to steady the movement of the saddle and relieve the pressure -and strain upon the <span class="sans">V</span> pieces. The bed-plate may be cut out to fit the -lower part of the bed on which it slides, both being planed for the -purpose, as shown at H.</p> - -<div class="figcenter" id="i-p110" style="width:414px;"> - <img - class="p2" - src="images/i-p110.png" - width="414" - height="321" - alt="" /> - <p class="center smcap">Fig. 162.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p111a" style="width:550px;"> - <img - class="p2" - src="images/i-p111a.png" - width="550" - height="254" - alt="" /> - <p class="center smcap">Figs. 163, 164.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p111b" style="width:378px;"> - <img - class="p2" - src="images/i-p111b.png" - width="378" - height="235" - alt="" /> - <p class="center smcap">Fig. 166.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p112a" style="width:350px;"> - <img - class="p2" - src="images/i-p112a.png" - width="350" - height="215" - alt="" /> - <p class="center smcap">Fig. 165.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p112b" style="width:500px;"> - <img - class="p2" - src="images/i-p112b.png" - width="500" - height="241" - alt="" /> - <p class="center smcap">Fig. 167.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p113as" style="width:500px;"> - <img - class="p2" - src="images/i-p113as.png" - width="500" - height="411" - alt="" /> - <p class="center smcap">Figs. 168, 169.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p113bs" style="width:700px;"> - <img - class="p2" - src="images/i-p113bs.png" - width="700" - height="349" - alt="" /> - <p class="center smcap">Figs. 170, 171.</p> - </div> - -<p>In <a href="#i-p113bs">Fig. 171</a> the half nuts slide up and down on the front of the -saddle, and are moved by a circular plate on the outside. The action -is very similar to that of <a href="#i-p112b">Fig. 167</a>, intervening links, attached to -the plate and to the halves of the nuts, giving motion to the latter -as required. Cams and eccentrics of varied forms are also made use -of for the same purpose, every lathe maker devising new and improved -movements from time to time. There is indeed little difficulty in -arranging a satisfactory method, the best being that which is under -easy control, of adequate strength, and not likely to be easily -disarranged by the rough treatment it is liable to receive at the -hands of the workman. The leading screw may either be placed on the -outside, in front of the bed next to the workman, or inside between -the bearers. The former is preferable as being more accessible, but -it is rather more exposed to injury. When between the bearers the -large saddle of the slide rest serves to protect it from the falling -chips and shavings of metal which,<span class="pagenum"><a name="Page_114" id="Page_114">[114]</a></span> mixing with the oil, are apt -to clog the threads and add to the friction of the parts, besides -increasing considerably the wear and tear, and no accidental blow is -likely to reach the screw thus protected on both sides by the lathe -bed. Nevertheless, all the various parts of a machine should be made -as accessible as possible, and, with the exercise of ordinary care in -its preservation, the position outside is on the whole the best. If -the lathe bed is very long, it may be desirable to support the screw -by allowing it to rest on friction wheels fixed to the saddle at both -ends, or by allowing it to pass through a pair of brasses. Thus, as -the saddle is often two feet in length, such bearings at each end, -with the split nut between the two, form points of support which go -far to prevent the screw from jagging or bending in the middle from -its own weight.</p> - -<p>The general arrangement of self-acting tools is similar with all the -makers. <a href="#i-p115s">Fig. 172</a> is a drawing of such a tool from a sketch of Eades & -Son, an old firm in Lichfield-street, Birmingham, the screw being here -placed in front. Whitworth, the eminent mechanician of Manchester, -makes many lathes with the screw between the beds. He also uses a -double slide rest, with a tool working at each side of the piece to -be turned, which cannot thus spring away from the cut. This is called -a duplex slide rest. By this method double the cut is taken, and the -strain upon the work lessened. In addition to the screw there is -usually a rack attached to the lathe bed, on the furthest side, and a -cog wheel working upon this, attached to the back of the slide rest -saddle, is turned by a handle in front of the rest, <a href="#i-p116">Fig. 173</a>. This -enables the workman, after having, by means of the screw, completed -the cut to the end of the work, to run the rest back again very -quickly, having first released the split nut from the screw. The tool -is thus brought into position for the next cut far more rapidly than -could be managed by reversing the motion of the screw. This is called, -therefore, the quick return motion, and is almost always attached to -the larger class of machine-lathes. Before entering upon the details -of other forms of gearing, and the arrangement of change-wheels for -cutting screws or for plain turning, we shall introduce a few remarks -upon the often-repeated question as to the advisability of self-acting -lathes for the purposes of the amateur. It must be remembered that -the chief object of such a lathe is the manufacture of large screws, -long shafts, and such work as the piston rods of engines, requiring -perfect accuracy from one end to the other. Boring cylinders and -similar work is now generally done in an upright or vertical boring -machine, which is for many reasons more convenient. This class of<span class="pagenum"><a name="Page_115" id="Page_115">[115]</a></span> -work, of course, the amateur has nothing to do with. The traverse of -an ordinary slide rest is generally adequate for surfacing or boring -to a length of six inches, which is sufficient for most purposes, and -can readily<span class="pagenum"><a name="Page_116" id="Page_116">[116]</a></span> be done by turning the leading screw of the rest by -hand. Then, as regards screw cutting in the lathe, it is questionable -whether it is not easier to turn up the blank and cut with stock and -dies. The thread thus formed is a copy of that of the tool, and the -latter, as made by Whitworth and other first-class makers, is as -perfect as machinery directed by talented workmen can produce. If -it is really desirable, however, to make use of the lathe for this -purpose, the plan already suggested is generally applicable, namely, -gearing the leading screw of the slide rest to the mandrel, either -by means of change-wheels attached to an arm, or by connection with -the overhead pulleys. There is, in addition, a plan of attaching a -pair of dies to the tool holder of the rest, after detachment of -the screw from its nut, which may be available in some cases. There -are also screw plates made in two halves, the plates being divided -lengthwise and clamped together at pleasure, admitting of application -to any screw-blank while revolving in the lathe; and, lastly, pairs -of dies, fitted like pliers, can be similarly used by hand without -any slide rest. On the whole, then, it will hardly pay to give £50, -or £60, for a screw-cutting lathe that is merely destined for small -work; that can be done sufficiently well in a common lathe with -hand motion to the rest. For cutting short screws, such as those of -boxes, a convenient and practically useful contrivance is still a -desideratum. The traversing mandrel is, no doubt, the best, but it is -an expensive pattern, if well made, and it is necessary to sacrifice, -in a measure, general utility to questionable and certainly partial -advantage. Turning is, moreover, an art, and to attain skill in it, -perseverance and practice are necessary—hence the zest experienced -in its pursuit by the real lover of it. This perseverance pays, and -to attain the skill required to trace a short screw with the chasing -tool is within the reach of any one who desires to accomplish it. The -art once acquired, the desire for a traversing mandrel ceases; for -no good workman would accept a contrivance of the kind when he can -more easily and quickly accomplish his end without it. Writing this -for the special benefit of amateurs, we would strongly advise them -not to throw away money to purchase the means of doing what after -all they will probably never, and certainly only seldom, carry into -practice. The pleasure afforded by all the mechanical arts is greatly -enhanced by meeting with and triumphantly surmounting all sorts of -difficulties. Let it be a standing rule of our readers to make use -of the appliances at hand instead of seeking others which only save<span class="pagenum"><a name="Page_117" id="Page_117">[117]</a></span> -trouble and render skill unnecessary. What can be more aggravating -than for an amateur, with his hundred guinea lathe and chests of -tools, to be obliged to take his work to a mechanic, and to see him, -whose whole stock might be bought with perhaps a tenth part of the -money, take in hand and finish with ease what has baffled the skill -of his more wealthy patron? The common fault of the amateur is undue -hurry. To him time is seldom an object, yet the mechanic, to whom it -is so precious, readily spends more upon his work. He never hurries, -never compromises, but with lathe and file fits the several parts of -his work with the most patient care and practised skill. The result is -at once seen when his productions are placed side by side with those -of the zealous but too hasty amateur.</p> - -<p>It remains, as previously described, to arrange certain cogwheels -gearing with each other upon the spindle of the mandrel and upon the -end of the screw, to enable the workman at pleasure to vary their -ratio of speed, in order to give him the means of regulating the -pitch of thread to be cut. For this purpose a set of change wheels is -supplied with the screw-cutting lathe, the number of cogs in which -usually commencing at fifteen, increase by five, until the number -one hundred and twenty is reached, then increasing by ten up to the -complete set. Duplicates of some numbers are also convenient. The -method of finding the proper sized wheels is, of course, based upon -the proportion borne by the required pitch to that of the leading -screw and one form of calculation for the purpose has already been -given. Thus, supposing the leading screw to have two threads to the -inch, it must revolve twice to move the tool that distance, and if -we wish to cut a screw of ten threads to the inch, the work on the -mandrel must revolve ten times while the leading screw revolves twice, -or, which is the same thing, the mandrel must revolve five times while -the screw revolves once. The cogs in the wheels must therefore be in -the proportion of five to one, say fifty on the screw and ten on the -mandrel, with an idle wheel on the stud to cause the motion of the -tool to be such as will cut a right-handed thread, or to cause the -mandrel and screw to take the same direction. Now, it seldom happens -that two wheels and an idle one will give the requisite speed to the -tool, and the number of cogs required soon mounts to inconvenient -numbers. In this case, therefore, according to a principle already -laid down, a stud-wheel with a pinion attached to the same, is -placed in the train of wheels, and the object readily attained. A -modification of the rule of calculation may make the system of change -wheels still clearer. Let the pitch of guide screw be as before, -namely, two threads to the inch, and let five be required. Place the -numbers thus, 2-5, and divide both into their factors, twice one, or 2 -× 1, and twice two and a half, or 2½ × 2.</p> - -<p><span class="pagenum"><a name="Page_118" id="Page_118">[118]</a></span></p> - -<div class="fraction"> -2 1 -<span class="bar">/</span> -<span class="fdn">2½..2</span> -</div> - -<p> Now, it is certain you can have no wheels containing half notches, nor -of such small numbers of cogs, therefore multiply by any convenient -numbers—ten, for instance, which give</p> - -<div class="fraction"> -20..10 -<span class="bar">/</span> -<span class="fdn">25..20</span> -</div> - -<p> This is all that is needed. Put a wheel of twenty -cogs on the mandrel, and let it work into one of twenty-five on the -stud, the latter carrying a pinion of ten cogs, driving one of twenty -cogs on the screw. To prove this, as before, the screw must make two -revolutions to carry the tool one inch, and during that time the -mandrel (carrying screws to be cut) must make five revolutions. Let -the screw wheel revolve twice, the pinion of ten teeth will revolve -four times (twice 20 = 40 and four times 10 = 40); but as the stud -wheel and pinion are as one, and revolve together, the stud wheel -must also revolve four times (4 × 25 = 100). Thus the mandrel wheel -will revolve five times as required (20 × 5 = 100). No other method -is so easy to understand and work as the above. To give full details -and provide working drawings of the various screw cutting lathes -by different makers would be to extend the present series to an -unnecessary limit, but we shall nevertheless describe another method -by which these lathes with traversing rests are made self-acting when -screw cutting is not required. Instead of a leading screw extending -from one end of the lathe to the other, there extends a bar of steel -about the diameter of the screw with a key groove or slot from end -to end. This bar is supported in bearings at each end, and carries -upon its surface a ferrule of steel with a screw cut upon its outside -similar to <a href="#i-p118s">Fig. 174</a>, where A is the bar and B the ferrule. The pitch -of screw is coarse, being similar in its object to the guide screw -previously described. A pin fixed into this ferrule falling into the -slot permits<span class="pagenum"><a name="Page_119" id="Page_119">[119]</a></span> it to travel along the bar but causes both to revolve -together when the bar is put in motion by means of a cog wheel or -strap pulley at one end. Along the same side of the lathe bed, and -level with the surface, is a rack, C, upon the face of which works a -pinion, D, carrying on the same axis a cog or rather worm wheel, E, -to gear with the screw ferrule. The bearings of this axis are secured -to the saddle of the slide rest. Consequently, when the bar revolves, -the screw is also put in motion, the wheel, A, <a href="#i-p119as">Fig. 175</a>, and pinion, -B, partake of the movement, and the latter traverses the face of the -rack, carrying the saddle with its rest and tool holder along the bed -of the lathe. By this movement the screw ferrule traverses the bar as -it revolves, thereby virtually becoming a long leading screw. In <a href="#i-p119bs">Fig. 176</a>, -which is a view from above, looking down upon the lathe bed, A -is the rack, B, B, the saddle cut away to show the rack and pinion C; -E is the worm wheel, D the long bar, the screw ferrule, being under -the worm wheel, is not visible. As above arranged it is evident that -the ferrule might escape from the worm wheel instead of proceeding on -its proper course. This is prevented by its lying in the hollow of -a bracket attached to the rest, as <a href="#i-p119as">Fig. 177</a>, A and B. This retains -it in contact with the worm wheel, and<span class="pagenum"><a name="Page_120" id="Page_120">[120]</a></span> also becomes a support to -the long bar. <a href="#i-p118s">Fig. 174</a> shows the side of the lathe that is furthest -from the operator. The axle of the worm wheel and pinion carries a -handle on the near side to give the workman power to use the rack by -hand as a quick return movement. The above is frequently attached to -those lathes provided with a long screw, the latter being on the near -side and the bar on the other. Thus, the same lathe can be used for -ordinary or screwed work. Whitworth, however, commonly uses the long -screw placed between the beds or bearers of the lathe for screwing -and surfacing, instead of adding the apparatus just described. A long -screw being, however, an expensive affair, ought to be carefully -cherished, and when the work is such as the bar will suffice to -accomplish, it may be well made use of to preserve the screw. There is -an arrangement for forward or cross-feed in the above apparatus, the -principle of which is the connection of the cross screw of the rest -by means of a pinion, either with the worm wheel or with a cogwheel -on the same axle. When this is put into gear the rack and pinion are -disconnected. It is also necessary to provide a method of reversing -the motion of the long screw bar, especially when the cross feed is -used in surfacing. There are several modes of accomplishing this, -the best being the following, <a href="#i-p120">Fig. 178</a>, which is a simple expedient -applicable to lathes or other machines. A is the end of the screw rod, -with bevel wheel attached, B, C, are similar wheels on the axle, D, -the latter being movable endwise in its bearings by means of the lever -handle; E, D, is the driving axle. By moving the lever to the right -B is geared to A. A movement to the left brings C into connection. -Between the two, both wheels are thrown out of gear, and though they -may continue to revolve, the screw bar will remain still. By this -contrivance the motion of the leading screw is reversed or stopped -in a second, with the advantage of its being unnecessary at the same -time to stop the working of the lathe altogether. It has probably -struck the reader that as the size of the change wheels are various, -there would be in some cases an impossibility of their touching so -as to gear together. This is partly remedied by the interposition of -dummies, or idle wheels, and partly by the following arrangement. The -stud wheel, or dummies, as the case may be, are not upon axles fixed -to the lathe-head or end standard, but upon such an arm as <a href="#i-p121">Fig. 179</a>, -which turns upon a pin at A, and carries in the slot the pins<span class="pagenum"><a name="Page_121" id="Page_121">[121]</a></span> upon -which the different wheels centre. These pins being made similar to B, C, -can be placed at any position in this slot, and are fixed by a nut -underneath. This arrangement gives considerable power of adjustment, -and enables the workman to place together wheels of various sizes -according to his need. It would not be by any means difficult to -arrange the above lathe for screw-cutting, especially if the pitch -of the required screw is not of great importance. An amateur's lathe -might be thus fitted to serve a good many purposes, although a leading -screw is to be preferred as the more complete and perfect arrangement. -It cannot, however, be denied that there is great friction produced -by the worm wheel and endless screw, which soon tells its own tale by -the wear and tear produced, and the power is not so economically used -as it is when the screw works in a nut. Expediency, however, in this, -as in many similar cases, must decide for or against the arrangement -in any particular case. It is, at any rate, a good addition to a -lathe provided with an ordinary leading screw, more especially in the -facility with which it can be arranged as a self-acting cross-feed to -the rest when used for surfacing.</p> - -<div class="figcenter" id="i-p115s" style="width:700px;"> - <img - class="p2" - src="images/i-p115s.png" - width="700" - height="289" - alt="" /> - <p class="center smcap">Fig. 172.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p116" style="width:446px;"> - <img - class="p2" - src="images/i-p116.png" - width="446" - height="323" - alt="" /> - <p class="center smcap">Fig. 173.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p118s" style="width:700px;"> - <img - class="p2" - src="images/i-p118s.png" - width="700" - height="355" - alt="" /> - <p class="center smcap">Fig. 174.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p119as" style="width:700px;"> - <img - class="p2" - src="images/i-p119as.png" - width="700" - height="252" - alt="" /> - <p class="center smcap">Figs. 175, 177.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p119bs" style="width:700px;"> - <img - class="p2" - src="images/i-p119bs.png" - width="700" - height="403" - alt="" /> - <p class="center smcap">Fig. 176.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p120" style="width:476px;"> - <img - class="p2" - src="images/i-p120.png" - width="476" - height="410" - alt="" /> - <p class="center smcap">Fig. 178.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p121" style="width:537px;"> - <img - class="p2" - src="images/i-p121.png" - width="537" - height="367" - alt="" /> - <p class="center smcap">Fig. 179.</p> - </div> - -<h3 class="sc"><a name="WHEEL_CUTTING" id="WHEEL_CUTTING">Wheel Cutting in the Lathe.</a></h3> - -<p>Among the various uses to which a lathe may be put, wheel-cutting -is one of the most important, so many pieces of mechanism requiring -cogged wheels of various pitches and forms of tooth. By the aid of -the slide rest such an apparatus as figured may be readily arranged, -and the work rapidly and accurately performed. The guide by which the -cogs and spaces are determined is the division plate already alluded -to, and which is not visible in the present drawing, but the index of -which is shown at G. C is the cutter frame with a side pulley (one on -each side) to conduct the catgut band from the revolving spindle to -the overhead motion on to the flywheel. The spindle carries a pulley -for the cord and a cutter wheel, I, to which an exceedingly rapid -evolution is given. There are many patterns of these wheels, the edges -of which, cut into teeth like a fine saw or file, are the exact form -of the spaces required between the cogs; hence, some are rectangular,<span class="pagenum"><a name="Page_122" id="Page_122">[122]</a></span> -some have a triangular section. The thicker the wheel to be cut the -larger should be the cutter, so that the bottom of the cut may be -virtually level.<span class="pagenum"><a name="Page_123" id="Page_123">[123]</a></span> In <a href="#i-p122s">Fig. 181</a> another form of cutter is shown, which -if put into sufficiently rapid motion answers as well, if not better, -than the wheel-shaped cutters. It is a simple short bar of hard steel, -with the edges bevelled in alternate directions, fitted into a slot -in the spindle and held by a wedge or screw. The shape of the end is -as before, a cross section of the space between two teeth. The cutter -frame is here arranged to fit into the ordinary tool-holder of the -slide rest, but the form may, of course, be varied at pleasure. It -will be noticed that the slide rest, as delineated here, is different -to that of which details have been given. It is made without the sole, -and fits into the socket of an ordinary rest. Thus it can be turned -on a centre, and becomes, to all intents and purposes, a compound -slide rest. It is on this plan the small ornamental turning rest of -lighter construction is made. The spindle fitting the socket projects -from the centre of the lowest frame, and is cast in one piece with it. -If the apparatus is compactly and strongly made, it becomes a very -serviceable form, and is much used for the small lathes in sea-going -steamers. The sides are made very short, so that the extent of -traverse is small. We may here mention an addition to the rest socket, -enabling the workman to raise this kind, or that used with drills and -cutters, which is simple and convenient. Inside the iron socket a few -turns of a screw are cut, and a second socket of brass with an outside -thread is made to fit into it Figs. <a href="#i-p123">182 A and B</a>, the latter being a -section. The edge of the inside socket is sometimes milled round, to -facilitate holding it by the thumb and finger. In this way the height -of the slide rest, or tee of the common rest, is adjustable to a great -nicety.</p> - -<div class="figcenter" id="i-p122s" style="width:700px;"> - <img - class="p2" - src="images/i-p122s.png" - width="700" - height="532" - alt="" /> - <p class="center smcap">Figs. 180, 181.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p123" style="width:550px;"> - <img - class="p2" - src="images/i-p123.png" - width="400" - height="276" - alt="" /> - <p class="center smcap">Fig. 182.</p> - </div> - -<p>When a wheel is to be cut of large size, or of substance exceeding -that of clock-wheel work, the above method is not suitable. The wheel -is then generally laid flat, and the cogs are shaped by a slotting -machine, the chisel of which has a vertical motion. The lathe is -then no longer used; as a separate machine is more convenient and -economical.</p> - -<p>A most serviceable addition to a lathe, especially an amateur's foot -lathe, is the circular saw, with guides for cutting parallel, taper, -or mitred work. Great rapidity of work is thus combined with perfect -accuracy. A five-inch lathe will of course take a saw nearly ten -inches diameter, but it is not advisable to attach one of quite this -size, for the larger the saw the greater is the leverage against which -the turner has to contend, and<span class="pagenum"><a name="Page_124" id="Page_124">[124]</a></span> the friction caused by a deep cut in -stuff of two inches diameter is quite sufficient to make the labour -considerable. When such work is necessary, it must be very gently -brought to bear upon the saw, and the flywheel of the lathe should -be heavy. The cord should also pass from the latter to the slowest -division of the pulley. If the workman, amateur or professional, -desires a lesson in practical mechanics, he has nothing to do but turn -a piece of ash six inches in diameter, with the lathe-cord extending -from the flywheel to the smallest part of the pulley, the diameter of -which is about half that of the object to be turned. This will teach -him what hard work is. Then let him try the job with the cord, from -the smallest part of the flywheel rim, to the largest diameter of -pulley. The change to a slower motion and greater power will not be -disagreeable. It must be remembered that a circular saw of six inches -diameter will not penetrate three-inch stuff, owing to the boss or -nut by which it is attached to its spindle. The above size will not -make good work of stuff exceeding two inches in thickness, and even -less thickness would be preferable. As to the size of saw, indeed, -that is most suitable to a five or six-inch foot lathe, much depends -upon the proposed work, and still more upon the weight and size of -the flywheel. As a general rule it is better to err upon the size -of smallness. The service to which this tool is commonly put is but -light; sawing narrow strips of mahogany, such as used at the angles -of bird-cages, cutting strips or segments of ivory (for which let the -saw be kept wet) sawing out mitred or dovetailed joints, and similar -work is within the compass of a five or six inch saw, and it is better -not to exceed this. The teeth should be tolerably fine for hardwood -and ivory, and coarser for deal and soft woods. Smaller saws of hard -steel, and made of thick plate, are used for metal.</p> - -<div class="figcenter" id="i-p124s" style="width:700px;"> - <img - class="p2" - src="images/i-p124s.png" - width="700" - height="243" - alt="" /> - <p class="center smcap">Figs. 183, 184.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p125" style="width:699px;"> - <img - class="p2" - src="images/i-p125.png" - width="699" - height="422" - alt="" /> - <p class="center smcap">Fig. 184, 185.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p126" style="width:379px;"> - <img - class="p2" - src="images/i-p126.png" - width="379" - height="500" - alt="" /> - <p class="center smcap">Fig. 184A.</p> - </div> - -<p>The method of mounting saws of small size, such as are suited to be -worked by the treadle of a foot-lathe, is shown in <a href="#i-p124s">Fig. 183</a>. E is -a steel spindle, of which the diameter equals that of the central -hole in the saw B. At F, about the middle of the spindle, is a fixed -flange, at the base of which is a short feather or inlaid key, X <a href="#i-p125">184</a>, -which fits the small slot seen in the centre of the saw and<span class="pagenum"><a name="Page_125" id="Page_125">[125]</a></span> reaches -also within a similar slot in the movable flange, G, but it must not -be so long as to come through to the back of the latter. This flange -and nut H having been removed, the saw is slid upon the spindle till -it rests against the fixed flange; the movable one is now to be -brought against it and clamped by the nut. The spindle is sometimes -made with a square end to fit the square hole chuck, and centred at -the other, or it is drilled at both ends, so as to be driven by the -carrier or driver chuck, C, D. It must be so placed as to run towards -the operator. The above arrangement must now be made complete by -the addition of a platform, B, on which to lay the work that is to -be sawn, and on which some contrivance can be adjusted to guide the -passage of the saw through the same, so as to cut the work in parallel -pieces, or at any desired angle, such as would be necessary for mitred -joints. For the general uses of the amateur a mahogany or hardwood -platform is as good as any, and such as is delineated in vol. ii. -of Holtzapffel's valuable work is perhaps the best arrangement. The -saw table rests on the opposite ends of a kind of open box, which -is represented without the two sides, although they may be added if -desired, and the whole when removed from the lathe would then form a -case for the saws, or serve other similar purpose. The platform is -hinged, so as to overlap, as seen in the <a href="#i-p126">Fig. 184<sub>A</sub></a>, and there -is in the middle of it a slit cut by the saw itself, which, when it -is mounted on its centres will be in the position shown. If sides are -added a notch must be made in the upper edge of both for the passage -of the spindle. The fillet B fits between the bearers of the lathe, -securing the parallelism of the whole. When made with four sides the -box must first be placed on the lathe bed and loosely held by the bolt -beneath. The saw is then mounted, and the box adjusted to its place -and fixed. The cover is then (if for the first time) brought carefully -down upon the saw, and the lathe being put in motion the slit is made, -and its position will be truly at right<span class="pagenum"><a name="Page_126" id="Page_126">[126]</a></span> angles with the spindle and -the lathe bed. Of course, in future operations the platform is lowered -over the saw before the holding down bolt is permanently screwed -up. The sides of the saw-kerf may be edged with brass if preferred, -but on the whole the plan is not to be recommended, for if, as will -occasionally happen, the saw should get slightly out of truth, or -vibrate a little when in use, the teeth will come into contact with -the metal and be blunted or broken. If the saw-kerf by constant wear -should widen too much, the whole platform is renewable at little -cost, or a new piece can be let in, and a fresh saw-kerf made. There -are several guides for parallel work. The one shown in <a href="#i-p125">Fig. 185</a> is -precisely such as is to be seen in the ordinary parallel ruler—A is -the back bar screwed to the platform at the right-hand edge; B the -guide or fence which, when the connecting links C, C are perpendicular -to A, should touch the saw; D, D are arcs of circles of which E, E -are the centres. They may be arcs of brass pivoted to the links and -passing through a slot in the bar, A, A, or may themselves be cut as -mortises in the platform, in which fit a pair of bolts with thumb-nuts -passing through the links, by which to clamp the fence in any desired -position. This form of parallel guide is not very substantial, and is -not correct in practice unless the pins are very nicely fitted, and -the links precisely of a length. The second figure shows the sectional -form of the fence G, the links being represented at H, and the fixed -bar at K. The following is a more solid and unyielding guide, and -much to be preferred. Holtzapffel attributes it to Professor Willis. -It is merely a modification of the T-square as used with the ordinary -drawing board with an arrangement for fixing it in the required -position. The present arrangement differs from that in Holtzapffel's -work in the manner of fixing it and the addition of a second T-piece -on the side next the workman. In <a href="#i-p127a">Fig. 186</a> A is the upright part of -the fence, B the bottom or sole, to which is attached at each end -the T or cross pieces, E, E, which slide along the straight edges of -the platform and secure the constant parallelism of the fence to the -surface of the saw; C is the groove or slot, in which a screw, D, -traverses, and the fence is thus fixed by a turn of the thumb-nut, -D. This fence can by no possibility get out of truth; it is easily<span class="pagenum"><a name="Page_127" id="Page_127">[127]</a></span> -removed by taking out the single screw, and it is far more simple and -more easily made than the one previously described. The nearest edge -of the platform may be marked in inches and eighths, and the fence -can then be instantaneously adjusted for sawing pieces of any desired -width. It is not always, however, that straight, rectangular, or -parallel strips are required, and an additional arrangement is needed -to form a guide for sawing angular pieces. Now it is not sufficient to -lay the guide fence at a given angle, for if the latter were arranged -for that adjustment by taking off the tees and causing it to turn -upon the screw which secures it in place, and a piece of board were -placed against it to be sawn, the latter would press against the saw -sideways as seen in <a href="#i-p127b">Fig. 187</a>. The guide fence for angles must itself -therefore travel in a line parallel to the saw and carry with it the -piece to be cut. The simplest and usual arrangement is that given -in Holtzapffel's work. A dovetailed groove in the platform running -in a direction parallel with the saw carries a sector attached to a -bar which fits the groove, and this bar is free to move forward or -backward without lateral movement. The piece to be sawn is thus rested -against the fence forming the straight face of the sector, and the -whole is moved forward together against the edge of the saw. <a href="#i-p127c">Fig. 188</a> -explains this. It will be seen that several grooves are made side -by side, all of which fit the slide alike, and by moving the latter -into either of these a lateral adjustment is effected to suit pieces -of different widths. The sliding strip<span class="pagenum"><a name="Page_128" id="Page_128">[128]</a></span> should be made of hard wood -and nicely fitted, and may be lubricated with soap, or polished with -black lead, either of which will cause it to slide with diminished -friction. <a href="#i-p128a">Fig. 189</a> shows a somewhat different arrangement, by which -more lateral adjustment may be given. The sector is replaced by a -T-square, the blade of which has a slot through which a screw passes -into the sliding bar. A second jointed rod is added, passing through -a staple in the slide, and by a screw in the latter the T is fixed as -required. The staple must turn on a centre to accommodate itself to -all positions of the T-square, and a second eye may be placed on the -opposite arm to allow the guide rod to be removed to that side, which -is sometimes more convenient. The sector also may be made adjustable -as in <a href="#i-p128b">Fig. 190</a>, and clamped by a simple screw in the slot. Either of -the above methods will allow sufficient range for small work, such as -is likely to be the object of amateurs or those who add small saws to -the foot lathe. The guide for angular pieces may indeed be in many -cases dispensed with by making use of patterns of wood chiefly in -the form of triangles; these sliding against the parallel guide, and -carrying the work with them, will answer well in a number of cases -where other provision for such work has not been made in arranging -the saw table. It must be remembered, however, that in this case the -length of the piece (supposing it to be the side of a picture frame -to be mitred) is limited to the space between the fence and the saw, -which in the more perfect arrangement is an evil plainly avoided. -It may sometimes be necessary to cut pieces with various angles not -in the same plane. By using the hinged platform, and adding a screw -attached to the front of the box, and standing perpendicularly, the -front of the table can be raised to a given angle, but those who are -likely to enter extensively into the cutting mathematical figures -are referred to vol. ii. of Holtzapffel's work, where the subject is -fully explained and illustrated. The following remarks upon the proper -speed of saws and sizes of teeth are copied from that work, and may -therefore be relied on:—</p> - -<blockquote> - -<p>"The harder the wood the smaller and more upright should be the -teeth, and the less the velocity of the saw.</p></blockquote> - -<p><span class="pagenum"><a name="Page_129" id="Page_129">[129]</a></span></p> - -<blockquote> - -<p>"In cutting with the grain the teeth should be coarse and -inclined, so as rather to remove shreds than sawdust.</p> - -<p>"In cutting across the grain the teeth should be finer and more -upright, and the velocity greater, so that each fibre may be cut -by the passage of some few of the consecutive teeth rather than -be torn asunder by the passage of one tooth only.</p> - -<p>"For gummy or resinous woods and ivory, the saw teeth must -be keen, and the speed comparatively slow, to avoid the -dust becoming adhesive (by reason of the heat engendered by -friction), and thus sticking to, and impeding the action of the -saw."</p></blockquote> - -<div class="figcenter" id="i-p127a" style="width:678px;"> - <img - class="p2" - src="images/i-p127a.png" - width="678" - height="423" - alt="" /> - <p class="center smcap">Fig. 186.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p127b" style="width:450px;"> - <img - class="p2" - src="images/i-p127b.png" - width="450" - height="333" - alt="" /> - <p class="center smcap">Fig. 187.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p127c" style="width:450px;"> - <img - class="p2" - src="images/i-p127c.png" - width="450" - height="253" - alt="" /> - <p class="center smcap">Fig. 188.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p128a" style="width:461px;"> - <img - class="p2" - src="images/i-p128a.png" - width="461" - height="335" - alt="" /> - <p class="center smcap">Fig. 189.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p128b" style="width:400px;"> - <img - class="p2" - src="images/i-p128b.png" - width="400" - height="187" - alt="" /> - <p class="center smcap">Fig. 190.</p> - </div> - -<p>By raising the platform so as only to expose a small portion of the -saw, it is easy to cut rebates, grooves for tongueing, and other work -of a similar kind. The above arrangement of hinged table facilitates -this application of the saw.</p> - - -<h3 class="sc"><a name="FRET_SAWS" id="FRET_SAWS">Fret Saws to Mount upon the Lathe Bed.</a></h3> - -<p>Convenient as the circular saw is when fitted as an adjunct to the -lathe, its use is confined to pieces which are rectilineal. Curved -lines cannot be cut by its means, and as it must frequently happen -that portions of the proposed work are composed of arcs of various -dimensions, it becomes necessary to provide the means of cutting them -out. We may remark here, that although the circular saw, and that of -which we are about to speak may be fitted to mount on the ordinary -lathe bed; it is better for many reasons to have a separate stand, -made like that of the lathe, but smaller, and fitted with crank, -treadle, and flywheel, to serve for the various purposes of sawing, -grinding, or polishing; the latter operations especially soiling and -tending to damage the lathe. The above description of the methods of -mounting circular saws will answer for a separate stand, as will the -following details of saws for curvilinear work. In respect of the -latter we have to provide for the perpendicular motion of the blade, -which is necessarily thin and narrow, and also for stretching the -blade so as effectually to prevent it from bending or buckling—guides -are not required in general, as the work is moved about by hand in all -directions according to the intricacies of pattern to be traced. For -plain circular pieces, however, a very simple expedient is sometimes -used, which will be described in its proper place, when treating -of Bergeron's <i>scie mecanique</i>. The guides for parallel motion are -various, and a selection may be made from the following <a href="#i-p130as">Fig. 191</a>. -No. 1 is the arrangement used by Professor Willis, and detailed in -Holtzapffel's work. A, A are wooden springs, one above, the other -below the platform B. C is a guide pulley, D an eccentric. The catgut -band which gives motion to the saw may be passed round this, or -affixed to a metal ring as in the eccentric of a steam engine<span class="pagenum"><a name="Page_130" id="Page_130">[130]</a></span>—or -may be attached to a ring slipped over the pin of a crank disc, as -shown at E. This pin being adjustable, permits the traverse of the -saw to be regulated, which gives it perhaps an advantage over the -first method. In the above the motion of the saw is not truly in a -right line, but the deviation in so short a traverse is unimportant. -The reader may, perhaps, imagine wooden springs a somewhat primitive -expedient, but this is by no means the case, as they will retain their -elasticity longer than metal ones when they are subjected to the -rapid vibration which they are called upon to undergo. No. 2 is the -parallel guide, used by Mr. Lund, and also described by Holtzapffel; -the metal springs, however, shown by the latter being here replaced -by india-rubber, which is now formed into springs of various sizes and -powers suitable for our present and many similar purposes. A, A, and -D, here form guide pulleys, the saw, E, being suspended from the first -by the two catgut bands, on the ends of which are the india-rubber -springs, F, F. The lower end of the saw is attached to another catgut -band which passes over the pulley, D, and thence to the eccentric -or crank disc as before. The platform is at B, B. <a href="#i-p130bs">Number 3</a> is an -arrangement similar to the<span class="pagenum"><a name="Page_131" id="Page_131">[131]</a></span> beam of Newcomen's engines. The arc at -the end of the oscillating rod, and from the furthest point of which -the saw is suspended, forms the guide for parallelism. Underneath -the platform the pulley and eccentric may be used as before, and the -saw is raised by the spring attached to the arc as shown. It will be -evident on inspection that this arrangement is similar in principal to -the last, as the arc forms part of a large wheel of which the centre -is the point of oscillation. Watt's parallel motion, represented -in the next diagram, is also suitable, the saw being attached to -the centre of the short link—the springs being so contrived as to -act upon the ends of the longer bars. With regard to the means of -producing the necessary rapidity of movement, the above-described -eccentric or crank disc can hardly be surpassed. In the saw patented -lately by Mr. Cunningham, the disc is attached to the mandrel like a -chuck, and the crank pin is connected to the oscillating rods that -carry the saw by an intervening rod or link.</p> - -<div class="figcenter" id="i-p130as" style="width:700px;"> - <img - class="p2" - src="images/i-p130as.png" - width="700" - height="360" - alt="" /> - <p class="center smcap">Fig. 191, no. 1 and 2.</p> - </div> - -<div class="figcenter" id="i-p130bs" style="width:700px;"> - <img - class="p2" - src="images/i-p130bs.png" - width="700" - height="344" - alt="" /> - <p class="center smcap">Fig. 191, no. 3 and 4.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p131" style="width:536px;"> - <img - class="p2" - src="images/i-p131.png" - width="536" - height="368" - alt="" /> - <p class="center smcap">Fig. 192.</p> - </div> - -<p>The whole is represented in <a href="#i-p131">Fig. 192</a>, which is copied from the -inventor's circular. There is a satisfactory parallel motion, and -an india-rubber ball with a small tube attached is pressed at every -stroke to blow away the sawdust. The whole plan and details are as -good probably as can be devised, and as an addition to the lathe this -saw is invaluable. Another form of mechanical saw to work with the -foot, but without any flywheel, is figured by Bergeron, and is thence -copied into Holtzapffel's book, and would therefore have been omitted -here were it not that the price of Holtzapffel's work places it beyond -the reach of many whom it is specially qualified to instruct; and that -the former is in French and has not been translated. Therefore, as the -arrangement of saw is exceedingly good, the writer has determined to -introduce it here. Its construction is simple enough to be within the -reach of any amateur in carpentry, and the only metal work required -consists of a few iron rods screwed at the ends, such as the village -blacksmith can readily supply. The saws are precisely those sold as -turn or web-saw blades. It must be understood that the use of this -tool is not the same as that to which<span class="pagenum"><a name="Page_132" id="Page_132">[132]</a></span> fret or buhl saws are applied, -but merely the cutting of boards in strips or curved pieces, such as -the felloes of small wheels, circular plates to be finished in the -lathe, as bread platters, or such other curvilinear works as the chair -or pattern maker is accustomed to cut out with the several sizes of -frame saws.</p> - -<p>A, B, <a href="#i-p132s">Fig. 193</a>, is a stout bench with cross bar, C, underneath, cut -away to allow of the movement of the treadle and its rod. On the top -of the bench is a pillar, D, to support the spring bow E, by which -after depression the saw is raised to its original position. F, F, and -G, G, are guide rods (not continuous). The lower ones are fixed to the -cross bar, <i>c</i>, and under side of the bench. The upper form the sides -of a rectangular frame, H, H, of which the top and bottom bars of wood -are dovetailed at the back to slide up and down the chamfered bar -behind them, K. The frame thus allows of being raised or lowered, not -only to suit work of various thicknesses, but also to act as a stop to -prevent the saw from lifting the<span class="pagenum"><a name="Page_133" id="Page_133">[133]</a></span> work as it ascends. The lower bar -is extended on one side as in the figure, and is divided into inches, -and on this graduated part is a slide with a point below, which can -be fixed by a screw. This is, as the drawing plainly shows, intended -for the guidance of the wood in cutting circular pieces. The saw is -similar to the ordinary framed saw used by chair makers, but has two -blades, and one central stretcher. The saw for curved work is narrow, -that for straight cutting is broader. Near the latter a parallel -guide is fixed, as described when treating of circular saws. This -simple contrivance, although planned so many years ago, is of great -value, and deserves to be far more generally known. To the joiner and -cabinet-maker it would form a most useful addition to the usual tools -of the workshop.</p> - -<div class="figcenter" id="i-p132s" style="width:370px;"> - <img - class="p2" - src="images/i-p132s.png" - width="370" - height="550" - alt="" /> - <p class="center smcap">Fig. 193.</p> - </div> - -<p>Akin to the circular saw are the various revolving cutters used either -for the purpose of ornamentation or for grinding, such as circular -files for flat surfaces, in which the teeth are cut upon the face or -tool-cutters of particular sections for cutting the teeth of wheels, -in the manner already described, to which may perhaps be added milling -and embossing tools, although the action of the latter is rather that -of a revolving die by which the work is stamped or indented with the -pattern formed upon the edge of the cutter. The small grindstones and -emery laps belong also to this section, as their action results from -the abrasion of the material by means of the combined cutting power of -innumerable small points or miniature teeth formed by the particles of -emery or other material attached to the surface of the laps.</p> - -<p>Most of the steel cutters may be made by the amateur, the metal -being turned to the required shape and the teeth cut by small files -or punches while the material is in a soft state. The little discs -are then hardened and mounted, by a central hole previously made, on -suitable spindles, the latter being either attached at one end to -the mandrel as arbor chucks, or centred at both ends and driven like -miniature circular saws. The ornamental cutters for embossing, <a href="#i-p133s">Fig. 193<sub>B</sub></a>, -A and B, are turned to the form of short cylinders, -and the patterns cut by punches. These and the milling tools are -mounted alike, <a href="#i-p133s">Fig. 194</a>. The rest is placed a short distance from the -work, and the tool revolves against it. Some pressure is necessary to -imprint the design, and this is easily obtained if the cutter<span class="pagenum"><a name="Page_134" id="Page_134">[134]</a></span> wheel -is placed so as to attack the work below the axis; the rest then -becomes a fulcrum, and the shank and handle of the tool acting as the -long arm of a lever supply the required force with little exertion -on the part of the operator. In this way the milling is done on the -edges of screw heads, and the embossed patterns on soft wood boxes. -It is not easy to understand how the patterns in these cases are -produced clearly without one part cutting into and effacing another, -unless the size of the work is exactly a multiple of that of the -tool. The error is plain if the work is stopped exactly at the end -of the first turn, but in successive revolutions this error becomes -gradually obliterated, and the pattern is eventually impressed clear -and well defined. The same shank is arranged for different patterns -of wheel-cutters, as the pin which forms the central axis is readily -withdrawn and is made to suit the holes in several sets of discs.</p> - -<div class="figcenter" id="i-p133s" style="width:700px;"> - <img - class="p2" - src="images/i-p133s.png" - width="700" - height="144" - alt="" /> - <p class="center smcap">Fig. 193B, 194.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p134" style="width:536px;"> - <img - class="p2" - src="images/i-p134.png" - width="536" - height="320" - alt="" /> - <p class="center smcap">Fig. 195.</p> - </div> - -<p>By the aid of the above simple tool a neat finish is readily given -to many small works in wood and metal. A modification of the beading -tools is here shown very similar to the screwing guide already -given, but made with figured instead of sharp-cutting edge. This was -communicated to the <i>English Mechanic</i>, Nov. 2, 1866. <a href="#i-p134">E, 195</a>, is the -guide which is placed on the handle A, B, C, D, and fixed by screw F. -The mark <i>i</i>, on the guide, is placed against the rim, A, B, which is -graduated and numbered. Each figure, as it is brought up and placed -opposite <i>i</i>, will cut a different pattern when the guide is fixed. -The tool must be held very firmly on the rest (the bottom of the guide -G, H, being flat, is carried on the rest), the tool is advanced to -the wood. The tool must be worked very steadily; but with a little -practice, any amateur will soon use it perfectly, and produce many -very pretty patterns. It is evident that provision is here made for -placing the cutter at different angles to the work, by which means -the circles of patterns may be traced spirally and in other positions -varying from the ordinary one at right angles to the axis of the work.</p> - -<p>The laps alluded to, which are to be mounted on spindles like the -circular saw, are composed of wood and metal of determinate forms. -First, there is the thin sheet-iron slitting wheel used by lapidaries, -and which, when charged with emery, or sand and water, forms the -nearest approach to the circular saw. It <i>is</i>, in fact, the circular -saw of the stone worker, the ordinary saw used in their trade being a -flat blade without teeth, stretched in a wooden frame and similarly<span class="pagenum"><a name="Page_135" id="Page_135">[135]</a></span> -fed with sharp sand and water in lieu of being made with teeth, the -latter being replaced by the grittiness of the material. The circular -plate of iron, brass, or lead alloyed with antimony, mounted on a -spindle vertically, is used in a similar manner for grinding flat -surfaces with the aid of emery, crocus, oilstone powder, and other -substances, and the same is used edgewise for other work, as grinding -and polishing tools, the section of the lap being such as will form -the article required by reproduction of the revised plan of its own -edge. Thus a lap running horizontally with a convex edge will produce -the concave form required in beading tools, the latter, however, are -more conveniently ground on brass cones mounted like the arbor chucks -used for turning washers, rings, &c. The face of the tool or flat side -is held towards the small end of the cone, and the latter is armed -with flour emery. See <a href="#i-p135">Fig. 196</a>.</p> - -<div class="figcenter" id="i-p135" style="width:342px;"> - <img - class="p2" - src="images/i-p135.png" - width="342" - height="126" - alt="" /> - <p class="center smcap">Fig. 196.</p> - </div> - -<p>Before describing the eccentric and other compound chucks, a few -examples will be given of the method of turning some of those forms -in which the circle does not appear, where, in short, the boundaries -of the figures are straight lines. It seems at first sight impossible -to produce in the lathe by any simple means such solids as are formed -from squares or triangles, of which the cube or die is the most common -and most generally understood. This can, however, be accomplished, -and a number of mathematical problems may be clearly demonstrated to -the eye by such works skilfully made in the lathe. In this kind of -work it is absolutely necessary to strive after perfection. In short, -as Bergeron rightly says, the work imperfectly done is simply worth -nothing at all; but when accomplished with exactness, nothing can be -more worthy of a place in a cabinet of curiosities. The usual method -of turning a cube is by shaping it out of a perfect sphere, but as the -latter can hardly be made without a special slide rest made for the -purpose, a method of turning the cube by hand alone will be given, -the foundation of it being that which the lathe so readily produces, -namely, a cylinder. By far the most proper material for the work in -question is sound boxwood, and special care is to be taken to keep all -angles as sharp as possible, and therefore to cut clean with sharp -tools, and to avoid as far as possible the use of sand or glass paper. -<a href="#i-p136a">Fig. 197</a> shows a square described in a circle. The non-mathematical -reader may be told to draw through the centre two diameters at right -angles to each other, and to complete the square, as in the figure, -by joining the extremities. The largest square that is possible to -be drawn in the circle is thus described. This square will form one -face of the cube, and the diameter of the<span class="pagenum"><a name="Page_136" id="Page_136">[136]</a></span> piece of wood must be -regulated according to the proposed size of the finished work. It is -evident that this diameter is equal to the line drawn from corner -to corner called the diagonal of the square. Now, in turning a ball -or sphere, a cylinder would be turned of the exact length of A, C, -because every measurement taken on a diameter of the sphere would -be of that length. In the present case, however, the cylinder must -be of the same length as the line A, B. Turn, therefore, with great -care a cylinder of any desired size, gauging it carefully with the -callipers and squaring off the ends truly. On one end, in which the -centre point just remains visible, draw diameters and construct the -figure <a href="#i-p136a">197</a>. Turn out a chuck to fit it exactly, and let the bottom -of this chuck be truly square. Take the precise length of the line -A, B, with finely pointed compasses that can be fixed with a screw, -and measure off the same, and mark it on the side of the cylinder. -When the figure is placed on the chuck, a mark must be traced round -it at this point, A, B, <a href="#i-p136a">Fig. 198</a>, <i>and this must remain to the end</i>. -It may be made with a hard pencil or steel scriber, and, though -distinct, must be very fine. It is at this line the wood will have -to be cut off, but in this operation keep beyond it so as not to -erase it. While the piece is in the chuck, rule lines, as E, G, from -the points C, D, E, F, 198. Bisect also the length of the cylinder -by the line, H, K, also finely drawn. Draw two more diameters, as -shown by the dotted lines bisecting the sides of the cylinder, which -is now divided round its circumference into eight equal parts. The -lines, E, G, &c., can be ruled along the edge of the rest, or, if the -latter is untrue, the cylinder may be laid on a plane surface, and -a scribing block, or gauge, <a href="#i-p136b">Fig. 199</a>, may be drawn across it, or, -lastly, a small steel square may be<span class="pagenum"><a name="Page_137" id="Page_137">[137]</a></span> used; one part being carefully -placed on the lines at the end of the piece in succession, the other -part will lie evenly along the side, and will form a ruler by which -to work. A division plate on the lathe pulley will facilitate the -above measurements, but they can be readily made without it, and once -carefully marked, all the guides required for cutting out the cube -will be complete, and the work can be proceeded with, with confidence -and decision. Proceed, therefore, to cut off the piece at A, B, with -a parting tool, but with the precaution already named of not erasing -the line by so doing. Now prepare a chuck which will take the piece -lengthwise, <a href="#i-p136b">Fig. 199<sup>2</sup></a>, and insert it in that position to the depth -of the diameter so as to hold it securely, and the central line will -show whether it lies evenly (which is, in fact, the use of this -line). If even, a point-tool held on this line will form a mere dot -upon it; if uneven, it will make a circle as it revolves. Place the -rest across the face of the work, and, beginning at the centre, cut -carefully towards the outside until you have cut away the wood as far -as the line, A, B. You will thus complete one face of the cube, and -an inspection of the end of the piece, shown black in the sketch to -show the quantity removed, will prove that you thus produce a right -line, C, D. Take out the work, and reverse it, and operate similarly -on the opposite face; but in every case do not quite obliterate the -lines first marked as guides. You have now a piece shaped like <a href="#i-p137s">Fig. 200</a>, -A and B, and must make a smaller chuck to hold it; you have then -to cut away in a similar manner the remaining parts of the cylindrical -portion, and the cube will be complete. To finish the sides more -neatly, lay upon the table the finest sand paper, and tack it at the -corners, and with gentle movements work down precisely to the guide -lines. This requires extreme care, for if once the piece is but in -the slightest degree tilted up, an angle will lose its sharpness, and -the beauty of the work will be marred. Hence we recommend to cut with -sharp tools, instead of trusting to the finishing process. To cut, -however, <i>exactly</i> to the line is very delicate work, and to the less -practised hand the use<span class="pagenum"><a name="Page_138" id="Page_138">[138]</a></span> of the sand paper on the faces in succession -may be the <i>necessary</i> expedient. The main secret of sharp edges in -works of wood and metal is to finish with hard substances, as emery -stick or glass paper glued to a piece of wood, or the same nailed on -the bench, and to try always to work on the centre, leaving the edges -or angles to take care of themselves. When the reader has made a cube, -as above, that will bear delicate measurement, he will be more than -usually gratified, and will be qualified for still more difficult -work. A chuck figured by Bergeron, <a href="#i-p137s">Fig. 201</a>, is very convenient, as -it holds the work truly central; the jaws work simultaneously by a -right and left-handed screw as in the die chuck. It is, however, -perfectly easy to do good work without it, but the chucks should -be carefully made, turned very flat at the bottom, with side truly -perpendicular. A little extra care bestowed upon chucks will save -many disappointments, and conduce to good work. The formation of a -four-sided solid, consisting of triangles solely, in the lathe is a -work of difficulty, owing to the impossibility of fixing the work -satisfactorily in an ordinary chuck. The natural way to form such a -solid is to turn a cone A, B, <a href="#i-p138s">Fig. 202</a>, and on its base to mark a -triangle of the required size. It is then necessary to place the cone -in a chuck, so that the ends of one of the lines thus marked and the -apex of the cone are precisely level with the surface of the chuck, as -shown in <a href="#i-p138s">Fig. 203</a>. But it is evident that adequate support is not thus -obtainable. The apex of the cone cannot, in point of fact, be inside -the chuck at all, as it is necessary to cut clean to its extremity, -and even the base of the cone is imperfectly held at two points. -Hence it becomes necessary to make use of "turner's cement," and to -imbed the work fairly in it, while both are warm, to such a depth as -will hold it securely and still allow the guide lines to be seen. -The latter should be carried from the three angles of the triangle -marked on the base to the apex. On the whole, this is the easiest -method of fixing such work in the lathe; and if the piece is itself -warmed before being placed, there will be time to adjust it precisely -before the cement is cold. To do this, place the rest parallel to the -lathe bed, hold a pointed tool steadily upon it, and note whether, -as the work slowly revolves, the three points in question, viz., -the two angles of the triangle and the<span class="pagenum"><a name="Page_139" id="Page_139">[139]</a></span> top of the cone, are in one -plane. When they are so placed, the rest is turned to face the work, -and the material is carefully cut away till the gauge lines are just -reached.<a name="FNanchor_14_14" id="FNanchor_14_14"></a><a href="#Footnote_14_14" class="fnanchor">[14]</a> A pyramidical solid with a square base may be similarly -turned. The following is the method of preparing the above turner's -cement:—Burgundy pitch, 2 lb.; yellow wax, 2 oz. Melt together in a -pipkin, and stir in 2 lb. of Spanish white. When the whole is well -mixed, pour it out on a marble slab and roll it into sticks. Fine -brickdust, whiteing, or any similar substance finely pulverised, will -answer equally well to add to the pitch and beeswax. This cement is -very useful, as it will hold the work firm enough to turn carefully, -and nevertheless a slight blow will loosen it. To clean it off, warm -or dip the work in hot water and wipe quickly with a piece of cloth. -The above is from the "Handbook of Turning," the author of which has -copied from Bergeron both the recipes given in his work; the one here -described is stated to be specially serviceable in cold weather. It -is perhaps rather less brittle than the first of Bergeron's, and for -this cause is the best for general use. Holtzapffel sells this at -one shilling the stick, which is of convenient size and generally of -excellent quality. Bergeron gives a method of turning pilasters or -balustrades, which is of great ingenuity, and applicable to work of -various sections. The rectangular and triangular sections illustrated -are not, indeed, strictly rectilineal figures, as the sides of the -balustrades thus formed are not flat but rounded surfaces; they are, -however, sufficiently curious, and when well turned are interesting -specimens of lathe work. Bergeron's description relates to the pole -lathe, or to work mounted between two centres with a pulley cut on -the work itself to receive the lathe cord. The ordinary method of -mounting on a foot-lathe will, of course, be much better and the whole -operation of more easy performance. Let it be required to turn a -moulded pillar or balustrade of the section <a href="#i-p138s">Fig. 204</a>, viz., a triangle -with slightly curved sides. A piece of wood of the requisite length -is planed up accurately to a triangular form, or, as it generally -happens that a set of such pilasters are required, a number of such -pieces are prepared which must be accurately planed to the same size, -for which purpose a gauge or template, <a href="#i-p138s">Fig. 205</a>, should be made -use of. Six or eight of these, if not too large, may be operated -upon at the same time; but as six pieces of two inches across each -face require a cylinder of about eight inches diameter, the number -must depend on height of centres. The larger the cylinder, however -(which, in fact, forms a chuck), the more nearly will the sides of -the finished work approach to plane surfaces, as they will form arcs -of a larger circle. Let a cylinder, then, be turned of sound wood -with a reduced part at one end so as to form a shoulder. Divide the -circumference into twice as many<span class="pagenum"><a name="Page_140" id="Page_140">[140]</a></span> equal parts as there are pieces to -be turned, the divisions being equal to one of the sides of these -pieces as measured in a cross section. These divisions are to mark the -positions of the grooves or channels in which the triangular strips -are destined to lie. Half the circumference will be so cut out, the -alternate divisions being left. Thus, to turn four pieces, each two -inches wide, a cylinder of sixteen inches will be required, affording -four grooves two inches wide, and four intermediate pieces forming the -partitions between the grooves. The latter must, by means of the saw -and chisel or other tools, be made to receive the strips exactly, and -the ends of the latter being carefully squared off, are to be made -to rest against the plate C, <a href="#i-p140s">Fig. 206</a>, which is cut out and screwed -against the shoulder, after the above-mentioned grooves have been cut. -The whole are then secured by two rings, with screws. Probably the -stoutest india-rubber rings now made would answer as well as the iron -clamps in Bergeron's description. Lay the strips in their places, but -as they are flat they will not form part of the cylindrical surface, -but will lie lower, as <a href="#i-p140s">Fig. 207</a>, or higher, <a href="#i-p140s">Fig. 208</a>; the latter is -the best, and the pieces may, for this cause, be cut out a trifle -deeper than ultimately required and they may be planed down a little -to remove the angles and assimilate them to the cylindrical surface. -The whole may then be turned together so as to form a plain cylinder, -the clamping rings, <a href="#i-p140s">Fig. 209</a>, being shifted when requisite. The whole -is now to be formed into a balustrade, but as the proportions of the -mouldings of such a large cylinder would not suit the small pieces, -the hollows must be less deep, and the raised parts less prominent -than they would ordinarily be made. The clamps are now to be loosened, -and the pieces reinserted with another face upwards, the flange or -plate against which their ends rest forming a gauge or stop to ensure -their position, without which precaution the mouldings would not -event<span class="pagenum"><a name="Page_141" id="Page_141">[141]</a></span>ually meet at the angles. In cutting a fresh side the utmost -care is requisite, for if the work on the original cylinder is cut by -the tool, it will be impossible to restore it, and the work will be -spoiled. In replacing the strips, let the finished part lie below, so -as to come first in contact with the tool, by which the angle will be -clean. Extra care is for this purpose required in cutting the last -side. It appears to the writer that another precaution should be taken -which Bergeron omits, namely, to arrange the mouldings so that certain -parts are left of the original size of the wood, in order to retain -a certain number of points of contact with the sides of the grooves, -so that the strips shall not fall deeper into them than at first. The -extremities of the strips should certainly not be left smaller than -the central portion, or the pieces will rock on the latter while in -process of being turned. The two ends, therefore, should be allowed -to retain their original triangular form, forming base and capital -of the pillar, or the pattern may be so planned that, after the -extremities have been left as supports they may be cut off when the -work is complete. Care must be taken, in working as above, to have -the cylinders so large above the estimated size that the inner apices -of the triangles do not nearly meet at the centre, else the whole -chuck would be very weak and split into triangular strips. The lathe -called a spoke-turning lathe would accomplish this kind of work in -a far more easy and speedy manner. The balustrade would have to be -made by hand as a pattern, and cast in metal, and any number could be -produced precisely similar. The lathe in question is on the following -principle:—The frame carrying the tool (a set of revolving gauges) -is made to oscillate backwards and forwards to and from the piece to -be operated on. This is accomplished by its having attached to it a -roller or rubber working against the cast-iron pattern placed parallel -to the work, and below or one side of it. The rubber and frame are -kept against the pattern by a strong steel spring. The cutters also -travel in a direction parallel to the axis of the piece. Hence any -elevated part of the pattern causes the tool to recede from the work -in a corresponding degree, and a hollow allows a nearer approach -of the tool. Thus, as the tool is carried by a screw slowly from -end to end of the work, it is made to advance and recede in exact -correspondence with the form of the pattern. An immense deal of work -is done in this way, such as balustrades, spokes of wheels, the long -handles of the American felling axes, and similar irregular forms.</p> - -<div class="footnote"> - -<p><a name="Footnote_14_14" id="Footnote_14_14"></a><a href="#FNanchor_14_14"><span class="label">[14]</span></a> With the universal cutting frame this kind of work is -much more readily accomplished.</p></div> - -<div class="figcenter" id="i-p136a" style="width:550px;"> - <img - class="p2" - src="images/i-p136a.png" - width="550" - height="228" - alt="" /> - <p class="center smcap">Figs. 197, 198.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p136b" style="width:642px;"> - <img - class="p2" - src="images/i-p136b.png" - width="642" - height="342" - alt="" /> - <p class="center smcap">Figs. 199<sup>2</sup>, 199.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p137s" style="width:700px;"> - <img - class="p2" - src="images/i-p137s.png" - width="700" - height="310" - alt="" /> - <p class="center smcap">Figs. 200, 201.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p138s" style="width:700px;"> - <img - class="p2" - src="images/i-p138s.png" - width="700" - height="193" - alt="" /> - <p class="center smcap">Figs. 202, 203, 205.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p140s" style="width:700px;"> - <img - class="p2" - src="images/i-p140s.png" - width="700" - height="463" - alt="" /> - <p class="center smcap">Figs. 206, 207, 208, 209.</p> - </div> - -<p>The <i>principle</i>, indeed, is not new, as the rose engine is a similar -tool, and, so long back as Bergeron's time, pattern plates were used -giving any desired motion, endlong or otherwise, to the tool, or, -which in effect is the same, to the work to be operated on.</p> - -<p><span class="pagenum"><a name="Page_142" id="Page_142">[142]</a></span></p> - - -<h3 class="sc"><a name="TURNING_SPHERES" id="TURNING_SPHERES">Turning Spheres.</a></h3> - -<p>We must now recur to the sphere of which we have already spoken. The -method previously given for producing it is not sufficiently accurate, -although a very close approximation can thus be made to the perfect -figure. It is probably impossible without special apparatus, rendering -the tool independent of the hand, to turn out an absolutely correct -sphere—indeed, it is a sufficiently delicate operation, even with the -following or similar apparatus. For ordinary purposes, indeed, where -the object is simply to produce a croquet ball, a spherical box, or a -globe to be afterwards covered with paper, or any such work, the plan -already given will generally suffice, and, indeed, is very extensively -used. Some practised workmen, too, will, without even the aid of ruled -lines, turn out spheres of average excellence by the eye alone, aided -by a template. When, however, it is proposed to hollow out a sphere -so as to leave a mere shell of ⅛ in. or less, and perhaps include a -number of such shells one within the other, and a star in the centre -of all, it evidently becomes necessary to work with greater accuracy, -and still more so with respect to billiard balls, in which even the -slight variation caused by increased temperature will seriously affect -the result of the most skilful play, and cause the very best players -to fail. The principle of the spherical rest is displayed by the -diagram, <a href="#i-p142as">Fig. 210</a>.</p> - -<div class="figcenter" id="i-p142as" style="width:500px;"> - <img - class="p2" - src="images/i-p142as.png" - width="500" - height="231" - alt="" /> - <p class="center smcap">Fig. 210.</p> - </div> - -<div class="figcenter" id="i-p142bs" style="width:550px;"> - <img - class="p2" - src="images/i-p142bs.png" - width="550" - height="347" - alt="" /> - <p class="center smcap">Fig. 211.</p> - </div> - -<p><span class="pagenum"><a name="Page_143" id="Page_143">[143]</a></span></p> - -<p>A is the chuck carrying the ball to be turned, of which C is the -centre. In a right line with the latter, and below it, is a pin fixed -to a block between the bearers of the lathe, and on this the arm, D, -turns. The latter carries a tool-holder in which a pointed tool, E, is -fixed. The point of this tool will evidently move in a circle, when -the arm is moved by means of the handle, D; and, as the centre of the -circle is exactly under that of the proposed sphere, the latter will -be correctly shaped when the lathe is put in motion. <a href="#i-p142bs">Fig. 211</a> gives -another view of the tool-holder. It is essential that the point of the -tool should be in a line with the centre of the lathe mandrel, so that -it shall act on a diametrical plane as it is carried round the work. -Such is the principle upon which a practically useful tool for turning -spheres has to be arranged.</p> - -<p>The faults in the above simple machine are many. In the first place -no provision is here made for the advance of the tool towards the -work. In the second place the requisite firmness and stability cannot -be obtained by merely causing the bar to revolve upon a centre-pin; -and thirdly, as the tool post is fixed to the horizontal bar, the -diameter of the ball must be limited. In point of fact, therefore, the -above arrangement would not answer, and it is only described in order -to illustrate the principle of all inventions for the production of -spheres in the lathe. To give steadiness of action the pin forming -the centre of motion is connected with a circular metal plate truly -turned, upon which a second similar plate works, and to the latter is -attached the tool-holding apparatus. It is difficult to make choice -of a circular or spherical rest so as to give it precedence, since -most of the patterns ordinarily made are good. To obtain the requisite -movement is, indeed, by no means a matter of difficulty; and one or -two adjustments in respect of the height and radius of the tool being<span class="pagenum"><a name="Page_144" id="Page_144">[144]</a></span> -provided, a very simple apparatus will answer the purpose. To commence -with Bergeron's, which, though venerable, is by no means inefficient. -This is represented in <a href="#i-p143s">Figs. 212 and 213</a>. A, B, is the base, the -tenon, B, accurately fitted to slide between the bearers of the lathe, -the whole being held down as usual by the bolt and nut, <i>c</i>. The top -part of the base is surmounted by the accurately faced plate <a href="#i-p144s">214</a>, on -which a side sectional view is given in <a href="#i-p144s">Fig. 215</a>. This is fastened -to the base plate (which, in Bergeron's description, is of wood) by -four countersunk screws. It is turned with a recess, so that the -outer part stands up in the form of a rim, and from its centre rises -a conical pin, <i>b</i>, the upper part of which is first octagonal, and -then rounded and tapped. It is this strong pin which forms the centre -of motion, and it must stand with its axial line precisely in the -centre of the lathe bed, so that if the plate were slipped close to -the poppet head this line would bisect the nose of the mandrel. This -is essential in all patterns of spherical slide rest. Upon the lower -circular plate rests that represented in <a href="#i-p144s">Fig. 216</a>, A and B, the latter -being the sectional representation. This plate is drilled in the lathe -with a central hole, the lower part conical to fit the pin in the -base plate, the upper part countersunk as in the figure, to receive -the octagonal part of the pin and the nut. The projections <i>a</i>, and -<i>b</i>, in B, represent the projecting rim, <i>a</i>, in the <a href="#i-p144s">Fig. 216</a>, A, and -this is made to fit very nicely within the rim of the lower plate, -while the adjacent part, <i>c</i>, rests upon the rim itself. The accuracy -of these bearing surfaces is of the utmost importance, It is evident -that<span class="pagenum"><a name="Page_145" id="Page_145">[145]</a></span> this arrangement is calculated to give great stability during -the revolution of the upper part of the rest, which is fixed securely -to the plate last named. This plate has a hollowed edge cut with a set -of fine teeth to be acted on by the tangent, screw D, <a href="#i-p143s">Figs. 212, 213,</a> -and shown in <a href="#i-p144s">Fig. 217</a> on a larger scale. The bearings of this screw -are attached to the base plate, and the screw is prevented from moving -endwise by collars as usual.</p> - -<div class="figcenter" id="i-p143s" style="width:550px;"> - <img - class="p2" - src="images/i-p143s.png" - width="550" - height="367" - alt="" /> - <p class="center smcap">Figs. 212, 213.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p144s" style="width:481px;"> - <img - class="p2" - src="images/i-p144s.png" - width="481" - height="550" - alt="" /> - <p class="center smcap">Figs. 214, 215, 216, 217.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p145s" style="width:700px;"> - <img - class="p2" - src="images/i-p145s.png" - width="700" - height="362" - alt="" /> - <p class="center smcap">Figs. 218, 219, 220.</p> - </div> - -<p>On the upper surface of the top plate are fixed parallel bars -chamfered beneath like those of a slide rest, and between these the -tool holder slides, the advance of the latter being effected by a -screw precisely as in the slide rest already described. In the plan of -this instrument, as seen from above, <a href="#i-p145s">Fig. 218</a>, A, B, are the bars. The -tool is seen in position at C, the tangent at D. A scale is attached -to the sliding part of the tool holder for determining the size of -the sphere. The tool is again seen in position in <a href="#i-p145s">219</a>, and detached -in <a href="#i-p145s">220</a>. In Bergeron's description of the above spherical slide rest -the method of using the apparatus is thus described:—"Commence by -placing in a chuck a cylinder of some sound wood, and reduce it to -a convenient diameter, which should be a little greater than that -of the proposed ball. With the gouge work down this, and give it -roughly the form of a ball attached to a cylindrical base." This base -serves to sustain the ball during the operation, and the form of -an inclined plane is to be given to it where it is attached to the -ball, as seen in the drawing, to facilitate the passage of the tool. -After this preliminary work, place the instrument on the lathe bed, -and cause the tool holder to advance by means of a screw (the one -attached to the lower slide, not the tangent screw) until, reckoning -from 0in., the starting point, the index attached to the sliding -part has travelled over the graduated divisions of the scale, so as -to<span class="pagenum"><a name="Page_146" id="Page_146">[146]</a></span> denote the size of the ball in its present rough state. Then -slide the instrument along the lathe bed, until the tool, accurately -adjusted as to height, just touches the ball at the quarter circle. -This will be better understood by the diagram <a href="#i-p146">Fig. 221</a>, in which A, B, -are the lathe bearers; C, the tool in position; D, the ball; E, -the chuck or the base of the cylinder. Having previously determined -the size of the finished ball, the work may now be carefully begun by -clamping the rest underneath the bed, and making use of the tangent -screw. Little by little the work is to be reduced, taking care not -to cut too near the base on which the ball is yet carried. This -base is to be cut away little by little as the tool comes round, -and at the last cut the ball will drop off finished, and it is not -to be further touched with sand paper or other material. Hence, as -it approaches the finish, the tool must be delicately and steadily -made to traverse, so as to leave a finished surface as it advances. -Bergeron adds certain precautions as follows:—"If the material is -very rough from the gouge, so that at any point the tool is likely to -meet with such resistance as would endanger the work, such part may be -pared down again by using the machine as a common rest for gouge or -chisel; for the apparatus once arranged should not be altered nor the -fixed tool shifted until the work is done. The tool throughout is to -be advanced very gently forward at each turn by means of the screw, -which causes the parallel movement, and the tool is to be accurately -adjusted so as to be exactly in a line with the centre of the mandrel; -it is also to be very keenly sharpened, and even polished." The first -impression given by an inspection of the above figures is that the -ball would be liable to drop off before it could be fairly severed by -the tool. The writer determined to test this objection personally. -He selected a piece of sycamore, which is very fit for the purpose, -and useful as a kind of medium between hard and soft woods. A ball -was turned by hand from this material having a diameter of about two -inches. The neck by which it was held was retained of the size of a -cedar pencil during the final shaping of the rest of the ball. It -was of course not thus reduced until the ball was nearly spherical. -Gradually the neck was cut away until it was perhaps as small as -the lead of a pencil, yet still the ball retained its position, and -the final stroke cut it off truly and tolerably cleanly, <a href="#i-p143s">E, 212 and 213</a>. -It is really astonishing how small a portion of sound wood will -retain a ball so turned, but the lathe should not be allowed to stop, -else the tendency to hang<span class="pagenum"><a name="Page_147" id="Page_147">[147]</a></span> down or sag would overcome the sustaining -power of the fibres. Bergeron states, indeed, plainly, that the -process answers satisfactorily, and as a man of large experience his -opinion is certainly reliable. Nevertheless, since sand papering or -after process is to be eschewed, it does appear to the writer that -the final cut would leave a minute portion untouched requiring to -be afterwards removed. Not having one of the rests in question the -writer's opinion is to be taken <i>quantum valeat</i>. The spherical rest -more commonly used is that represented in the "Handbook of Turning," -since it is necessary not only that the machine should be efficient -for turning a sphere, but likewise applicable to the ornamentation -of the same by the revolving cutter and other apparatus used in such -processes. This and some other forms will presently be described, and -also an ingenious adaptation of the ordinary slide rest by means of -guide pieces or templets to work of this character. A very good form -of chuck for holding spheres during the operation of hollowing them -out or forming stars or cubes within them will, however, be first -introduced here as described by Bergeron. It will be at once seen how -simply and efficiently a ball can be thus held during such processes.</p> - -<div class="figcenter" id="i-p146" style="width:496px;"> - <img - class="p2" - src="images/i-p146.png" - width="496" - height="287" - alt="" /> - <p class="center smcap">Fig. 221.</p> - </div> - -<p><a href="#i-p147s">Fig. 222</a> represents a chuck for holding balls, A being a sectional -view, B an elevation. In the first, <i>b, b</i>, represents the body of the -chuck, made as usual to screw on the mandrel. At <i>a</i>, the chuck is -formed with a shoulder like an ordinary box. This part of the chuck is -to be hollowed out to fit the ball on which it is intended to operate. -On the side of the chuck at <i>b</i>, is to be cut a screw of medium pitch. -Mounting another piece of wood in the lathe a kind of cover, <i>c, c</i>, -is now to be made to fit over the body of the chuck like the cover of -a box, but hollowed out to the curvature of the ball. A ring of brass -or wood of section D being screwed on the inside to the pitch of the -male screw on the outside of the chuck will hold the three separate -parts of the apparatus firmly together. Let them be thus arranged and -finished as one piece on the mandrel. Afterwards drill a hole<span class="pagenum"><a name="Page_148" id="Page_148">[148]</a></span> in the -centre of the part which forms the cover, and enlarge it so that its -diameter shall slightly exceed that of the openings necessary to be -made in the ball for the purpose of hollowing out and forming within -it stars, or lesser spheres, box, cube, or other design, at pleasure. -In this chuck the ball will be held not only centrally but securely. -It is of course necessary to have a chuck specially made for each -different sized ball, but when it is considered that such things as -these are merely turned as curiosities and to prove the capabilities -of the workman, it is not probable that more than two or three sizes -of chuck will be needed, and the difficulty of making them is not -great nor the necessary expenditure of time, either. They should be -made entirely of sound boxwood, and so arranged as to the size of the -respective parts that when the ball is inserted and the cover placed -on, the latter shall not quite reach the shoulder on the base of the -chuck. In the spherical rest of more modern times the principle of -that already described is almost necessarily retained. It is figured -in <a href="#i-p148">223</a>. The sole A is formed like that of an ordinary hand rest, so -that it can be advanced across the lathe bed, and secured by the nut -and screw underneath as usual. From this rises a central circular -plate, which need not be more than a quarter of an inch thick, but -turned truly flat, that it may be parallel with the surface of the -lathe bed. From this rises the conical central pin upon which works -the plate B, the edge of which is racked to be moved by the tangent -screw C. Across this circular plate is securely fixed the chamfered -frame D surmounted by the part E which carries the socket and tool -receptacle, the details of which will be entered into when describing -the rest for ornamental work.<a name="FNanchor_15_15" id="FNanchor_15_15"></a><a href="#Footnote_15_15" class="fnanchor">[15]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_15_15" id="Footnote_15_15"></a><a href="#FNanchor_15_15"><span class="label">[15]</span></a> The drawing shows a band at X encompassing the screw. -This is an error, as the whole upper part, including this screw, is -made to revolve by means of the tangent screw.</p></div> - -<div class="figcenter" id="i-p147s" style="width:700px;"> - <img - class="p2" - src="images/i-p147s.png" - width="700" - height="305" - alt="" /> - <p class="center smcap">Fig. 222.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p148" style="width:537px;"> - <img - class="p2" - src="images/i-p148.png" - width="537" - height="527" - alt="" /> - <p class="center smcap">Fig. 223.</p> - </div> - -<p><span class="pagenum"><a name="Page_149" id="Page_149">[149]</a></span></p> - -<p>The method of turning from a pattern acting on the tool has been -alluded to. In some cases a similar method is pursued, in which the -hand supplies the place of automatic machinery, an instance of this -is the application of pattern plates or templets to the small slide -rest now to be described, by which not only parallel or spherical -work may be done, but the elevations and hollows in moulded work may -be followed without difficulty. The pattern plates can be made by -the amateur or workman so that not only is no extra cost incurred, -but any desired form can be given to the work and as many duplicates -made as may be requisite. The simple slide rest itself is represented -in <a href="#i-p149s">Fig. 224</a>. The lower iron or steel frame is rectangular, chamfered -underneath, and is cast with a projecting part B underneath to the -socket of the hand rest. There is, therefore, no sole or saddle -required, and the height is adjustable at pleasure to suit 3, 4 or -5-inch centres. C is a plate of brass, cast with one <span class="sans">V</span>-piece similar -to D, the second E being removable at pleasure, or both <span class="sans">V</span>-pieces or -guide bars may be attached by screws. They are attached by two or -three screws passing through oval holes in the plate and tapped into -the bar, so that a little play to or fro is allowed, by which they -can be adjusted to grasp with more or less friction the iron bevelled -frame. They are kept up to their places by a pair of large headed -screws tapped into the edge of the brass plate and marked <i>e, e</i>, in -the drawing of the rest. On the top of the brass plate is fixed in -a like<span class="pagenum"><a name="Page_150" id="Page_150">[150]</a></span> manner another pair of chamfered bars similar to those of a -slide rest for metal, but in the ornamental turning slide rests, where -lightness and accuracy are more needed than strength, the parts are -proportionally smaller. The frame, for example, may be six inches -or six and a half inches in length by two in width, the brass plate -two inches square, or perhaps two and a half by two, the longest -measurement in the direction of the upper guide bars, between which -the tool receptacle will slide. This will be quite large enough for -a five-inch lathe, although the measurement may be more or less if -desired. If taken as above, the iron frame may be half an inch deep -and the face of each side of similar size, leaving one inch between, -in which the screw will lie. <a href="#i-p151s">224 B</a> shows the under side of the frame -with a cross piece to which the part, B 224, is attached. The guide -bars for the tool receptacle may be similarly small and light. If -the plate is ¼ in. thick and two in width the bars may be ⅜ in. -stuff before being bevelled, the attaching screws can then be ⅓ in. -or <sup>3</sup>/<sub>16</sub> in. in the shank, the heads being large and flat, and not -countersunk. It is probable that many amateurs would like to attempt -such a rest themselves, hence we have given the above details. We -must however, warn them that as the above is for ornamental turning, -where accuracy is of the utmost importance, great care must be -exercised in the work, and the various parts must be fitted to the -utmost perfection. The upper face of the lower frame must be quite -level, and the sides quite parallel, and the upper or cross slide must -be fitted precisely at right angles to it. Above all, the screw by -which the upper part is advanced in either direction requires great -precision. It should be made with a fine thread deeply cut, and must -fit its nut under the brass plate, D, without shake. The nut itself -should be long, and must be carefully bored and tapped; it should -be also sawn through its length underneath, to give it a spring, so -that it may grasp the screw tightly yet easily, and this will also -compensate for wear. This will be understood when it is stated that -the milled head by which the screw can be turned is graduated round -its circumference, as is also the face of the bed or lower frame of -the rest. Hence to give the head a turn, or half, or a quarter turn, -must draw the sliding plate exactly the same distance to or fro, at -whatever part of the frame it may be at the time. This necessitates -all the threads being precisely alike. [We say precisely with a -certain mental reservation, for, strictly speaking, perfection is -hardly possible, and the skill and science brought to bear upon screw -cutting when perfect work has been necessary, as for astronomical -instruments, would hardly be credited, so extremely difficult is this -part of the mechanical art.] It would be better for the amateur to -get the screw and nut cut by Holtzapffel, Munro, or other first-class -maker, who has the requisite means and can command the highest<span class="pagenum"><a name="Page_151" id="Page_151">[151]</a></span> skill. -Between the upper guide bars are fitted various tool receptacles. The -only one which need as yet be spoken of is that which holds the little -inch-long tools for ordinary work or for use with the eccentric chuck. -This consists of a brass plate bevelled to fit the chamfered bars, on -the end of which is a small piece of steel with a rectangular hole and -set screw, as seen in the drawing marked X. This plate has a tailpiece -of rather thicker metal, through which pass two set screws, which -regulate the depth of the cut to be made, their points bearing against -the end of the brass plate on which this tool receptacle works. No -screw is attached to move this upper slide, but a wooden handle -projects from it at right angles to be moved by hand, or a lever Y is -made use of. This has two projecting pins, the front one taking one -of the holes, 1, 2, 3 of the slide, the other one of a set of similar -holes in the top of the chamfered bars. By this the slide can be -advanced with ease and great steadiness. We now come to the pattern -plates or templets F, alluded to. These are formed of sheet iron about -<sup>1</sup>/<sub>20</sub> in. to <sup>1</sup>/<sub>16</sub> in. thick, and must be long enough to reach from one -end to the other of the iron frame A, underneath which at each end are -two holes <i>a, a</i>., <a href="#i-p151s">Fig. 224 B</a>, to receive screws by which the templets -are attached by means of the slots, <i>b, b</i>. The outer edge, <i>a</i>, of -templet is the pattern to be copied. The dotted lines in <a href="#i-p149s">Fig. 224</a> show -a plate in position. The<span class="pagenum"><a name="Page_152" id="Page_152">[152]</a></span> tailpiece of the tool holder to be used has -a projecting stud, or is made with a screw with or without the roller -seen at H, and this is kept in contact with the templet by the hand -or by a spring, so that when the slide traverses the lower frame the -tool-holder necessarily follows all the curves of the pattern plate. -An inspection of K will make it evident that the projecting screw must -be so regulated as to length as to allow the tool-holder to go to the -extremes of the projections and hollows. It must therefore in the -pattern shown be at least as long as the line <i>a, b</i>, Fig. K, and a -tool-holder of sufficient length must for similar reasons be selected, -or the tailpiece might touch the fixed plate on which it works before -the guide pin had penetrated the deepest hollow of the pattern. With -these precautions nothing can exceed the ease with which this clever -adaptation of the slide rest is made and used, the greatest advantage -being that the workman can make his own templets to any curve or -series of curves that may be desired.</p> - -<div class="figcenter" id="i-p149s" style="width:700px;"> - <img - class="p2" - src="images/i-p149s.png" - width="700" - height="525" - alt="" /> - <p class="center smcap">Fig. 224.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p151s" style="width:504px;"> - <img - class="p2" - src="images/i-p151s.png" - width="504" - height="550" - alt="" /> - <p class="center smcap">Fig. 224B.</p> - </div> - -<p>At a later page is described a slide rest with the arrangements of -the tool-holder somewhat improved, and calculated for the reception -of larger tools and apparatus. The little rest here described is, -however, very light and useful.</p> - - -<h3 class="sc"><a name="HOBLYN" id="HOBLYN">Hoblyn's Compound Slide-Rest.</a></h3> - -<p>A compound spherical slide-rest, for ornamental turning lathes, which -has been patented by Mr. Hoblyn, Rickling-green, Essex, is capable -of turning and ornamenting accurately spheres and any segments of -circles convex or concave, either on the surface or cylinder; also, -it is stated that by the addition of templates any other curves, -not segments of circles, can be turned out, in addition to the work -performed by an ordinary compound slide-rest. In our illustrations, -<a href="#i-p153as">Fig. 1</a> is a side view, and <a href="#i-p153bs">Fig. 2</a>, an elevation of the rest. A is -the lower, and B the top plate, C the carriage, and the saddle as -usual. The lower plate, of iron, is planed on bottom and sides, -and has a longitudinal bevelled slot in the bottom to receive the -fastening bolt, so that the plate can be tightened up at any point -on the lathe bed. At one end of this bottom plate is a piece raised -the whole of its breadth, accurately turned and faced, with a stout -turned pin, <i>b</i>, for a pivot in the centre. A wheel, <i>c</i>, is placed -around this raised piece, having any specified number of cogs, and on -its top any specified number of small holes drilled to receive two -pins as segment stops. The top plate is slightly narrower than the -bottom one, and has on its underside a corresponding surface to that -raised on the plate A, turned and faced with countersunk hole in the -centre to fit on the pivot <i>b</i>, on which it is tightened by a screw -and washer. The top of B is placed to receive two parallel bars of -brass, bevelled on the inner edge, so as to form sliding bars for the -carriage C, one bar being a fixture, the other capable of adjustment -by tightening<span class="pagenum"><a name="Page_153" id="Page_153">[153]</a></span> screws. The sides are also accurately planed, and on -one a tangent screw, <i>e</i>, is so fixed as to be put in and out of gear -with the brass wheel, <i>c</i>, for the purpose of driving the top plate -round the pivot <i>b</i>. In the raised surface of B, is a countersunk -slot forming a quarter circle, with screw passing through it into the -bottom plate; by this means the top plate can be firmly fixed at any -angle to the bottom plate for the purpose of slide-rest turning. A -small pointer, <i>f</i>, works clear of the brass wheel in the capacity -of segment stop—two small pins being placed in the specified number -of holes in <i>c</i>. On the opposite side of the screw, <i>e</i>, on the top -surface, a screw, <i>g</i>, works in two standards screwed into the plate -through slots in the bar, which works through a traveller, <i>h</i>, firmly -attached to the carriage, C, and therefore capable of driving the -carriage in a rectilinear direction—for slide-rest purposes. This -carriage, C, consists of an iron plate <i>i</i>,<span class="pagenum"><a name="Page_154" id="Page_154">[154]</a></span> with standard <i>k</i>, top -plate <i>l</i>, with parallel brass bars to receive tool receptacle <i>m</i>, -the bottom plate and standard being in one piece with the plate, -planed side and bottom, so as to slide truly between the parallel bar -on B. The standard has its surface accurately turned with a pin in -centre to form pivot. The top plate is planed true, bottom, sides, -and top, and has a countersunk hole in the exact centre, so as to -work on the pin, and tightens up with a large nut. In the plate is a -countersunk slot forming a quarter-circle, with screw passing through -into the standard, to set the tool receptacle either parallel with -B for spherical turning, at right angles to B for slide turning, or -at any angle for thick and thin cuts, and similar patterns when used -either as a spherical or slide rest. The parallel bars are to be -similar to those on B, to enable the tool receptacle to be advanced or -retired by screw or lever. This part of the machine can be adjusted -for height of centre thus:—The standard <i>k</i> to be a hollow cylinder -with fixing screw on one side; the plate <i>i</i> to be made with turned -pin on bottom, to fit into standard; elevating screw; saddle as usual, -but with the addition of a small hole drilled in one of the sides, and -a corresponding one in the side of the lower plate A, so placed that -when a pin is fixed into these holes the pivot is exactly central to -the lathe centre.</p> - -<div class="figcenter" id="i-p153as" style="width:700px;"> - <img - class="p2" - src="images/i-p153as.png" - width="700" - height="288" - alt="" /> - <p class="center smcap">Fig. 1.</p> - </div> - -<div class="figcenter" id="i-p153bs" style="width:700px;"> - <img - class="p2" - src="images/i-p153bs.png" - width="700" - height="466" - alt="" /> - <p class="center smcap">Fig. 2.</p> - </div> - -<p>The way of using the spherical rest is thus described by Mr. -Hoblyn:—"When altogether, and the point of tool adjusted by means of -a square exactly over centre of pivot, it is evident, if the top plate -moves round, the point of the tool will still be in the same place; -but if we retire the point one half-inch, on moving the plate right -round it would describe an inch circle, so that if the centre of pivot -be exactly under the centre of the lathe, and we move the rest the -half-circle, it will cut a perfect ball (or any part of one, if the -cut be less than half a circle) of such size as the distance doubled -of point of tool from centre of pivot. Therefore, by adjustment of -the lower plate on the lathe bed according to the size of material -(this, of course, does not allude to the act of turning a ball, when -the centre of pivot must be exactly under centre of lathe), adjustment -of carriage from centre according to the size of circle required, and -adjustment of tool for depth of cut, we are enabled to turn any convex -curve. To turn the concaves, instead of retiring from centre of pivot, -it is only requisite to advance the point beyond the centre to the -distance required, when the same rules apply as to the convex curves. -In turning the concaves, however, it is necessary to turn the plates -half-round, so that A and B are in the same straight line, instead of -over each other. This enables you to work on any sized piece of wood, -the object of the longitudinal slot in the lower plate being to enable -you to adjust your previously arranged curve to any sized wood or -ivory that your lathe will take, less 2 in., the height of<span class="pagenum"><a name="Page_155" id="Page_155">[155]</a></span> machine. -The desired curve having been turned, take out the chisel, and place -in the receptacle any ornamenting instrument, drill, eccentric, &c.; -advance the point till it touches the work, then set your screw for -depth of cut, and work according to fancy. Whatever it is it must be -mathematically correct on the curve, as you have not altered it in -any way. You then remove your rest to cut the next desired curve, and -proceed as before. The best way to execute a piece of work is first to -make a sectional pattern of your design, either by drawing or cutting -it out with scissors from a double piece of paper, when, of course, -both sides come the same, the line where the paper is doubled being -the line of centre of lathe. You can then, with a pair of compasses, -ascertain with accuracy the necessary size of circle, and the position -of centre of pivot to procure the desired curves. You may also produce -a very good effect by a combination of two different curves in this -way:—Let your ornamental instrument be the universal cutter; working -horizontally follow up your curve with it, but, instead of cutting -right out on your curve, let the instrument finish of itself in wood -previously turned so as to fit its curve, when you get the lesser and -greater curves following in unbroken succession. With the eccentric -chuck numberless effects of the most curious description may be -produced, even work supposed to be only possible with a rose engine. -We believe the tool is to be seen at the shop of Mr. Evans, 104, -Wardour-street.</p> - -<p>To turn a sphere by means of a template attached to the slide rest as -described, the following adjustment of the rest and mode of proceeding -should be followed. A, B, <a href="#i-p156s">Fig. 225</a>, is the chuck containing the -material, H, to be worked into a sphere. Upon this the length, or -diameter (equal to that of the template, as will be explained), is -to be marked at K, K, which being divided equally by the line L, L, -will give the dimensions of the ball as if it were about to be turned -by hand. The corners are to be turned off with the gouge, as far as -shown, K being equal to <i>e</i> L, and K <i>f</i> equal to K <i>e</i>. The outline -of the ball will with these measurements not be touched. The angles -left may also carefully be removed, but (as shown by the figure) this -operation must be conducted with great care. A template must now -be made containing a full semicircle, <i>every part</i> of which can be -traversed by the stud or screw upon the under part of the slide, or -the ball will not be severed by the final cut. It is evident that the -traverse of the slide during the operation will be the full radius -of the ball, and in this, and indeed all cases of deep recesses, and -greatly projecting mouldings, the ordinary tool-holder with tailpiece -had better be removed, and replaced with a slide like M, having a pin -straight through it to rest in contact with the template. This will -preclude the necessity for the long stud or screw spoken of before -as necessary when the slide with the tailpiece is<span class="pagenum"><a name="Page_156" id="Page_156">[156]</a></span> used, but the -tool cannot be advanced independently of the template as when the -other form is used. Fix the rest so that when the top slide is at its -central position the tool may stand as in the sketch exactly upon the -central line of the ball. Take care that thus placed the tangent-pin -of the slide is on the central mark of the template. The long frame -of the rest must likewise be parallel with the bed of the lathe, -keeping the top slide pressed against the template with the left hand, -while the top part traverses the frame under the action of the screw -moved by the right hand, the ball will be correctly cut.<a name="FNanchor_16_16" id="FNanchor_16_16"></a><a href="#Footnote_16_16" class="fnanchor">[16]</a> One or -two cautions must, however, be given here, to ensure a satisfactory -result. In the first place the cylinder from which the ball is to -be made must be exactly of the diameter of the semicircle on the -template. H, H is the cylinder to be turned to a sphere, G, G, B shews -the position of the tool at starting, the dot on A, the templet, the -tangent pin of the slide, <a href="#i-p157as">Fig. 226</a>. As the work proceeds the tool will -take the several positions shown, the dotted lines, D, being equal and -parallel. The tool will thus repeat the form of the template. Let the -latter remain as before, but let a smaller cylinder<span class="pagenum"><a name="Page_157" id="Page_157">[157]</a></span> be inserted in -the lathe, or, which is the same thing, let the tool be now lengthened -so as to start at C on the inner dotted line. When the pin, F, has -reached K, which should be the axis of the ball, the tool will be -at M, quite out of cut. <a href="#i-p157b">Fig. 227</a> represents three forms of tool in -contact with the ball at two points. The first two will evidently be -out of cut at the axial line, as the side of these bevels will then -touch the piece to be turned. C is a form that will remain in contact -from the diameter to the axial line. The left side of the edge is -slightly overhanging the side line of the tool, D.</p> - -<div class="footnote"> - -<p><a name="Footnote_16_16" id="Footnote_16_16"></a><a href="#FNanchor_16_16"><span class="label">[16]</span></a> See Appendix</p></div> - -<div class="figcenter" id="i-p156s" style="width:484px;"> - <img - class="p2" - src="images/i-p156s.png" - width="484" - height="550" - alt="" /> - <p class="center smcap">Fig. 225.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p157as" style="width:316px;"> - <img - class="p2" - src="images/i-p157as.png" - width="316" - height="450" - alt="" /> - <p class="center smcap">Fig. 226.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p157b" style="width:435px;"> - <img - class="p2" - src="images/i-p157b.png" - width="435" - height="342" - alt="" /> - <p class="center smcap">Fig. 227.</p> - </div> - -<p>When the part shown has been cut this tool must be removed and a -similar tool bevelled in the reverse direction, adjusted by reference -to the central line of the ball as before.<a name="FNanchor_17_17" id="FNanchor_17_17"></a><a href="#Footnote_17_17" class="fnanchor">[17]</a> It is recommended to -roughly shape the work with the gouge, and partially to cut it off -with the parting tool so as to relieve the tool as much as possible, -and when the last finishing cut is to be taken a freshly sharpened -tool is to be made use of. It is evident that in the above and -similar work the rest may be placed across the end of the cylinder if -preferred to turn the <i>right</i> hand hemisphere, but it would have to -be moved for the second half, which should be avoided, if possible. -The advantage which the circular rest has over the above is due to -the fact that the tool and rest once in position, neither has to be -readjusted until the work is complete. The slide rest and semicircular -template forms, however, if judiciously used, a very serviceable -substitute and makes very satisfactory work. Whether or no the reader -has a complete rest for spherical work, he should decidedly provide -templates to use as above. They are not only useful for turning or -ornamenting spheres, but any forms whatever that may be desired, and -they possess this special advantage, that when a dome or other pattern -has been thus turned with a plain tool the same template used with -revolving cutters will enable the work to be ornamented with perfect -ease, doing away in a<span class="pagenum"><a name="Page_158" id="Page_158">[158]</a></span> great measure with the need of a dome chuck. -Suppose, again, that a number of pieces are desired precisely similar, -as a set of pawns for a set of chessmen, a sectional drawing made and -transferred to a piece of sheet-iron, and the latter cut to form a -pattern plate, will enable the most unskilful to work satisfactorily. -Nothing more need be said of the uses of templates, and for the -present the subject will be dismissed, though it may possibly be -referred to again in a future page.</p> - -<div class="footnote"> - -<p><a name="Footnote_17_17" id="Footnote_17_17"></a><a href="#FNanchor_17_17"><span class="label">[17]</span></a> Holtzapffel uses a tool, the plan of which is -semicircular, like a small round tool, cutting on front and two side -edges; the tool is very narrow and bevelled below.</p></div> - - -<h3 class="sc"><a name="SLIDES_AND_COMPOUND" id="SLIDES_AND_COMPOUND">Chucks with Slides and Compound Movements.</a></h3> - -<p>The first of the chucks comprised under the above head is the oval or -elliptical chuck, and it is introduced first in order because it is -not essentially a machine for ornamental turning, as are the eccentric -and others of this class. There are many plain works required of -elliptical section, as bradawl and other tool handles, for which a -very simple arrangement is required.</p> - -<p>The principle of the oval chuck is as follows:—There is an -arrangement of slide, by which as the piece revolves it is drawn -gradually further from the tool during half a revolution, and in -a similar manner caused to approach it during the remaining half -revolution, each point in the circumference alternately partaking of -such movement; the whole of these points together, which, of course, -form the circumference, will become an ellipse. Let D, <a href="#i-p158">Fig. 228</a>, be -the centre of the mandrel, A, B the direction of the slide moving -up and down in a right line, and carrying the work upon a screw -in the centre of it. C, E become centres, and may be taken as the -extremes, for as the work revolves a succession of centres are formed -and instantaneously changed. The figure produced will be the oval -shown. To render this, however, clearer, <a href="#i-p159s">Fig. 229</a> may be taken, which -represents the chuck in its most simple form with separate details of -the parts which compose it. A is the chuck with central slider and -chamfered bars, as described in speaking of the slide and rest and -previous apparatus; B is the slide detached; D, front view of the -same. The short arms <i>a, b</i>, pass through slots in the back plate as -seen at C, which shows this plate with slide removed. Through these -short arms pass a pair of adjusting screws; or still better <i>a</i> and -<i>b</i> are themselves cross arms or pallets extending the width of the -plate as seen next drawing, and in the chuck of Muir which follows. -They are merely flat plates of steel embracing the guide ring, so that -some point in their inner surface may rest against it during every -part of the revolution of the chuck.</p> - -<p><span class="pagenum"><a name="Page_159" id="Page_159">[159]</a></span></p> - -<div class="figcenter" id="i-p158" style="width:181px;"> - <img - class="p2" - src="images/i-p158.png" - width="181" - height="350" - alt="" /> - <p class="center smcap">Fig. 228.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p159s" style="width:700px;"> - <img - class="p2" - src="images/i-p159s.png" - width="700" - height="437" - alt="" /> - <p class="center smcap">Fig. 229.</p> - </div> - -<p>The guide ring here alluded to is shown at E, and also at G, fixed in -its place upon the poppet. It is in the form of a raised ring with -arms, B, C., which are turned at right angles near their ends, and -through which pass adjusting screws with conical points. This plate -is flat at the back and bears against the face of the poppet, the -mandrel nose falling into the central opening E. It is kept in place -by the points of the screws falling into conical holes at the sides -of the poppet head. At F is a side sectional view of this plate, -with its raised and accurately turned ring, H, and at G is seen the -poppet<span class="pagenum"><a name="Page_160" id="Page_160">[160]</a></span> with the plate attached, the left arm being dotted to show -the position of the adjusting screw. It is this ring and plate which -regulate the movement of the slider, and, with it, of the work, the -latter being attached to the screw in the centre of the sliding plate, -which screw is a counterpart of that upon the nose of the mandrel. -Suppose the chuck A screwed to the mandrel, and the ring accurately -concentric with the mandrel, in which position, the pallets must touch -at two opposite points. In the best chucks there is an adjusting screw -to each, by which the contact can be regulated. In this position -any object of a circular form can be turned, for the slider remains -in one position, and its screw, upon which the work is fixed, is a -continuation of the mandrel. But if now the adjusting screws of the -part E are turned, the one being loosened and the other tightened, -the guide ring will no longer be concentric with the mandrel, and, -as the screws of the slider bear upon it, the slider will during -its revolution be moved to and fro to a distance regulated by the -eccentricity of the guide ring. The combination of this circular -motion of the chuck and rectilineal movement of the slider will -produce an ellipse, and a stationary tool applied to the work will cut -it, into that form.</p> - -<p>The above simple arrangement of oval chuck suffices only for plain -work. The only figures that can be described by its means, upon the -cover of a box, for instance, being a series of ellipses of which -the longest diameters fall in the same right line, and of which the -centres are coincident with the axis of the mandrel, as <a href="#i-p160">Fig. 229</a>.</p> - -<div class="figcenter" id="i-p160" style="width:450px;"> - <img - class="p2" - src="images/i-p160.png" - width="450" - height="259" - alt="" /> - <p class="center smcap">Fig. 229.</p> - </div> - -<p>Even these, however, cannot be done without some compensating -arrangement, as the minor axis does not diminish in length at the same -rate as the major—hence the ellipses get narrower and narrower until -the central one becomes a mere right line. This is referred to again -in the ornamental section of this work.</p> - -<p><span class="pagenum"><a name="Page_161" id="Page_161">[161]</a></span></p> - -<div class="figcenter" id="i-p161a" style="width:350px;"> - <img - class="p2" - src="images/i-p161a.png" - width="350" - height="354" - alt="" /> - <p class="center smcap">Fig. 231.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p161bs" style="width:700px;"> - <img - class="p2" - src="images/i-p161bs.png" - width="700" - height="530" - alt="" /> - <p class="center smcap">Figs. 232, 233, 234.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p162" style="width:350px;"> - <img - class="p2" - src="images/i-p162.png" - width="350" - height="119" - alt="" /> - <p class="center smcap">X</p> - </div> - -<p>Combinations like <a href="#i-p161a">231</a>, in which the ellipses intersect, cannot be -so obtained. Hence the oval chuck is provided with a wheel, either -racked to work by a tangent screw or fitted with a spring catch, by -which it becomes a dividing plate. This wheel revolves on a central -pin<a name="FNanchor_18_18" id="FNanchor_18_18"></a><a href="#Footnote_18_18" class="fnanchor">[18]</a> fixed to the middle of the sliding plate, and carries a screw -of the same pitch as that upon the mandrel to which other chucks can -be attached. By this means the axial lines of the ellipse can be -varied in direction. This addition is shown in <a href="#i-p161bs">Fig. 232</a>, which is -a section, and <a href="#i-p161bs">233</a>, which is a front view. In the former, A is the -wheel,<span class="pagenum"><a name="Page_162" id="Page_162">[162]</a></span> which, as previously explained, should be so arranged as to -contain a number of cogs divisible by as many figures as possible; 96 -is such a number, being divisible by 2, 3, 4, 6, 8, 12; 72 is also -a good number, as it will divide by 2, 3, 4, 6, 8, 9. If the edge -is racked and moved by a tangent-screw with divided head a greater -range can be taken and finer work done. In this case the face of the -wheel can be marked with divisions, and a fine steel pointer, as -shown at F, added to count by. The pin B, which is firmly attached to -the centre of the slider plate, must be strong, and the lower part -at least should be conical. It is drilled and tapped at the smallest -end, and when the circular plate with its screw is slipped upon it, a -screw, E, the head of which is countersunk into the face of the large -screw, retains it in place. The slide, C, has a recess turned to fit -the wheel plate, and the latter is cut as shown at <a href="#i-p162">X</a>, which ensures a -more accurate bearing than if it was left flat on the lower surface. -In making this chuck certain precautions are necessary. In the first -place, the guide ring fixed to the poppet must be exactly concentric -with the mandrel when in its central position; and when it is drawn by -the adjusting screws to the right or left the central line must remain -parallel with the surface of the lathe bed. To ensure this centrality -it is necessary to turn its outer surface when it is in position on -the lathe head. So at least says Bergeron; and it is perhaps the best -method whereby to ensure the accuracy that is required.<a name="FNanchor_19_19" id="FNanchor_19_19"></a><a href="#Footnote_19_19" class="fnanchor">[19]</a> For this -purpose Bergeron directs the use of a cutter similar to <a href="#i-p161bs">Fig. 234</a> -attached to the mandrel as a chuck, the edge which is on the inside of -the bent part at <i>a</i> acting on the exterior of the ring as the mandrel -revolves. The screws allow the tool to be advanced closer to the ring -as the work proceeds, while they secure it at any desired point. Such -a contrivance as this, used merely as a finishing tool to correct any -slight error, is no doubt sufficiently satisfactory. The various parts -of this and other compound chucks should be first turned separately -to near the required size, and accurately finished when in their -respective places upon the chuck. Any parts which present a difficulty -from the impossibility of retaining them in place while operated upon, -may be soldered with tinman's solder, and thus turned, after which -the application of moderate heat will detach them, and the fluid -solder can at the same time be wiped off with a pledget of tow or -cotton waste. As many of our readers may wish<span class="pagenum"><a name="Page_163" id="Page_163">[163]</a></span> to make such apparatus -as the above, it may be desirable to add a few directions for the -preparation of chamfered edges such as those of the slide and guide -bars, the latter of which should be of iron or steel. Let the slide, -for instance, be cast as a rectangular plate and the two flat surfaces -be roughly levelled with a file. One of these must now be made -perfectly true, either by mounting it with solder upon the face plate -of the lathe, and levelling it with the aid of the slide rest, which -is perhaps the safest plan, or by careful working with the file, using -a straight-edge in all directions, and finishing by careful grinding -upon a flat stone slab with water, or on a wooden grinder charged -with emery and oil. After one side is finished, the opposite face may -be similarly treated; but for this the plate may be secured to the -finished surface of the lower plate of the chuck itself, and turned -with a tool fixed in the slide rest. The edges must now be filed truly -at right angles to the sides, care being taken to keep the long sides -of the plate parallel. (The short sides or ends will be rounded by -being turned true with the edge of the chuck.) The work must now be -tested with the straight-edge and small steel square, and any error -carefully corrected. Of course, if the reader is the happy possessor -of a planing machine, all these operations will be facilitated and -accuracy more likely to be ensured. It may here be mentioned that, -to supply the want of such planing machine (a want often felt by -amateurs who have not mastered the use of file and scraper), Monro, of -Gibson-street, has cleverly added a planing apparatus to the ordinary -foot lathe, rendering the latter tool complete for all purposes of -amateur engineering.</p> - -<div class="footnote"> - -<p><a name="Footnote_18_18" id="Footnote_18_18"></a><a href="#FNanchor_18_18"><span class="label">[18]</span></a> This pin should have been shown of a conical not -cylindrical form, and much stronger in proportion.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_19_19" id="Footnote_19_19"></a><a href="#FNanchor_19_19"><span class="label">[19]</span></a> This part is always so turned by the best makers.</p></div> - -<p>This handy apparatus will be found on a later page fully described and -illustrated by a photograph of the machine. The writer has seen it and -used it, and can testify to its satisfactory working, as a lathe thus -fitted does not run heavier or require greater exertion than when used -for ordinary turning.</p> - -<p>The next step will be the chamfering of the edges of the plate. Let -235 represent the plate in its present condition, with rectangular -edges. To produce a chamfer of 45°, draw a line, <i>a, b</i>, at a distance -from the edge equal to the thickness of the piece. If a smaller angle -is desired, the line must be drawn further back. An angle of 30° to -35°, is, in the writer's opinion, better than one of 45°, as the -chamfered bars will then have a wider bearing on the upper surface of -the plate, tending to hold it more securely down upon the lower part -of the chuck. Nothing remains but to file carefully down from the -line thus drawn to the lower edge, by no means a difficult operation -if care is exercised not to obliterate the mark, or to trespass the -least beyond the assigned limit. A template, cut like <a href="#i-p164s">Fig. 236</a>, of the -desired angle, will be a gauge for the edges of the plate, as well as -for those of the chamfered bars, and will serve to make assurance<span class="pagenum"><a name="Page_164" id="Page_164">[164]</a></span> -doubly sure. The arms which stand out at the back of the slider to -embrace the guide ring are not fastened to the plate immovably, but -with power of adjustment. A pair of short slots are made in the -slider, into which a square projection from the arms fits, and the -whole is clamped by a screw, as shown in <a href="#i-p164s">237</a>, A, B, and C.</p> - -<div class="figcenter" id="i-p164s" style="width:550px;"> - <img - class="p2" - src="images/i-p164s.png" - width="550" - height="465" - alt="" /> - <p class="center smcap">Figs. 235, 236, 237.</p> - </div> - -<p>A more accurate method is shown in the <a href="#Page_195">Ornamental Section</a> -for finer adjustment than can be secured in this way, but for a home -made chuck the above will suffice and is the easiest plan to carry -into effect. To use this chuck, the guide is first arranged, so that -its ring is concentric with the mandrel. A mark is generally made -upon it, and also upon the lathe-head, by which this position can be -readily insured. The chuck is then screwed upon the mandrel, and the -arms adjusted, as just described, so as to embrace accurately, but -not too tightly, the guide ring. They are then, once for all, fixed -in that position by the screws alluded to. A few drops of oil are -necessary to lubricate their inner surface and the exterior of the -guide, and the latter being withdrawn by its adjusting screws to the -desired eccentricity, the work may be proceeded with. A rough piece -of wood, however, should always be first turned to a cylindrical -form, as an oval chuck being an expensive article is to be carefully -preserved, and not exposed to the shocks inseparable from the process -of roughing down the work. Moreover, there should always be one or -two screws passing through the slider into the back plate, to take<span class="pagenum"><a name="Page_165" id="Page_165">[165]</a></span> -away the strain from the chamfered bars, which can be removed when -the slider is to be brought into action. Two precautions are here -laid down respecting oval turning, which, in all probability, a -tyro would not suspect to be necessary until taught by failure. In -the first place, at whatever point of the circumference the tool is -held, at that point it must remain, or rather, it must remain in the -same horizontal line, being neither raised nor depressed. Hence, for -all work where accuracy is needed, oval turning should be done with -the slide rest. In the second place, when it is desired to place a -succession of ellipses one within the other on the face of the work, -like <a href="#i-p160">Fig. 229</a>, it will not be sufficient to place the tool nearer to -the centre for each ring, but the eccentricity of the guide ring must -be reduced at the same time; otherwise, when the middle is reached, a -straight line will be the result, instead of the proposed ellipse, as -already stated. The lathe should not be driven at a very high speed, -and the moving parts should be lubricated from time to time. There are -other ways of compensating the error produced by the oval chuck, or -elliptic cutting frame, which however are so entirely connected with -ornamental turning that they are reserved to be introduced into that -section. A contrivance for turning ovals invented, and communicated to -the <i>English Mechanic</i> by a Suffolk amateur, deserves a place here. It -is thus described by the inventor:—</p> - - -<h3 class="sc"><a name="TURNING_OVALS" id="TURNING_OVALS">Turning Ovals, etc., by Means of a Template.</a></h3> - -<p>Ovals are generally turned by causing the work to move in and under -guidance of an "oval chuck".</p> - -<p>There seems no reason why the same result should not be arrived at by -communicating a movement to the rest supporting the cutting tool in -the following manner:—Let A, A, be lathe bearers, B, pulley,<span class="pagenum"><a name="Page_166" id="Page_166">[166]</a></span> C, screw -of mandrel, D, template fixed thereon, E, friction wheel on the end of -bar F, G rest (a board of any convenient width) moving on pivots at -H. The friction roller, E, is to be kept in contact with the template -by the cord running over the pulley T, stretched by the weight L. The -rest will thus oscillate under the guidance of the template, which may -be either oval or rose engine pattern, and the cutting tool form the -pattern of the template used. There might be other modes of causing -the rest to oscillate on the same principle. The lathe would require a -slow motion, the same as with an oscillating mandrel.</p> - -<div class="figcenter" id="i-p165" style="width:431px;"> - <img - class="p2" - src="images/i-p165.png" - width="431" - height="543" - alt="" /> - <p class="center smcap">Fig. 238.</p> - </div> - -<h3 class="sc"><a name="ECCENTRIC_CHUCK" id="ECCENTRIC_CHUCK">Eccentric Chuck.</a></h3> - -<p>Next in order of the compound chucks stands the eccentric, the use -of which is not entirely confined to mere ornamentation, as it is -often very convenient to the turner to have the power of shifting the -centre of his work. Thus, a <i>solitaire</i> board may be drilled with -the necessary cup-shaped holes, or any work of a similar character -completed by the help of this chuck without the necessity for -constant re-centering. The <i>general</i> work of the chuck in question -is nevertheless ornamentation, for which it is peculiarly adapted -either alone or in combination with other compound chucks, or overhead -apparatus. The sliding plate of this chuck works between chamfered -steel bars, the same as in the oval chuck. There is, however, no guide -ring on the lathe head to regulate the movement of the slide, and -therefore also no necessity for the projecting arms at the back. The -slide, in fact, is moved by a screw with a graduated head, similar -to those already described. <a href="#i-p166s">Fig. 239</a> represents the common<span class="pagenum"><a name="Page_167" id="Page_167">[167]</a></span> form of -this chuck, in which the wheel which forms a dividing plate is moved -by a tangent screw. The sliding plate is shown slightly drawn out by -its screw, the degree to which it is moved being that of its required -eccentricity. When the plate is drawn back to correspond with the -base plate, the centre will be in a line with that of the mandrel, -and any work turned upon the chuck in this position of the slide will -be cylindrical. The central screw of all these compound chucks being -alike and of the pitch of that on the mandrel, any of the ordinary cup -chucks can be used with them to hold the work; or the eccentric chuck -can be screwed to the elliptic, cycloidal, or any other in the set, by -which means an endless variety of curves can be described. The effect -produced by the simple eccentric chuck now described is as follows, -the slide rest being used with it as a matter of course. Let a piece -of box or other wood be fixed by means of a cup or other chuck upon -the screw of the eccentric chuck, and the slide rest with a single -point tool be brought in front of it. By means of this the work must -be carefully faced, and made uniformly level. A ring A, <a href="#i-p167s">Fig. 240</a>, may -now be cut, which will be concentric with the mandrel. The slide of -the chuck being now drawn down by a few turns of the leading screw -(the tool and rest being kept in its original position), the centre -of the work will thereby be shifted, and the tool being advanced to -touch the same, the<span class="pagenum"><a name="Page_168" id="Page_168">[168]</a></span> circle B will be formed of the same size as the -first, but necessarily cutting it at two points. Another turn of the -screw will enable C, and similarly D, or any number of circles to be -successively formed. The centres of these circles will be in a line -across the face of the work. The ratchet wheel is added to enable -the turner to arrange his circles round a common centre, instead of -being thus obliged to keep them in a right line, and it will presently -be seen what a beautiful variety of interlaced circles can thus be -accomplished. The dividing wheel is, as previously explained, divided -on its edge into an equal number of teeth, or racked for a tangent -screw and divided on the face and edge. We shall suppose the number of -divisions to be 120. Face the work afresh, and, drawing back the slide -until the centre is concentric with the mandrel, as at first, cut a -boundary circle, A, <a href="#i-p167s">Fig. 241</a>. Move the slide of the chuck a few turns, -as before, and cut an eccentric circle. Now move the dividing wheel -thirty teeth, and cut a second, and, advancing by thirty each time, -cut a third and fourth, and <a href="#i-p167s">Fig. 241</a> will be the result; the centres -of the eccentric circles falling upon four points of the inner dotted -circle, which is itself concentric with that first made.</p> - -<div class="figcenter" id="i-p166s" style="width:550px;"> - <img - class="p2" - src="images/i-p166s.png" - width="550" - height="271" - alt="" /> - <p class="center smcap">Fig. 239.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p167s" style="width:500px;"> - <img - class="p2" - src="images/i-p167s.png" - width="500" - height="470" - alt="" /> - <p class="center smcap">Figs. 240, 241, 242.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p168" style="width:350px;"> - <img - class="p2" - src="images/i-p168.png" - width="350" - height="392" - alt="" /> - <p class="center smcap">Fig. 243.</p> - </div> - -<p>If the same process is followed, but the number of the circles -increased, a very neat snake-like ring will be formed, constituting -a border, in the inside of which other combinations may be made. In -<a href="#i-p167s">Fig. 242</a>, twelve interlacing circles are shown; in <a href="#i-p168">Fig. 243</a>, twelve -circles, described upon centres, which lie upon the circumference of -a central circle of equal size. This last pattern, when more finely -executed, by doubling or trebling the number of eccentric circles, -forms the device generally cut upon watch cases, under the name of -engine-turned. The best way to <i>try</i> patterns, is to cover the face -of a piece of boxwood with paper, using a pencil in the tool-holder -of<span class="pagenum"><a name="Page_169" id="Page_169">[169]</a></span> a slide rest instead of a cutting tool. If a softer disc is used -instead of box, round pieces of paper or thin card can be fixed -upon it with ordinary drawing pins; and if the first pattern is -unsatisfactory, a second, and any successive number of pieces, can -be mounted, and fresh patterns traced by the same means. It would be -mere waste of time to multiply specimens of the patterns that may be -executed by the aid of the chuck just described; and, indeed, this -could only be done by cutting in the lathe itself the blocks from -which such specimens must be printed. For the present, at any rate, -the <i>principles</i> only by which such devices may be executed will -be given (as above,) and the designs will be left to exercise the -ingenuity and taste of the reader.</p> - -<p>It happens, moreover, that few as are the works devoted to the -general principles and practice of plain turning, more than one has -been published on ornamentation by the eccentric and other compound -chucks, in which a variety of executed patterns appear, of more or -less beauty; and in the <i>English Mechanic</i> has lately been printed a -selection of exquisite designs by Mr. G. Plant, whose chuck, indeed -(to be presently noticed), bids fair to supplant the most simple one -now described. The chief recommendation, perhaps, in the latter, is -its great simplicity, as it may be made by any amateur sufficiently -practised in the use of tools; whereas the geometric chuck is too -complicated to permit this. It will be observed, on inspecting the -drawing, <a href="#i-p166s">Fig. 239</a>, that the divisions on the face of the wheel are -continued on the side above the part that is racked; this permits them -to be seen when the piece of work overlaps the circle of the wheel. -The steel point shown at B, answers as an index, either to the surface -marks, or to those on the side. The tangent screw is now generally -fitted in a small frame, which is itself pinned at one end to the top -plate, and kept up to the dividing wheel by an eccentric cam. This is -not shown in the drawing; the plan is nevertheless good, as the screw -is instantaneously released from gear at pleasure, when the wheel -may be turned by hand to any desired position; after which a slight -movement of the cam brings up the screw, and all is made ready for -work. The eccentric chuck becomes available for such work as shown -in <a href="#i-p170a">Fig. 244</a>, representing the bottom of a candlestick, ringstand, -or similar article. In this case the centres of the eccentric work -(now cut quite through) are on the circumference of a circle larger -than, and outside, the work itself. Instead of cutting through the -whole thickness of the stuff the outer circle may remain such, and -the blackened part may represent an inner raised surface, when the -contrast formed by the sharp edges round the pattern with the smooth -circular part will be very agreeable to the eye. To improve still more -this design, the outer part may be ebony nicely moulded and edged with -ivory, and<span class="pagenum"><a name="Page_170" id="Page_170">[170]</a></span> the raised part ivory; or the same may be alternations of -ebony and holly, which will form a contrast almost equally agreeable. -A small chisel-ended tool must be made for this work if the whole is -in one block, as it will be necessary to leave a level surface upon -the face of the lower part. There are an infinite number of designs -of similar nature, which will occur to the reader when the principles -of the chuck have been mastered, some of which would at first sight -appear to have been worked by other means. <a href="#i-p170a">Fig. 245</a>, for instance, -which is but a modification of the last, scarcely looks like lathe -work, but can be cut more rapidly this way than any other—of course -the fret saw will do similar work, but it would first have to be -marked out, and afterwards the marks of the saw teeth removed, whereas -the above is cut and polished at once. It may here be observed that -the eccentric chuck itself is used to fix the <i>position</i> of the -various circles to be cut, whereas the <i>size</i> of these circles is -determined by the slide rest. Thus in <a href="#i-p170b">Fig. 246</a>, while the centre of -the chuck is concentric with the mandrel, bring up the tool in the -rest and cut the circle F, G, H, of which B is the centre; draw down -the slide of the chuck until its centre is at C, leaving the slide -rest as it is, and the circle F, E, D, will be formed of <i>equal size -with the first</i>. Now move the screw of the slide rest so as to draw -in the tool towards the centre of the lathe bed without altering the -chuck, and<span class="pagenum"><a name="Page_171" id="Page_171">[171]</a></span> the small circle will be the result, whose centre (being -dependent on the chuck alone) is the same as that of the larger -circle. Bearing in mind this principle, that the chuck determines the -various centres only, and the slide rest the radii, little difficulty -will be experienced in devising and executing designs. Such is the -simple eccentric chuck, of which the use is tolerably extensive; but -there are, nevertheless, certain positions in which the eccentric -designs are required, which cannot readily be obtained by its means. -<a href="#i-p171">Fig. 247</a> is one of these, in which a moment's inspection will show -the necessity of two distinct movements of the slide at right angles -to each other. Hence a second slide is attached to the first at right -angles, much the same in effect as a second chuck screwed upon the -first but standing across it. This is the compound eccentric chuck -to be subsequently described in detail. There is one drawback to the -use of these chucks, namely—their excessive weight, which causes -a great deal of vibration in the lathe itself, especially when the -eccentricity of the slide or slides is great. An accidental blow -moreover from the chuck under the above condition would be very -severe. Hence the various cutters eccentric and others, worked by -the overhead apparatus already in part described are infinitely more -pleasant to use and even more effective and more easily managed. -The eccentric chuck can be used in combination with these, and the -capabilities of the two will thus be vastly extended, but in this -case the chuck is kept stationary while motion is given to the tool, -and the defect just alluded to no longer exists. In cutting patterns -upon hard wood and ivory a common defect is shallowness of work, the -cuts should not be so light as to give merely an effect of a design -<i>scratched</i> upon the surface. The cut should be deep and clean, and -the tool not only sharpened but polished so as to leave the device -boldly executed, the small triangular and other shaped pieces left -between the cuts standing up clear and solid. Some patterns, as the -shell, which will be presently spoken of, require to be deep at one -part and shallow at another. Some devices look best when cut with a -point tool with<span class="pagenum"><a name="Page_172" id="Page_172">[172]</a></span> double and others with single bevel to the edge, and -the same design worked with different tools will appear almost like -two distinct patterns.</p> - -<div class="figcenter" id="i-p170a" style="width:500px;"> - <img - class="p2" - src="images/i-p170a.png" - width="500" - height="283" - alt="" /> - <p class="center smcap">Figs. 244, 245.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p170b" style="width:300px;"> - <img - class="p2" - src="images/i-p170b.png" - width="300" - height="262" - alt="" /> - <p class="center smcap">Fig. 246.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p171" style="width:320px;"> - <img - class="p2" - src="images/i-p171.png" - width="320" - height="346" - alt="" /> - <p class="center smcap">Fig. 247.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p172s" style="width:528px;"> - <img - class="p2" - src="images/i-p172s.png" - width="528" - height="550" - alt="" /> - <p class="center smcap">Fig. 248.</p> - </div> - -<p>The double eccentric is represented in <a href="#i-p172s">Fig. 248</a>. The part A is the -foundation plate, with a projection at the back, tapped to fit the -mandrel. B, B, the lower guide bars; K, K, the lower sliding plate. -All the above parts are precisely similar to those of the simple -eccentric chuck. Upon the face of this lower slide are attached two -chamfered guides, C, C, at right angles to the first. They are kept -in place by screws passing through oval holes on their faces, and -tightened when required by screws, tapped into four little square -blocks, D, D. Between these guides slides the upper plate, which -carries the screw for chucks, and the dividing wheel as before worked -by a tangent screw, G; to either end of which a key is fitted. The -leading screws, E and F, which move the two slides, have squared -ends projecting both ways, so that the plates can be made to work -eccentrically in either direction, which is sometimes an advantage. -The chucks do not screw down upon the face of the<span class="pagenum"><a name="Page_173" id="Page_173">[173]</a></span> division plate, -on account of their projecting parts at the back; and very commonly -a round plate, O, somewhat smaller than the wheel and about ¼ in. -thick is attached to the face of the latter to raise the work still -higher, so that the dividing plate can be readily seen. The more -compactly, however, the parts of this chuck are made, and the less -the work projects from its face the better; as there will be the less -strain upon the central pin, and upon the plates and their guide bars -when the tools are applied to the work.</p> - -<p>To be able thus to place in the centre of rotation any given point in -a piece of work, whatever may be the form of its boundary lines, is -of immeasurable advantage, even though the capabilities of this chuck -are confined to objects of plane superficies, it being impossible -to reach by its means the side of a cylinder, or the surface of a -sphere or spheroid. It is evident that any line upon the face of a -box, for instance, whether the latter be square, round, octagonal, or -of any other form, may be followed with two movements of the slides, -combined with the rotatory movement of the dividing wheel. Thus, a -border of interlacing circles may be carried round the edge of such -a box, <a href="#i-p172s">Fig. 248</a>; or, a series of such circles forming constantly -diminishing octagons, hexagons, squares, &c., may be thus readily -executed. Nevertheless, what was said of the simple eccentric chuck, -applies with even greater force to the compound eccentric. It is a -heavy piece of apparatus, requiring a lathe with substantial poppets -and bed; the whole well braced to the floor and wall, to withstand the -excessive vibration caused by the revolution of the apparatus. It was, -indeed, in view of this and similar appliances that we insisted in our -initiatory paper upon the great importance to the workman, of adequate -strength and solidity in the various parts of the lathe itself.</p> - -<p>In <a href="#i-p173">Fig. 249</a>, we give a simple specimen of work to be executed by the -compound eccentric chuck.</p> - -<div class="figcenter" id="i-p173" style="width:350px;"> - <img - class="p2" - src="images/i-p173.png" - width="350" - height="378" - alt="" /> - <p class="center smcap">Fig. 249.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p174s" style="width:359px;"> - <img - class="p2" - src="images/i-p174s.png" - width="359" - height="550" - alt="" /> - <p class="center smcap">Fig. 250.</p> - </div> - -<p><span class="pagenum"><a name="Page_174" id="Page_174">[174]</a></span></p> - -<p>The compound geometric chuck of Ibbetson, manufactured by Holtzapffel -and Co., is a double eccentric considerably improved and of very -extensive application. A full description of it is published in a -book written by the inventor, in which an immense number of patterns -executed by its means is given with detailed directions for their -execution. As these patterns are almost essential to a description of -the apparatus as exemplifying the working of its several parts, the -reader is referred to the book in question, or to a translation of it -into French in the supplement to Bergeron's work. To enable the turner -to execute patterns on the side of cylindrical pieces a chuck is used -called a dome chuck, similar to <a href="#i-p174s">Fig. 250</a>. A rectangular frame of -brass, A, carries a sliding plate C, at right angles to it, the latter -having a tailpiece which fits accurately between the frame, and is -tapped to receive the finely cut leading screw with divided head, B. A -nut at the back of the frame clamps the slide in any desired position. -Upon the upper face of the latter is a wheel racked on the edge so as -to be moved by the tangent screw, E.<span class="pagenum"><a name="Page_175" id="Page_175">[175]</a></span> This wheel, like that of the -oval and eccentric chucks, turns on a strong conical central pin, and -has a screw attached of the same pitch as that on the mandrel. The -chuck is screwed to the mandrel by the projecting flange, F. The work -is thus mounted at right angles to its ordinary position.</p> - -<p>By this arrangement any point in the side of a cylinder can be brought -in contact with a tool fixed in the slide rest, and by means of the -graduated screw heads of the latter and of the chuck various devices -can be accurately made. This chuck may be used alone or in combination -with the eccentric, and the quick revolution of such cumbrous pieces -that would be a great drawback to their use is less frequently -required, now that the following apparatus has been added to the -lathe, and eccentric revolving cutters, with drills and other tools, -have taken the place of heavier and more inconvenient apparatus. It is -indeed much more convenient in the majority of cases to keep the work -itself fixed, and to operate upon it by tools put in rapid motion, -because the latter, from their excessive velocity compared with that -which can be conveniently given to the material, make better work, and -at the same time from their lightness impart no tremor to the lathe -while in motion. The cuts thus made are in consequence very clean -and smooth, and free from those slight undulations apparent when any -vibration takes place in the lathe itself. The different varieties of -overhead apparatus have been already described and illustrated, and it -only remains to describe more in detail the revolving cutter frame, -drills, and other apparatus used therewith.</p> - -<p>The following pieces fit into the top of the slide rest in what is -called the tool receptacle, and are advanced to the work by means -of a lever as already described. <a href="#i-p176as">Fig. 251</a> is the revolving cutter -frame, the spindle of which is put in rapid motion by a cord from -the flywheel passing to the small pulley through the medium of the -overhead apparatus, as shown in a previous page. For the purpose of -cutting <i>small</i> intersecting circles, a forked drill, <a href="#i-p176b">Fig. 252</a>, or -a crank formed drill, <a href="#i-p176b">253</a>, will suffice, and if these are made to -cut deeply the result will be a succession of hemispherical knobs or -beads (these must not intersect). A drill like <a href="#i-p176b">Fig. 254</a> will give a -knob raised in steps, and it is plain that by cutting the end of the -drill to a section of the required moulding the latter may be rapidly -executed. The flat inch long cutters used with the geometrical chucks -(when the work revolves instead of the tool) are, of course, made of -a variety of forms upon the same principle. Cases of these drills -and cutters beautifully finished are sold by all the leading dealers -in turning lathes and apparatus. It is essential that these tools be -kept very sharp, and that their cutting edges should be <i>polished</i> if -first-class work is to be done. The difference in the ap<span class="pagenum"><a name="Page_176" id="Page_176">[176]</a></span>pearance of -execution is very evident when the cutter is thus perfect, as every -cut bears a high polish, which cannot otherwise be imparted. Nothing -can be applied to finish eccentric work except friction with a hard -brush, and even this is much better avoided, as rubbing of any kind -tends to round edges which should be kept sharp and to obliterate -the finer and more delicate lines. It is likewise the best plan to -finish with any particular tool all the work to be done by it without -removing it from the tool holder for the purpose of sharpening. If, -however, this is necessary the following contrivance must be used to -insure the precise form which the cutter had at the commencement of -the work. This being likewise necessary with respect to the fixed -tools for ornamentation, the apparatus requisite in either case will -be introduced here, the drawings and description being extracted from -Holtzapffel's valuable work already alluded to.</p> - -<div class="figcenter" id="i-p176as" style="width:550px;"> - <img - class="p2" - src="images/i-p176as.png" - width="550" - height="372" - alt="" /> <p class="center smcap">Fig. 251.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p176b" style="width:417px;"> - <img - class="p2" - src="images/i-p176b.png" - width="417" - height="228" - alt="" /> - <p class="center smcap">Figs. 252, 253, 254.</p> - </div> - -<p><a href="#i-p177s">Fig. 255</a> is arranged for flat tools of various angles, or drills with -single joints. A, is the stand of brass, with two turned and hardened -steel legs. To this is hinged at G, by a screw joint, the part K, the<span class="pagenum"><a name="Page_177" id="Page_177">[177]</a></span> -upper part of which forms a semicircular arc, C. A second arc, B is -fixed at one end to the stand A, and passes stiffly through a mortise -at the top of K. The latter can be raised, therefore or lowered at -pleasure upon this second graduated arc, and clamped at any angle -by the screw H. To the lower part of K is pivotted the tool holder, -D, the upper part of which is pointed, and screws as an index upon -the arc C, showing the angle at which it is placed. This tool holder -is clamped by a nut at the back, which fits the end of a screw seen -near the point. The figure below shows a tool holder which fits into -the projecting parts of D, and serves to hold the small flat tools. -Below is a similar holder, used for round-shanked drills. F is one of -three flat slabs upon which the tools are to be ground,<span class="pagenum"><a name="Page_178" id="Page_178">[178]</a></span> there being -one of iron, one of brass, and one of hard wood with a flat strip of -oilstone imbedded in it, flush with its upper surface. The tool and -its fittings are generally arranged in a box with three drawers; these -contain the slabs of oilstone and metal, with the powders necessary -for grinding and polishing. To use this instrument, the point of D -is adjusted to the required angle for one side of the point of the -tool. (It is shown at 40 deg. in the sketch.) The latter is then -placed in the holder, and made to project until, when the angle of the -chamfer is adjusted on the arc B, the part A is level, and therefore -parallel to the surface of the grinding plate. The whole thus forms -a tripod, the third leg of which is formed by the tool itself. The -latter is first rubbed on the oilstone with a little oil. It is then -finished more perfectly on the brass slab, dressed with oilstone -powder and oil. Previous to this the tool is moved one or two degrees -more upright by the arc B. A narrow facet is thus ground, having a -dull grey polish. The tool is now carefully wiped clean, and polished -with crocus and oil upon the slab of iron. If the point of the tool -is central, with a chamfer both ways, the point of the tool holder -is first adjusted on one limb of the arc and the tool ground, and -then the same adjustment made on the opposite limb, so that the other -side of the point can be operated upon. Thus tools of any angle and -any bevel may be sharpened to a nicety without fear of altering the -original form of the point, and this may be done, if necessary, during -the process of eccentric turning, although, as before stated, it is -better to fix the tools well sharpened at the commencement of the -work, and not remove them until at <i>least</i> one complete set of circles -or other patterns have been cut.</p> - -<div class="figcenter" id="i-p177s" style="width:444px;"> - <img - class="p2" - src="images/i-p177s.png" - width="444" - height="550" - alt="" /> - <p class="center smcap">Fig. 255.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p178" style="width:391px;"> - <img - class="p2" - src="images/i-p178.png" - width="391" - height="400" - alt="" /> - <p class="center smcap">Figs. 246, 247.</p> - </div> - -<p>The instrument just described is evidently unsuited for the drills and -bead tools which present a concave edge like <a href="#i-p178">246</a> A, B, C, enlarged<span class="pagenum"><a name="Page_179" id="Page_179">[179]</a></span> -sketches of tools copied from Holtzapffel's work. For these the -latter directs to use large or small cones (<a href="#i-p178">247</a>) of iron and brass, -to be dressed, the first (which is the polisher) with crocus, the -second with fine emery and oil, the flat side of the tool being held -towards the point of the cone, the bevel towards the thick end. Part -of the edge of C must be delicately sharpened by hand, as no guide -can be used for the step-like portion of the edge. The cones for -sharpening are either mounted in the usual manner, by one or both ends -in the mandrel of the lathe, or fitted into the spindle of a small -drilling lathe-head, the pulley of which is connected by a catgut -band with that of the mandrel of the small lathe-head, being fitted -with a tailpiece to fit the rest socket, or otherwise mounted on the -lathe-bed. The smaller cones especially require to be driven at a high -speed. When larger circles or mouldings are to be cut, these small -crank-form drills are no longer available, and are replaced by a very -simple, but most effective contrivance called the eccentric cutter, -by which any work that is within the scope of the eccentric chuck -and fixed tool may be executed with great precision and rapidity. -This is represented in <a href="#i-p179s">Fig. 248</a><a name="FNanchor_20_20" id="FNanchor_20_20"></a><a href="#Footnote_20_20" class="fnanchor">[20]</a>—a small oblong frame of brass, -about two or two-and-a-half inches in length, and half an inch or -so in breadth is traversed by a fine screw, prevented from moving -endwise by a collar, as in the slide rest (of which, indeed, this is -a miniature). A slide, C, with a little tool holder at the top of it, -is moved along the frame by the leading screw, the head of the latter -being graduated, and also the upper surface of one or both sides of -the frame. The projection A, fits into the end of the drill holder, -and is secured by a screw. Circles of a diameter equal to B, B" may -thus be cut, and their effect varied by placing tools of any form of -edge in the tool holder. Such a tool as A, will thus no longer cut a -minute circle forming a hemispherical raised knob, but will form a -circular moulding, such as that shown in part at <a href="#i-p179s">Fig. 249</a>, except when -the tool holder is on the middle of the frame and the tool concentric -with the mandrel. The single point tools, however, with single or -double bevel, are more commonly used, in this cutter, as mouldings<span class="pagenum"><a name="Page_180" id="Page_180">[180]</a></span> -can be turned as efficiently with hand beading tools, with or without -the eccentric chuck, according to their required position. It may here -be mentioned that eccentric work should always be cut on wood of one -colour, or on ivory, as the veinings of the richer fancy woods, which -are so beautiful in other cases, only serve to confuse the tracery -made by the eccentric cutter. Of all woods for fancy work with the -eccentric chuck or cutter, nothing equals African black wood. It is, -however, costly, and only ranges to a diameter of five inches, as -great part is unsound. The rind is hard, thick, and white, similar to -boxwood. Next to this for such work stands, perhaps, cocus, or cocoa -wood, which is not the tree bearing the cocoa nut, the latter being a -palm, which is more like cane in texture. One of the most effective -patterns to be formed by the eccentric cutter is the shell, <a href="#i-p180">Fig. 250</a>, -in which one side, or rather one portion of the circles composing it, -is very deeply cut, while the opposite part is shallow. This can be -simply effected by throwing the sole of the rest out of the level, -by placing a thin piece of wood or metal across the lathe bed, so as -to tilt up the rest and place it (with the cutter) in an inclined -position. The tool will thus begin to cut at one part before it -touches the surface elsewhere, and the desired effect will be readily -produced. In using the eccentric cutter great rapidity of motion -must be given to it, but the tool must be advanced very carefully, -or it will be broken. The lever handle is the best to use for the -purpose. Akin to the shell pattern are those in which part only of -the circles are cut, leaving an effect shown by the border round <a href="#i-p180">Fig. 250</a>. -This is produced in the same way as the last, being, in fact, a -ring of shells in their initiatory stages. This is a very effective -snake-like pattern, when fairly and cleanly cut. When the eccentric -cutter is used, it must be remembered that the principle of work is -not quite the same as with the eccentric chuck. With the latter it -was<span class="pagenum"><a name="Page_181" id="Page_181">[181]</a></span> stated that the size of the circles depends on the slide rest and -the position of their centres on the chuck. In the present case the -eccentric cutter regulates the sizes, and the screw of the slide rest -itself the positions of the centres of the circles, since the part -A of the cutter will always be in the centres of the same, and this -part is attached to the rest. It will be understood that this remark -respecting position of centres only relates to circles lying on the -diameter of the work, such as <a href="#i-p181">Fig. 251</a>, the distance between <i>a</i> and -<i>b</i> will be taken from the division plate on the pulley of the lathe. -The way to cut the above, for example, will be as follows:—Place -the slide rest so that when the cutter tool is in the centre of the -frame it shall be concentric with the mandrel. In this position it -will only make a dot in the centre of the work. Turn the screw of the -cutter frame until you have a radius sufficient for the centre circle. -Set the mandrel pulley with the index in No. 360, put in motion the -overhead apparatus and cut the circle, move the screw of the slide -rest a few turns (<i>thus fixing the centre of the second circle</i>), -until you find that the cutter will form the circle cutting the first, -and passing through its centre. (<i>Observe, this being the size of the -first, the screw of the cutter frame is not turned.</i>) Cut the circle -in question, move the mandrel pulley a quarter round, so that the -index is in No. 90, and cut another; repeat the process twice more, -and 1, 2, 3, 4, will be cut. The <i>position of the centres</i> of Nos. 5, -6, 7, 8, will now have to be determined as before, by working the main -screw of the slide rest; but, as their size is less than the preceding -set, the screw of the cutter frame must likewise be turned to diminish -them to the required degree. When by these combined movements their -position and size have been determined, they must be cut by the aid -of the division plate, in the same manner as the last, and so on, -till the whole have been cut. With respect to the ratio in which the -circles diminish, and the precise sizes of them, no rule can be given, -as this<span class="pagenum"><a name="Page_182" id="Page_182">[182]</a></span> must depend on the taste of the operator. The sole object in -this place is to show the <i>principles</i> whereby these patterns are to -be executed. A good deal of care is requisite in practice, and the -memory has to be often rather severely tasked. The best plan is always -to try a proposed pattern upon boxwood or paper, before risking it -upon more valuable material; and, where it can be done, it is well to -write down the numbers to be used on the various division plates. A -single false cut, it must be remembered, will spoil the whole work, -at a great waste of time, loss of material, and annoyance, only to -be appreciated by those to whom such an untoward accident may have -happened. The drilling apparatus, without the eccentric cutter, but -fitted with a round-headed drill, is used for the production of fluted -works, such as that shown in <a href="#i-p183s">Fig. 252</a>, A and B. The drill being -inserted in the end of the spindle, and its point or end (of any -desired form, either round, flat, or pointed) being brought opposite -one end of the flute, the lathe is to be put in motion as in ordinary -ornamental drilling, the mandrel being, of course, held fast by the -index and division plate. At the same time that the drill in rapid -motion is brought against the work by the lever handle, the screw -of the slide rest is slowly turned, and thus the groove or flute is -drilled out by the combination of longitudinal and vertical action. -The number of flutes in any given size of cylinder is determined, -first by a horizontal sectional plan on paper, and regulated -accordingly by help of the division plate and index. In making such -an article as <a href="#i-p183s">Fig. 252</a>, it will economise material, whether ivory or -blackwood, or a combination of the two, to form it of at least three -pieces, making the divisions at C, D. Care should be taken to leave -below the bowl, which should be as thin as paper if of ivory, the -part C on which the beads are to be drilled. The pedestal can then -be screwed into this, and will not penetrate the bottom of the bowl. -Ivory may be screwed in an ordinary set of stocks and dies if care is -taken not to screw up the latter too quickly. Lard may be used as a -lubricant in cutting this material, whether for sawing or drilling. -The part with raised mouldings between A and D is ornamented with -a vertical or universal cutter, and for greater ease and exactness -a template may be used in the slide rest by means of which all the -curves of the moulding may be accurately followed by drill or cutter. -The minute beads round the edges of the small mouldings are made with -two sizes of A, <a href="#i-p178">Fig. 246</a>; a little knob is thus formed rising from a -hollow. The small knobs used as feet may be rapidly formed by a hand -beading tool of semicircular section, similar also to A, <a href="#i-p178">Fig. 246</a>. A -pin may be left on each, or they may be drilled and attached by small -screws of brass wire made on purpose. The following cement will enable -the turner to make an ivory bowl for the above ornament so thin as to -be transparent; indeed it may be thus made so<span class="pagenum"><a name="Page_183" id="Page_183">[183]</a></span> thin as to bend under -the fingers, although such extreme tenuity is not required in the -present case.</p> - -<div class="footnote"> - -<p><a name="Footnote_20_20" id="Footnote_20_20"></a><a href="#FNanchor_20_20"><span class="label">[20]</span></a> A newer pattern appears on a later page.</p></div> - -<div class="figcenter" id="i-p179s" style="width:700px;"> - <img - class="p2" - src="images/i-p179s.png" - width="700" - height="265" - alt="" /> - <p class="center smcap">Figs. 248, 249.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p180" style="width:350px;"> - <img - class="p2" - src="images/i-p180.png" - width="350" - height="378" - alt="" /> - <p class="center smcap">Fig. 250.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p181" style="width:350px;"> - <img - class="p2" - src="images/i-p181.png" - width="350" - height="388" - alt="" /> - <p class="center smcap">Fig. 251.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p183s" style="width:249px;"> - <img - class="p2" - src="images/i-p183s.png" - width="249" - height="550" - alt="" /> - <p class="center smcap">Fig. 252.</p> - </div> - -<p>Take the finest sifted lampblack and make it into a paste with glue, -about as thick in consistency as paint. After turning the ivory -tolerably thin, paint this on the inside; let it dry, and repeat the -process till sufficient is laid on to form a kind of hollow core, -of strength sufficient to support the ivory against the action of -the tool.<span class="pagenum"><a name="Page_184" id="Page_184">[184]</a></span> The material may now be thinned and ornamented from the -outside. When finished, soak a few minutes in warm water, and then -agitate in cold; it will become quite clean as before.</p> - -<p>By altering the direction of the motion of the revolving cutter, the -several cuts made by it will assume a different character, and the -work will present a series of hollows scooped out, so to speak. The -cutter, <a href="#i-p184a">253</a>, being fixed in the tool holder of the top slide, will -work vertically only, and produce patterns similar to <a href="#i-p184a">Fig. 254</a>, of -the nature of basket work. This is exceedingly effective, and, as it -may be cut so deeply as to penetrate the material of hollowed works, -the latter may be lined with red or other bright coloured silk or -velvet, and a variety of designs thus worked out. It is very necessary -in using the vertical cutters to move the tool holder forward very -gently, giving it at the same time great rapidity of revolution. -Without this it will at once stick fast in the work. The character -of the designs may, of course, be infinitely varied by using cutters -of different sections, as in the case of work done with fixed tools -with the aid of the eccentric chuck. The same cutters will, in fact, -serve both purposes. <a href="#i-p184b">Fig. 255</a> represents a tool similar to the last, -but<span class="pagenum"><a name="Page_185" id="Page_185">[185]</a></span> arranged to cut horizontally. With this, fluted work can be -done: but it is evident that the cord from the overhead apparatus -cannot here be directly applied, owing to the horizontal position -of the driving pulley. Additional guide pulleys, therefore, become -necessary, and, when these have to be arranged, the apparatus is -generally modified, and the universal cutter is used, of which one -form is shown in <a href="#i-p185s">Fig. 256</a>, and though it is not so good a pattern as -that which is described in a later page, it is nevertheless suited -for use with the old pattern of slide rest already delineated. With -this the direction of the cuts may be varied at pleasure—they may -be perpendicular, horizontal, or radial, and, when the templates -before mentioned are added to the slide rest, an infinite variety of -devices may be cut upon spherical and curved surfaces, so that the -cutter thus modified is fully entitled to its title of "universal." -The design, <a href="#i-p186s">Fig. 258</a>, is entirely the work of revolving cutters and -drills used with a template of the required section. It is intended -for a lady's workbox, opening with a hinge on the line, <i>a, b</i>, and -containing in separate compartments the various articles required. -It may be made entirely of ivory, lined with red or blue satin, and -the flutes<span class="pagenum"><a name="Page_186" id="Page_186">[186]</a></span> round the body may be cut through to allow the lining to -appear. In the latter case, however, if the box is of ivory, black -velvet may be used to enhance the contrast, and, as the glossy pile -would be outwards, a second lining of any desired colour should be -added with the best side inwards. The rings for the handles, as for -all similar purposes, can be quickly made with the tool, <a href="#i-p187a">Fig. 259</a>. A -hollow piece of ivory being taken, and turned smooth inside and out, -one side of the tool is applied, as in the figure, so as to cut half -through the work. It is then removed, and the opposite edge applied -to the inside until the ring falls off completely finished. It is -then cut through with a thin saw or knife, and inserted in the tailed -ring or other projection intended to receive it. Handsome works in -ivory should always be kept under glass shades. The universal cutter -shown in <a href="#i-p185s">Fig. 256</a> consists of a plate with chamfered edges to fit -the tool receptacle of the slide rest, having near each end small<span class="pagenum"><a name="Page_187" id="Page_187">[187]</a></span> -poppets which support the round rod connecting the pulley bearing -piece, A, with the part, E, which carries the tool, F, the latter -being attached by a small slot and set screw to a cylinder revolving -in E, and having at its upper end the driving wheel, C. At G is a -circular piece or wheel racked on the edge, and turned by the tangent -screw, G. The hinder poppet is rectangular, and has divisions marked -upon it on each side of the angle numbered from the apex. The racked -wheel may with advantage be similarly graduated. When the part E is -vertical the cutter will be in a position to work horizontally, and -the pulley support will be vertical. By turning the tangent screw, -both the parts move together; but if desired the pulleys can move -independently by unscrewing D and L. The angular poppet may be made -semicircular if preferred, the degrees being numbered either way from -0" in the centre. When the tool holder is horizontal, or approaching -that position, the nut, D, must be loosened, and the pulleys placed -so that the cord will not slip off. They may be dispensed with if the -apparatus is to be used <span class="smcap">only</span> for vertical cuts (the <i>holder</i>, -E, will be horizontal); but if a radial pattern is to be cut, in -which the angle is to be constantly varied, the pulley piece must be -used and the pulleys re-arranged at D, as required from time to time. -There is a somewhat neat and serviceable little apparatus represented -in <a href="#i-p187bs">Fig. 259<sub>A</sub></a>, to take the place of the<span class="pagenum"><a name="Page_188" id="Page_188">[188]</a></span> slide rest and its -revolving cutters, and although its powers are limited, much may be -done with it. The spindle A, works through brasses in the poppets, B, B, and is put in motion by a cord from the overhead passing over the -pulley in the centre. This spindle, which holds the crank-formed and -other drills in a socket at one end, moves freely through the bearings -endwise, and is kept back from the work by a spiral spring working -against the end of the handle, C. This handle does not turn with the -spindle, but is mounted like the handle of a carpenter's brace, or -that of an Archimedean drill stock. The whole apparatus fits into the -socket of the ordinary rest. A screw should have been shown in the -drawing, passing through B towards the pulley, to regulate depth of -cut.</p> - -<div class="figcenter" id="i-p184a" style="width:550px;"> - <img - class="p2" - src="images/i-p184a.png" - width="550" - height="285" - alt="" /> - <p class="center smcap">Figs. 253, 254.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p184b" style="width:347px;"> - <img - class="p2" - src="images/i-p184b.png" - width="347" - height="300" - alt="" /> - <p class="center smcap">Fig. 255.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p185s" style="width:550px;"> - <img - class="p2" - src="images/i-p185s.png" - width="550" - height="481" - alt="" /> - <p class="center smcap">Fig. 256.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p186s" style="width:426px;"> - <img - class="p2" - src="images/i-p186s.png" - width="426" - height="550" - alt="" /> - <p class="center smcap">Fig. 258.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p187a" style="width:350px;"> - <img - class="p2" - src="images/i-p187a.png" - width="350" - height="108" - alt="" /> - <p class="center smcap">Fig. 259.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p187bs" style="width:550px;"> - <img - class="p2" - src="images/i-p187bs.png" - width="550" - height="327" - alt="" /> - <p class="center smcap">Figs. 259A, 260.</p> - </div> - -<p>Once fixed by the screw of the latter in its intended position the -tool is advanced to the work in a straight line by pressing the handle -C, and is released from the cut as soon as this pressure is withdrawn. -With different sizes of cranked, forked, or round ended drills, a good -deal of ornamentation may be done with this simple tool, which is also -useful for ordinary light drilling. By putting in the socket a round -ended drill, and using the radial movement (turning the whole round in -its socket in the arc of a circle), short flutes can be drilled out -deep in the middle, forming basket work similar to <a href="#i-p187bs">Fig. 260</a>, which is -exceedingly pretty when carefully executed. There is little difficulty -in making drills and cutters, as steel of all sizes in round and -square bars may be had at the chief tool shops, especially at Fenn's, -in Newgate-street. In making the revolving cutters, however, it is -necessary to observe the position of the axial line, which must -pass through the cutting edge. After the drill is roughly finished, -therefore, it should be mounted in the tool holder with which it is -to be used, and carefully tested upon a piece of unimportant work. -If in revolving against the latter it leaves a part of the material -untouched, the edge is not truly in the centre of rotation. The flat -side of the drills are to be diametrical, and hence, as Holtzapffel -remarks, these drills can only be sharpened on the end. The latter -authority also says most of the drills embrace (in contour of edge) -only about one-fourth of the circle, as when the drills are sharpened -with one bevel they can only cut on the one side of the centre, and -if the drills were made to embrace the half circle the chamfer of the -edge on the second side would be in the wrong direction for cutting, -and consequently it could only rub against the work and impede the -action of the drill. All ornamental cutters and drills should be kept -in a box with small separate divisions to fit the shanks, which are -all of one size. The points can then be seen and the selection made of -any required pattern.</p> - -<p><span class="pagenum"><a name="Page_189" id="Page_189">[189]</a></span></p> - - -<h3 class="sc"><a name="CURIOSITIES" id="CURIOSITIES">Curiosities.</a></h3> - -<p>Many turners take special interest in the production of objects in the -lathe, that at first sight appear impossible to be produced solely -by its means. Inasmuch as such works manifest the skill and patience -of the artificer, they will always meet with appreciation; and, -although otherwise useless, they serve as elegant objects of vertu, -and are well worthy a place among the rare ornaments of the drawing -rooms. When first the Chinese balls, consisting of a set of hollow -spheres one within the other, all exquisitely carved, were brought -to England, it was believed they were made in hemispherical pieces, -united round the equatorial line with some kind of cement, the joint -being carefully concealed. I am not sure that they are made in a lathe -in China; but, at all events, they are so made in England, and our -home productions almost rival those of that strange yet clever nation. -I say almost, because the carving in ivory done by the Chinese is in -some respects unequalled, nor do I suppose that work requiring in many -instances years of patient industry could be made to repay the cost -of manufacture in England. No sooner were these curiosities in vogue -here than all kinds of similar impossibilities were manufactured. -Stars with from three to a dozen rays made their appearance, enclosed -sometimes in similar sets of hollow spheres—the rays projecting -beyond the limits of the outer shell—others were wondrously enclosed -in cases with flat sides, cubes, pyramids, six, eight, twelve-sided -hollow cases, all turned fairly in the lathe, were produced with -similar contents, so that the apple in King George's dumpling became a -very secondary wonder. The starry inmates were evidently too large for -the houses; yet there they were—legs and arms, of course, sticking -out through doors and windows, simply because there was no room for -them inside. We will penetrate the mystery, commencing with a single -hollow ball containing a star of six rays, the bases of the latter -standing on a central cube.</p> - -<p>In the first place a perfect sphere is required, and consequently the -slide rest and template, or spherical rest, must come into requisition -unless the turner can produce a ball by hand tools alone. Let this -sphere, or rather its boundary line, be drawn on paper of full size -with the compasses, <a href="#i-p190as">Fig. 262</a>, A, B, C, D. Draw the diameters -A, D, C, B, at right angles to each other. This will give you five points, -which on the sphere itself (on which these lines will have to be -drawn, including also another, answering to A, B, C, D) are centres of -six openings, here represented by the circles, through which the tools -have to be introduced to hollow out the sphere and form the star. The -points of the latter will be in the centres of these openings. Draw in -addition the plan of the central cube, and one ray of the<span class="pagenum"><a name="Page_190" id="Page_190">[190]</a></span> proposed -star; next draw an inner circle, here dotted to mark the thickness of -the outer envelope. The object of this drawing is to enable you to -make a set of curved tools, one of which is shown black at E, and a -set are marked on a plate of steel, from which they must be cut out. -A close inspection of the figure will show that if ball, <a href="#i-p190as">Fig. 262</a>, -were turning on the point A, A D being its axis of revolution, tools -of the given section introduced at D would cut away the material -round the point or ray, leaving the latter standing;<a name="FNanchor_21_21" id="FNanchor_21_21"></a><a href="#Footnote_21_21" class="fnanchor">[21]</a> and this -operation repeated at the five remaining openings would entirely free -the central cube with its rays according to the proposed design. The -tools have to be introduced in order, beginning with the smallest; and -although the above remarks will make clear the principle, there are -several points to be attended to in practice, and some few accessories -are required which will now be explained. It is evident that for -every different sized sphere fresh sets of tools will be requisite, -which will also vary in pattern according to the intended form of -the central base on which the rays stand; a cube or flat-sided solid -requiring one tool at least, with a rectilineal edge; spherical or -other solids demanding others whose ends are of different section. -Hence, in all cases, full-sized plans of the proposed work must be -drawn, and special tools designed therefrom.</p> - -<div class="footnote"> - -<p><a name="Footnote_21_21" id="Footnote_21_21"></a><a href="#FNanchor_21_21"><span class="label">[21]</span></a> There is an error in the position of this tool, which, -thus placed, would not leave the point of the star. <a href="#i-p190bs">Fig. 270</a> will -explain the method better.</p></div> - -<div class="figcenter" id="i-p190as" style="width:450px;"> - <img - class="p2" - src="images/i-p190as.png" - width="450" - height="246" - alt="" /> - <p class="center smcap">Fig. 262.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p190bs" style="width:550px;"> - <img - class="p2" - src="images/i-p190bs.png" - width="550" - height="239" - alt="" /> - <p class="center smcap">Figs. 269, 269B, 270.</p> - </div> - -<p><a href="#i-p190bs">Fig. 269<sub>A</sub></a> is introduced to show more clearly the result of -the appli<span class="pagenum"><a name="Page_191" id="Page_191">[191]</a></span>cation of the first set of tools, or rather of the first -application of the set, as the latter are used throughout.</p> - -<p>The blackened part will be entirely cut away in this operation, the -shaded part meeting it will be removed when the tools are transferred -to the adjacent opening, the cuts meeting those first made. Hence -the tools need only reach from <i>a</i> to <i>b</i>, and can be more easily -introduced than if the curved part were longer. Gauges, <a href="#i-p190bs">Fig. 269<sub>B</sub></a>, -A, must likewise be made of thin brass or tin, that the -progress of the work may be examined, and each opening in the sphere -should likewise be measured with a gauge, or with compasses fixed to -one width by an adjusting screw.</p> - -<p>The proper chuck for this work is the capped ball chuck already -described, by loosening the cap of which any one of the six openings -may be brought under the action of the tool, these openings being, in -fact, bored out simultaneously with the formation of the star. After -the first point or ray of the star has been completed, the ball may -be reversed and the opposite ray formed. These are now to be secured -by plugs, which are to be turned conical, to fit the opening of the -ball at one end, and of a length to rest upon the central cube at the -other, being also bored out to fit over the rays, which they should -embrace closely at top and bottom, even if not at the other points -of its length. (<a href="#i-p190bs">Fig. 269<sub>C</sub></a>, A and B.) This is to be repeated -as each ray is formed, so that the central star may be held in place -until the work is finished, when the plugs are removed, and the star -will be entirely detached. The above-named tools being straight on the -right hand side of the shank will not form a finished <i>conical</i> point -or ray. Hence it is recommended to file away that side, so that when -flat upon the rest, the back of the tool may be an exact counterpart -of a ray, <a href="#i-p191">Fig. 270, A</a>. There is, however, no absolute necessity for -this, as the star point can be first made blunt, with perpendicular -sides, which can then be neatly finished by a separate tool made for -the purpose, and kept up to a very keen edge. The first and smallest<span class="pagenum"><a name="Page_192" id="Page_192">[192]</a></span> -of the set of tools here shown, is the one with which the flat sides -of the cube are formed, and it must be bevelled from underneath, so as -to present a cutting edge on the end. The curved tools should cut on -the end and both sides of the crook.</p> - -<div class="figcenter" id="i-p191" style="width:450px;"> - <img - class="p2" - src="images/i-p191.png" - width="450" - height="317" - alt="" /> - <p class="center smcap">Figs. 270A, 271.</p> - </div> - -<p>It is quite possible to make the above in mahogany, but a closer -grained wood is much to be preferred, as the tools used—which are -held flat upon the rest—are rather scraping than cutting, and -mahogany, and fibrous woods in general, cannot be thus worked neatly. -Boxwood is, in every respect, the best material to begin upon, ivory -and blackwood being reserved until the eye and hand have become -accustomed to such work. The whole operation requires great care, and -is rather tedious, but the result ought to be a sufficient reward. -The external surface may, of course, be ornamented with the usual -apparatus, but the star should be left clear and sharp. The edges of -the openings should have a light beading, cut with a bead tool, <a href="#i-p191">Fig. 271</a>, -A and B.</p> - - -<h3 class="sc"><a name="GROOVING_AND_MORTISING" id="GROOVING_AND_MORTISING">Grooving and Mortising Small Work.</a></h3> - -<p>Amongst the various purposes to which it is possible to apply the -lathe, may be noticed the drilling out grooves and mortises, a method -used in some of our Government arsenals, for cutting the recesses -for the reception of the Venetian lath work in cabin doors. The same -method is, of course, applicable to numberless similar cases, although -designed for the special object named. The apparatus is shown complete -in the drawing, <a href="#i-p192s">Fig. 272</a>, and the component parts in the succeeding -diagrams. A is a kind of compound slide rest, or vertical straight -line chuck, having a movement in a direction parallel with the lathe -bed at F; while the circular plate being pinned through its centre -to a slide, H, can be moved up and down by means of the<span class="pagenum"><a name="Page_193" id="Page_193">[193]</a></span> handle G. -This circular plate can be set in any position, and has a projecting -shelf or rest to carry the work, which is steadied by guide pins, as -will presently be explained. The part F, has a bed similar to that -of an ordinary slide rest, which is clamped to the lathe bed by a -bolt and nut, as usual. This carries likewise chamfered bars, between -which slides the horizontal plate to which the vertical part of the -apparatus is attached. This is first a plate with chamfered edges, -<a href="#i-p193s">Fig. 273</a> A, and a second similar but rather wider plate, <a href="#i-p193s">Fig. 274</a> B, with -guide bars, likewise chamfered, to slide upon A. From the front of B -rises a stout pin, on which the circular plate, C, turns, which can -be clamped by a central nut, or otherwise, as in an ordinary compound -slide rest. This nut should not project above the general level of the -plate. On the face of the latter is, as previously stated, a rest, or -narrow metal shelf, D, and pins, <i>e</i>, <i>f</i>. The plate may be variously -arranged in this respect by substituting any kind of holdfast or -guide, according to the work desired to be done by its aid. The upper -slide is depressed by a hand lever acting on a pin fixed in the -sliding plate, <a href="#i-p193s">Fig. 275</a>; or, if preferred, by a similar lever, with a -quadrant and chain, or rack movement. The horizontal slide is worked -by means of a stirrup for the foot, with cord attached, acting on a -bell-cranked lever, seen in the first figure. To cut the grooves in -a bar, for Venetian blinds—as described—the lath to be<span class="pagenum"><a name="Page_194" id="Page_194">[194]</a></span> drilled is -attached to a flat strip of thin iron, drilled with holes, <a href="#i-p194s">Fig. 276</a> A, -as wide apart as the required distance between the grooves. It is then -laid against the shelf, and the guide pins are made to enter the holes -in the iron. The clamping nut of the round plate is loosened, until -the bar is set to such an angle that the grooves to be cut will form -vertical lines, <a href="#i-p194s">Fig. 276</a>. It is then clamped securely.</p> - -<div class="figcenter" id="i-p192s" style="width:700px;"> - <img - class="p2" - src="images/i-p192s.png" - width="700" - height="503" - alt="" /> - <p class="center smcap">Fig. 272.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p193s" style="width:700px;"> - <img - class="p2" - src="images/i-p193s.png" - width="700" - height="545" - alt="" /> - <p class="center smcap">Figs. 273, 274, 275.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p194s" style="width:450px;"> - <img - class="p2" - src="images/i-p194s.png" - width="450" - height="411" - alt="" /> - <p class="center smcap">Fig. 276.</p> - </div> - -<p>It is necessary to be able to adjust the piece to be cut, as regards -its height, above the lathe bed. This is effected in part by the -position of the movable shelf—fixed by pins—and partly by guide or -set screws, which regulate the traverse of the slides. Suppose the bar -adjusted as in <a href="#i-p194s">Fig. 276</a>, the groove to be cut being brought opposite -to the drill. The set screws—two of which are seen at <i>x, x</i>, -<a href="#i-p193s">Fig. 275</a>—acting on the handle, regulate the precise length of each groove. -A similar stop, connected with the horizontal part of the machine, -regulates the advance of the wood towards the drill, and thus the -depth of the cut. Hence it is only necessary to set these carefully -at starting—the pins on the guide plate insuring the proper width -between the grooves—and the lathe being put in motion, any number of -precisely similar grooves can be drilled with the utmost rapidity and -neatness.</p> - -<p>An inspection of the drawings will show what numberless purposes may -be served by this simple apparatus, which may be modified in its -details, while its principle of action is maintained. The drill should -have a chisel and be kept to a keen edge. The lathe should be put in -rapid motion, and if the required cut is to be deep, it should be cut -at twice. The lower slide should return to its place by means of a -spring when the foot is raised, the vertical<span class="pagenum"><a name="Page_195" id="Page_195">[195]</a></span> slide being movable in -both directions by means of the slotted part of the handle.</p> - -<blockquote> - -<p><span class="smcap">Note.</span>—The above being taken from an apparatus for a -steam lathe, the stirrup action maybe used, as the foot is at -liberty. A foot lathe would require a slight modification. In -<a href="#i-p193s">Fig. 275</a>, the depressing handle is shown as if the chamfered -bars were fixed to the sole plate, and the plate A, were -movable, as is sometimes the case. When made according to the -above description, the handle would, of course, be pinned to -the fixed vertical plate, A, to which also the stops would be -attached, and the pin which passes through the slot of the -handle, must project from one of the chamfered bars. Either -plan may be followed, but the pattern described is calculated -for a stronger apparatus; inasmuch as the vertical plate can be -secured more firmly to the chamfered horizontal slide than the -mere pair of guide bars—the two might, in fact, be made in one -casting, if preferred.</p></blockquote> - - -<h3 class="sc"><a name="ORNAMENTAL_TURNING" id="ORNAMENTAL_TURNING">Ornamental Turning.</a></h3> - -<p>The slide rest previously described, although applicable to the -purposes of ornamental turning, has one disadvantage. It is necessary -that the various pieces of apparatus to be used with it should have a -foundation plate with chamfered edges to fit accurately between the -guide bars. This is often inconvenient, and adds to the difficulty of -making, and consequently to the cost of such pieces. In addition to -this drawback, it may happen that one of these fittings by being more -frequently used becomes more worn than another, so that the guide bars -require constant re-adjustment, and their accuracy and parallelism -become impaired. To obviate these and similar inconveniences the -slide rest is now commonly made like <a href="#i-p196s">Fig. 277</a>, and a tool receptacle, -<a href="#i-p197as">Fig. 278</a>, is fitted to slide between M, M, and is so arranged as to -hold securely the universal cutters and other apparatus required -for ornamentation or for plain turning. These are all made with a -rectangular bar fitting the longitudinal channel in the middle of the -receptacle, and are secured by the following simple contrivance. It -will be seen by the drawing that the central channel is widened at -A, A, and that a groove or saw-cut B runs along the inside from end to -end. This groove is continued in a similar manner on the side next -to the reader. <a href="#i-p196s">Fig. 280</a> represents an ordinary tool holder, with a -rectangular shank A, and clamping screw B, by which the tool <i>c</i> is -secured. The part A is laid in the central channel, and a small piece -of metal shaped like <a href="#i-p196s">Fig. 279</a> is inserted in one of the open spaces, -A, A of the receptacle and slid along with its lower flange in the -saw-cut until clear of the enlarged part of the channel. It is thus -retained, and the clamping screw which passes through its centre is -brought to bear upon the piece to be fixed, which is thereby securely -held in its required position. Two of these holdfasts are generally<span class="pagenum"><a name="Page_196" id="Page_196">[196]</a></span> -used at the same time. If the main bar of the tool holder is not -quite thick enough to be clamped, then it is only necessary to lay a -small plate below it.<span class="pagenum"><a name="Page_197" id="Page_197">[197]</a></span> By the above simple means, the necessity for -fitting each individual piece of apparatus to work upon the chamfered -guides is done away. In order to ensure the position of the sole of -the rest at right angles to the lathe bed a kind of saddle, A,<span class="pagenum"><a name="Page_198" id="Page_198">[198]</a></span> -<a href="#i-p197bs">Fig. 281</a>, is used. This is of cast iron or brass, accurately planed on -the upper surface, and has a projection fitting between the bearers -of the lathe. The usual holding down-bolt passes through the hole in -the centre, securing the saddle and the rest at the same time. The -usual arrangement of a kind of double socket, the inner one rising at -pleasure by being tapped into the outer, has already been described, -and serves for accurate adjustment of the height of the rest. It is -convenient, in addition, to have a stop or set screw under the bed -of the rest, and a similar one on the top of the socket, so placed -that when the frame is swung round it shall stop precisely at right -angles to its former position. Thus, if the tool is first required -to be used upon the side, and then upon the face of the object to -be turned, these two positions are obtained at once, and can, if -necessary, be alternated without any re-adjustment of the moving -parts of the rest by the aid of the set square. The receptacle-holder -is generally advanced by the hand lever, <a href="#i-p196s">Fig. 279</a>, one pin of which -fits into the hole in the guide-bar as seen in the drawing, while -the other falls into a short slot <i>e</i>, made in the upper surface of -the receptacle, or of the piece of apparatus to be used in it. Of -course, this arrangement may be reversed, one or both pins being -fixed to the rest and its receptacle slide, and the holes made in -the lever. Sometimes, however, a slower and more regular movement is -required than it is possible to give in this way, and the lever is -replaced by the leading screw C, D, <a href="#i-p197as">Fig. 278</a>, the head of which is -removable, and can be replaced by a small winch handle. This screw -is tapped into the lug cast upon the receptacle, and its point is of -the form shown. The latter fits into a hole in the pillar A, <a href="#i-p197as">278</a>, and -is retained by a pin, which falls into the groove, D, <a href="#i-p197as">Fig. 278</a>, and -prevents the screw from advancing or receding without carrying the -sliding plate with it. The pin being removed, the screw will no longer -act in this way, and the slide may be moved by the lever instead. -The other screw, E, F, of fine pitch, serves to regulate the advance -of the receptacle, and consequently the depth of cut of the tool—a -round head with divisions on its edge is attached to one end, which -abuts against the pillar B, <a href="#i-p196s">Fig. 277</a>, which latter has a mark on its -top to act as an index. Thus the advance of the tool can be regulated -to a great nicety, and successive predetermined and different depths -may be reached and repeated at pleasure, as is sometimes necessary. -C, C, <a href="#i-p196s">Fig. 277</a>, is one of a pair of stops which can be fixed by their -screws at any two points of the bed of the slide rest. These serve -to regulate the distance which the top slide and tool holder are -intended<span class="pagenum"><a name="Page_199" id="Page_199">[199]</a></span> to traverse, as in drilling a number of flutes of equal -length, and many similar works. They are usually made of gun-metal, -the screws of iron or steel, or of a metal called homogeneous, which -may be described as between the two, and, being pleasant to work, is -worthy of notice. It is absolutely necessary that the slide rest for -ornamentation should be made with the greatest nicety. The slides must -work equally smoothly from end to end of their traverse. The pitch of -the screws must be not only fine, but even and regular, and the screw -itself of precisely the same diameter from end to end, else it will -work loosely through its nut in one place, and jamb in another. It is -extremely pleasant to feel the exquisite smoothness and oiliness, for -no other word will express it, of the movements of sliding parts in -the workmanship of Munro or Holtzapffel, especially if compared with -inferior work. <i>Good</i> amateur's work indeed is often far superior to -that which is sometimes advertised, and perhaps a few hints may not -be out of place here, relative to the construction of this necessary -addition to the lathe.</p> - -<div class="figcenter" id="i-p196s" style="width:700px;"> - <img - class="p2" - src="images/i-p196s.png" - width="700" - height="404" - alt="" /> - <p class="center smcap">Figs. 277, 279, 280.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p197as" style="width:700px;"> - <img - class="p2" - src="images/i-p197as.png" - width="700" - height="283" - alt="" /> - <p class="center smcap">Fig. 278.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p197bs" style="width:550px;"> - <img - class="p2" - src="images/i-p197bs.png" - width="550" - height="247" - alt="" /> - <p class="center smcap">Fig. 281.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p197cs" style="width:700px;"> - <img - class="p2" - src="images/i-p197cs.png" - width="700" - height="533" - alt="" /> - <p class="center smcap">Fig. 282.</p> - </div> - -<p>First of all, the frame of the rest must be accurately at right angles -to the spindle, which fits into the socket. These should, therefore, -be turned together, supposing the amateur not to have a planing -machine. The whole may be mounted as <a href="#i-p197cs">Fig. 282</a>, where A represents the -carrier plate or chuck; B, the driver, the tail of which should be as -long or nearly so as the frame from <i>c</i> to D; F is the side tool to -be fixed in the slide rest for metal. The effect of this arrangement -is to plane the face of the slide with transverse strokes instead of -lengthwise. It may be afterwards finished and polished with oilstone -powder on a flat slab of planed iron. When the face is finished, -the whole must be reversed, the pin of the carrier plate will bear -against the frame, which thus acts as a driver, and the spindle must -be turned. In this way accuracy is ensured if the slide rest used is -carefully set. The chamfered sides of the slides are difficult to work -with the file, but may be so done with care, and with a template of -the desired bevel as a guide. The great secret is to take plenty of -time, not to press too much upon the file nor to move it too quickly -over the surface; fine even strokes, especially towards the finish, -must be given, and a final polish with oilstone powder and oil used -on a piece of a stick. In turning the screw a back stay must be fixed -opposite to the tool in the slide rest to insure the contact of the -cutting edge without bending the work.</p> - -<p>Presuming that the screw will be cut with stock and dies, it may be -stated as a caution that the latter must not be tightened except at -the commencement of cutting the thread deeper. The return of the tool -by a backward motion (or unscrewing), should not be used as a cutting -action, and therefore, should be carried on with the dies in the same -position which they had during their descent.</p> - -<p><span class="pagenum"><a name="Page_200" id="Page_200">[200]</a></span></p> - -<p>At the beginning, therefore, of each downward movement the dies must -be tightened and oiled, and they must not again be touched till the -bottom of the screw has been reached, and the upward movement also has -been completed, so that they have arrived again at the starting point. -If tightened at any other time the screw will be either conical or of -a wavy section, either of which forms would be fatal to its use. The -castings for such a rest should be of malleable iron, if possible, as -being much more easy to work; the guide bars may be of gun metal, as -also the chamfered bars, which work on the main frame. This will give -a more finished appearance, and will on the whole be more durable and -satisfactory.</p> - - -<h3 class="sc"><a name="ECCENTRIC_CUTTER" id="ECCENTRIC_CUTTER">The Eccentric Cutter Frame.</a></h3> - -<p>One of the most useful tools for ornamentation, especially of plain -surfaces, such as the top of a box cover, is the eccentric cutter, -<a href="#i-p200s">Fig. 283</a>. The shank, A, lies in the receptacle holder of the slide -rest, and is drilled throughout to receive a steel spindle, carrying -at one end a double pulley, B, to receive the cord from the overhead -motion, and at the other frame, E, with its leading screw, of which -the movable milled and graduated head is seen at H. This frame has -one surface, level with the centre of the main spindle, which is cut -away as shown, and, consequently, as the point of the tool is on its -flat side, which latter rests upon the frame (the bevel being below), -this point can, by the tangent screw, be brought into a line with the -centre of the main spindle, so that when the cord from the overhead -is passed round B, the spindle revolves with great rapidity,<span class="pagenum"><a name="Page_201" id="Page_201">[201]</a></span> and the -point of the tool, K, in the position described, makes a simple dot. -By turning round the milled screw head, H, either by the thumb and -finger or by a small winch handle, fitted on the square part beyond -the head of the screw, the tool holder, D (which is in one piece with -the nut of the leading screw), is made to traverse the frame, and the -tool will cut a circle small or large according to the eccentricity -thus given to it. In <a href="#i-p200s">Fig. 285</a> D, is the tool holder on the front of -the frame; C, the end of the spindle; L, a bell-shaped washer, which -is acted on by the small square-headed screw, drawing D towards the -frame and clamping the tool. The whole is in the figure of full size. -The tool holder is in one piece with the nut, through which passes -the leading screw, and which is continued as a screw for the action -of the bell-shaped washer and tightening nut; hence it is necessary -to allow a degree of play between the nut and leading screw, to -prevent bending the latter when clamping the tool. This is effected -by filing off the threads in the nut at the top and bottom, to render -the whole slightly oval. The remaining threads suffice for the action -of the leading screw: a very slight degree of play in the required -direction will be found sufficient. The powers of the eccentric -cutter frame will be found sufficiently extensive to make it a most -serviceable, perhaps necessary, piece of lathe apparatus. If it cannot -be said absolutely to supply the place of the eccentric chuck, it has -nevertheless the advantage of great lightness of construction, lowness -of cost, and ease of manipulation. The weight of the eccentric chuck, -whether single or double, as of all chucks in which sliding plates -are used, is a sad drawback to their value—a drawback unfortunately -beyond remedy, and specially felt when the slides are drawn out to -a great degree of eccentricity. Combined together, these two form a -<i>compound</i> eccentric chuck, and in this way are capable of nearly -everything in the way of eccentric ornamentation. Where the <i>chuck</i> -is not to be had, it is by all means advisable to procure the cutting -frame, for which the writer confesses a great partiality. It appears, -indeed, to him a far more rational proceeding, as it is also now of -extensive application, to act upon fixed work by revolving or moving -tools, instead of proceeding in the contrary way; and all these little -tools used with the overhead apparatus are so lightly and elegantly -constructed, and so well adapted for the parts they have to perform, -that the originator of them (<i>native talent devised them</i>), deserves -to be well and lastingly remembered; instead of which it is doubtful -whether his name is even known. (<i>Sic transit</i> is a quotation too -stale for this work.)</p> - -<div class="figcenter" id="i-p200s" style="width:700px;"> - <img - class="p2" - src="images/i-p200s.png" - width="700" - height="405" - alt="" /> - <p class="center smcap">Figs. 283, 285, 285B.</p> - </div> - -<p>To cut circles deeper in one part than another—the shell pattern, -for instance—with this tool, it is not necessary to alter the level -of the sole of the rest, as it is when the eccentric chuck is used -with a fixed tool, as it suffices to set the rest itself at an angle, -by moving<span class="pagenum"><a name="Page_202" id="Page_202">[202]</a></span> it round in the socket, so that the revolving tool should -touch the face of the work sooner at one point than at an opposite -one. In the same way the work may be considerably undercut on one -side of the circles, by giving the angular set to the rest, and -placing a tool in the holder, with a point of the form shown at <a href="#i-p200s">285</a> B. -There is nothing prettier than this undercut work when well and -sharply done, for which purpose the tool should not only be rendered -keen on the hone, but burnished and polished on the brass and iron -slabs already described. - -The following remarks on the work of this -cutter frame on flat surfaces only, will be useful to the reader -in designing and working out the various combinations of circles, -intersecting or otherwise, which it is calculated to produce. On a -surface represented by <a href="#i-p202s">286</a> A, the line of circles, <i>a, a</i>, is on a -diameter, and, supposing them to be described by the eccentric cutter -(or by a simple double-pointed drill), their centres are obtained by -means of the leading screw of the slide rest, moved the requisite -number of turns between each cut, while the work is retained in a -fixed position on the mandrel. But if the line of circles is on such -a line as <i>b b</i>, above or below the centre, and consequently not -on a diameter, it is plain that no movement of the slide rest or -cutter, or both, can avail to place them in position, except with -great difficulty and tedious working with the division plate of the -lathe and the screw of the slide rest. Hence the eccentric chuck must -be brought into play, and being fixed with its slide in a vertical -position, the screw is turned and the work is lowered thereby until -the line <i>b, b</i>, is on a level with the point of the tool. The<span class="pagenum"><a name="Page_203" id="Page_203">[203]</a></span> -eccentric cutter or double drill will then suffice to work the row of -circles. When the centres of the circles are themselves on parts of -the circumferences of other circles, the division plate of the lathe -or of the eccentric chuck will be called into requisition, according -as these circles are concentric with the mandrel or otherwise. In -<a href="#i-p202s">Fig. 286<sup>B</sup></a>, the curved lines are parts of circles of equal size with -that representing the surface of the work, and their centres lie on -one and the same diameter, viz., at opposite extremities of the line, -<i>a, b</i>. Being thus eccentric to the work, the division plate of the -chuck is used to arrange the intersecting circles of the pattern—its -slide having been first drawn down, until the centre of the arc to be -worked with circles is brought opposite to the tool. The work will be -in position when, on turning the mandrel slowly, the cutting point -of the tool passes across its centre. The division of the original -circle is in this instance into four parts, two of which are thirds, -and two sixths of its circumference. The arcs of circles are also -lines equal to thirds of the circumference of the work. It is well to -remember this division of a circle by other equal circles described -round it from points on its circumference, these circles passing -through the centre. The original circle will in this way be divided, -as shown at C, into six equal parts. To produce it with the aid of -the eccentric cutter is easy. Set the tool of the cutter first to the -centre of the work, so that on revolving it will make a simple dot. -This should always be done, whatever pattern is subsequently to be -cut. Fix the index of the division plate of the lathe at 360. Move -the screw of the slide rest until the point of the cutter, on being -advanced, rests on the circumference of the circle previously cut -upon the work, or on the circumference of the work itself, if the -divisions are to reach the edge. Screw back the <i>tool</i> (not the rest) -until its point reaches the centre of the work and cause it to revolve -so as to cut one arc. Move the lathe pulley forward to 60° and cut a -second arc, and so on, advancing 60° each time, and the figure will -be cut. This division of the circle will form the groundwork of many -handsome patterns. When the arcs thus formed are intended merely to -be the lines of centres, and not themselves to form integral parts of -the pattern, they should, nevertheless, be marked with a pencil in the -tool holder, if possible, as there will be less liability to error in -working the proposed pattern. In the present advanced stage of the -art of turning, mere surface work done by the eccentric cutter is -rather apt to be despised, owing to the extended powers of Ibbetson's -or Plant's geometric chuck; but, valuable as the two latter are, they -are necessarily so costly that few can obtain them, whereas the little -cutter frame is comparatively cheap, and it is really capable of very -exquisite work in skilful hands.</p> - -<div class="figcenter" id="i-p202s" style="width:550px;"> - <img - class="p2" - src="images/i-p202s.png" - width="550" - height="344" - alt="" /> - <p class="center smcap">Fig. 286A, B, C.</p> - </div> - -<p><span class="pagenum"><a name="Page_204" id="Page_204">[204]</a></span></p> - -<h3 class="sc"><a name="SEGMENT_ENGINE" id="SEGMENT_ENGINE">Segment Engine.</a> <a href="#i-p204as">Fig. 287</a>.</h3> - -<p>In very many cases of ornamentation it is required that the mandrel, -instead of making an entire revolution, should stop at a given point -in both directions, so that, for instance, the turner should be able -to move it 60, 80, or 100 divisions to and fro, with the certainty -of its not advancing beyond that distance. This is effected by the -racked and divided brass wheel B, fixed on the mandrel against the -small end of the pulley. This wheel is sufficiently thick to allow of -racking part of its edge to be acted on when necessary by the tangent -screw, and leaving the other part for divisions, which are generally -seventy-two in number, and marked in figures at every sixth division. -On the other side of the plate are a number of holes drilled through -its whole thickness to receive stop pins, <a href="#i-p204b">Fig. 289</a>, P, which are sawn -through as shown, that they may spring, and fit the holes tightly. -There are seventy-two holes corresponding with the divisions. These -pins are about <sup>3</sup>/<sub>16ths</sub> of an inch diameter, generally with flattened -heads, and a hole through them to receive a pin to aid in removing -them. The<span class="pagenum"><a name="Page_205" id="Page_205">[205]</a></span> holes are sometimes made in the edge, instead of the side -of the segment plate, but the latter is the best position. At -<a href="#i-p204c">Fig. 288</a>, T, is seen the interior part of the poppet, with a piece of brass -let in, and fixed securely, in which are inserted two screws, against -which the segment stops abut, and prevents further rotation of the -pulley. Side by side with this latter piece is placed the frame which -carries the tangent screw. It is shown at <a href="#i-p204b">Fig. 289</a>. This frame is not -fixed to the base of the poppet, but pivotted at <i>e</i>, between two -short standards screwed into the poppet for that purpose. When not in -use, the whole frame, therefore, drops down towards the front, but -it can be raised by the small cam, K, <a href="#i-p204b">Fig. 289</a>, so as to gear with -the worm wheel. In many cases the latter is not used, but the pulley -turned by hand. The screw, however, gives a steadier and more easily -regulated movement, essential in delicate operations, and sometimes -convenient, even when the stops do not require to be inserted. The -use of the cam, acting on the frame which carries the tangent screw, -is now generally followed in the eccentric and oval chucks, and also -in the dome chuck. It enables the workman, by throwing out of gear -this part, to turn the worm wheel with the fingers, to set it at the -required number on the division plate, a slow process when effected by -the screw.</p> - -<div class="figcenter" id="i-p204as" style="width:400px;"> - <img - class="p2" - src="images/i-p204as.png" - width="400" - height="384" - alt="" /> - <p class="center smcap">Fig. 287.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p204b" style="width:400px;"> - <img - class="p2" - src="images/i-p204b.png" - width="400" - height="196" - alt="" /> - <p class="center smcap">Fig. 289.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p204c" style="width:300px;"> - <img - class="p2" - src="images/i-p204c.png" - width="300" - height="287" - alt="" /> - <p class="center smcap">Fig. 288.</p> - </div> - -<h3 class="sc"><a name="HOLTZAPFFEL" id="HOLTZAPFFEL">Holtzapffel's Rose Cutter Frame.</a></h3> - -<p>Among the newer devices for ornamental turning, must be mentioned the -rose cutter frame of Holtzapffel and Co., an ingenious adaptation -of the principle of the rose engine, without the drawback of -cumbersomeness and costliness. It works like the ordinary eccentric -and other cutters by a cord from overhead motion. The apparatus is -represented in <a href="#i-p206s">Fig. 290</a>, and its various parts in <a href="#i-p206s">Fig. 291</a>, &c.</p> - -<div class="figcenter" id="i-p206s" style="width:383px;"> - <img - class="p2" - src="images/i-p206s.png" - width="383" - height="550" - alt="" /> - <p class="center smcap">Figs. 290, 291, 293, 294.</p> - </div> - -<p>In the first of these figures, A is the shank, fitting the receptacle -of the slide rest, and drilled to receive a hardened spindle, at one -end of which is a worm wheel, turned by tangent screw B C, and shown -again at A, B, C, <a href="#i-p208">Fig. 292</a>. By this are turned the parts beyond K, -namely, the frame D, carrying the tool, as in the eccentric cutter, -adjacent parts S, representing chamfered bar, P, back plate, and -O, which is a round piece in one casting, with the back plate, and -having a hole through it for the coiled spring seen between O and N. -All these are secured to the spindle, and turn together as one piece -with it. <a href="#i-p206s">Fig. 291</a> is a front view of these parts. H is the back plate -of brass, with steel chamfered bars on its face, E, E, as in the<span class="pagenum"><a name="Page_206" id="Page_206">[206]</a></span> -eccentric chuck. Between these slides the plate, D, D, to the face -of which is attached the long steel frame, carrying the tool holder. -Close to the letter H, it will be noticed that a slot is cut in<span class="pagenum"><a name="Page_207" id="Page_207">[207]</a></span> the -back plate, through which projects a hard steel pin, screwed into -the back of the sliding plate. This is seen at O, <a href="#i-p206s">Fig. 290</a>, and is -attached to one end of a coiled spring, the opposite end of which is -secured to a pin fixed in the back plate of this part. The pin O, is -thus kept in contact with the edge of the rosette or pattern plate, -K, and, as the whole turns with the spindle while the rosette is -fixed, the pin, or rubber, is compelled to follow the undulations of -the pattern, the motion being, of course, communicated to the tool. -An inspection of <a href="#i-p206s">Fig. 294</a> will show the arrangement of the parts on -which the rosettes are fixed, and which is capable of turning, but -does not, unless the tangent screw and wheel, H, are brought into -requisition, as will be presently explained. The end of the main shank -of the instrument is round, as seen at C, the worm wheel B being -screwed fast, by four small screws, to the end of the square part of -the shank. Upon this rounded end fits what may be called the sleeve -E, to which is fixed the tangent screw, and on which also are placed -the rosettes. The latter have a large central hole, <a href="#i-p206s">Fig. 293</a>, A and B, -and fitting closely beyond the screw F, F, of the sleeve, and, being -prohibited from turning upon it by a small key or feather, are secured -by a screwed ring or ferrule seen at L, <a href="#i-p206s">Fig. 296</a>, the edge of which is -milled. At F, <a href="#i-p206s">Fig. 291</a>, is seen a short stop, or set screw, the head -of which is divided into ten degrees. By this, the rubber is prevented -from penetrating to the bottom of the undulations on the edge of the -rosette, and, if it is allowed only just to touch the summits of them, -the tool will cut a circle. Thus, as the screw stop can be accurately -set, one rosette will produce at pleasure graduated waved lines, the -waves growing less and less undulated as the centre (or circumference) -of the work is approached, giving a most delicate and chaste pattern, -and <i>chased</i> it certainly is.</p> - -<p>Another variation of the pattern producible from any rosette results -from the frame of the tool holder being extended beyond the axis -of the spindle in both directions. When the tool is on that side -of the axis nearest to the rubber pin, the undulations of the -rosettes will be so followed as to produce their exact counterpart -on the work. When the tool-holder is on the other side of the axis, -the undulations become reversed, the raised parts of the rosettes -producing hollows and <i>vice versa</i>. It may here be mentioned that in -the case of the rose cutter, eccentric, and universal cutter, and -similar apparatus, the screw heads carry ten chief divisions and ten -smaller divisions. The screws are cut with ten threads to the inch, -so that one turn advances the slide, or the tool, or wheel as the -case may be, one-tenth of an inch. One large division, therefore, -produces a movement equal to one-hundredth, and one small division one -two-hundredth of an inch. If the screw is small it is generally<span class="pagenum"><a name="Page_208" id="Page_208">[208]</a></span> cut -with a double thread equal to one-twentieth of an inch. It is evident -that in addition to the movements of the various parts of the rose -cutter, the turner also has in his power those of the slide rest, and -of the division plate on the lathe pulley, by one or both of which -further complications become possible. Six modifications of pattern -produced from one rosette alone are shown in Holtzapffel and Co.'s -catalogue, and these may be further multiplied according to the taste -and skill of the operator.</p> - -<p>It is not possible to apply rapid movement to this rose cutter, else -the rubber would probably miss touching the rosette in places; hence -the tangent or worm wheel is used to give motion to the central -spindle. An end view of this is given in <a href="#i-p208">Fig. 292</a>. The object of the -other tangent screw is, to move the sleeve and therewith the rosette -at pleasure, so that the higher parts of the undulations in the second -cut may, if desired, be arranged to meet the lower parts of the same -in the first cut or to fall intermediately. The effect of the gradual -shifting of the rosettes in this way is perfectly marvellous, and the -writer much regrets that he is unable to supply specimen plates, as he -is not in possession of the rose cutter. In the end of Holtzapffel's -latest edition of his catalogue are several such specimens, but -without any drawing or description of the instrument, the cost of -which is moreover omitted.</p> - -<div class="figcenter" id="i-p208" style="width:314px;"> - <img - class="p2" - src="images/i-p208.png" - width="314" - height="306" - alt="" /> - <p class="center smcap">Fig. 292.</p> - </div> - -<p>The centres of circles cut by this eccentric tool will be always -regulated in regard to position by the slide rest, because these -centres are, as explained, always in a line with the centre of the -spindle. Hence, to place a circle in any desired position, it is only -necessary to determine its centre, and, after drawing back the tool by -means of the screw till its centre runs truly as a mere drill, turn -the screw of the slide rest until the point touches the required spot.</p> - - -<h3 class="sc"><a name="UNIVERSAL_CUTTER" id="UNIVERSAL_CUTTER">Universal Cutter Frame.</a></h3> - -<p>This is represented in <a href="#i-p209s">Fig. 284</a>, in its latest improved form. It -consists of a shank, A, which fits the tool receptacle, and is bored<span class="pagenum"><a name="Page_209" id="Page_209">[209]</a></span> -throughout its length for the reception of a central steel spindle, -to which is securely attached at one end the worm wheel, G, acting -as a dividing plate, and at the other the crank-formed frame, B, C, -with its small poppets, D, D. These are sawn lengthwise, and thus -spring upon the centre screws, which pass through them and carry the -revolving cutter spindle, K, L, M, in the centre of which is a slot to -receive the tool, the latter being clamped by the tightening screw, -L. There are certain points to be attended to in the construction of -this instrument, which must on no account be neglected. In the first -place, the screws which pass through the poppets must lie in the line -which would bisect at right angles that of the main spindle in the -same plane. A line, in fact (as dotted), passing from screw to screw -will pass across the centre of the end of the spindle. In the next -place, when the tool-holder, with its pulleys, is in place between D, D, -this line must be even with the <i>top line</i> of the central mortise, -H, for the <i>point</i> of the tool is level with its upper surface, it -being bevelled below; and it is essential that this point be capable<span class="pagenum"><a name="Page_210" id="Page_210">[210]</a></span> -of being so placed as to form a continuation of the centre of the main -spindle. At E, E, are shown two of four thin pulleys. The two front -ones are removed to show the poppets. They should not be made thicker -than necessary, in order to avoid their interfering with the action of -the tool. Either pair will be used with either pulley, K, K, according -as the right or left side of the instrument is the highest, for, as -will be explained, the cutter frame is used at all angles between -the horizontal and the vertical lines, the cuts being consequently -inclined in either direction, left, or right, at pleasure. The centre -screws and points of the tool spindle must be carefully hardened. -Before commencing to use this cutter, it is necessary to test the -centrality of the point of the tool. Place the latter in its holder. -Let the part C of the instrument be turned till vertical; cause the -tool to revolve and to cut a light line or scratch on the face of the -work. By means of the tangent screw cause C to become vertical in -the opposite direction, so as to bring the other pulley upwards, and -with the small screws in the poppets set the revolving tool holder, -till the tool falls exactly on the line first made. It is, of course, -understood that the line in question passed through the <i>centre</i> of -the work. If in both positions of the tool the central point is passed -through, the cutter tool is correctly placed. The poppet screws are -for this purpose specially, though sometimes used to place the cutter -purposely above or below the centre of the work. Compared with the -old form previously given, this pattern of universal cutter is very -superior.</p> - -<div class="figcenter" id="i-p209s" style="width:550px;"> - <img - class="p2" - src="images/i-p209s.png" - width="550" - height="497" - alt="" /> - <p class="center smcap">Fig. 284.</p> - </div> - -<h3 class="sc"><a name="ROSE_ENGINE" id="ROSE_ENGINE">Rose Engine.</a></h3> - -<p>The rose engine, as hitherto constructed, has not been entirely -supplanted by the neat little apparatus already described, but is -still used almost universally by the watch case makers; and its -construction differs little, if at all, from that described by -Bergeron; although the slide rest used with it is somewhat modified -and improved. There are two kinds of rose engine, in one of which -the mandrel with its poppets and fittings oscillates between centres -fixed beneath the lathe bed; while in the other, the frame carrying -the slide rest is thus movable, the mandrel head remaining stationary -as in an ordinary lathe. In both cases the mandrel is allowed a -to-and-fro or pumping movement in its collars; as the rosettes used -are cut upon the face as well as upon the edge; and the rounded parts -of an article can be operated on as well as the plane surfaces.</p> - -<p>The second pattern, in which the poppet remains a fixture, will be -first described, because it is capable of being applied to an ordinary -lathe for surface work, and if the lathe has a traversing mandrel, it -can be completely fitted for rose work.</p> - -<p><span class="pagenum"><a name="Page_211" id="Page_211">[211]</a></span></p> - -<p>The drawings and description annexed are from Bergeron's work; but the -slide rest there represented, and arrangement of screwed mandrel, are -omitted as obsolete:—</p> - -<p>A strong iron frame, A, A, <a href="#i-p212s">Figs. 295 A, 295 B, and 296</a>, is made -with one of the ends carried up and branched, so as to embrace the -mandrel and rosette; which latter is attached to the back part of -the chuck which carries the work. The top of the frame is double, so -as to form of itself a lathe bed of small dimensions, upon which an -ordinary slide rest can be fitted. It must, however, be used with a -short socket, or it will be too high; as the top of the frame alluded -to stands slightly above the level of the bearers. B, is a point of -hardened steel which fits into a conical hole in the bottom of the -lathe poppet, or (if this is not long enough to reach a good way down -between the bearers) into a piece of iron arranged for the purpose -similar to that now to be described, and which is again shown in -<a href="#i-p213s">Figs. 297 and 298</a>. This is a kind of poppet in a reversed position, the -clamping nut and screw being above the bed, and the head with centre -screw below. The frame lies, therefore, between the mandrel head and -this reversed poppet, or between two of the latter, and oscillates -upon their centres whenever the projections or depressions of the -rosette compel it to assume such motion.</p> - -<div class="figcenter" id="i-p212s" style="width:700px;"> - <img - class="p2" - src="images/i-p212s.png" - width="700" - height="361" - alt="" /> - <p class="center smcap">Figs. 295A, 296, 299.</p> - </div> - -<p><a href="#i-p212s">Fig. 299</a> is a section of the chuck which carries the rosette, the -latter being shown in position. A, is the body of the chuck; B, the -inside screw to fit the mandrel. On the outside of this part are a -few turns of a somewhat finer thread, beyond which a plain part is -left next to the flange, C, and on this the rosette is placed, and is -clamped by the nut, cut outside into beads, or milled, or left plain -and drilled for the insertion of a lever pin; this nut is marked D -in the figure. It will be seen to lie within a recess formed in the -face of the rosette, E. The latter is shown in <a href="#i-p213s">Fig. 300</a>. A, is the -recess just alluded to; B, C, the pattern on the face and edge; D, the -large hole in its centre, allowing it to be slipped on the back of -the chuck. It is prevented from turning on the latter by a pin, which -fits into the small hole, F. From the front face of the chuck rises -a conical pin, G, similar to that on the eccentric chuck, over which -fits the circular division plate, I, with its projecting screw, H, to -hold the ordinary chucks. This plate is recessed at the back, leaving -a mere ring of metal, <i>e, e</i>, which fits a corresponding circular -groove, and secures the steady movement of the plate, which is fixed -by a conical washer and screw, as seen in the plate. This division -plate is formed with cogs, into which a stop falls, as described, -when treating of the eccentric, but the divisions are differently -arranged, the cogs being divided into sets of eight or ten teeth. Let<span class="pagenum"><a name="Page_212" id="Page_212">[212]</a></span> -the whole circumference be first divided into six equal parts, and, -beginning at the first division, cut six or eight teeth, as if the -whole circle were<span class="pagenum"><a name="Page_213" id="Page_213">[213]</a></span> to be divided into 60. Pass to the second portion, -and cut eight teeth, as if the circle were to be divided into 72. Let -the third carry eight teeth, with a pitch of 80 to the circle; the -fourth a similar number, with a pitch of 84; the fifth 96; the sixth -100 to the circle. These must be cut with the same cutter, so that the -spring click, or stop teeth, may fit any of the six sets. There will -be several undivided spaces, which are to be left plain. The several -sets are to be marked in numbers, so that the pitch may be discovered -at a glance, and the teeth in each being so few will hardly require -separate numbering. The part of the apparatus which carries the -rubber—that is to say, the heads of the branched part of the swinging -frame, are made flat on the top, which projects on three sides, -forming small tables on which the actual holder or clamp can be fixed -by a turn of the screw, X, in the first figure. The rubbers are merely -flat pieces of steel, with edges sufficiently sharp to penetrate to -the lowest depths of the undulations and recesses on the rosettes, but -rounded off and polished, so as not to cut and damage the softer metal -against which they act; other materials have been tried, as ivory, and -the harder tusk of the hippopotamus, but hard steel is most generally -preferred. It is, of course, necessary that the rubber press with -some force against the rosette, which force should, moreover, admit -of being regulated at pleasure. This is effected by a spring of steel -under the lathe bed,<span class="pagenum"><a name="Page_214" id="Page_214">[214]</a></span> to the end of which is affixed the arm, W, which -has a ring handle nearest to the operator, and is perforated with a -row of holes from end to end. This arm is flat, and falls into a fork -at the end of the tail piece, Y, which is seen in the second figure -attached to the centre of the lower bar of the frame. A pin passes -through holes in this fork, and through one of those in the arm. By -this arrangement it is easy to regulate the force which the spring -shall exercise, as this will be increased by moving the pin nearer -to the spring, and diminished by placing it in a hole nearer to the -ring handle. In forming the rosettes great care should be exercised -to make the corresponding parts agree. The depth of similar hollows -must be precisely equal, and elevated portions intended to match, must -do so with great accuracy. Supposing, for instance, a rosette to be -made with ten elevations and ten recesses, all of equal curves. If -these are accidentally unequal, and it is desired to arrange a set of -these waved rings one within the other, so that the depressions of -the one shall be opposite to the elevations of the other, or so that -this effect shall take place gradually—if the curves of the pattern -are unequally cut the several portions of the device will not tally, -and an irregularity will be produced of disagreeable appearance; an -inspection showing at once that such irregularity is not part of the -device, but unintentional and erroneous. This leads to a consideration -of the division plate of this rose engine, and an explanation of the -object of its peculiar construction. The pattern of the rosette is, -as it were, in sections; either similar elevations and recesses are -alternately repeated, or there may be a variety of such, extending -over a part of the circumference, and forming a certain complete -device, which may then give place to a second pattern, extending a -similar distance; and these two may alternate regularly round the -circumference. Each of these sections must be of precisely similar -length, and the repetition of the pattern must also be precisely -similar, for the reason stated above.</p> - -<div class="figcenter" id="i-p213s" style="width:600px;"> - <img - class="p2" - src="images/i-p213s.png" - width="600" - height="458" - alt="" /> - <p class="center smcap">Figs. 295B, 297, 298, 300.</p> - </div> - -<p>It is evident that all possible alternations of the device or set -of devices may be obtained by means of six or eight notches of the -division plate; for, by moving it forward to that extent, the whole -pattern may be compassed. In treating of the second form of rose -engine, and of the method of using it, this will again be adverted to, -and illustrated by an example.</p> - -<p>Hitherto we have spoken only of the use of the pattern on the edge of -the rosette, but, as already stated, it is frequently repeated on the -face, and by this means it becomes easier to work upon the outside of -a cylindrical piece, as well as on the two ends. Patterns thus cut on -the face of a rosette tend, of course, to move the mandrel to and fro -in its collars, which is only possible when the lathe is made on the -plan of a screw-cutting or traversing mandrel lathe. The<span class="pagenum"><a name="Page_215" id="Page_215">[215]</a></span> spring which -keeps the rubber in contact with the face of the rosette is shown at P.</p> - -<p>The head on the top of the arm, which forms the clamp or holder of -the rubber, must be turned round to face the rosette, or a separate -rubber must be used, which passes through the clamp at right angles -to that used in surface work, and the frame must be prevented from -oscillating by a stop which fits between the bearers of the lathe, and -embraces the upright side of the frame. The top of the slide rest must -be turned round, or a side tool used. In this case, the rest and frame -with its rubber become fixtures, as in ordinary turning, the mandrel -and work being alone moved in correspondence with the pattern on the -face of the rosette. It would indeed be much better to do away with -the frame altogether, fixing the rubber to an upright pedestal mounted -on the lathe bed, and using the slide rest in the usual way, were it -not that in general the work is constantly being varied, the side -and face being worked in turn—and the apparatus is rather cumbrous -to remove and re-mount often. It is, nevertheless, easy to finish the -ornamentation of plane surfaces first, and then to remove the frame -altogether, and substitute a fixed rubber, as stated.</p> - -<p>The rose engine now described has certain evident advantages over the -rose cutter frame, and is capable of the most exquisite devices. It -may be, perhaps, a mere question of taste, whether rose engine work -finely executed is not in point of beauty, superior to any that can -be done by geometric chucks, however elaborate. That it is so, is -decidedly the writer's opinion, more especially when this apparatus is -used in combination with the oval chuck. Moreover, there is nothing in -the form of rose engine described to make it a very expensive article, -or beyond the skill of an amateur; and with a set of only three -rosettes, the patterns may be varied continually, and multiplied—if -not <i>ad infinitum</i>—yet quite sufficiently for the display of skill -and taste of the operator.</p> - -<p>In using the rose engine, it is necessary to carry the cord to the -pulley from a very small wheel on the axle. Sometimes the lowest speed -pulley of the flywheel may answer, but if the recesses of the rosette -are deep and sharp, or only slightly rounded, it may become necessary -to mount a still smaller wheel on purpose; else the rubber will jump -over and miss parts of the design, thereby spoiling the work. The -watch-case turners, indeed, altogether dispense with the flywheel, and -use instead a small pulley, fixed to the side of the lathe bed, and -turned by hand.</p> - -<p>These artificers always use a more elaborate form of rose engine, -which will be presently described, and which is the most perfect in -detail of all similar contrivances, but it is necessarily costly, and -cannot be said to be well adapted for plain turning also, except in a<span class="pagenum"><a name="Page_216" id="Page_216">[216]</a></span> -limited degree. The work, if not of soft material, like a watch-case, -should be turned first of all upon an ordinary lathe, the mandrel -screw of which is a counterpart to that of the rose engine, and the -latter should merely be used for the final cut, to perfect the form of -the material previous to its ornamentation.</p> - -<p>In the Appendix will be found a new method of obtaining the required -oscillatory motion of the rose engine, which might apparently be -applied to tool holder<a name="FNanchor_22_22" id="FNanchor_22_22"></a><a href="#Footnote_22_22" class="fnanchor">[22]</a> frame here described, or to the poppet head.</p> - -<div class="footnote"> - -<p><a name="Footnote_22_22" id="Footnote_22_22"></a><a href="#FNanchor_22_22"><span class="label">[22]</span></a> <i>I.e.</i>, the main frame carrying the slide rest.</p></div> - -<p>The rose engine proper is arranged with an oscillating poppet head -carrying the mandrel and its rosettes, the tool being stationary. The -following account of this machine, and the drawings, are copied almost -exactly from Bergeron. The modern rose engine is not indeed made with -the projecting lugs referred to as intended for the application of -the guide ring in oval turning, as this guide is now altered to fit -a poppet head of ordinary form, as already detailed. The pulley and -division plate are also of obsolete form, but as the main arrangement -of parts described are sufficiently similar to that now followed, -Bergeron's drawing and description have been retained. <a href="#i-p218s">Fig. 302</a> is -a longitudinal view, and <a href="#i-p217s">Fig. 303</a> a transverse view of the working -parts of this lathe. A, A are the poppets, which are in one casting, -with the connecting piece shown by the dotted lines, which latter -has a tail piece firmly attached to its centre, to which a spring -is affixed as in the lathe previously described. In the drawing the -cylindrical collars carrying the mandrel are split, so that in case -of wear they can be tightened in the usual manner by a screw at the -top of the poppet marked B, <a href="#i-p217s">303</a>. The lugs, <i>f, f</i>, with square holes -<i>e, e</i>, are for the application of the guide for oval turning, the -latter being originally a ring with slotted arms on either side. The -points of oscillation are precisely similar to those of the rose -engine first described, two short poppets C, Figs. <a href="#i-p218s">302</a> and <a href="#i-p217s">303</a>, having -centre screws, whose points fall into conical holes made in opposite -faces of the poppet, a little below the level of the lathe bed. These -are formed with a slit to receive the stop <i>h</i>, which is hinged at -the point <i>o</i>, and which, when raised by a wedge, catches into a -small projection <i>p</i>, thereby fixing the poppet in a perpendicular -position and preventing its oscillation. The rose engine can then be -used as an ordinary lathe, to finish the preparation of the work to be -operated on, which should, if possible, be commenced and mainly formed -on an ordinary lathe, the mandrel of which is a counterpart of that -of the rose engine. The tail piece, E, does not require a separate -description, being precisely similar to that already described. The -to-and-fro movement of the mandrel caused by the action of the<span class="pagenum"><a name="Page_217" id="Page_217">[217]</a></span> -rubbers on the face of rosette, is also arranged in a manner similar -to the last. F is the spring, turning in the middle of its length -on<span class="pagenum"><a name="Page_218" id="Page_218">[218]</a></span> a pin in a piece of iron fixed on the bed, so that if both ends -wore free it could swing backwards and forwards between the cheeks -of the lathe on this pin as a centre. The upper end of this spring -is branched in a semicircular form to embrace the mandrel, this fork<span class="pagenum"><a name="Page_219" id="Page_219">[219]</a></span> -falling into a groove formed to receive it. It can thus be brought to -bear against either of the shoulders visible at this part. The lower -end of the spring fits into a notch, or rather a slot in the arm H -of the second figure; the handle of this arm being L in both figs. -This piece is pivotted at K, and at its other end falls into one of -the notches in the retaining plate, G, of the first figure. By this -plan the tension of the spring, can be brought against the mandrel in -either direction at pleasure, for if the lever is placed in one of -the left hand notches, the tendency of the spring will be to move the -mandrel towards the right, and <i>vice versa</i>. The tension of the spring -can also be regulated by the use of the groove B or X at pleasure. In -the second figure of Bergeron's the piece which at first sight appears -to be a continuation of the holding down bolt of the short poppet -carrying the centre screw, is the tail piece or lower end of the long -spring just described, and its reduced extremity is visible passing -through a short slot in the lever H, near the handle of which appears -the <i>edge</i> of the notched piece G of the other figure. All the above -parts are commonly of iron, the following are in brass or gun metal.</p> - -<div class="figcenter" id="i-p217s" style="width:467px;"> - <img - class="p2" - src="images/i-p217s.png" - width="467" - height="550" - alt="" /> - <p class="center smcap">Fig. 303.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p218s" style="width:504px;"> - <img - class="p2" - src="images/i-p218s.png" - width="504" - height="600" - alt="" /> - <p class="center smcap">Figs. 302, 304, 305, 306, 308.</p> - </div> - -<p>On the bed and parallel to it, two pieces of brass, or standards, -rise, similar to H in the first figure, the two being opposite to each -other, one on each side of the mandrel, as shown in the second figure. -Both these are firmly secured to the bed by long bolts and nuts, it -being of the utmost importance that they should not move or vibrate in -the least. They are in addition united to each other by two horizontal -braces, one of which is seen at N in the second figure. At <i>l, l</i> -are seen two rectangular notches, which are the ends of grooves made -in the upper part of the head piece, H, and which traverse its whole -length. They receive the crooked part, <i>a</i>, of the rubber holder, -<a href="#i-p218s">Fig. 304</a>, so that the latter can be slid along this bar, and brought -opposite to any one of the rosettes, after which it can be secured in -position by the screw, <i>b</i>, <a href="#i-p218s">Fig. 304</a>. The mandrel is thus arranged. -It is cylindrical, with a shoulder against which the chucks can rest, -as in an ordinary traversing mandrel, and a similar but reversed -shoulder at <i>g</i>, <a href="#i-p218s">Fig. 302</a>. Against the latter abuts the end of an -accurately turned sleeve of brass, which fits over the mandrel with -slight friction, so as to have no shake or play upon it. Upon this -sleeve the rosettes are placed. They fit accurately over it, and are -prevented from turning round upon it by a feather extending the length -of the sleeve, which fits into a corresponding notch cut on the inside -of the rosettes. These are arranged in pairs<span class="pagenum"><a name="Page_220" id="Page_220">[220]</a></span> back to back, and each -couple is separated from the next by a short sleeve or ferrule, which -Bergeron recommends to be of wood, as tending to hold the rosettes -more securely than metal when pressed together by the nut at the end -of the set. The fibres of the wood are to be placed parallel with the -mandrel, because there is no shrinkage of this substance as regards -its length. The pulley is fixed beyond the rosettes on a part of the -mandrel filed into six faces for that purpose, and lastly comes the -nut, which secures all the parts to their several positions, but which -nevertheless does not so jam them together but that the mandrel can be -turned within the sleeve when the positions of the rosettes are to be -changed in the course of working a pattern. The division plate is not -attached to the pulley, though lying close upon its surface. It slips -on to the sleeve on which the rosettes fit, and its spring-catch only -on the face of the pulley. Thus the latter is held to the sleeve and -its fittings when the catch is down, so that all turn together, but, -when the catch is raised, the division plate, carrying with it the -rosettes, can be turned round upon the mandrel as may be required. It -is not necessary to repeat what has been said respecting the manner -of graduating the division plate, as that used with the lathe already -described is in that respect a counterpart of what is used with the -rose engine now treated of.</p> - -<div class="figcenter" id="i-p221" style="width:340px;"> - <img - class="p2" - src="images/i-p221.png" - width="340" - height="350" - alt="" /> - <p class="center smcap">Fig. 307.</p> - </div> - -<p>The following description of the method pursued in turning a pattern -shown in <a href="#i-p221">Fig. 307</a> will suffice to show the working of the rose -engine:—First, says Bergeron:—It is not enough to know the general -construction of the rose engine, it is necessary to know thoroughly -the particular one in use, <i>i. e.</i>, as regards the details of its -construction, the slight defects or imperfections it may chance to -have, and the means whereby they may be lessened or corrected. It is -necessary, in addition, to know well, and to have always at hand, the -numbers of each rosette, or any rate to have a table of them which -can be readily referred to. It is equally necessary to recognise at -a glance the various sets of divisions on the division plate, for -which purpose, and that no mistake may be made, such numbers ought -to be engraved upon each. The same holds good with regard to the -slide rest, and, in addition, practice should be frequent upon box or -other inexpensive material by which the turner may have made himself -perfect in the several combinations possible, and the various effects -producible by the rosettes and different shaped tools over which he -has control. It is thus, by actual experiment only, that the turner -can become acquainted with the powers of his own lathe and apparatus, -and thus only, after working out the patterns already executed, will -he be in a position to design new ones, and to work with ease and -certainty. The rose engines are usually fitted with tools of variously -shaped edges, as shown in Figs. <a href="#i-p218s">305 and 306</a>,<span class="pagenum"><a name="Page_221" id="Page_221">[221]</a></span> by this means a pattern -of some width and great variety is of course produced at once, and -by one rosette. In the following, however, a tool with single point, -<a href="#i-p218s">Fig. 308</a>, is to be used. This simplest design is supposed to be on -the cover of a box or other plane surface, and it is evident that -the movement or oscillation required of the mandrel is that at right -angles to the bed of the lathe. To obtain this movement, when the -rubber is fixed in its clamp, on the side of the workman, as it is -necessary that the rubber should press against the rosette through the -medium of the spring, the handle of the lever, <a href="#i-p218s">Fig. 302</a>, must be drawn -forward towards the operator, and kept by a pin, as described, passing -through it and the tail piece of the mandrel frame. The tension must -not be too great, especially if the rosette to be used is deeply -indented, and care must be taken to free the frame from the action of -the stop, <i>p</i>, by removing its wedge before making any attempt to try -the pressure by moving the mandrel. The design under consideration is -produced from rosette numbered 2 in the drawing, and in fixing the -rubber care must be taken that it does not bear against the adjacent -rosette. Choose a rosette of forty-eight teeth or undulations, and -as the second circle of ornamentation exactly intersects the first, -the raised part of the one falling under the depression of the other, -and as it were <i>halving</i> it, the set of divisions on the click plate -to be used will be twice 48, or 96. Place the rest parallel to the -face of the work and so that the forward motion of the tool shall be -perpendicular to it. By means of the leading screw of the rest, place -the tool near the edge of the work and level with the centre, and -gently moving it forward and putting the lathe in motion, commence -the cut. After having made a light cut, without moving the tool, stop -the lathe and judge of<span class="pagenum"><a name="Page_222" id="Page_222">[222]</a></span> the depth of cut, and if sufficient, screw up -the stop screw of the slide rest, to insure all the following cuts -penetrating to the same depth. Observe the position of the tool as -marked by the graduations of the slide rest, and then withdrawing -it from the cut, move the click plate one notch, which will divide -exactly in half the several undulations of the rosette. By the rest -screw move the tool towards the centre of the work and mark the -number of divisions passed over, so that the circles of undulations -may be equidistant, and cut a second. Now for the third, <i>go back or -advance</i> on the click plate one division, for the position of the -undulations in the third is precisely that of the first circle. It is -indeed immaterial whether an advance or retreat of one notch is made -in this case, but now is evident the reason for not dividing the plate -equally all round, five or six teeth being ample for each division. If -there are eight rosettes the plate should be first divided into eight -parts, and each rosette having a different number of undulations, -these eight parts should be divided into degrees proportionate to -the numbers on the rosette, the one being a multiple of the other. -In working the <i>side</i> of a cylinder, that of a box, for example, the -longitudinal movement of the mandrel is required, the poppet being -retained immovable by the wedge and stop. The tool is to be placed at -right angles to the side of the work, the rubber brought to bear on -the face of the rosette. The method of working will be self-evident, -after the description already given. It is impossible in a brief work -like the present, to go into details of other patterns referred to and -illustrated by Bergeron, one or two of which are nevertheless of great -beauty, and are executed with the aid of the eccentric chuck mounted -on the mandrel of the rose engine. There is, however, a different -class of work, to which reference will be made in our next, and we -shall also give a description of a simple addition to the slide rest, -used by watch case turners, which does away with the necessity of -counting the number of divisions upon this instrument when used as -above.</p> - -<p>The slide rest used by the watch case turners is almost identical -in form with one figured and described by Bergeron. It is necessary -that the tool holder should have a circular motion, somewhat similar -to that of a spherical rest, in order to reach the sides and curved -surfaces of the articles to be engine turned; hence the tool -receptacle and its bed work upon a central pin. The pin here called -"the bed" is usually a flat brass plate of a quadrant form, the -central pin being at the apex, and carrying on its face the guides for -the tool receptacle. The pin on which it turns is a reversed truncated -cone rising from a similar flat plate, which itself forms the sole -of the rest, or traverses the lower frame as usual; when the tool is -beyond the central pin, it will ornament conical surfaces, and <i>vice -versa</i>. On the edge of the<span class="pagenum"><a name="Page_223" id="Page_223">[223]</a></span> arc is a racked part, and a tangent screw -works into it. The tool is moved to and fro by a lever, as usual, the -depth of cut being regulated by a stop screw. These details being -already entered into, in treating of slide rests and chucks, need not -be more specially explained here; but a contrivance for regulating the -traverse of the upper part upon the frame underneath, is ingenious and -serviceable, and will therefore be described. The end of the leading -screw is fitted with a ratchet wheel of the same construction as -that of the ratchet brace for drilling, patented by Fenn, of Newgate -Street, to which in the same way a handle and spring are attached, -as shown in the drawing, <a href="#i-p223s">Fig. 309</a>, A, and <a href="#i-p223s">Fig. 310</a>. The handle rises -between two semicircular plates drilled in the face, with holes for -the reception of stop pins, B, C. These regulate the traverse of -the handle, and thence of the screw. If the former, therefore, is -thrown over till the left stop is touched, and then pulled forward to -the other stop, between each cut of the tool, the latter will leave -equidistant spaces upon the work, without need of counting divisions -at each cut. As a traverse of one inch or more of the lever handle -at the place of the stop pins only moves the screw a very minute -quantity, the holes for the pins need not be very close together even -for fine work. This is a very simple contrivance, and perfect in -action, enabling the operator to work with ease and certainty, and -with great speed.</p> - -<div class="figcenter" id="i-p223s" style="width:550px;"> - <img - class="p2" - src="images/i-p223s.png" - width="550" - height="167" - alt="" /> - <p class="center smcap">Figs. 309, 310.</p> - </div> - -<h3 class="sc"><a name="RECTILINEAL_CHUCK" id="RECTILINEAL_CHUCK">Rectilineal Chuck.</a></h3> - -<p><a href="#i-p224s">Fig. 311</a> represents a modification of the eccentric chuck, when the -latter is used as a fixture, to present to revolving cutters and -drills the different parts of the work which is to be operated on. The -eccentric chuck is commonly made to slide in one direction only, and -the traverse is limited. In the present case there is ample traverse -in both directions, the slide being arranged to descend to the lathe -bed, and upwards to an equal degree. A is a cross section of this -chuck, the length of which is 7½ inches. It is very strongly made -in brass, and is altogether much more substantial than the eccentric -chuck. B and C are the guide bars, between which works<span class="pagenum"><a name="Page_224" id="Page_224">[224]</a></span> the sliding -part. The nut of the leading screw is below this as usual. The tangent -wheel has 120 teeth, and is thus divided: 0—12—24, &c. The tangent -screw head is divided thus: 0—1—2—3—4—5, with half divisions, -marked but not numbered. This rectilineal chuck is most commonly used -in a vertical position, but may be otherwise placed. In using it for -any work likely to bring a strain upon it, the ordinary spring index -attached to the lathe for use with the face plate, should not be -entirely relied on to keep it in position. It is safer to make use in -addition of the segment engine stops or other available contrivance. -The special function of the chuck is the production of straight lines -on the face of work forming stars or radial flutes, which can be -worked with a drill. Fluting is also readily done by its aid, with the -addition of the vertical eccentric, or dome chuck, already described. -Its use is, however, by no means confined to ornamental work—small -tenons, mortises, and even dovetails are producible by it; and in -fitting together the various parts of temples, shrines, and similar -complicated specimens, its uses will be <span class="pagenum"><a name="Page_225" id="Page_225">[225]</a></span>innumerable; and here may be -noted the extension of the lathe and its apparatus to work apparently -in no way suited to it. It has now become more of a universal shaping -machine than it used to be, owing to the great accuracy of the work -done by it, and the variety of fittings that can be added to it. In a -later page will be found a drawing and description of a new device of -the kind—a planing machine, devised by an ingenious and first-class -maker, Munro, of Lambeth, and patented by him. Mention is made of it -in this place, because the rectilineal chuck is in some degree capable -of similar work. The slide moved up and down by a screw the handle -of which is of extra length to allow the vertical traverse, is also -capable of being moved by a cam-eccentric chain or rack and cogged -wheel, so that by pulling down a handle the slide may be made to slide -up and down more rapidly than by the screw motion; any piece of wood -of rectangular or other figure may thus be planed on the face, by -being fixed on the rectilineal chuck, and acted upon by a fixed tool -in the slide rest, the latter affording the horizontal traverse of -the tool across the face of the work, the former the perpendicular -movement of the material. If a slide rest is thus arranged in -combination with the chuck in question, and the lathe bed is imagined -to be set up on end with the chuck downwards and horizontal, the -whole will become, in fact, a precise counterpart of those planing -machines, the bed of which traverses to and fro, with the work under -a fixed tool. Munro's arrangement is, of course, of far more extended -application, and more suited for metal work; but for lighter and more -delicate operations of a similar kind the rectilinear chuck and slide -rest will be found very serviceable. It is with such an adaptation of -this chuck as has been alluded to, namely, a quick speed movement of -the slide by a lever handle, that the rays are drawn so exquisitely<span class="pagenum"><a name="Page_226" id="Page_226">[226]</a></span> -fine and close upon the faces of many gold dial plates of watches, -the handle being arrested by a stop at any given point, so that these -rays shall not transgress their appointed limits. It will be hardly -necessary to allude to those other applications of this apparatus, or -other particulars in which it is identical with the eccentric chuck, -as the description already given of the latter applies to both alike, -the extra traverse of the present in both directions being its chief -distinguishing feature.</p> - -<div class="figcenter" id="i-p224s" style="width:390px;"> - <img - class="p2" - src="images/i-p224s.png" - width="390" - height="550" - alt="" /> - <p class="center smcap">Fig. 311.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p225" style="width:450px;"> - <img - class="p2" - src="images/i-p225.png" - width="450" - height="409" - alt="" /> - <p class="center smcap">Fig. 312.</p> - </div> - -<h3 class="sc"><a name="EPICYCLOIDAL_CHUCK" id="EPICYCLOIDAL_CHUCK">Epicycloidal Chuck.</a></h3> - -<p>This chuck has been in use for many years, and has in consequence -been of late rather neglected. It is, nevertheless, the parent of -those more elaborate contrivances included under the general title of -Geometric Chucks, of which Ibbetson's stands first in order of date, -and possibly of merit, though this last qualification may admit of -question. The epicycloid, defined mathematically, is a curve described -by the revolution of a point in the circumference of a circle, when -the latter is made to roll upon the concave or convex side of another -circle. A pin in the rim of a wheel revolving round and in contact -with another wheel, therefore, describes this curve, which constitutes -two or more loops, as will be seen by the annexed illustrations. The -number of these loops is variable, and the chuck will produce almost -any number by changing the pinions, and thus altering the relative -velocities of the revolving parts. The following description will -make the action of this chuck clear, and enable any good mechanic to -construct one for himself. In the first place, the above remarks show -a necessity for a fixed wheel, round which another may revolve. -<a href="#i-p226">Fig. 313</a> represents this attached to a plate<span class="pagenum"><a name="Page_227" id="Page_227">[227]</a></span> of brass, which can be fixed -to the lathe head, the mandrel passing through its centre. This is -the original pattern of plate, and need not, of course, be adhered -to, as the form can be modified to suit the lathe to which it is to -be applied. It is merely necessary to affix such a wheel to the face -of the poppet, so as to be concentric with the mandrel [a plan done -away with, however, or rather reversed, in Plant's geometric chuck]. -The epicycloidal chuck, which screws to the mandrel as usual, consists -of a foundation plate of brass, A, <a href="#i-p227s">Fig. 314</a>, behind which is mounted -the cogwheel, B. The axis of this wheel passes through the plate, -and is carried by another plate, <i>e</i>, which is curved and adjustable -upon the former. The axis of this wheel carries a small pinion, D, so -that the whole turn together. This pinion being one of a set of change -wheels, necessitates the possibility of adjusting the plate which -carries its axis, as all the several change wheels must gear with E, -which always retains its position on the chuck. The sliding plate in -question being put in place, is clamped by the screw F. A plate of -iron, G, of the form shown, and of sufficient thickness for the secure -attachment of the wheel and of the screw which carries the ordinary -chucks, is fitted to turn on the axis of the wheel E. Its larger end -traverses within the arc H, which is graduated. The arc is bevelled -underneath, serving to hold down securely to the foundation plate the -piece of iron which is chamfered to fit it. At the left side of the -back plate is seen a stop, L, which is placed in such a position, that -when the iron plate rests against it, the screw M is concentric with -the mandrel, and<span class="pagenum"><a name="Page_228" id="Page_228">[228]</a></span> work may be turned as upon an ordinary chuck. To -throw the iron plate, and consequently the nose of the chuck, on one -side, or in other words to place the work eccentrically, the screws -which retain the arc are loosened and the adjustment made by hand. The -eccentricity is marked by an index on the iron plate, which points -to the graduations seen upon the face of the arc. The eccentricity -being determined, the arc is again screwed down to retain the movable -plate in its new position. [Although this is Bergeron's method, it -appears vastly inferior to the plan of racking the edge of the iron -plate, and moving it to any required degree of eccentricity by the -aid of a tangent screw.] When made as above, the chuck will produce -loops varying in number according to the relative dimensions of the -pinion (or change wheels gearing with E) and the central wheel, M. -If the latter has 120 teeth, and the change wheel 60, two loops will -result. If the pinion has ten teeth, the number of loops will be 12, -and so forth. The practical <i>limit</i> to the number depends on the -possibility of diminishing the pinion in size and number of cogs, -and still keeping the latter of such size and pitch as to gear with -E. If, therefore, a larger number of loops is required than can be -obtained thus, it becomes necessary so to modify the form of chuck as -to permit of intermediate change wheels, and when the modification is -carried out, we have the geometric chuck, the most perfect, but the -most complicated and expensive of all. To understand the nature of the -work, the following is given in clear language by Bergeron, and will -sufficiently explain and simplify matters.</p> - -<div class="figcenter" id="i-p226" style="width:550px;"> - <img - class="p2" - src="images/i-p226.png" - width="550" - height="322" - alt="" /> - <p class="center smcap">Fig. 313.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p227s" style="width:500px;"> - <img - class="p2" - src="images/i-p227s.png" - width="500" - height="492" - alt="" /> - <p class="center smcap">Fig. 314.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p228" style="width:340px;"> - <img - class="p2" - src="images/i-p228.png" - width="340" - height="350" - alt="" /> - <p class="center smcap">Fig. 315.</p> - </div> - -<p>If one considers the movement of the piece (of work) when the wheel -M is concentric with the mandrel, it will be perceived that although -it makes two revolutions upon its axis, yet inasmuch as it has no -eccentricity it will describe no particular curve or figure; but if an -eccentricity of three divisions is given to it, two buckles or loops -will result as in <a href="#i-p228">Fig. 315</a>. Before cutting the material, how<span class="pagenum"><a name="Page_229" id="Page_229">[229]</a></span>ever, -approach the tool as near the work as possible, and putting the lathe -in motion, observe whether the buckle<a name="FNanchor_23_23" id="FNanchor_23_23"></a><a href="#Footnote_23_23" class="fnanchor">[23]</a> passes too near the centre -or too far from it, and also how near it goes to the circumference. -If another change wheel with forty teeth instead of sixty is -substituted, the slide C, being adjusted accordingly, three loops -will be described (forty being one-third of one hundred and twenty), -but it is always necessary before actually cutting the material, to -try whether the buckles will pass near to the centre without going -beyond it. The result of the latter movement will be shown presently, -as it entirely alters the appearance of the pattern. The divisions -commence on the arc at the left hand, the index resting at 0° when the -plate is against the stop L, and the screw of the chuck concentric -with the mandrel. The preceding figure of three loops will become -similar to <a href="#i-p230">Fig. 317</a>, retaining the same wheels and some degree of -eccentricity, but by means of the slide rest moving the tool towards -the circumference, so that the buckles overlap the centre. The effect -thus produced is, that of a set of three curvilineal triangles of -which the apex of one falls upon the base of the next. The use of this -chuck is stated to require upon the part of the operator more care -than any other, as regards the derangement of work or tool in the -least during the operation, as, if either is once moved in the least -out of position, it will be found next to impossible to strike the -line again, owing to the peculiar nature of the curve, for although -the tool may be replaced upon any one part of the line already cut -with the intention of deepening—it is by no means certain that it -will trace the same curve again. This curve, says Bergeron does not -produce an agreeable effect on the cover of a box,<span class="pagenum"><a name="Page_230" id="Page_230">[230]</a></span> unless it is -very finely cut, the tool, therefore, should be very sharp in the -angle and very keen. Bergeron specially mentions this in reference -to filling the cuts with thin strips of horn or shell, a method of -inlaid ornamentation not much known or admired in the present day, but -to which allusion may probably be made again in this series. To form -the second set of loops, which are parallel with the first in these -designs, it is only necessary to use the leading screw of the slide -rest, to move the tool nearer to or further from the centre, while the -eccentricity and the arrangement of change wheels remain as before. It -is scarcely necessary to detail the formation of the larger series of -four loops and upwards, as these are simply the result of different -sized change wheels: the following principles, however, by which -the buckling of the several loops is controlled or prevented, may -perhaps be serviceable. "When, for example an eccentricity of sixteen -divisions is used—if the tool is placed at a distance of two such -divisions from the centre of the piece, a line only will be produced -of as many <i>curves</i> as the wheel or pinion D would produce <i>buckles</i>. -If the tool is moved further from the centre by a quarter division, -the angles (connecting the curves) will be more defined, but still -no buckles will be made. A little further movement of the tool will -produce very small buckles which will thus gradually increase as the -tool is set further and farther from the centre—until at last when -the curves pass beyond the centre, the result is arrived at already -shown in <a href="#i-p230">Fig. 317</a>. Another form<span class="pagenum"><a name="Page_231" id="Page_231">[231]</a></span> -of this chuck is shown in <a href="#i-p231s">318</a>, in -which, instead of the iron plate being pivotted for the purpose of -eccentricity upon the axis of the wheel E, a parallel slide motion is -given to the main wheel by guide bars, as in the eccentric and oval -chucks. This form is figured in "Lardner's Cabinet Cyclopædia." The -large front wheel carrying the screw for chucks is pivotted to the -slide C, and protected by a plate D which nearly covers it. The wheel -L, is arranged to follow this slide, so as to remain in gear with the -large wheel without leaving the fixed wheel or ring on the face of -the poppet. In both patterns of this chuck the front wheel is used -as a division plate, being moved in either direction as many cogs as -desired to produce interlacing of the looped designs. It is better, -however, to add a racked division plate and tangent screw, as in the -eccentric chuck to act as one piece with the chuck screw, and with -the latter turning on a conical pin in the centre of the large wheel -underneath. The above apparatus requires to be used with a slow motion -owing to the complication of parts, and the whole ought to be so well -constructed, that the various wheels revolve with perfect smoothness -and without shake or noise.</p> - -<div class="footnote"> - -<p><a name="Footnote_23_23" id="Footnote_23_23"></a><a href="#FNanchor_23_23"><span class="label">[23]</span></a> The word <i>buckle</i> is used to signify the small -loops—not the large curves.</p></div> - -<div class="figcenter" id="i-p229" style="width:344px;"> - <img - class="p2" - src="images/i-p229.png" - width="344" - height="350" - alt="" /> - <p class="center smcap">Fig. 316.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p230" style="width:348px;"> - <img - class="p2" - src="images/i-p230.png" - width="348" - height="350" - alt="" /> - <p class="center smcap">Fig. 317.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p231s" style="width:450px;"> - <img - class="p2" - src="images/i-p231s.png" - width="450" - height="335" - alt="" /> - <p class="center smcap">Fig. 318.</p> - </div> - -<h3 class="sc"><a name="SPIRAL_CHUCK" id="SPIRAL_CHUCK">The Spiral Chuck</a> (<a href="#i-p233s">Fig. 319</a>).</h3> - -<p>There is no class of work on the whole more interesting than that -executed by the aid of the spiral chuck, especially with an addition -to be described here. This apparatus has grown, almost as a matter -of course, from the adaptation to the ordinary lathe of the system -of change wheels for the production of screws of various pitches. A -spiral is, in fact, a screw with very extended pitch, the threads -either closely enwrapping a cylinder which forms the core or body of -the screw, or being entirely separate and independent of such core, -the latter being by far the most light and elegant. The chuck here -described is used with the same arm or bracket as has been already<span class="pagenum"><a name="Page_232" id="Page_232">[232]</a></span> -spoken of, standing out from the poppet to carry change wheels, and -is itself adjustable to suit different diameters of the same. In -the sectional view of this chuck given here, A, H, is the body with -internal screw as B, to fit the mandrel. The cog wheel of the chuck -which gears into the first on the movable arm or standard, is cast -with a large central hole to allow it to be stopped on at D, where it -is retained by a nut C. This permits a change of such wheel for one of -different size or for the apparatus to be presently described.</p> - -<p>Thus far the chuck is only applicable to the production of screws -or spirals with a single thread. F, is a dividing plate with racked -edge acted on by the tangent-screw E, and carrying the screw, G, a -counterpart of that upon the mandrel. This plate carries 96 divisions -or teeth. The latter may be used with a spring click if preferred; but -the racked edge gives perhaps the more delicate power of adjustment. -The spiral chuck constructed in this way is capable of producing -any required number of screw threads or spirals, solid or detached, -and of any ordinary pitch. It is, however, chiefly intended for the -production of spirals or twists for articles of <i>virtu</i>. The method -of proceeding has already been described in a previous page. It is -one rather of care than skill, as the lathe apparatus ensures the -correct movement of the tool where the shape of the latter determines -the form of thread, angular, round, or moulded at pleasure. A few -of the tools required are shown in the drawing. For finishing the -rounded threads, Nos. 3 and 4 may be used, which are similar to those -required for turning ivory rings, the one completing half the thread, -the other applied in the opposite direction, meeting the cut of the -first and finishing the operation. As it is necessary to get round to -the back of the threads in this case, no inner mandrel can be used to -support the work, and, therefore, great care and delicate handling -are necessary to prevent breaking the twists. The stops should also -be used upon the bed of the slide-rest, to limit the traverse of the -tool and prevent it from striking the shoulder, and destroying any -bead or other moulding formed there. This is more specially needed, -when there are two or more such twists rising from the same base (that -is when there are two or more threads to the screw). The additional -apparatus now to be described, adds considerably to the powers of the -spiral chuck. It is called the reciprocating apparatus, and its effect -is, to cause a to and fro movement of the work, at the same time that -the motion of the tool is continued in a horizontal direction. -<a href="#i-p233s">Fig. 320</a> shows the simplest of the effects thus produced. The screw is -commenced and carried to any desired distance on the cylinder. The -action and horizontal traverse of the tool is continued, but that of<span class="pagenum"><a name="Page_233" id="Page_233">[233]</a></span> -the cylinder reversed, and the cut is thus carried upwards. The tool -may be a revolving cutter, the action of which, being continuous and -in the same direction, would seem<span class="pagenum"><a name="Page_234" id="Page_234">[234]</a></span> preferable, as the greater the -speed with which the tool attacks the material the better is generally -the result in work of this kind. A fixed tool, moreover, must have a -central edge chamfered above and below, and there is also a tendency -with any such fixed tool to unscrew the chuck, as the resistance -occurs in that direction in the upward cut.</p> - -<div class="figcenter" id="i-p233s" style="width:700px;"> - <img - class="p2" - src="images/i-p233s.png" - width="700" - height="421" - alt="" /> - <p class="center smcap">Figs. 320, 321, 322, 323, 324, 325.</p> - </div> - -<p>The details of the arrangement are as follows:—The several parts -being drawn of full size, <a href="#i-p233s">Fig. 321</a> A is an eccentric capable of -slight adjustment by the use of either hole, one being further from -the centre than the other. <a href="#i-p233s">Fig. 322</a> gives another view of this -eccentric, which is precisely similar to that used in model engines. -It is turned as a circular plate of gun-metal, with one flange. The -plate being five-tenths of an inch thick, a second plate, forming -another flange, is attached by four small screws, after the ring of -the eccentric is in place. This ring is of iron, or, still better, -of steel, and is made in one piece, with the arm B, which is six -inches long; the main part of it is flat, but it is rounded towards -the end, and turned at E, after which it is again flattened to work -against the arm D, or still better forked to embrace the latter. It -will be seen that D is also a flat plate, with a turned ring similar -to the first, but without the enclosed eccentric. In this is drilled -a series of ten holes, into any of which a pin can be fitted, so as -to unite the arms B and D, the pin becoming a hinge or centre of -oscillation. The circular ring of the part D fits on the part D, D -of the chuck, on which it can be secured by the ferrule C, the arm -D being then in a vertical position. The holes in the eccentric can -(either of them) be fitted over and secured to the end of the leading -screw of the slide-rest. The handle being then placed on the other -end of the screw and turned by the hand, the eccentric will cause the -arm D to oscillate to and fro through the medium of the connecting -rod B, thereby giving to the chuck, and to the work attached to it, -a similar to and fro movement. The extent of this movement depends -upon the length of the lever D brought into action. With the pin in -the holes 1, 2, 3, the oscillation will be inconsiderable, but with -the pin in either hole numbered 8, 9, 10, it will be much increased. -In the first, therefore, a short wave, <a href="#i-p233s">Fig. 320</a>, will result; in the -second case these will be more like <a href="#i-p233s">Fig. 320</a> B. This apparatus will -completely alter the character of a spiral, which, if cut through a -hollow cylinder (as in the case of <i>detached</i> twists) becomes a zigzag -of curved sides curious enough to behold. The apparatus, it must -be understood, is worked entirely by the handle of the slide-rest, -the lathe-cord being thrown off unless the latter is carried to the -overhead instead, to put in action revolving cutters. The reciprocal -action is, in fact, a self-acting segment engine.</p> - -<p>It has been already stated that for the production of spiral work<span class="pagenum"><a name="Page_235" id="Page_235">[235]</a></span> -revolving cutters are preferable to fixed ones, unless, indeed, it is -required to finish up a perfectly round thread, when <a href="#i-p233s">Figs. 3 and 4</a> -of the tools drawn are required. Revolving cutters must be placed in<span class="pagenum"><a name="Page_236" id="Page_236">[236]</a></span> -the frame of the universal cutter and set to the rake of the thread. -Drills may be used for the reciprocating movement, as they make very -clean work, and the rake need not with these be attended to. In face<span class="pagenum"><a name="Page_237" id="Page_237">[237]</a></span> -work drills are specially to be used to produce patterns like -<a href="#i-p233s">Fig. 325</a>, and others derived from this simple one. An additional apparatus, -represented in <a href="#i-p233s">Fig. 323</a>, is required for the latter process, to enable -the rest to be turned in its socket so as to face the work, and -notwithstanding the alteration of its position still to keep up the -gearing of the wheels. A rest socket to be made and mounted as usual -is fitted with a stem surmounted by an accurately drilled boss A, -through which passes a spindle fitted with the wheel C, to gear with -that on the arm carrying the change-wheels, and which may be changed -for one of larger or smaller size. This is for cutting such work as -<a href="#i-p233s">Fig. 324</a>, representing, of course, only a single spiral, very open and -of itself of no beauty, but which by intersection of other spirals -can be converted into a pattern of great elegance. When it is desired -to produce the waved spiral the eccentric is fixed to the rod instead -of the wheel C, and the work proceeds the same as when a cylindrical -surface is to be worked. In the Fig. shown the division plate of this -chuck is of course used.</p> - -<div class="figcenter" id="i-p235a" style="width:361px;"> - <img - class="p2" - src="images/i-p235a.png" - width="361" - height="350" - alt="" /> - <p class="center smcap">Fig. 1.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p235b" style="width:366px;"> - <img - class="p2" - src="images/i-p235b.png" - width="366" - height="350" - alt="" /> - <p class="center smcap">Fig. 2.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p235c" style="width:369px;"> - <img - class="p2" - src="images/i-p235c.png" - width="369" - height="350" - alt="" /> - <p class="center smcap">Fig. 3.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p236a" style="width:365px;"> - <img - class="p2" - src="images/i-p236a.png" - width="365" - height="350" - alt="" /> - <p class="center smcap">Fig. 4.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p236b" style="width:350px;"> - <img - class="p2" - src="images/i-p236b.png" - width="350" - height="350" - alt="" /> - <p class="center smcap">Fig. 5.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p236c" style="width:367px;"> - <img - class="p2" - src="images/i-p236c.png" - width="367" - height="350" - alt="" /> - <p class="center smcap">Fig. 6.</p> - </div> - -<p>It is evident that the variations producible by working intersecting -spirals and waved lines are very numerous, and these may be -additionally varied by the combination of eccentric and spiral -movements.</p> - -<p>The following six patterns are re-engraved from Valicourt's Hand -Book, which is almost identical with that of Bergeron. They were not -engraved in time to be inserted under the head of eccentric chuck -work. The notation and description annexed is from a manuscript book -kindly lent to the writer by an amateur. "<i>Bed-plate</i>," 4 deg., must -be taken to mean that the work is shifted (on one of the beds of the -chuck) four of the marked divisions for eccentricity, counting from -the axial line of the mandrel.</p> - -<p>"<i>Slide rest</i>, 4 deg.," means that the cutting tool is moved four -corresponding divisions in its bed for radius of the circle to be cut; -and so throughout.</p> - -<p>"4 *," means four times repeated.</p> - -<p>The cutting tools, unless otherwise expressed, are double angled, and -"25 cutting tool," means 25 deg. of cutting edge.</p> - -<div class="figcenter" id="i-p237a" style="width:700px;"> -<p class="center">Holtzapffel's scale of divisions is</p> - <img - class="ph" - src="images/i-p237a.png" - width="350" - height="86" - alt="" /> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p237b" style="width:700px;"> -<p class="center">The scale used in Valicourt is</p> - <img - class="ph" - src="images/i-p237b.png" - width="350" - height="56" - alt="" /> -<p class="center">which is that here quoted.</p> - </div> - -<p><span class="pagenum"><a name="Page_238" id="Page_238">[238]</a></span></p> - -<p>If bed-plate and slide rest are both equally diminished at each cut, a -shell results, with the close part internal. If bed-plate is increased -and slide rest diminished, the close part of the shell is external.</p> - - -<p class="center p2">SPECIMEN I.—Tools 25, 32, 36; Click-plate 96 or 288.</p> - -<table summary=""> - <tr> - <td class="ctr">Bed-plate moved.</td> - <td class="ctr">Slide rest moved.</td> - <td class="ctr">Circles done.</td> - <td></td> - <td class="ctr">Tool.</td> - </tr> - <tr> - <td class="ctr">3</td> - <td class="ctr">2</td> - <td class="ctr">12*</td> - <td>(1 done 7 missed)</td> - <td class="ctr">25</td> - </tr> - <tr> - <td class="ctr">6</td> - <td class="ctr">1</td> - <td class="ctr">12*</td> - <td> (1 done 7 missed)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">10</td> - <td class="ctr">3</td> - <td class="ctr">48*</td> - <td>(1 done 1 missed)</td> - <td class="ctr">36</td> - </tr> - <tr> - <td class="ctr">3</td> - <td class="ctr">16</td> - <td class="ctr">24*</td> - <td>(1 done 3 missed)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">23</td> - <td class="ctr"> 4½</td> - <td class="ctr"> 4*</td> - <td>(16 done 8 missed)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 29½</td> - <td class="ctr">2</td> - <td class="ctr">96*</td> - <td></td> - <td class="ctr">25</td> - </tr> - <tr> - <td class="ctr">33</td> - <td class="ctr">1</td> - <td class="ctr">96*</td> - <td></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">or 33</td> - <td class="ctr"> ⅝</td> - <td class="ctr">288*</td> - <td></td> - <td class="ctr"></td> - </tr> -</table> - -<p class="center p2">SPECIMEN II.—Tools 28, 36; Click-plate 288.</p> - -<table summary=""> - <tr> - <td class="ctr">Bed-plate.</td> - <td class="ctr">Slide rest.</td> - <td class="ctr">Circles done.</td> - <td class="tab6"></td> - <td></td> - <td class="ctr">Tool.</td> - </tr> - <tr> - <td class="ctr">1</td> - <td class="ctr"> ½</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td></td> - <td class="ctr">28</td> - </tr> - <tr> - <td class="ctr">4</td> - <td class="ctr"> 1½</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 7½</td> - <td class="ctr">2</td> - <td class="ctr">4</td> - <td class="tab6"></td> - <td>(8 done 4 missed)</td> - <td class="ctr">36</td> - </tr> - <tr> - <td class="ctr">13</td> - <td class="ctr"> 3½</td> - <td class="ctr">24</td> - <td class="tab6"></td> - <td></td> - <td class="ctr">28</td> - </tr> - <tr> - <td class="ctr"> 19¾</td> - <td class="ctr"> 3½</td> - <td class="ctr">4</td> - <td class="tab6"></td> - <td>(16 done 8 missed)</td> - <td class="ctr">36</td> - </tr> - <tr> - <td class="ctr"> 19¾</td> - <td class="ctr"> ½</td> - <td class="ctr">4</td> - <td class="tab6"></td> - <td>(in spaces)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 21¾</td> - <td class="ctr">1</td> - <td class="ctr">4</td> - <td class="tab6"></td> - <td>(above last)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">B 17¾</td> - <td class="ctr">1</td> - <td class="ctr">4</td> - <td class="tab6"></td> - <td>(below last)</td> - <td class="ctr">36</td> - </tr> - <tr> - <td class="ctr">30</td> - <td class="ctr"> ½</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td>(20 done 4 missed)</td> - <td class="ctr">28</td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;"> 29⅜</td> - <td class="ctr" style="vertical-align: middle;"> ½</td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: -1em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>( 1 " 18 " )</p> - <p>( 1 " 4 " )</p></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 28¾</td> - <td class="ctr"> ½</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td class="ctr">Ditto.</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 28⅛</td> - <td class="ctr"> ½</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;"> 27½</td> - <td class="ctr" style="vertical-align: middle;"> ½</td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: -1em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>(15 done 4 missed)</p> - <p>( 1 " 4 " )</p></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;"> 26⅞</td> - <td class="ctr" style="vertical-align: middle;"> ½</td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: -1em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>(1 " 18 " )</p> - <p>(1 " 4 " )</p></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 26¼</td> - <td class="ctr"> ½</td> - <td class="ctr"></td> - <td class="tab6"></td> - <td class="ctr">As before</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr"> 25⅝</td> - <td class="ctr"> ½</td> - <td class="ctr"></td> - <td class="tab6"></td> - <td class="ctr">Ditto.</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">25</td> - <td class="ctr"> ½</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td>(20 done 4 missed)</td> - <td class="ctr"></td> - </tr> -</table> - -<p>From B to here, border, if with 96 click-plate, not good-looking; tool a boring-bit.</p> - -<table summary=""> - <tr> - <td class="ctr">33<sup>1</sup>/<sub>16</sub></td> - <td class="ctr">⅞</td> - <td class="ctr">12</td> - <td class="tab6"></td> - <td>(7 done 1 missed)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;">31<sup>9</sup>/<sub>16</sub></td> - <td class="ctr" style="vertical-align: middle;"><sup>13</sup>/<sub>16th</sub></td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: 2em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>(1 " 5 " )</p> - <p>(1 " 1 " )</p></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;">29<sup>1</sup>/<sub>16</sub></td> - <td class="ctr" style="vertical-align: middle;">¾</td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: 2em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>(1 " 1 " )</p> - <p>(5 " 1 " )</p></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;">27<sup>9</sup>/<sub>16</sub></td> - <td class="ctr" style="vertical-align: middle;"><sup>11</sup>/<sub>16th</sub></td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: 2em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>(1 " 1 " )</p> - <p>(1 " 5 " )</p></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr" style="vertical-align: middle;">25¾</td> - <td class="ctr" style="vertical-align: middle;">¾</td> - <td class="ctr" style="vertical-align: middle;">12</td> - <td class="tab6"><img src="images/big_left_bracket.png" alt="big left bracket" - style="margin-left: 2em; height:3em;padding:0 1em 0 1em;" /></td> - <td><p>(1 " 1 " )</p> - <p>(7 " 1 " )</p></td> - <td class="ctr"></td> - </tr> -</table> - -<p><span class="pagenum"><a name="Page_239" id="Page_239">[239]</a></span></p> - -<p class="center p2">SPECIMEN III.—Click-plate 96.</p> - -<table summary=""> - <tr> - <td class="ctr">Bed-plate.</td> - <td class="ctr">Slide rest.</td> - <td class="ctr">Circles done.</td> - <td class="ctr"></td> - <td class="ctr">Tool.</td> - </tr> - <tr> - <td class="ctr">1¼</td> - <td class="ctr">1⅛</td> - <td class="ctr">8</td> - <td class="ctr"></td> - <td class="ctr">36</td> - </tr> - <tr> - <td class="ctr">4¼</td> - <td class="ctr">2⅛</td> - <td class="ctr">24</td> - <td class="ctr"></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">5⅛</td> - <td class="ctr">11¾</td> - <td class="ctr">24</td> - <td class="ctr"></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">21½</td> - <td class="ctr">4¾</td> - <td class="ctr">96</td> - <td class="ctr"></td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">27¾</td> - <td class="ctr">1½</td> - <td class="ctr">96</td> - <td class="ctr"></td> - <td class="ctr">28</td> - </tr> -</table> - -<p class="center p2">SPECIMEN IV.</p> - -<p>The centre of this is a star of six curved rays, described by fixing -the cutter at the centre and turning the mandrel by hand through so -many divisions—for convenience so many 48ths of the circumference. -These rays are marked by B. (The segment stop is constructed for this -very kind of work, and is to be used in the present case):—</p> - -<table summary=""> - <tr> - <td>Bed-plate.</td> - <td>Slide rest.</td> - <td>Arcs done for star.</td> - </tr> - <tr> - <td class="ctr">5</td> - <td class="ctr">B 5</td> - <td class="tab7"> 6 (<sup>12</sup>/<sub>48ths</sub> of the circle)</td> - </tr> - <tr> - <td class="ctr">5</td> - <td class="ctr">B 5</td> - <td class="tab7">12 (<sup>11</sup>/<sub>48ths</sub> " )</td> - </tr> - <tr> - <td class="ctr">5</td> - <td class="ctr">B 5</td> - <td class="tab7">12 (<sup>10</sup>/<sub>48ths</sub> " )</td> - </tr> - <tr> - <td class="ctr">5</td> - <td class="ctr">B 5</td> - <td class="tab7">12 ( <sup>8</sup>/<sub>48ths</sub> " )</td> - </tr> - <tr> - <td class="ctr">14⅛</td> - <td class="ctr"> 5</td> - <td class="tab7">24 (2 done, 2 missed)</td> - </tr> - <tr> - <td class="ctr">19¾</td> - <td class="ctr"> ½</td> - <td class="tab7">96</td> - </tr> - <tr> - <td class="ctr">24¼</td> - <td class="ctr"> 4</td> - <td class="tab7">32</td> - </tr> - <tr> - <td class="ctr">29½</td> - <td class="ctr"> 2½</td> - <td class="tab7">32 (intersecting)</td> - </tr> - <tr> - <td class="ctr">30½</td> - <td class="ctr"> 2</td> - <td class="tab7">32</td> - </tr> - -</table> - -<p class="center p2">SPECIMEN V.—Catherine wheel; tool 28.</p> - -<p>The ground grailed by concentric circles contiguous to each other. The -arcs by fours, all of same radius.</p> - -<table summary=""> - <tr> - <td class="ctr">Bed-plate.</td> - <td class="ctr">Rest.</td> - <td class="ctr">Arcs done.</td> - </tr> - <tr> - <td class="ctr">0</td> - <td class="ctr">½ ¾ 1¼ &c. (for grailing)</td> - <td class="ctr"></td> - </tr> - <tr> - <td class="ctr">B 30</td> - <td class="ctr">30</td> - <td class="ctr">12 (<sup>16</sup>/<sub>48</sub>)</td> - </tr> -</table> - -<p class="center">(Repeat at three next divisions.)</p> - -<p class="center p2">SPECIMEN VI.—Tools 28, 36; Click-plate, 288.</p> - -<table summary=""> - <tr> - <td class="ctr">Bed-plate.</td> - <td class="ctr">Rest.</td> - <td class="ctr">Number.</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr"> 1¼</td> - <td class="ctr">1</td> - <td class="ctr">8</td> - <td class="left">done</td> - </tr> - <tr> - <td class="ctr">B 12</td> - <td class="ctr">12</td> - <td class="ctr"> 12<sup>7</sup>/<sub>48</sub></td> - <td class="left">(to meet next circle)</td> - </tr> - <tr> - <td class="ctr"> 4⅜</td> - <td class="ctr">17</td> - <td class="ctr">24</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr">30</td> - <td class="ctr"> ½</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr"> 29½</td> - <td class="ctr"> 1</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td colspan="4" class="footer">(On same radius as the last, and surrounding it.)</td> - </tr> - <tr> - <td class="ctr">29</td> - <td class="ctr"> 1½</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr"> 28½</td> - <td class="ctr">2</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr">28</td> - <td class="ctr"> 2½</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr"> 27½</td> - <td class="ctr">3</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr">27</td> - <td class="ctr"> 3½</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr"> 26½</td> - <td class="ctr">4</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td class="ctr"> 23½</td> - <td class="ctr">1</td> - <td class="ctr">12</td> - <td class="left"></td> - </tr> - <tr> - <td colspan="4" class="footer">(3 done, 21 missed between last, or if click-plate 96.)</td> - </tr> - <tr> - <td class="ctr">25</td> - <td class="ctr">1</td> - <td class="ctr">12</td> - <td class="left">(between last)</td> - </tr> -</table> - -<p><span class="pagenum"><a name="Page_240" id="Page_240">[240]</a></span></p> - -<p class="p2">Although in the matter of beauty the patterns here given are by no -means comparable to many others, especially to some lately published -from blocks cut by Mr. George Plant, for the <i>English Mechanic</i>; -they are, by their comparative simplicity, well selected to give the -learner a good idea of designing and working with the eccentric chuck. -It is not, indeed, proposed by the writer to multiply patterns, as -mere copying of such is of small interest to those who are really -endued with taste and skill; and the variations producible by -combinations of different numbers of divisions of the click-plate and -slide rest are of such infinite number, that printed designs of a -score or two would not serve to teach the nature of this work better -than the half dozen now before the reader. When a new chuck, indeed, -is brought out, it is well to give a few specimens of its work, to -show the possible purchaser its value as a means of ornamentation and -the extent of its capabilities; but when these are understood, the -purchaser had much better design for himself, instead of becoming a -lazy imitator and copying patterns laid down by others. Details of -designs that are presented in a tabular form remind us sadly (for we -are married) of the old "<i>knit one, drop two</i>," "<i>purl</i>" or some such -mysterious and, to us, detestable jargon wherewith ladies were, or -are, wont to worry the ears of mankind.</p> - -<hr class="tb" /> - -<p>The chuck of Professor Ibbetson, and the elliptic cutting frame -of Captain Ash, are not introduced here, partly because this work -has reached its intended limit, and partly because the inventors -themselves have published separate works entirely devoted to a -description of the arrangements and capabilities of their respective -chucks. A brief notice is appended of Plant's geometric chuck, -contributed by the inventor to the pages of the <i>English Mechanic</i>.<a name="FNanchor_24_24" id="FNanchor_24_24"></a><a href="#Footnote_24_24" class="fnanchor">[24]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_24_24" id="Footnote_24_24"></a><a href="#FNanchor_24_24"><span class="label">[24]</span></a> See Appendix.</p></div> - -<hr class="tb" /> - -<p>The author now concludes his pleasant labours, the result of which -is contained in the preceding pages. These labours have been -lightened, and the work itself benefited, by several kindly-written -remarks received from various readers of the <i>English Mechanic</i>, -while the articles were in course of production in that paper. -Criticisms and suggestions also came to hand in which no such kindly -feelings appeared. These also have, nevertheless, had an equal share -of attention, and where they appeared to be of value they have -been turned to profit, and have resulted in various more or less -important alterations and additions. "The Lathe and its Uses," thus -re-arranged and modified, must now take its chance in the world with -other productions of a similar character; and the writer hopes it -may suffice to help those who need such assistance, and may be well -received by others who though able to walk alone may yet cherish a -kindly feeling for the friendly walking-stick.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_241" id="Page_241">[241]</a></span></p> - - -<div class="chapter"></div> - -<h2><a name="APPENDIX" id="APPENDIX">APPENDIX.</a></h2> - - -<h3 class="sc"><a name="WILLIS" id="WILLIS">Professor Willis's Tool Holder for the Slide Rest.</a></h3> - -<div class="figcenter" id="i-p241s" style="width:700px;"> - <img - class="p2" - src="images/i-p241s.png" - width="700" - height="352" - alt="" /> - </div> - -<p>This—described and drawn first in "Holtzapffel's Mechanical -Manipulation," to which work the author, and, indeed, most authors of -books of the nature of the present, are indebted for much of their -information—is now become very general, and from its perfect action -ought to be universally used in all factories in which the lathe bears -a part. It permits the tool to be set at any required angle upon the -bed of the slide rest, and holds it securely when placed in position. -It is likewise so constructed as to be easily removed from the table -of the rest, so that other forms of apparatus may be attached if -desired. One nut only has to be turned to fix the tool, this nut -turning on a strong central screw, A, in the figure, the lower part of -which, as far as the shoulder, is screwed into the top plate of the -rest. This shoulder is directed to be made with flattened sides, so -as to be capable of being unscrewed by the application of a wrench. -The actual clamp is a triangular piece of cast or wrought iron, B, in -the centre of which is a hole to allow this piece to go easily over -the screw. The hole is hollowed out into a cup-shaped cavity, into -which fits a hemispherical washer, shown at C in the section. The -clamping nut, D, acts upon this washer, which permits the triangle -to take up a position not <i>necessarily</i> quite parallel to the bed of -the slide rest, and thus a tool whose upper and lower surfaces may -not be strictly parallel will be securely grasped. The piece called -triangular is not precisely of that form, but of the shape shown in -the second figure, in which E, E, represent two hard steel pins, -slightly projecting—one of these, E, appearing in the first figure. -These pins rest upon the upper surface of the tool. At the third -angle the<span class="pagenum"><a name="Page_242" id="Page_242">[242]</a></span> clamping piece is drilled and tapped to receive a screw, -which must work stiffly in this hole. Thus when a tool is placed in -position, as shown, the clamping nut maintains a pressure upon the -three points beneath the apices of the triangle. As thus arranged the -tool would be stiffly and securely held; but Professor Willis has -added a second triangular piece, nearly similar to the first, except -that it is provided with a boss, in which a notch or groove is cut, K, -in both figures, into which the point of the small screw falls. This -lower triangle, which is free to revolve round the central screw, is -also cut away at the line L, L, of the second figure, so as to form -a guide or rest for the side of the tool, which is thus kept at the -same distance from the central screw, and placed in a moment exactly -under the studs or points of the upper plate. A careful inspection of -the two drawings will make the precise arrangement clear. In <i>making</i> -it, which is not very difficult, care must be taken to make the -triangle of such size and so to place it, that no angle can overhang -the top plate of the rest, in whatever position it may be. The hole -in the upper triangle or clamp must be tolerably large and slightly -conical—the base of the cone upwards, to allow this piece to take -up a bearing, as described. The hemispherical washer is always in a -horizontal position, and the hole through it may be only of sufficient -diameter to allow it to pass freely over the central screw.</p> - - -<h3 class="sc"><a name="MUNRO" id="MUNRO">Munro's Planing Machine to be attached to the Lathe, and worked -with the foot.</a></h3> - -<p>In the <i>English Mechanic</i> of Nov. 2, 1866, a brief notice was given of -the above. The author of the present work having carefully inspected -the machine and seen it in operation, considers it of such great -value to the amateur mechanic, as well as to the professional turner -of metal work, that he has had an engraving of the machine carefully -made from a photograph, and has here appended it to illustrate the -description given.</p> - -<div class="figcenter" id="i-f242s" style="width:465px;"> - <img - class="p2" - src="images/i-f242s.png" - width="465" - height="550" - alt="" /> - <p class="center xs">MUNRO'S MACHINE TURNING LATHE FOR PLANING, ETC.</p> - </div> - -<p>It is a lathe for planing, cutting key-grooves in wheels, collars, -&c., and cutting racks on the teeth of wheels. The lathe is of the -usual construction, but outside the right hand standard is fixed a -vertical spindle, which is made to rotate by a pair of bevel wheels, -the pinion being fast to the end of the crank shaft, and in contact -with a wheel of double the number of teeth on the vertical spindle. -On the top of the latter is a crank-plate, which will give a stroke -of ten inches or less at pleasure. The planing-machine is fixed by -two bolts to the lathe-bed, and a connecting rod is attached to the -sliding plate or bed of the planing machine, the other end of which is -made fast to the pin of the crank-plate. The work is clamped by simple -means to this sliding bed, and thus passes to and fro under the tool -which, by self-acting gear, is made to traverse sideways <span class="pagenum"><a name="Page_243" id="Page_243">[243]</a></span>after -each stroke as in the large planing machines. The whole works almost -noiselessly and with the greatest ease, each part being accurately -fitted, and the whole well finished. For such purposes as planing -the face of the slide valve and its bed in small engines, or shaping -the guide bars of eccentric and other chucks, facing the frames -of slide-rests, &c., it is exactly what is needed by the amateur, -rendering the workshop complete for all purposes without the necessity -for adding a large and separate planing machine, which takes up room -that cannot always be conveniently spared. With such a lathe as that -in the frontispiece, fitted with one of these planing machines, there -is scarcely a model of machinery that could not be made. Any of our -readers interested in mechanics would be wise to trip over to Lambeth -and view the machine in operation; and the writer will guarantee, not -only the most civil and obliging attention from the inventor, but the -greatest pleasure and satisfaction from the working of the machine -itself. There is a <i>simple arrangement</i> for key-grooving and slotting, -by attaching the upper slide of the ordinary rest to the crank plate -of this machine, in which case most of the apparatus is removed.</p> - -<h3 class="sc"><a name="HICKS" id="HICKS">Hicks' Expanding Mandrel.</a></h3> - -<div class="figcenter" id="i-p243s" style="width:400px;"> - <img - class="p0" - src="images/i-p243s.png" - width="400" - height="353" - alt="" /> - <p class="center smcap">Figs. 1, 2, 3.</p> - </div> - -<p>Mention of this has been made in the body of the work. It is used for -turning rings and washers, and various sizes of these can be turned -upon the same mandrel, so that a set of three will suffice for all -the work likely to be met with even in the largest factories. -<a href="#i-p235a">Fig. 1</a> represents the mandrel complete. F, F is the central part, with -a conical boss, A, cast upon it, and the whole turned with great -accuracy. Four longitudinal dovetailed slots, seen plainly in <a href="#i-p235c">Fig. 3</a>,<span class="pagenum"><a name="Page_244" id="Page_244">[244]</a></span> -are then planed in the conical part, and into these are fitted -steel wedges, Fig. 2, A and B, and B, Fig. 3. C, Fig. 1, is a hollow -conical washer, which can be advanced over the central part when -driven forward by the nut D. This washer, acting on the ends of the -sliding wedges, causes them to move towards the large end of the cone -A, and, from the form of these and of the cone, any washer or ring -will be held tightly when placed outside these wedges, and will also -be mounted concentrically.</p> - - -<h3 class="sc"><a name="TURNING_SPHERES2" id="TURNING_SPHERES2">Turning Spheres by means of Templates.</a></h3> - -<p>It is but right to state that the above method has been objected to by -a practical workman, whose business has led him to study the matter -closely. He states that it is impossible in this way to effect the -desired object. As the writer has not been able to test the working -of the apparatus on his own lathe, he felt inclined, at first, to -withdraw the whole chapter. The objections offered, however, were -not, to his mind, entirely satisfactory; and the opinion of other -equally scientific and practical men being favourable, the chapter -has been retained. It is possible, nevertheless, that there may be -a mathematical reason which the writer is not competent to work -out, and the objector being a man of great mechanical knowledge and -experience, his remarks are worthy of consideration. The practical -(not insuperable) difficulty appears to be the production of a proper -tool for this work.</p> - - -<h3 class="sc"><a name="PLANT" id="PLANT">Plant's Geometric Chuck.</a></h3> - -<p>This chuck is put in motion by an entirely new method; none of its -parts being attached to the lathe head, the whole can be put in motion -or released in an instant, and without stopping the lathe.</p> - -<p>The whole of its work is executed by the continuous motion of the -lathe, so that, when the chuck is adjusted, any figure (no matter how -complex) may be begun and completed without once stopping the lathe.</p> - -<p>By the different arrangements and adjustments of the chuck and slide -rest, an infinite variety of the most beautiful geometrical figures -may be produced; and some of them of so strange and fortuitous a -nature as to bid defiance to any imitation.</p> - - -<p><i>Description of the Drawings.</i></p> - -<p><a href="#i-p245s">Fig. 1</a> is a front view, and</p> - -<p><a href="#i-p246s">Fig. 2</a> a view of the back of the chuck.</p> - -<p><span class="pagenum"><a name="Page_245" id="Page_245">[245]</a></span></p> - -<div class="figcenter" id="i-p245s" style="width:550px;"> - <img - class="p0" - src="images/i-p245s.png" - width="550" - height="459" - alt="" /> - <p class="center smcap">Fig. 1.</p> - </div> - -<hr class="r10" /> - -<p><span class="pagenum"><a name="Page_246" id="Page_246">[246]</a></span></p> - -<div class="figcenter" id="i-p246s" style="width:404px;"> - <img - class="p0" - src="images/i-p246s.png" - width="404" - height="550" - alt="" /> - <p class="center smcap">Fig. 2.</p> - </div> - -<hr class="r10" /> - -<p><span class="pagenum"><a name="Page_247" id="Page_247">[247]</a></span></p> - -<div class="figcenter" id="i-p247s" style="width:358px;"> - <img - class="p0" - src="images/i-p247s.png" - width="358" - height="550" - alt="" /> - <p class="center sm">FRONT ELEVATION</p> - </div> - -<hr class="r10" /> - -<p><span class="pagenum"><a name="Page_248" id="Page_248">[248]</a></span></p> - -<div class="figcenter" id="i-p248a" style="width:372px;"> - <img - class="p0" - src="images/i-p248a.png" - width="372" - height="350" - alt="" /> - </div> - -<div class="figcenter" id="i-p248b" style="width:372px;"> - <img - class="p0" - src="images/i-p248b.png" - width="391" - height="350" - alt="" /> - </div> - -<p><span class="pagenum"><a name="Page_249" id="Page_249">[249]</a></span></p> - -<div class="figcenter" id="i-p249a" style="width:364px;"> - <img - class="p0" - src="images/i-p249a.png" - width="364" - height="350" - alt="" /> - </div> - -<div class="figcenter" id="i-p249b" style="width:352px;"> - <img - class="p0" - src="images/i-p249b.png" - width="352" - height="350" - alt="" /> - </div> - -<p><span class="pagenum"><a name="Page_250" id="Page_250">[250]</a></span></p> - -<div class="figcenter" id="i-p250a" style="width:361px;"> - <img - class="p0" - src="images/i-p250a.png" - width="361" - height="350" - alt="" /> - </div> - -<div class="figcenter" id="i-p250b" style="width:566px;"> - <img - class="p0" - src="images/i-p250b.png" - width="566" - height="550" - alt="" /> - </div> - -<p><span class="pagenum"><a name="Page_251" id="Page_251">[251]</a></span></p> - -<p>A A. The foundation plate screwing on the plate of the mandrel and -carrying the whole of the other parts of the chuck.</p> - -<p>B, C. The two driving wheels giving an independent motion to the chuck.</p> - -<p>D. Angular wheel moving freely on the wheel C for the angular -adjustment of the figures.</p> - -<p>E. Pinion of any number of teeth fitting on the shaft carrying D and C.</p> - -<p>H. Large wheel of 120 teeth, forming the foundation of the second -part, and driven from the pinion E by the wheels F, G, and T.</p> - -<p>L. Large wheel of 96 teeth driven by the pinions and wheels U, I, J, K, -and forming the foundation plate of the third part, M, which -carries the nose of the chuck.</p> - -<p>N, N. Self-adjusting radius plates for carrying the various change -wheels.</p> - -<p>O, P. The eccentric slides of the first and second parts.</p> - -<p><a href="#i-p246s">Fig. 2</a> shows the arrangement of the driving wheels and pinions on the -back of the chuck.</p> - -<p>The working of the chuck is as follows:—</p> - -<p>If the pinion E has 20 teeth, and is geared direct into the wheel H, -by means of an intermediate wheel, it will give six loops inwards if -the motions are similar, and outward loops if the motions are contrary.</p> - -<p>If the wheel H is driven from the pinion G it will give 12, 24, or 48 -loops.</p> - -<p>Pinion of 24 teeth will give 5, 10, 20, or 40 loops.</p> - -<p>Pinion of 30 teeth will give 4, 8, 16, or 32 loops.</p> - -<p>Pinion of 40 teeth will give 3, 6, 18, or 36 loops.</p> - -<p>Pinion of 60 teeth will give two loops inwards, if the motions are -similar, but, if the motions are contrary, it will produce an ellipse -of any proportion from a straight line to a circle.</p> - -<p>Other combinations will give circulating or overlaying loops.</p> - -<p>By the different arrangements of wheels and pinions on the plates N, N -any number of loops can be produced up to 2,592 in the circle.</p> - -<p>On the opposite page we illustrate some work executed with this chuck -by Mr. Plant.</p> - -<p><a href="#i-p247s">Fig. 3</a> is a side elevation of the chuck full size.</p> - -<p>A, A, the foundation plate screwing on the nose of the mandrel, and -carrying the whole of the other parts of the chuck.</p> - -<p>B, C, the two driving wheels giving an independent motion to the chuck.</p> - -<p>D, D, angular wheel moving freely on the wheel C, for the angular -adjustment of the figures.</p> - -<p>E, E, pinion of any number of teeth fitting on the shaft carrying C -and D.</p> - -<p>H, H, large wheel of 120 teeth, forming foundation of the second part, -and driven from the pinion E by the wheels F, G, and T.</p> - -<p><span class="pagenum"><a name="Page_252" id="Page_252">[252]</a></span></p> - -<p>L, large wheel of 96 teeth driven by the wheels and pinions I, J, K, -and forming the foundation of the third part, M, which carries the -nose of the chuck.</p> - -<p>N, N, self-adjusting radius plates for carrying the various change -wheels, &c.</p> - -<p>O, P, the eccentric slides of the first and second parts.</p> - -<p>Q, R, the screws working the eccentric slides.</p> - - -<h3 class="sc"><a name="PAPER_ON_PRINCIPLES" id="PAPER_ON_PRINCIPLES">A Paper on the Principles which Govern the Formation and -Application of Acute Edges, with special reference to Fixed -Turning-tools, contributed by Mr. Dodsworth Haydon.</a></h3> - -<blockquote> - -<p class="sm">"The formation of the tools used for turning and planing the -metals is a subject of very great importance to the practical -engineer, and it is indeed only when the mathematical principles -upon which such tools act are closely followed by the workman -that they produce their best effects."—Holtzapffel, vol. 2, p. -983.</p></blockquote> - -<p>As the best lathe can do no more than place the work in the most -favourable position for the operation of the tool, and the best tool -can only do good work when <i>applied</i> as well as <i>constructed</i> on true -principles, no argument is needed to prove the truth of the statement -taken as the text of this paper.</p> - -<p>But while many of our most eminent practical authorities, such -as Nasmyth, Holtzapffel, Babbage, Prof. Willis, and others, have -contributed valuable papers on the subject, no single writer can be -said to have embodied all that should be known upon it as a whole.</p> - -<p>Principle may be looked upon as the essence of practice, and in -connection with this particular subject, the reduction of practice -to principle is of comparatively modern growth. This will account -for the fragmentary character and occasional difference of opinion, -which marks the treatises of the above-named eminent authorities when -compared with each other. As a step towards some more concise and -perfect code of principle, I have endeavoured to collate and arrange -in consecutive order, all those laws which govern the action of acute -edged turning tools.</p> - -<p>The object of this paper is not to supply patterns of tools, as the -best form will be no better than the worst unless properly applied; -but to set forth those general principles, which may enable the -workman to distinguish between forms which are accidental and those -which are essential, and thus to make the shape of any tool his -servant rather than his guide.</p> - -<p>Whatever the shape or purpose of any acute-edged tool may be, its -action will always depend on the manner in which the extreme<span class="pagenum"><a name="Page_253" id="Page_253">[253]</a></span> edge is -applied to the surface acted upon; and as the same laws govern the -action of every acute edge, whether formed on a razor or a tool for -cast iron, it will assist a clear comprehension of this subject to -consider first the action of edges generally, without reference to any -particular tool.</p> - -<p>The same edge may be made to act in four different ways, viz.: to -cut, dig, chatter or scrape. Digging and chattering are intermediate -stages between cutting and scraping, and are fatal to good work. Thus -<i>cutting</i> and <i>scraping</i> remain the two standard principles, on one of -which every tool should be made to act; and while cutting depends on -the penetration of the edge, scraping results from using an edge so -that it cannot penetrate. Consequently, the conditions most favourable -to cutting will give the key to both principles of action.</p> - -<p>Every cutting edge is simply a wedge, keen enough to guide its own -path without depending on the grain or other accidental line of -separation in the material on which it is employed; and when such a -wedge is forced into any substance, it will show a constant tendency -to penetrate in a line with that face which receives most opposition. -The comparative amount of opposition which each face receives, will -be determined either by one having more of its surface in contact -with the material than the other as in <a href="#i-p254s">Fig. 2</a>, or by the material -giving way on one side, as in <a href="#i-p253">Fig. 1</a> and <a href="#i-p259">3</a>. These last two figures -illustrate the action of all <i>paring</i> tools, to which class cutting -lathe tools belong. The dotted lines are added in <a href="#i-p254s">Fig. 2</a>, to show that -the action of the edge is the same, whether it be formed by one or two -bevels.</p> - -<div class="figcenter" id="i-p253" style="width:452px;"> - <img - class="p0" - src="images/i-p253.png" - width="452" - height="385" - alt="" /> - <p class="center smcap">Illustration No. 1.(1, 2, 3)</p> - </div> - -<p>Thus in all cases,—except when an edge is applied so that the -pressure is equal on both faces,—one face will guide the course of -the edge, and in paring tools this will always be the lower face, or -that next the surface of the work.</p> - -<p>The first consideration in placing any paring tool must therefore -always be that, <i>the lower face of the edge should lie as nearly as -possible in a line with the direction the cut is intended to follow</i>, -so as to place<span class="pagenum"><a name="Page_254" id="Page_254">[254]</a></span> the whole edge in its natural wedge-like position: for -when any edge is compelled to act in a manner contrary to this, it -will assuredly assert its natural tendency by digging and chattering -in the direction of its lower face. But when the action of the tool -is continuous as in turning, planing, or boring, care must be taken -that this face of the edge does not actually rub against that of the -work; and, to avoid this, Nasmyth recommends that the face of the edge -should be inclined from the surface of the work at an angle of 3°. -Babbage calls this angle "the angle of relief," because it relieves -the friction; and to show how little variation is admissible in this -angle, Holtzapffel places its maximum at 6°. In cylindrical work the -angle of relief is estimated from a tangent to the circumference. -Thus, in Figs. <a href="#i-p254s">4 and 7</a>, the lines C, D, may represent plane surfaces -or tangents at pleasure, and in either case the lower face of each -edge is supposed to make an angle of 3° with these lines respectively.</p> - -<div class="figcenter" id="i-p254s" style="width:450px;"> - <img - class="p0" - src="images/i-p254s.png" - width="450" - height="395" - alt="" /> - <p class="center smcap">Illustration No. 2.(4, 5, 6, 7)</p> - </div> - -<p>An examination of the nature of the force required to separate any -shaving will show the importance of close attention to the above -rule. Babbage has pointed out that this process involves two forces, -which, though simultaneous in their action, are distinct in the -nature of their operation. The first is that necessary to divide the -material atom from atom, and depends on the kind of edge employed. -The second force is that required to wedge back the shaving, so as -to make way for the further progress of the edge, and depends on the -manner in which it is applied to the work. Now in fibrous and cohesive -materials, the amount of force required to wedge back the shaving is -usually greater than that required to effect the initial penetration, -and must always depend on the angle which the <i>upper surface</i> of -the edge makes with the face of the work; while it is obvious that, -whatever the acuteness of the particular edge employed may be, this -angle will be reduced to the minimum obtainable with such<span class="pagenum"><a name="Page_255" id="Page_255">[255]</a></span> an edge, -by keeping its lower face as close as possible to the surface from -which the shaving is being wedged off.<a name="FNanchor_25_25" id="FNanchor_25_25"></a><a href="#Footnote_25_25" class="fnanchor">[25]</a> A comparison of Figs. 4 -<a href="#i-p261s">4 and 5</a> will illustrate this. Both edges are supposed to be of the same -acuteness, viz., 60°, and in <a href="#i-p261s">Fig. 4</a>, where the angle of relief is -only 3°, the edge of 60° will wedge off the shaving at the smallest -available angle, viz., 63°, while the position of the same edge in -<a href="#i-p264">Fig. 5</a> increases this angle to 90°.</p> - -<div class="footnote"> - -<p><a name="Footnote_25_25" id="Footnote_25_25"></a><a href="#FNanchor_25_25"><span class="label">[25]</span></a> In adopting Mr. Babbage's arguments I have varied their -form. Mr. Babbage takes the square of 90° and divides it into three -parts, viz.: -</p> - -<table summary=""> - <tr> - <td class="left"> - <p>Angle of relief 3°<br /> - Angle of edge 60°<br /> - Angle of escape 27°</p></td> - <td class="tab6"><img src="images/big_right_bracket.png" alt="big right bracket" - style="margin-left: -1em; height:3em;padding:0 1em 0 1em;" /></td> - <td>90°</td> - </tr> -</table> - - -<p> -The angle of escape is thus estimated from the horizontal line -perpendicular to a base line presented by the surface of the work or -by a tangent to it. But as the value of this angle depends directly on -its relation to the base line, and has only a complementary relation -to the horizontal line, I have thought it better to confine the -illustration to the same base as being more directly connected with -the wedge-like action of the edge.</p></div> - -<p>Thus, as far as regards the force required to bend back the shaving, -the edge of <a href="#i-p264">Fig. 5</a> might just as well be nearly square, or 87°, taking -off 3° for the angle of relief. Indeed, this less acute edge would -work better than one more acute but badly placed, as in <a href="#i-p264">Fig. 5</a>; for -the lower face here points too much <i>into</i> the work, creating the -tendency to dig explained above. The same arguments and illustrations -apply with equal force to drills and boring tools, and <a href="#i-p264">Fig. 5</a> may -be looked at as representing one edge of a common drill, in which -the acuteness is obtained by bevelling the under sides only, leaving -the upper face of each edge perpendicular to the surface acted upon. -Nasmyth has pointed out that the less acute drills of this class are -made the better and more smoothly they will cut; for, so long as the -upper faces are left square to the surface of the work, increasing the -bevel of the lower faces can only increase the tendency to dig and -chatter. Thus, whenever acuteness is desired in any cutting edge, it -should always be obtained from the upper face; and the dotted lines -in <a href="#i-p261s">Fig. 4</a>, suggesting a tool for metal in one case, and a common -wood-turning chisel in the other, are added to illustrate this, by -showing that the line of the lower face is common to both. No tools -afford a better illustration of this principle in boring tools than -the American twist drills, which owe the ease and beauty of their -action to the spiral flutes being placed so as to give the necessary -acuteness from the upper face of each edge, thus allowing the lower -faces to be kept as close as possible to the surface of the work. -There is yet one more important practical advantage to be gained from -adopting the smallest possible angle of relief. The arrow in Figs. <a href="#i-p261s">4 and 5</a> -shows the direction in which the strain of the cut will fall on -the edges respectively. It<span class="pagenum"><a name="Page_256" id="Page_256">[256]</a></span> has been shown that the position of -<a href="#i-p264">Fig. 5</a> increases the amount of strain on the edge, and yet it is apparent -that it is less able to bear this increased strain; for while this -falls on Fig. 4 in its strongest direction—viz., almost down the -length of one face—it falls on <a href="#i-p264">Fig. 5</a> <i>across</i> the end of the edge, -thus rendering it far more liable to wear and fracture.</p> - -<p>It is therefore evident that, in treating plane surfaces, the cutting -action of any acute edge is most favoured when its lower face is -placed nearly parallel with the surface acted on; and in treating -cylindrical surfaces, when the same face occupies the same position -with regard to some tangent of the circumference; or, in other words, -when the lower face is almost at right angles to some radius of the -circle, as in <a href="#i-p261s">Fig. 4</a>: and it follows that the tendency to penetrate -will be most effectually counteracted when a line at right angles to -the surface, or a radius of the circle, as in <a href="#i-p266">Fig. 6</a>, bisects the -edge, making each face equidistant from the surface which moves across -it. Thus, <a href="#i-p266">Fig. 6</a> represents the <i>scraping</i> position; and it is obvious -that all bow-drills or other tools, which are <i>said to cut both ways</i>, -must really act on the scraping principle.</p> - -<p>Practical illustrations in support of the universal application of -these principles might be multiplied indefinitely; but two very -common operations will suffice to prove that the position of the edge -determines the nature of its action. If a penknife be not held with -its blade perpendicular to the paper, when used for scratching out, it -will be sure to hang and chatter; and the flatter a razor is held to -the skin in shaving the more free will the chin be from uncomfortable -digs and chatters afterwards.</p> - -<p>The conditions which next demand notice in the case of turning-tools -are those which must be observed to preserve the proper position of -the edge under the strain put upon it. These relate to the form of the -tool, and, in the case of cylindrical work with fixed tools, to the -part of the surface at which the edge of the tool should be applied. -Drills and boring tools require little notice in this respect, for, as -the strain is round their axis, it is only necessary that their shafts -should be strong enough not to twist or bend. It must, however, be -remembered that when common drills are required to be very acute, the -edges should be thrown up a little or hollowed out so as to give the -acuteness on the upper face as explained above.<a name="FNanchor_26_26" id="FNanchor_26_26"></a><a href="#Footnote_26_26" class="fnanchor">[26]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_26_26" id="Footnote_26_26"></a><a href="#FNanchor_26_26"><span class="label">[26]</span></a> The common form of drill is rendered far more efficient -with wrought iron and materials that require <i>cutting</i>, by twisting -the flat shaft when hot, so as to reverse the position of each edge -after the manner of a screw-auger. The lower faces can then be kept as -close as possible to the face of the work while the twist will give a -moderate degree of acuteness on the upper face.</p></div> - -<p>Hand-turning is simply a matter of manual dexterity, and as any -part of the same plane or the same circumference presents the same -surface to the edge of the tool, the correct relation between the -edge<span class="pagenum"><a name="Page_257" id="Page_257">[257]</a></span> and the surface can be obtained in many places, and therefore -the particular point at which the edge should be applied is simply -a matter of personal convenience, and may vary with the height of -the lathe or that of the workman, or the shape and nature of the -tool employed. The use of the graver affords a good illustration of -this; and it may be remarked, in connection with this tool, that none -is more simple in construction, more perfect in principle, or more -convenient in application. When its use is once thoroughly mastered -it will do anything from smoothing a pin to roughing out a cylinder -four or five inches in diameter. The graver is simply a square bar of -steel ground off obliquely at the end; and by varying the obliquity of -this slope the act of grinding one plane face will give two cutting -edges of any desired acuteness, and three heels from which to use -these edges at choice. In hand-turning only one edge of the graver -is used at a time, and the lozenge-shaped face is made the lower -face common to each edge. Now, when the graver is used for roughing, -the point is generally buried in the clean metal <i>below</i> the central -line of the work, and the lower face is placed against, and takes the -shaving from, the little shoulder which it forms on the cylinder. When -the graver is used for smoothing, the lower face is placed nearly -flat against the face of the work, and the edge is generally made to -bite on, or a <i>little above</i>, the central line. But for very light -finishing cuts the graver may be used from the heel at the bottom of -its lozenge face, and in this position its point is over the top of -the work, bringing the biting part of the edge <i>still more above</i> -the central line. Thus, the only three points to consider in placing -the tool in hand-turning are—first, that the lower face of the -edge should occupy the proper position with regard to the surface; -secondly, that the handle of the tool should come up conveniently -to the hands of the operator; and thirdly, that while these two -conditions are observed, the heel of the tool should be able to take a -firm bearing on the rest.</p> - -<p>The best rule for hand-turning is, therefore, to apply the tool to -the work, with these ends in view before fixing the rest, and then to -bring that up to the necessary position.</p> - -<p>When the heel of any hand tool has a firm bearing on the rest, and the -edge is applied in the wedge-like position, the preservation of this -during the progress of the work depends on delicacy of touch rather -than muscular power. But when the edges are applied out of their -natural line, it puzzles a strong wrist to keep them to their cut at -all without digging into the work. This affords the best practical -illustration of the necessity of careful attention to the position of -slide-rest tools, which are deprived of all power of accommodation to -the sense of touch, and which therefore require accurate adjustment in -the first instance.</p> - -<p><span class="pagenum"><a name="Page_258" id="Page_258">[258]</a></span></p> - -<p>For the motion of the tool is now confined to that of the rest, and -as this moves in horizontal planes, the edge of the tool must be -applied to the work on that parallel plane which passes through the -lathe centres. The reason for this rule will be at once apparent, if -the edge be not placed on this central line in facing up a plate—for -then it will lose its cut before reaching the centre, leaving a core -untouched. Now although it would require an exaggerated error in the -position of the edge to lose cut altogether in turning a cylinder, yet -this example proves that, unless the edge be applied exactly on the -central line the relative position between it and the surface of the -work, on which the cutting action depends, will imperceptibly change -with the reduction of the work; and supposing this to vary much in -diameter, the same tool may cut beautifully on one part and badly on -another. <a href="#i-p261s">Fig. 4</a>, which illustrates the cutting action of the edge, -has been purposely placed on a part of the circle where a slide-rest -tool could only act for a very short time, in order to draw attention -to the difference between those conditions which govern the cutting -action, and those which depend on the motion of the rest from which -the tool is used. It is obvious that if <a href="#i-p261s">Fig. 4</a> were moved inwards on -a horizontal line the edge would pass over the smaller circle without -touching it. The illustration is of course exaggerated, but it proves -that <a href="#i-p254s">Fig. 7</a> is the only position in which the tool will cut over -varying diameters without some change in the relative positions of its -lower face and that of the work. Hence the usual instructions to apply -the edge about the centre of the work. But Babbage has observed, that -however good this direction may be as far it goes, it is insufficient -and liable to mislead when given alone. It is impossible to do away -with elasticity when the tool is supported at some lateral distance -from the line of strain, as in the slide rest or planing machine; and -unless this elasticity is counteracted by the position of the tool, it -may upset the best position of the edge. To meet this, Babbage gives -the following rule—First, consider whereabouts the tool itself will -bend under strain on its edge, when fixed in the rest; and then take -care that this part of the tool, which Babbage calls "the centre of -flexure,"—is placed above a line joining the centre of the work and -the edge of the tool. <a href="#i-p254s">Fig. 7</a> will explain the reasons for this rule -and the consequences of neglecting it when there is much strain put on -the edge.</p> - -<p>Let <a href="#i-p254s">E, I, F,</a> be the line joining the centre of the work and the edge -of the tool. Then if G above this line be the centre of flexure, -when the tool bends its edge must follow some part of the arc, H, I, J, -from G as a centre, and will be thrown out of the work. But if K -below the line, E, I, F, be the centre of flexure, then, under the -same circumstances, the edge will follow some part of the arc L, I, M, -from K as a centre, and must dig into the work. It is <span class="pagenum"><a name="Page_259" id="Page_259">[259]</a></span>important -to recognise this principle, because while it shows that every tool -in which the top of the edge stands <i>above</i> the shaft must be liable -to the evils resulting from elasticity, it shows also that even -cranked tools may fail to obviate the danger, unless care is taken to -place the weakest point in the shaft above the central line. Babbage -remarks, that although it is not always possible to strengthen any -part of a tool, it is always possible and sometimes desirable to make -some particular point weaker than the rest, by cutting away a little -where the weak point should be. <a href="#i-p259">Fig. 9</a> shows that the crank principle -may be applied in another form, and although the crank is upwards in -this case, the same object is attained by making P the weakest point, -and placing it above the central line, N, O. This form, however, is -only used for light finishing cuts; for any unnecessary length of -crank evidently adds elasticity, and Holtzapffel observes that, "in -adopting the crank form tools the principle must not be carried to -excess, as it must be remembered we can never expunge elasticity from -our materials, whether viewed in relation to the machine, the tool, -or the work." The crank, therefore, should only be just sufficient -to give the edge the right direction if the tool should spring; and -Holtzapffel remarks, that as a tool will generally bend somewhere in -the central line of its shaft, it is sufficient if the top of the edge -is kept on or just below this line, as in <a href="#i-p259">Fig. 8</a>. Referring again -to <a href="#i-p254s">Fig. 7</a>, and looking at the line C, D, as a plane surface, and I, -F, as a line perpendicular to that surface, the same arguments and -illustrations apply to the form of a tool in the planing machine. The -point at which the tool is now applied ceases to be of moment.</p> - -<div class="figcenter" id="i-p259" style="width:450px;"> - <img - class="p0" - src="images/i-p259.png" - width="450" - height="206" - alt="" /> - <p class="center smcap">Illustration No. 3.(8, 9)</p> - </div> - -<p>Having considered the conditions necessary to insure the best cutting -action of acute edges and the preservation of that action during the -progress of the work, it remains to treat of the edges most suitable -to particular materials, the method of giving them any desired angle, -and the manner of applying slide-rest tools so as to obtain the best -work with the least expenditure of force and time.</p> - -<p>Willis observes that different metals and qualities of the same -metal require to be treated with edges differing in their degree -of acuteness, and all the standard authorities concur in giving -the following code as near enough for all practical purposes. The -<span class="pagenum"><a name="Page_260" id="Page_260">[260]</a></span>modification of these angles is ruled by the general principle -that fibrous and cohesive materials require more acute edges than -crystalline and granular substances, as will be apparent in the -following code:—</p> - -<table summary=""> - <tr> - <td class="left">Wrought iron and steel</td> - <td class="tab1">60°</td> - </tr> - <tr> - <td class="left">Cast do. do. </td> - <td class="tab1">70°</td> - </tr> - <tr> - <td class="left">Roughing brass</td> - <td class="tab1">80°</td> - </tr> - <tr> - <td class="left">Finishing do.</td> - <td class="tab1">90°</td> - </tr> -</table> - -<p>Thus the edges available for the metals commonly treated in the lathe -find their maximum at 90° and minimum at 60°. The maximum requires no -explanation, as when any edge is larger it ceases to be an acute edge.</p> - -<p>With regard to the minimum of 60°, Babbage has pointed out that this -is dependent not only on the strength necessary to resist the strain -of the cut, but further and chiefly on the temper which must be -preserved in the edge; and if this be less than 60° the mass of metal -composing the extreme edge will be too small to carry off the heat -generated by the cut, consequently the extreme edge would soon lose -temper and become useless.</p> - -<p>But these different edges are formed in very different ways according -to the purpose for which the tool is intended; and this will be best -understood by comparing the action of a hand-turning chisel with that -of a pointed slide-rest tool. In the first case the edge is applied at -an oblique tangent to the surface, and removes the shaving by passing -under its whole width, much after the manner in which an apple is -pared, or a ribbon unwound from a stick, when the lower edge of one -turn just overlaps the top edge of the turn below it, and so on. In -this case the shaving can be cleanly detached by one straight edge. -But the position and motion of the slide-rest tool being perpendicular -to the axis of the work, its action becomes that of uncoiling rather -than paring; and as a cord or wire wound round a stick touches the -face of the stick in one direction, and the coil next to itself in -another, so in this case the width and thickness of the shaving lie -in opposite directions, as illustrated by the dark band in <a href="#i-p261s">Fig. 10</a>. -Consequently, unless the shaving be cut simultaneously in these two -directions—viz., from the face of the work on one side, and from -the matter under removal on the other, it is obvious that it must be -<i>torn</i> from the work in one direction, thus increasing the labour and -spoiling the appearance of the work if the tearing should be from its -face. Now, in practice, at any rate in the rough cut, it is usual to -take the width of the shaving from the superfluous matter; and if the -tool be placed, as in <a href="#i-p261s">Fig. 11</a>, it can only cut on one edge; thus the -edge of the shaving will be torn from the face of the work, while the -point of the tool will trace a fine thread in its progress along it, -leaving the face with a rough unfinished appearance.</p> - -<p><span class="pagenum"><a name="Page_261" id="Page_261">[261]</a></span></p> - -<p>But if the edges be formed so that they can be placed as in Figs. <a href="#i-p261s">10 and 12</a>, -then both can cut simultaneously, and the screw-like trace -of the point may be obliterated. This method of using the tool will -leave the work with a good face from the first rough cut, leaving -very little for the finishing cut to do; in addition to which the -labour will be reduced to a minimum, thereby permitting a much heavier -cut from the same amount of force. In turning any plane surface the -corner of the edge should be sufficiently relieved from it to avoid -the danger of catching; but, in turning cylindrical surfaces, if the -tool be carefully made and placed, the slope of the upper surface -will carry the corner out of cut. Experiment must decide the exact -adjustment; but the great aim should be to keep the face of the tool -next the work as nearly parallel with it as possible, because it is -only that face which leaves any trace of the tool's action on the face -of the work—the action of the other edge being lost with the shaving.</p> - -<div class="figcenter" id="i-p261s" style="width:450px;"> - <img - class="p0" - src="images/i-p261s.png" - width="450" - height="299" - alt="" /> - <p class="center smcap">Illustration No. 4.(10, 11, 12)</p> - </div> - -<p>Thus tools may be broadly divided into two classes—viz., single-edged -and double-edged—remembering always that this distinction refers -to the manner in which they should act, and not to the number of -edges which it may be convenient to form on the same tool. In -single-edged tools, whether there be one or many edges, each edge acts -independently in removing its own shaving, and may therefore be formed -separately. In this case a longitudinal section, showing the angle of -the point, will give a true idea of that of the cutting edge. But, in -the case of double-edged tools, as the two edges should co-operate in -the removal of the same shaving, they must also be formed so that, -while each lower face can occupy its proper position with regard to -that surface of the work opposed to it, both edges shall possess -the same degree of acuteness. In this case the two edges are formed -by three planes—viz., two side faces and one upper surface common -to both; and the angle of the point is now not only not that of the -cutting edges, but has not even any fixed relation to them, for the -cutting edges may vary some 25° or more on the very same longitudinal -section of the point.</p> - -<p><span class="pagenum"><a name="Page_262" id="Page_262">[262]</a></span></p> - -<p>Prof. Willis has pointed out that in these tools the angles of the -cutting edges depend on the <i>section</i> and <i>plan</i> angles of the point -<i>conjointly</i> (<a href="#i-p259">Fig. 8</a> is a <i>section</i> view; <a href="#i-p261s">Figs. 10, 11 and 12</a> are -<i>plan</i> views). From this it follows that cutting edges of exactly the -same angle may be obtained by a great variety of combinations in the -plan and section angles; and in note A, U, of Holtzapffel's work, -vol. ii. p. 994, Prof. Willis has given a table, showing some of the -different combinations by which cutting edges of certain angles may be -produced with accuracy and simplicity. The following short table is -arranged from this source and though much abbreviated will be found -sufficient for all ordinary purposes.</p> - -<div class="figcenter" id="i-p262" style="width:450px;"> - <img - class="p0" - src="images/i-p262.png" - width="600" - height="423" - alt="" /> - </div> - - <p class="center">PLAN ANGLE WITH SECTION ANGLES</p> - -<table summary=""> - - <tr> - <td class="ctr1">140°</td> - <td class="tab8b ctr">79.5°</td> - <td class="tab8b ctr">69°</td> - <td class="tab8c ctr">58°</td> - </tr> - <tr> - <td class="ctr1">120°</td> - <td class="tab8 ctr">78.5</td> - <td class="tab8 ctr">67</td> - <td class="tab8e ctr">55</td> - </tr> - <tr> - <td class="ctr1">100°</td> - <td class="tab8 ctr">77</td> - <td class="tab8 ctr">63.5</td> - <td class="tab8e ctr">49.5</td> - </tr> - <tr> - <td class="ctr1">90°</td> - <td class="tab8 ctr">76</td> - <td class="tab8 ctr">61</td> - <td class="tab8e ctr">45</td> - </tr> - <tr> - <td class="ctr1">70°</td> - <td class="tab8a ctr">72.5</td> - <td class="tab8a ctr">53.5</td> - <td class="tab8d ctr">29</td> - </tr> - <tr> - <td colspan="4" class="footer">WILL GIVE ——— CUTTING EDGES</td> - </tr> - <tr> - <td class="ctr1"></td> - <td class="tab8f ctr">80°</td> - <td class="tab8f ctr">70°</td> - <td class="tab8f ctr">60°</td> - </tr> - -</table> - -<p class="p2">The graver will again serve to illustrate the use of this table; -for although only one edge is employed at the same time in hand -turning, it belongs properly to the double edged class. This will be -very apparent if a graver is held point upwards side by side with a -point tool, and the dotted lines are added in <a href="#i-p259">Fig. 8</a>, to make the -similarity of form more evident. Now Holtzapffel has said of the -graver when employed for its original purpose of engraving, that "no -instrument works more perfectly," pointing out that, while both the -edges are engaged in cutting the same shaving, both the lower faces -of the edges are respectively inclined at the smallest possible -angle from the sides of the <span class="sans">V</span>-shaped groove. <a href="#i-p261s">Fig. 10</a> has already -been used to illustrate the best position of the slide-rest tool,<span class="pagenum"><a name="Page_263" id="Page_263">[263]</a></span> -and if the illustration be turned round until the letters Q, R, read -horizontally, and this line be taken to represent a flat surface -with the graver acting upon it, it will be seen that the shaving is -removed in exactly the same manner in both cases; the only difference -being that the section of the shaving is triangular in one case and -rectangular in the other. But so far as the tool is concerned the -action is identical in each case, thus proving that every point -tool may be so made and placed as to merit Holtzapffel's eulogium -on the graver, and that this simple tool is in fact the type of all -double-edged tools.</p> - -<p>The graver being made from a square bar has of course a plan angle of -90°, and using it to illustrate the table, we will suppose that it is -desired to give it two cutting edges of 60° each. Referring to 90° -under the heading of "plan angle," 45° will be found on this line in -the column over "cutting edge" 60°; denoting that the section angle of -the point, <i>i.e.</i>, the slope at which the graver is ground, must be -45° to give the desired edges. In the same way, if the section angle -were 61° the cutting edges would be 70°. But taking the plan angle of -120°, the table shows that this would produce the same cutting edges -of 60° with the larger section of 55°; and from this we have the -important rule that, <i>in obtaining cutting edges of any given degree -of acuteness the larger the plan angle is made, the larger also may -be the section angle</i>. Thus pointed tools though constructed on the -principle of the graver are an improvement on it in its simple form; -for by making both plan and section angles as wide as possible, it is -obvious that the strength and durability of the point will be much -increased. It is, therefore, always better to give slide-rest tools -a large plan angle, as in <a href="#i-p261s">Fig. 12</a>; and plan 120°, with section 55°, -will be found a very useful and durable tool for surfacing purposes -with wrought iron. When there are rectangular corners to cut in and -out of, of course the plan angle cannot be more than 90°, and then -it is well to sacrifice a little of the acuteness, as the section of -45° makes the point rather too weak. It is also worthy of remark as -a mathematical fact, that unless the plan angle exceed 60°, it is -impossible to obtain two cutting edges of that degree of acuteness; -and in any case, such a plan angle would be radically bad, because it -could not be used on the double-edged principle without <i>undercutting</i> -the shaving. It is somewhat remarkable, in connection with this point, -that while Holtzapffel, vol. ii. p. 536, recommends prismatic cutters, -he should add a footnote which indirectly but most conclusively -corroborates Prof. Willis' condemnation of that particular form, by -admitting that the proper degree of acuteness cannot be given to both -edges.</p> - -<p>As the practical result of a circular edge is to cut in two opposite -directions,—the edge passing gradually from one to the other,—so<span class="pagenum"><a name="Page_264" id="Page_264">[264]</a></span> -round-nosed tools belong properly to the double-edged class, and are -open to great objections unless carefully formed on this principle.</p> - -<div class="figcenter" id="i-p264" style="width:450px;"> - <img - class="p0" - src="images/i-p264.png" - width="450" - height="199" - alt="" /> - <p class="center smcap">Illustration No. 5.(13, 14)</p> - </div> - -<p>This is illustrated in <a href="#i-p264">Fig. 13</a>, representing an oblique section of a -round bar; and supposing the section to be made at an angle of 45°, -it is obvious that the highest part of the edge at S will be exactly -of this angle, while the lower point at T will be 135°, and the side -points at U and V will be 90° each. Thus, between the point S and the -points U and V on each side respectively, the edge will gradually pass -through a range of 45°, consequently no two adjacent points on the -same side will be of the same angle, and the highest point S may be -too acute to stand while the lowest, U or V, is too blunt to cut.</p> - -<p>Whenever, therefore, it is intended to round the nose of the tool, it -should be first formed as a double-edged point tool, with a section -angle agreeing as nearly as practicable with the intended degree of -acuteness in the edge, so as to secure the highest points from being -too weak, and the table given above will show what plan angle must be -used, in combination with this section, to secure any part from being -too blunt.</p> - -<p>Thus, supposing a circular edge of about 60° is desired, the section -of 58° approaches this most nearly, and if the plan of 140°, which, -with this section, gives two straight cutting edges of 60°, be -adopted, there can only be a variation of 2° in different parts of the -edge. But it will be observed that this combination admits of very -little rounding; and although less acute edges, being obtainable with -a smaller plan-angle, admit of rather more rounding, it may be taken -as a general rule that when any tool is much rounded on the nose, so -as to present a large segment of a circle, different parts of the edge -must vary considerably in acuteness. Although Professor Willis objects -to rounding the nose of a tool at all on account of the necessary -variation in the character of the edge and some other reasons, I -am disposed to think that when the tool is carefully formed on the -principles given above, it is very advantageous to round off the point -slightly for taking heavy cuts; and I have found this form a favourite -one in such workshops as Woolwich Arsenal and Portsmouth Dockyard. But -care must be taken to place the nose of the tool towards the width -of the shaving (presuming that this is taken<span class="pagenum"><a name="Page_265" id="Page_265">[265]</a></span> from the matter to be -removed, as it usually is,) for unless the edge is straight, and -almost parallel with the face of the work as it leaves it, the face -would be marked with a series of concave grooves of greater or less -width, according to the feed given to the tool; and even when this is -very slow, if the curved part of the edge were placed towards the face -of the work it would present the appearance of corrugated iron, when -examined under a magnifying lens. Willis further advances against the -round nose that, as the shaving removed by it must be of a curvilinear -section, it will oppose more force in rolling itself off the edge, -than a flat shaving. This would be quite true if a flat shaving could -be rolled up on itself like a piece of tape or ribbon; but I think the -professor has overlooked the fact that when two cutting edges have one -common upper face the shaving must be bent laterally as well as in its -length; and I am disposed to think, from practical experiment, that -there is very little difference on the point of the force required, -and that when a point of large plan angle is just rounded off it -stands better and cuts sweeter than when the point is not so rounded. -But this only applies to heavy cuts, and for ordinary surfacing work -nothing can act more perfectly than a point tool of wide plan-angle -placed as described above. If a double-edged tool, with edges of 60°, -be thus used in turning wrought iron or steel, and be well lubricated -with clean water during the progress of the work, its face may be left -with a burnished brilliancy that a touch of the finest emery would -spoil. But, as the scheme of this paper is confined to the principles -which determine the action of edges, and the rules by which those -edges may be formed with certainty, it will be well to conclude these -remarks with a few hints as to the construction of ordinary slide-rest -tools. Bearing in mind that all double-edged tools belong to the -graver class, it is well to form the side faces carefully in the first -instance, and then never to alter these, but to keep the tool in order -by grinding in the upper surface only, just as the graver is treated. -Nasmyth's cone gauge, illustrated in Holtzapffel, vol. ii., p. 534, -and also in "Baker's Mechanism," p. 236, affords a ready means of -forming the side faces with accuracy. But the range and convenience -of this gauge is much increased by dispensing with every part of the -arrangement, except the cone itself. This can be made of any piece -of stout metal bar turned truly, with the slide-rest set at an angle -of 3°, and the base should be broad enough to stand steady by itself -when squared off truly in the lathe, as in <a href="#i-p264">Fig. 14</a>. Two marks can -then be made upon it: one as at W, showing the exact height of the -lathe-centre when the cone stands on the bed of the lathe, and another -as at X, showing the height of the centre when the cone is placed on -any given part of the slide-rest. Thus, in whatever direction the tool -is to be used, its adjust<span class="pagenum"><a name="Page_266" id="Page_266">[266]</a></span>ment can be accurately made in the first -instance on the slide-rest itself, and again tested after the tool is -clamped down.</p> - -<p>It is too common a practice in setting slide-rest tools to wedge up -one end or the other, with regard only to the application of the edge -on the central line. But this generally sacrifices the position of the -lower faces, which is essential, to a consideration which has been -shown to be only secondary. The best plan is to keep several strips, -varying from <sup>1</sup>/<sub>32</sub> to ½ inch in thickness, but all about as long and -wide as the shaft of the tool. These can be made of bar iron for the -thicker strips, and sheet iron or tin for the thinner ones; and by -using any two or three of these together, the tool can be packed up -parallel to the bed of the slide-rest. The adjustment of the edge can -thus be made with the greatest ease and certainty without altering the -relative position of the lower faces.</p> - -<p>It may be well to remark that in using the cone gauge, it is the lower -faces of each edge which are to be tried against it, and not the front -line of the point, as the inclination of this rule will vary slightly -with variations in the plan-angle of the tool, although the slope of -the faces remains the same. But the section angle is always to be -estimated from the front line, whatever its slope may be.</p> - -<div class="figcenter" id="i-p266" style="width:344px;"> - <img - class="p0" - src="images/i-p266.png" - width="344" - height="258" - alt="" /> - <p class="center smcap">Illustration No. 6.(15, 16)</p> - </div> - -<p>When the principles which this paper has endeavoured to embody are -once thoroughly understood, no handy workmen need ever be at a loss -to form and apply his edges with the best effect under any shape the -circumstances may require. The first point to be observed is the -manner in which the work should be attacked—that is to say, whether -the removal of the shaving or scraping requires the use of a single or -double-edged tool. The next point is the position of the lower face -or faces of the edges, so that they may be applied in the required -direction, and in the position explained above. This involves the -nature of the treatment best suited to the material, both as regards -the kind of edge employed and the principle on which it should be -applied—viz., cutting or scraping. In double-edged tools the position -of the two lower faces determines that of the point, which is simply -an accident resulting from the meeting of the cutting edges; but -which, when so determined, affords a guide for the slope of the upper -face. This must be so ground that it gives each edge the same degree -of acuteness. Thus, in <a href="#i-p266">Fig. 15</a>,<span class="pagenum"><a name="Page_267" id="Page_267">[267]</a></span> the point of the tool being at A, the -slope must be made in the direction A, B; while, in <a href="#i-p266">Fig. 16</a>, the point -being at C, the slope of the upper face must be in the direction C, D.</p> - -<p>The writer is fully aware that those who expect to find "a rule of -thumb" in this paper, will be miserably disappointed. But while he -is conscious that the principles of which he has treated admit of -a much fuller and yet more concise definition, he would remind the -novice that there is "no royal road to learning," and that where -practice of hand is wanting it can only be supplied by greater -knowledge of principle. His object will therefore be fulfilled if -this supplementary paper can supply any explanation or illustration -of principle that may add to the practical utility of a work so -exhaustive of its subject as "the Lathe and its Uses."</p> - - -<h3 class="sc"><a name="DETACHED_CUTTER" id="DETACHED_CUTTER">Detached-cutter Holders.</a></h3> - -<p>Where amateurs experience inconvenience in making their tools from -the want of a forge, the use of detached cutters in a tool holder -will be found of the greatest advantage for outside work. Even in -plain turning there must always be some special forms for cutting -into odd corners and deep grooves; but with a good tool holder and -a grindstone, which is an indispensable piece of furniture in every -metal turner's shop, the cumbrous array of slide-rest tools may be -reduced to a few special forms and a very small box of cutters. These -also possess another great advantage; for the spirit of the old adage -quoted by Holtzapffel—</p> - -<div class="poetry-container"> - -<div class="poetry"> - -<div class="stanza"> -<div>"He that would a good edge win</div> -<div class="ih">Must forge thick and grind thin,"</div> -</div></div> -</div> - -<p>may be carried out far more conveniently than in the case of whole -tools which are generally filed into shape before tempering, and when -worn down must go to the fire again and have the process repeated. But -the detached cutter admits of being tempered evenly throughout its -whole length and ground up afterwards as long as it lasts, without -going to the forge again to the deterioration of the steel.</p> - -<p>The patterns of tool-holders are innumerable, but very few are good -for general service, because most of them are arranged so that the -natural sides of the cutter are used for the face or faces of the -edge. Thus either the plan angle of the point is limited to the angles -presented by the transverse section of the cutter employed, or else -the section angle is fixed by the position in which the cutter is -clamped. Holtzapffel's arrangement is open to the first objection, -Babbage's to the second. To obviate this inconvenience, Prof. Willis -arranged a holder which clamps the cutter at an angle of 55°<span class="pagenum"><a name="Page_268" id="Page_268">[268]</a></span> from -the horizontal line. Thus no side can be used either for the lower or -upper face of the edge, but any faces can be ground upon it; and the -plan and section angle of the edge may be varied at pleasure within -the whole range available for metal turning. Prof. Willis's holder -for the cutter is almost a facsimile of his admirable tool-holder for -the slide-rest, than which none is more convenient or can act more -perfectly. But the arrangement is a little complicated for a cutter -holder, and must be very carefully made with the knowledge of certain -laws, if it is to insure a perfect grip of the cutter. It is also -designed for the use of sound wire cutters which require filing flat -on one side.</p> - -<div class="figcenter" id="i-p268s" style="width:500px;"> - <img - class="p0" - src="images/i-p268s.png" - width="500" - height="489" - alt="" /> - </div> - -<p>Adopting Willis's inclination for the cutter I have found that all its -advantages may be secured with a simpler form of holder and common -square for steel for the cutter. The holder is simply the modification -of an old pattern to suit the inclination of 55°, and the sketch needs -little explanation beyond saying that the nick in the solid part -should be rather less than a square angle, and made perfectly true all -the way down, or, if anything, rather hollowed in the middle, so as -to insure the greatest amount of pressure at the top and bottom, as -otherwise the cutter might not sit quite true and firm. The angle at -the end of the strap against which the cutter bears should be rather -<i>more</i> than square, both to allow for any want of exact truth in the -squaring of the cutter and to avoid the wedging action which would be -set up on tightening the screw if this angle were <i>less</i> than square, -as this could of course create a risk of splitting the strap. The end -of the screw and the cup in which it fits should be round, as this -allows of a little play and insures a truer grip in the strap<span class="pagenum"><a name="Page_269" id="Page_269">[269]</a></span> than a -pointed screw working into a conical hole. A perspective sketch of a -detached cutter is added, with dotted lines to show how exactly the -arrangement of the faces can be accommodated to the positions which -have been shown to be the best in solid tools for the slide-rest.</p> - -<p class="right" style="margin-right: 5%"><span class="smcap">D. Haydon.</span></p> - - -<h3 class="sc"><a name="TAYLOR" id="TAYLOR">New form of Rose Engine by E. Taylor.</a></h3> - -<p>Seeing that the Editor of the above Articles has illustrated and -described Holtzapffel and Co.'s Rose Cutter and two methods of -executing rose cutting, the latter being the ordinary rose engine, I -am induced to send you a description of a method that I have adopted -whereby I can with considerable despatch execute this description of -turning.</p> - -<p>I will first preface my description by saying some thirty years ago -I purchased Ibbetson's Book on eccentric turning, and I was so much -taken with it and the illustrations, that I determined to make myself -in accordance with his description and engravings an eccentric chuck; -and although I was a long time about it, being at the time much -otherwise engaged, I succeeded beyond my expectations, and was enabled -to do some very fine work with it; and I have never regretted the time -I spent over the chuck, as I became familiar with metal turning and -screw cutting <i>flying</i> in the lathe, which latter I was surprised to -find how easily I could execute. However, I was much disappointed in -the usefulness of the chuck (Holtzapffel's eccentric cutter, which I -purchased is far more useful), and also with the tediousness of using -it (fancy stopping the lathe to alter the chuck 360 times or 180 times -to cut a row of circles either distinct or overlaying each other), -and there was also a certain vibration occasioned in using the chuck -which I also disliked. I therefore determined to cut up some rosettes -and convert my headstock into a rose engine, to effect which object -I got Holtzapffel and Co. to return up with a new steel collar and -make my mandrel traversing. I cut myself a rosette both ways with -16 waves, and I was much pleased with the variety of work I could -perform with this one, but the rosette took me a long time to make, -and disheartened me from cutting up a variety. It, however, occurred -to me that if I added an extra mandrel by the side of and attached to -my headstock, and on which extra mandrel, if I had an eccentric chuck -connected with a rod to the wall of my room, I could get my headstock -to oscillate, and by connecting and multiplying wheels cause as many -waves on each revolution of my principal mandrel I pleased; this after -much time and patience I succeeded in doing, and worked it with the -hand motion often adopted for rose work. After between<span class="pagenum"><a name="Page_270" id="Page_270">[270]</a></span> two and three -years, I put the extra mandrel over my principal mandrel instead of by -the side as before, to enable me to dispense with the hand motion and -to work the upper mandrel with the slow motion on my lathe wheel, and -which I found a very great improvement, and I now give the details of -the plan I have adopted for the benefit of your numerous readers.</p> - -<p>The drawings are to a two-inch scale, or one sixth of their full size.</p> - -<div class="figcenter" id="i-f270as" style="width:574px;"> - <img - class="p0" - src="images/i-f270as.png" - width="574" - height="600" - alt="" /> - <p class="center smcap">Fig. 400.</p> - </div> - -<p><a href="#i-f270as">Fig. 400</a> is a side view of my headstock (part in section) with the -upper mandrel, A, added, showing the connection by an intermediate -spindle, B, with the large cog wheel, C, on my lower mandrel, D, and -other additions.</p> - -<p>The back centre, E, of my headstock is connected with the back screw, -F, and drawn out or pushed in with it, and is fixed by the set screw, -G. When drawn out the steel screw, H, at the end of the mandrel, D, -removes to receive the screw guides which are then fastened by it, and -the piece, I, with segments of a thread to match the guides, is slid -up by a wedge to the guides and then fastened by the screw J, I, can -also fix some roses cut on the side, and other apparatus with this -screw H.<a name="FNanchor_27_27" id="FNanchor_27_27"></a><a href="#Footnote_27_27" class="fnanchor">[27]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_27_27" id="Footnote_27_27"></a><a href="#FNanchor_27_27"><span class="label">[27]</span></a> It is not a good plan to make the point, E, movable. It -would be better to slip the guides or rosettes over it: and generally -to arrange this part as usual with a traversing mandrel, P, H.</p></div> - -<p>The large cog wheel, C, is screwed up with the screw, K, to the -mandrel pulley, L. On the front of the pulley is the division plate as -usual.</p> - -<p>The intermediate adjustable spindle, B, is carried in a frame shown -separately by <a href="#i-p273s">Fig. 405</a>; it is allowed to rise or fall as may be -required for the wheel, M, to gear with the great wheel, C; provision -being also made for an intermediate wheel, N, (see <a href="#i-p273s">Fig. 403</a>) to -connect the wheel, O, with the wheel, P, on the upper mandrel when -required.</p> - -<p>The eccentric chuck is fixed on screw Q of the upper mandrel.</p> - -<p><a href="#i-f270b">Fig. 401</a> is a plan of the mould for the back cast-iron upright, fixed -to the headstock with screws at the foot, showing the circular grooves -1, 2 and 3, necessary for the spindles for the connecting wheels; the -centre hole, 4, is for the gun-metal collar, or the upper mandrel.</p> - -<p><a href="#i-f270b">Fig. 402</a>, is a plan of the mould for the front cast-iron upright; the -centre holes 1 and 2 are for the collars of the mandrels. No. 2 is -made to just fit over the steel collar of the lower mandrel, and is -fixed to the headstock by a brass rose and three screws; it is also -fixed at the foot with two screws to the headstock.</p> - -<div class="figcenter" id="i-f270b" style="width:474px;"> - <img - class="p0" - src="images/i-f270b.png" - width="585" - height="550" - alt="" /> - <p class="center smcap">Figs. 401, 402.</p> - </div> - -<p>These two castings, 401 and 402, are bolted together with two bolts -and nuts through the holes 5 and 6, as shown in <a href="#i-f270as">Fig. 400</a>.<span class="pagenum"><a name="Page_271" id="Page_271">[271]</a></span> Fig. 403, -is a back view of the additions, showing the cog wheels and their -connections, also the brass bearings for the lower mandrel required -when allowed to traverse. This was a solid piece of brass with a hole<span class="pagenum"><a name="Page_272" id="Page_272">[272]</a></span> -bored out and ground to fit the mandrel. It was then drilled the whole -depth in two places, for two steel steady pins, <i>b</i>, <i>c</i>, made to fit -quite tight, and at both ends for bolts and nuts, <i>a</i>, <i>d</i>, afterwards -sawn in two with the circular saw, and when put together and two holes -drilled through the thickness for fixing it was put in its place, -adjusted, and re-ground on. The holes for fixing were very carefully -continued through the cast iron upright, and the whole was finally -fixed with two screw bolts and nuts.</p> - -<p><a href="#i-p273s">Fig. 404</a>, is a front view, showing the eccentric chuck, R, on the -upper mandrel, the slide of which when used is connected with the -bracket in the wall, <a href="#i-p273s">Fig. 406</a>, causing the whole apparatus to -oscillate in proportion to the eccentricity of the chuck on its -centres one of which is marked at S. The chuck has a circular movement -for laying the waves in any position with one another, but which also -is effected by another plan to be presently described. The whole -poppet with its fittings is hung on centres similar to the rose engine -described in this work. The top part of the bed T removes, and the two -screws, one shown at V, are taken out to allow the oscillation. The -large cog wheel has 192 teeth.</p> - -<div class="figcenter" id="i-p273s" style="width:419px;"> - <img - class="p0" - src="images/i-p273s.png" - width="419" - height="600" - alt="" /> - <p class="center smcap">Figs. 403, 404, 405, 406.</p> - </div> - -<p>The whole of the additions to my headstock were all of my own fitting -up. The brass cog wheels were bored out and ground to fit an arbor -made on purpose, exactly corresponding in diameter with the ends -of the spindles so that they might fit indiscriminately on either -spindle. When turned up, the teeth were cut with a circular cutter, -which I made just of the exact shape and thickness required for the -space between the teeth. The cutter was turned of steel; then wrapped -in leather and enclosed in sheet iron. It was then put in the fire, -made red hot, and left for the fire to go out, the next day being -soft, it was cut with sharp chisels into a circular file and hardened, -and with it in the cutter frame the teeth of the wheels were cut. The -central boss of each wheel has a notch cut across the face to receive -a pin in the arbor and in the spindles, which prevents the wheels from -turning round on the latter when screwed up.</p> - -<p>This rose engine works beautifully smooth and easy, and ornamentation -can be done with it with greater rapidity than with the ordinary -engine, by arranging the connecting wheels so that the upper mandrel -makes so many waves and one-half, one-third, one-fourth, one-fifth,<span class="pagenum"><a name="Page_273" id="Page_273">[273]</a></span> -one-sixth, or any other part of a wave, on each revolution of the -lower mandrel, because then it requires certain revolutions of the -lower mandrel before the tool comes into the same cut again—say,<span class="pagenum"><a name="Page_274" id="Page_274">[274]</a></span> -for instance, it makes 4<sup>5</sup>/<sub>6</sub> waves on each revolution, then it takes -29 revolutions of the upper mandrel to complete the pattern, whereby -certain patterns are completed without stopping the lathe, which is -an advantage that the rose engine proper does not possess. Another -great advantage is, that the waves can be either flat, sharp, or -intermediate, as required for large or small work, by altering the -eccentric chuck on the upper mandrel.</p> - -<p>I give a few specimens, not for the beauty of design, but to -illustrate the working of the engine. The centre of <a href="#i-p275a">Fig. 407</a> is -performed by having a wheel of 80 teeth on the upper mandrel, -connected with one of 25 teeth on the intermediate spindle, which has -another of 50 teeth connected with the large wheel of 192 teeth on -the lower mandrel; thus,</p> - -<table summary=""> - <tr> - <td>80</td> - <td></td> - <td></td> - </tr> - <tr> - <td>25</td> - <td>50</td> - <td>=1<sup>1</sup>/<sub>5</sub></td> - </tr> - <tr> - <td></td> - <td>190</td> - <td></td> - </tr> - -</table> - -<p class="left">producing on each revolution of the lower mandrel one wave, and -one-fifth of another wave, requiring six revolutions to complete the -pattern.</p> - -<div class="figcenter" id="i-p275a" style="width:332px;"> - <img - class="p0" - src="images/i-p275a.png" - width="332" - height="350" - alt="" /> - <p class="center smcap">Fig. 407.</p> - </div> - -<p>The remainder of the pattern is completed by wheels, 16, 50; 48, 192 -making 12½ waves on each revolution of the lower mandrel, requiring -25 waves to complete the pattern, and laying the waves over each -other, and with the slide rest movement of the tool.</p> - -<p><a href="#i-p275b">Fig. 408</a> is produced by wheels 32, 48; 24, 192 making 12 waves. The -centre is done by altering the eccentric chuck each time. It was -purposely executed askew, by the tool not being placed in the centre, -to show the importance of doing so for some patterns. The rim was -executed with the same wheels, and with the slide rest movement of the -tool, and, after two cuts, the chuck turned half round, to lay the -waves over each other for the other two cuts.</p> - -<div class="figcenter" id="i-p275b" style="width:316px;"> - <img - class="p0" - src="images/i-p275b.png" - width="316" - height="350" - alt="" /> - <p class="center smcap">Fig. 408.</p> - </div> - -<p><a href="#i-p275c">Fig. 409</a> is all executed with wheels 96, 30; 25, 192 making two -waves and two-fifths of another wave, requiring 12 waves to complete -the pattern. The two centre rims produced by placing the tool above -the centre. The outside by four movements of the slide rest tool, -illustrating how soon patterns are produced, and when well cut up look -very pretty.</p> - -<div class="figcenter" id="i-p275c" style="width:339px;"> - <img - class="p0" - src="images/i-p275c.png" - width="339" - height="350" - alt="" /> - <p class="center smcap">Fig. 409.</p> - </div> - -<p><a href="#i-p275d">Fig. 410</a> is executed with wheels 80, 50; 25, 192 making four waves -and four-fifths of another wave, requiring 24 waves to complete the -pattern. The centre is all done without stopping; the outside rim by -altering the eccentric chuck four times, to make each successive wave -flatter.</p> - -<div class="figcenter" id="i-p275d" style="width:316px;"> - <img - class="p0" - src="images/i-p275d.png" - width="316" - height="350" - alt="" /> - <p class="center smcap">Fig. 410.</p> - </div> - -<p><a href="#i-p275e">Fig. 411</a> is an illustration of the upper mandrel, making 5⅓ -revolutions to one of the lathe, requiring 16 revolutions to complete -the pattern and slide-rest movement.</p> - -<div class="figcenter" id="i-p275e" style="width:327px;"> - <img - class="p0" - src="images/i-p275e.png" - width="327" - height="350" - alt="" /> - <p class="center smcap">Fig. 411.</p> - </div> - -<p><a href="#i-p275f">Fig. 412</a>. The outer pattern of this figure is produced by the upper -mandrel making 12⅘ revolutions to one of the lathe, requiring 64 -revolutions to complete the pattern. The centre is a rosette of 5 -waves, slide-rest movement and placed across each other.</p> - -<div class="figcenter" id="i-p275f" style="width:321px;"> - <img - class="p0" - src="images/i-p275f.png" - width="321" - height="350" - alt="" /> - <p class="center smcap">Fig. 412.</p> - </div> - -<p><span class="pagenum"><a name="Page_275" id="Page_275">[275]</a></span></p> - -<p><a href="#i-p277a">Fig. 413</a>. The whole of this pattern produced by the upper mandrel -making 3⅗ revolutions to one of the lathe, producing 18 waves<span class="pagenum"><a name="Page_276" id="Page_276">[276]</a></span> -across each other with slide-rest movement for the middle rim.</p> - -<div class="figcenter" id="i-p277a" style="width:338px;"> - <img - class="p0" - src="images/i-p277a.png" - width="338" - height="350" - alt="" /> - <p class="center smcap">Fig. 413.</p> - </div> - -<p><a href="#i-p277b">Fig. 414</a> illustrates a rosette of nine waves with slide-rest movement, -and 3 divisions of the circular movement of the eccentric chuck for -each successive line, producing the waved appearance.</p> - -<div class="figcenter" id="i-p277b" style="width:319px;"> - <img - class="p0" - src="images/i-p277b.png" - width="319" - height="350" - alt="" /> - <p class="center smcap">Fig. 414.</p> - </div> - -<p><a href="#i-p277c">Fig. 415</a> illustrates a rosette of 24 waves with the slide-rest -movement.</p> - -<div class="figcenter" id="i-p277c" style="width:317px;"> - <img - class="p0" - src="images/i-p277c.png" - width="317" - height="350" - alt="" /> - <p class="center smcap">Fig. 415.</p> - </div> - -<p><a href="#i-p277d">Fig. 416</a>. Another illustration of a rosette of 24 waves, rather more -sharp than in <a href="#i-p277c">Fig. 415</a>, with slide-rest movement and 9 divisions of -the circular movement of the eccentric chuck, giving it a pleasing -circular waved appearance.</p> - -<div class="figcenter" id="i-p277d" style="width:329px;"> - <img - class="p0" - src="images/i-p277d.png" - width="329" - height="350" - alt="" /> - <p class="center smcap">Fig. 416.</p> - </div> - -<p><a href="#i-p277e">Fig. 417</a>. Also another illustration as the last, but with the waves -much sharper, the slide-rest movement and only two divisions of the -circular movement of the eccentric chuck producing the star-like -pattern.</p> - -<div class="figcenter" id="i-p277e" style="width:330px;"> - <img - class="p0" - src="images/i-p277e.png" - width="330" - height="350" - alt="" /> - <p class="center smcap">Fig. 417.</p> - </div> - -<p><a href="#i-p277f">Fig. 418</a> illustrates also a rosette of 24 waves, with the eccentric -chuck turned half-way round with each movement of the slide-rest, -producing the pattern so often seen on the back of watches, only being -on wood it is on a larger scale.</p> - -<div class="figcenter" id="i-p277f" style="width:331px;"> - <img - class="p0" - src="images/i-p277f.png" - width="331" - height="350" - alt="" /> - <p class="center smcap">Fig. 418.</p> - </div> - -<p>The above illustrations are sufficient to give a distinct idea of the -working of my engine, and the last four show how easily patterns are -multiplied and varied.</p> - -<p>The whole of the preceding patterns were executed by the wood being -chucked in the lathe in the usual ordinary way without any particular -chuck whatever, but in combination with any of the ornamental chucks -innumerable patterns can be produced.</p> - -<p><a href="#i-p281a">Fig. 419</a> is one illustration with an eccentric chuck on the lathe -mandrel.</p> - -<div class="figcenter" id="i-p281a" style="width:343px;"> - <img - class="p0" - src="images/i-p281a.png" - width="343" - height="350" - alt="" /> - <p class="center smcap">Fig. 419.</p> - </div> - -<p>That my description may be complete I will now give drawings of my -eccentric chuck for the upper mandrel. It requires to be constructed -differently to the ordinary eccentric chuck, as the circular movement -requires to be always <i>central</i>, and only the slide carrying the pin -to receive the rod must move eccentrically.</p> - -<div class="figcenter" id="i-p279s" style="width:313px;"> - <img - class="p0" - src="images/i-p279s.png" - width="313" - height="600" - alt="" /> - <p class="center smcap">Fig. 420, also 422.</p> - </div> - -<hr class="r10" /> - -<div class="figcenter" id="i-p280s" style="width:332px;"> - <img - class="p0" - src="images/i-p280s.png" - width="332" - height="600" - alt="" /> - <p class="center smcap">Fig. 421, also 423.</p> - </div> - -<p>Figs. <a href="#i-p279s">420</a> and <a href="#i-p280s">421</a>, are full-size drawings of my eccentric chuck on my -upper mandrel, used for producing the foregoing specimens. In this -case I have preferred a wood foundation, as not being so likely to run -off as metal, on reversing the motion which is sometimes necessary -on account of idle wheels for the connections. I used a piece of -well-seasoned Spanish mahogany, taking care that the grain of the -wood was at right angles with the length of the screw of the mandrel. -A piece of brass is screwed at the back to prevent the screw cutting<span class="pagenum"><a name="Page_277" id="Page_277">[277]</a></span> -into the wood. <a href="#i-p279s">Fig. 420</a> is a section, and <a href="#i-p280s">Fig. 421</a> a front view of -the chuck, and I think all sufficiently clear. I will just say the -long fine threaded screw I cut up with the stocks and<span class="pagenum"><a name="Page_278" id="Page_278">[278]</a></span> dies in the -lathe, using steel wire of the necessary size. This I manage easily, -and keep the wire straight <i>by allowing it to expand in length</i>. I -chuck the steel wire concentrically, and removing the centre from the -back poppet, substitute a brass centre with a hole the size of the -steel wire, which is allowed about a quarter of an inch entry. I then -turn down a little below the depth of the intended screw thread for -about half an inch in length next the back centre, to allow the dies -to come back to be tightened up, and which must only be done at the -commencement and not on the return motion of the dies. The collar on -the screw is a piece of brass with a hole of a size to drive on the -wire tight, and is then pinned on and turned up true, and finished -with the division marks.</p> - - -<h3 class="sc"><a name="OVAL_TURNING_AND_ROSE_CUTTING" id="OVAL_TURNING_AND_ROSE_CUTTING">Oval Turning and Rose Cutting with Templates with my -Apparatus.</a></h3> - -<p>Figs. <a href="#i-p279s">422</a> and <a href="#i-p280s">423</a> are full size drawings of my chuck, with circular -movement for templates for my upper mandrel, which has also a wood -foundation. Fig. 422 is a section, and Fig. 423 is a front view.</p> - -<p>By removing the eccentric chuck from the upper mandrel, and -substituting the chuck Figs. 422 and 423 with a circular movement, -to receive templates of any pattern, <span class="smcap">ovals</span> with the oval -template can be turned and also with any irregular templates, patterns -cut and placed in any direction over each other, by causing the -templates to work against a rubber or roller as most desirable, with -an india-rubber spring to keep them together.</p> - -<p>The following illustrations will give some faint idea of productions -from templates.</p> - -<p><a href="#i-p281b">Fig. 424</a>, is the production of an oval template and slide-rest -movement, both mandrels making equal revolutions.</p> - -<div class="figcenter" id="i-p281b" style="width:319px;"> - <img - class="p0" - src="images/i-p281b.png" - width="319" - height="350" - alt="" /> - <p class="center smcap">Fig. 424.</p> - </div> - -<p><a href="#i-p281c">Fig. 425</a> the same as <a href="#i-p281b">Fig. 424</a>, with the patterns laid across each -other by turning the circular movement of the chuck 12 divisions.</p> - -<div class="figcenter" id="i-p281c" style="width:322px;"> - <img - class="p0" - src="images/i-p281c.png" - width="322" - height="350" - alt="" /> - <p class="center smcap">Fig. 425.</p> - </div> - -<p><a href="#i-p281d">Fig. 426</a>, is from an oval template, which is caused to make two -revolutions to one of the lathe mandrel producing 4 waves and -undulations and with the slide-rest movement. It will be perceived in -this case the form of the <i>oval</i> is superseded by another pattern, and -shows how great a change in the form of patterns from templates my -rose engine with change wheels effects.</p> - -<div class="figcenter" id="i-p281d" style="width:316px;"> - <img - class="p0" - src="images/i-p281d.png" - width="316" - height="350" - alt="" /> - <p class="center smcap">Fig. 426.</p> - </div> - -<p><a href="#i-p281e">Fig. 427</a>, is also from an oval template, caused to make 5 revolutions -to one of the lathe, and with the circular movement of the chuck -and the slide-rest movement, and in this case the form of the oval -is also superseded. Indeed, none but those who have made the matter -their study would have the slightest idea that this pattern could be -produced from an oval template.</p> - -<div class="figcenter" id="i-p281e" style="width:330px;"> - <img - class="p0" - src="images/i-p281e.png" - width="330" - height="350" - alt="" /> - <p class="center smcap">Fig. 427.</p> - </div> - -<p><span class="pagenum"><a name="Page_279" id="Page_279">[279]</a></span></p> - -<p><a href="#i-p281f">Fig. 428</a>, is also from an oval template, it is finer than 427, but is -done in the same way by the template making <i>nine</i> revolutions to one<span class="pagenum"><a name="Page_280" id="Page_280">[280]</a></span> -of the lathe mandrel.</p> - -<div class="figcenter" id="i-p281f" style="width:325px;"> - <img - class="p0" - src="images/i-p281f.png" - width="325" - height="350" - alt="" /> - <p class="center smcap">Fig. 428.</p> - </div> - -<p>The above are a few specimens of the oval, but sufficient to draw<span class="pagenum"><a name="Page_281" id="Page_281">[281]</a></span> -attention to the great variety of patterns that can be executed, -and these illustrations have only been made to go even revolutions -with the lathe mandrel; but of course can be made to go, as already<span class="pagenum"><a name="Page_282" id="Page_282">[282]</a></span> -described, uneven revolutions, laying the lines over each other for -variety of patterns.</p> - -<p><a href="#i-p283a">Fig. 429</a>, is a curiosity from a square template with equal -revolutions, the outside rim and inside pattern by the circular -movement of the template chuck.</p> - -<div class="figcenter" id="i-p283a" style="width:329px;"> - <img - class="p0" - src="images/i-p283a.png" - width="329" - height="350" - alt="" /> - <p class="center smcap">Fig. 429.</p> - </div> - -<p><a href="#i-p283b">Fig. 430</a>, is also from a square template made to go two revolutions to -one of the lathe and with the slide-rest movement. The centre pattern -with the circular movement of the chuck.</p> - -<div class="figcenter" id="i-p283b" style="width:329px;"> - <img - class="p0" - src="images/i-p283b.png" - width="311" - height="350" - alt="" /> - <p class="center smcap">Fig. 430.</p> - </div> - -<p><a href="#i-p283c">Fig. 431</a>, is the production of a heart-shape template, and with the -slide-rest movement and the patterns laid across each other, the -mandrels making equal revolutions.</p> - -<div class="figcenter" id="i-p283c" style="width:328px;"> - <img - class="p0" - src="images/i-p283c.png" - width="328" - height="350" - alt="" /> - <p class="center smcap">Fig. 431.</p> - </div> - -<p><a href="#i-p283d">Fig. 432</a>, is also from a heart-shape template made to go two -revolutions to one of the lathe and the slide-rest movement. But in -this case the slide-rest tool is used <i>on the opposite side of the -lathe bed</i> to the roller against the template, and therefore reversing -the pattern, that is, the projections of the pattern are the hollows -of the template, and <i>vice versa</i>. I have introduced it to show how -easily patterns are multiplied in the most simple way. It will also be -observed that the form of the template is superseded.</p> - -<div class="figcenter" id="i-p283d" style="width:336px;"> - <img - class="p0" - src="images/i-p283d.png" - width="336" - height="350" - alt="" /> - <p class="center smcap">Fig. 432.</p> - </div> - -<p><a href="#i-p283e">Fig. 433</a>, is another illustration of the heart-shape template, but -made to go five revolutions to one of the lathe, with the circular -movement of the template chuck, and the slide-rest movement, and in -which case the form of the template is entirely superseded.</p> - -<div class="figcenter" id="i-p283e" style="width:325px;"> - <img - class="p0" - src="images/i-p283e.png" - width="325" - height="350" - alt="" /> - <p class="center smcap">Fig. 433.</p> - </div> - -<p><a href="#i-p283f">Fig. 434</a>, is also a similar illustration to 433, only finer; they can -be of course as fine as desired.</p> - -<div class="figcenter" id="i-p283f" style="width:308px;"> - <img - class="p0" - src="images/i-p283f.png" - width="308" - height="350" - alt="" /> - <p class="center smcap">Fig. 434.</p> - </div> - -<p>The above are, I think, sufficient to illustrate the productions from -templates, some very pretty patterns can be executed. My object is -more particularly to exhibit the use and extended application of my -rose engine, and it will be perceived the last two are not the most -easily working templates.</p> - -<p>The variety of patterns that can be executed with this engine are -so innumerable that one may say they are infinite. Well may you in -your article quote what Bergeron says of the rose engine, "that it is<span class="pagenum"><a name="Page_283" id="Page_283">[283]</a></span> -necessary to know thoroughly the particular one in use."</p> - -<p>I also make use of the cogwheel on my mandrel, by connecting it by a -spindle and the change wheels with a large compound slide rest, for -executing spiral turning, and also with my slide rest for <span class="pagenum"><a name="Page_284" id="Page_284">[284]</a></span>ornamental -turning, for small spiral work; and with a chuck with a circular -movement I can cut several spirals to one stem.</p> - -<p>In concluding my description I will say the specimens given have all -been cut on a plain surface, and this has been unavoidable on account -of printing, but for the information of those unacquainted with the -rose engine, the very great advantages of which over the eccentric -and geometrical chucks are that the work can be executed on concave -or convex surfaces. I make use of mine for ornamenting the roofs of -temples and Chinese pagodas, either domed, curvilinear, or circular -pointed, by representing them covered with shingles, &c. The geometric -chuck will produce very beautiful intricate lacework, but not more so -than my apparatus, as they both are on the same principle of change -wheels, and can both produce equally fine work; but with my apparatus -the work is always concentric with the mandrel, and therefore much -more pleasing to execute.</p> - -<p class="right"><span class="smcap">Elias Taylor.</span></p> - -<p>Hartford Villa, Patcham, near Brighton, Sussex.</p> - - -<hr class="chap" /> - -<p class="center"><span class="smcap">Judd & glass, phœnix printing works, -doctors' commons, e.c.</span></p> - -<p><span class="pagenum"><a name="Page_285" id="Page_285">[285]</a></span></p> - -<p class="center xs p6">ADVERTISEMENTS.</p> - -<hr class="full" /> - -<p class="sm" style="margin-left: 10%">ESTABLISHED A.D. 1822.</p> - -<div class="figcenter" id="ad295a"> - <img - class="p0" - src="images/ad295a.png" - width="550" - height="207" - alt="" /> - </div> - -<p class="center xxl gesperrt">JAMES LEWIS.</p> - -<p class="bold center sm">41, GREAT QUEEN STREET, LINCOLN'S INN FIELDS,</p> - -<p class="sm center">(Late <span class="smcap">Lewis & Son</span>, of Wych Street, Strand),</p> - -<p>Engineer, Machinist, Lathe and Tool Maker, and Modeller of New -Inventions, for English or Foreign Patents, from Drawings or -Specifications, in Brass, Iron, or Wood.</p> - -<p>Also Manufacturer of Steam Engines and Boilers for driving Amateur -Lathes, Pleasure Boats, &c., the Boilers fitted with Messrs. Field's -Patent Circulating Tubes; whereby a great saving of Fuel and space is -effected; or can be fitted for Gas.</p> - -<blockquote> - -<p class="sm">Model Steam Engines and Boilers kept in Stock, and the different -parts may be had for making the same.</p> - -<p class="sm center"><i>Estimates given for all kinds of Work. Country Orders -punctually attended to.</i></p></blockquote> - -<hr class="full" /> - -<div class="figleft" id="ad295bs"> - <img - class="p0" - src="images/ad295bs.png" - width="198" - height="300" - alt="" /> - </div> - -<p class="center xxl gesperrt">JOSEPH LEWIS'S.</p> - -<p class="center">PATENT</p> - -<p class="bold center xl arial" >COMBINED DRILL, CIRCULAR SAW,</p> - -<p class="center bold">AND FRET MACHINE.</p> - -<p class="center"><i>Patterns and designs for Picture Frames, Brackets, Reading Desks, -etc., from 3d. each, or 2s. 6d. per dozen assorted.</i></p> - -<table class="sm" summary=""> - <tr> - <td>To fix on Lathe</td> - <td class="tab1">£3</td> - <td class="tab1">0</td> - <td class="tab1">0</td> - </tr> - <tr> - <td>Ladies' Machine</td> - <td class="tab1">4</td> - <td class="tab1">0</td> - <td class="tab1">0</td> - </tr> - <tr> - <td>Ditto ditto</td> - <td class="tab1">5</td> - <td class="tab1">0</td> - <td class="tab1">0</td> - </tr> - <tr> - <td>Gentlemen's ditto</td> - <td class="tab1">5</td> - <td class="tab1">0</td> - <td class="tab1">0</td> - </tr> - <tr> - <td>Ditto, with drill</td> - <td class="tab1">6</td> - <td class="tab1">10</td> - <td class="tab1">0</td> - </tr> - <tr> - <td>Gentlemen's Machines with Circular Saw</td> - <td class="tab1">8</td> - <td class="tab1">0</td> - <td class="tab1">0</td> - </tr> - <tr> - <td>Ditto, ditto, ditto, with the improved Saw-shifting Apparatus complete</td> - <td class="tab1">9</td> - <td class="tab1">10</td> - <td class="tab1">0</td> - </tr> -</table> - -<p class="center sm">Best Saws from 4½d. per doz., 4s. per gross. Ornamental Drills from -1s. each.</p> - -<p class="center bold gesperrt">51, HIGH STREET, BLOOMSBURY.</p> - -<div class="figright" id="ad295cs"> - <img - class="p0" - src="images/ad295cs.png" - width="172" - height="175" - alt="" /> - </div> - -<p class="center sans">JOSEPH LEWIS,</p> - -<p class="center sm bold">ENGINEER, MACHINIST, LATHE AND TOOL MAKER, AND MODELLER OF NEW -INVENTIONS.</p> - -<p class="sm">Manufacturer of every description of Plain and Ornamental Lathes, -Chucks, Slide Rests, Tools, Drills, over-hand motions, Division -Plates, &c.</p> - -<p class="center bold">Lathes £8 0 0, £10 0 0, £12 0 0, £14 0 0, £16 0 0, £25 0 0.</p> - -<p class="center sm">Amateurs supplied with Castings, Forgings of Lathe Engines, &c., and -assisted in making the same.</p> - -<p class="center gesperrt bold">JOSEPH LEWIS'S</p> - -<p class="center sm">Apparatus for cutting Screws of all nitches, self-acting, made and -fitted to any Lathe.</p> - -<p class="center xl arial">51, High St., Bloomsbury, London.</p> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_286" id="Page_286">[286]</a></span></p> - -<p class="center sans bold gesperrt xl">JAMES MUNRO,</p> - -<p class="center sm">(<i>From Messrs. HOLTZAPFFEL & Co.</i>)</p> - - -<p class="center bold lg">ENGINEER, MACHINIST,</p> - -<p class="center xl arial">LATHE AND TOOL MAKER,</p> - -<p class="center xs">MANUFACTURER OF ALL KINDS OF</p> - -<p class="center arial">LATHE APPARATUS FOR PLAIN OR ORNAMENTAL TURNING,</p> - -<p class="center sm">DIE STOCKS, TAPS, SCREW TOOLS, OVAL AND ECCENTRIC CHUCKS, CUTTING -FRAMES, &c.</p> - -<p class="center">4, GIBSON STREET, WATERLOO ROAD,</p> - -<p class="center gesperrt sm">LONDON, S.</p> - -<hr class="r10" /> - -<div class="figleft" id="ad296as" style="width: 290px;"> - <img - class="p0" - src="images/ad296as.png" - width="290" - height="300" - alt="" /> - <p class="center xs">MACHINE TURNING LATHE FOR PLANING, ETC., ETC. INVENTED -BY J. MUNRO.</p> - </div> - -<div class="figright" id="ad296bs" style="width: 253px;"> - <img - class="p0" - src="images/ad296bs.png" - width="253" - height="300" - alt="" /> - <p class="center xs">HAND PLANING MACHINE.</p> - </div> - -<hr class="r10" /> - -<p class="sm"><span class="smcap">James Munro</span> respectfully invites the attention of Amateurs -and Manufacturers to the excellence of workmanship and construction of -the various descriptions of Lathe Machines and apparatus produced in -his manufactory, which has secured the approval of numerous patrons.</p> - -<hr class="r10" /> - -<p class="center sm arial">Specimens may be seen at the Museum of Patents, South Kensington.</p> - -<hr class="full1" /> - -<p><span class="pagenum"><a name="Page_287" id="Page_287">[287]</a></span></p> - -<p class="center xxl arial">THE ENGLISH MECHANIC</p> - -<p class="center font1 lg">And Mirror of Science,</p> - -<p class="center xs">IS AN ILLUSTRATED RECORD OF</p> - -<p class="center bold">Engineering, Building, New Inventions, Photography, Chemistry, -Electricity, &c., &c.</p> - -<hr class="r10" /> - -<p class="center sm">Weekly, price 2d.; post 3d. Monthly parts, 9d.; post 11d. Quarterly -Subscription, post-free, 3s. 3d. Vol. VI. now ready, 7s.; post-free, -8s.</p> - -<hr class="r10" /> - -<p class="center sm">(From the <i>Weekly Times</i>.)</p> - -<blockquote class="p0"> - -<p class="sm">"Technical education forms just now a topic of more than -ordinary importance, and, as far as we can see, 'The English -Mechanic' fills a large space in providing technical food for -the workmen of Great Britain. There is scarcely a subject in -the scientific or mechanical world that is not practically -described in this excellent journal, and all the technicalities -explained with a particularity quite remarkable. Here the -workman in all departments of trade will find something to -interest him, and many things explained by which he will be -able to make the best use of his knowledge. The editor is -always anxious to satisfy the cravings of his readers by giving -every information possible to those who may require it. The -trouble taken in this department is apparent on reference to -the 'Letters to the Editor' and 'Replies to Queries,' both -of which form original, very important, and useful features -of the magazine. Under the head, also, of 'Our Subscribers' -Exchange Club,' a means is opened for persons to exchange one -article for another on mutually advantageous terms, and for this -accommodation no charge is made. For instance, one correspondent -says he has a silver watch which he would exchange for 'The -Lives of Eminent Men;' another wants 'a cottage piano' for 'a -three-horse power horizontal engine;' and a third has 'a hand -sewing machine,' which he would give for 'a parallel sliding -vice.' The illustrations of 'The English Mechanic' are worthy -of all praise; they are drawn with an exactness which is so -necessary, and so much appreciated by workmen, and are also well -printed. Throughout the whole publication there is a visible, -a practical, and technical knowledge of a high order—a kind -of knowledge that is highly prized by all mechanics and men of -science."</p></blockquote> - -<hr class="r10" /> - -<p class="center sm">(From the Morning <i>Advertiser</i>)</p> - -<blockquote class="p0"> - -<p class="sm">"'The English Mechanic.'—Illustrated with appropriate -engravings, this valuable periodical is replete with information -of the most valuable kind in every department of engineering, -and in all applications of the principles of physical science. -Its contents are exceedingly varied, and embrace, in a form -adapted for immediate and convenient reference, a well-digested -account of any noteworthy progress made in the mechanical or -chemical arts, at home or abroad. For all purposes of the -inventor, we do not know a periodical more likely to give him -that assistance which he could expect to derive from recent -means and appliances."</p></blockquote> - -<hr class="r10" /> - -<p class="center sm">(From the <i>Observer</i>.)</p> - -<blockquote class="p0"> - -<p class="sm">"'The English Mechanic and Mirror of Science' is a publication -which contains much that is new and instructive in various -branches of science."</p></blockquote> - -<hr class="full" /> - -<p class="center sm">Now ready, price 9d.; post free, 10d.</p> - -<p class="drop-cap sm">THE ENGINEER'S SLIDE RULE, and its APPLICATIONS. A complete -investigation of the principles upon which the Slide Rule is -constructed, together with the method of its application to all -purposes of the Practical Mechanic.</p> - -<hr class="r10" /> - -<p class="center sm">Published by the Proprietor, <span class="smcap">Geo. Maddick</span>, 2 & 3, Shoe Lane, Fleet Street,<br /> -<i>And to be had of all Booksellers.</i><br /> -</p> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_288" id="Page_288">[288]</a></span></p> - -<p class="center sans sm gesperrt">ESTABLISHED A.D. 1810.</p> - -<p class="center xxl gesperrt">W. J. EVANS,</p> - -<p class="center bold lg">ENGINE, LATHE AND TOOL MAKER,</p> - -<p class="center sans">AND GENERAL MACHINIST,</p> - -<p class="center"> 104, WARDOUR STREET, SOHO, LONDON.</p> - -<hr class="r10" /> - -<p class="center sm">TURNING, PLANING, SCREW AND WHEEL CUTTING TO DRAWINGS AND MODELS.</p> - -<p class="center sm">Amateurs' turning Lathes of every description for Plain, Eccentric, -Oval and Ornamental turning, also the various tools and apparatus the -Mechanical Arts.</p> - -<p class="center sm"><i>Instruction given to Amateurs in Plain and Ornamental Turning in all -its Branches.</i></p> - -<p class="center xs bold">Contractor to Her Majesty's War Department.</p> - -<hr class="full" /> - -<p class="center xl copper gesperrt">LATHES,</p> - -<p class="center sm bold">AND EVERY DESCRIPTION OF TOOL FOR AMATEUR TURNERS.</p> - -<hr class="r10" /> - -<p class="center arial">Lathes complete, £7 5s., £9, £11, £16 16s.</p> - -<hr class="r10" /> - -<p class="center sm">CHUCKS & ALL KINDS OF APPARATUS FITTED TO LATHES.</p> - -<p class="center bold sm">Engineers' Files and Tools of every description.</p> - -<p class="center gesperrt bold lg">AMERICAN TWIST DRILLS,</p> - -<p class="center sm"><i>And Self-centering Chucks for holding all sized Drills.</i></p> - -<p class="center sm gesperrt bold sans">AMERICAN SCROLL CHUCKS OF ALL SIZES</p> - -<p class="center sm">Can be readily fitted to any Lathe.</p> - -<hr class="r10" /> - -<p class="center lg gesperrt">JOSEPH BUCK,</p> -<p class="center sm">124, <span class="arial bold sm">NEWGATE STREET, E.C.,</span></p> -<p class="center sm">And 164, <span class="arial bold sm">WATERLOO ROAD, S., LONDON.</span></p> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_289" id="Page_289">[289]</a></span></p> - -<p class="center xl gesperrt">W. BLACKETT,</p> - -<p class="center p0 arial bold">HOPE IRON WORKS,</p> - -<p class="center sans bold lg">SOUTHWARK BRIDGE ROAD, LONDON,</p> - -<p class="center xs">MANUFACTURER OF</p> - -<p class="center sm">Engineers, Millwrights, Iron Ship Builders, and Boiler Makers' Tools.</p> - -<div class="figcenter" id="ad299a" style="width: 276px;"> - <img - class="p0" - src="images/ad299a.png" - width="276" - height="350" - alt="" /> - <p class="center">PLANING MACHINE.</p> - </div> - -<div class="figcenter" id="ad299b" style="width: 360px;"> - <img - class="p0" - src="images/ad299b.png" - width="360" - height="300" - alt="" /> - <p class="center">SCREW CUTTING FOOT LATHE.</p> - </div> - -<div class="figcenter" id="ad299c" style="width: 582px;"> - <img - class="p0" - src="images/ad299c.png" - width="582" - height="250" - alt="" /> - <p class="center">SLIDING AND SCREW CUTTING LATHE.</p> - </div> - -<p class="sm">The Machines usually on hand consist of large and small Boring -and Drilling Machines; Universal Shaping, Planing, Slotting, -Bolt-screwing, Single and Double ended Punching and Shearing Machines; -a variety of Self-acting, Sliding, and Screw-cutting Lathes, Hand -Lathes, Foot Lathes, Compound Slide Rests, Planed Iron Lathe Beds, -Ratchet Drill Braces, Screwing Tackle, Screw Jacks, and other Tools, -such as are usually required in Engineering Establishments. Tools not -in stock made to order.</p> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_290" id="Page_290">[290]</a></span></p> - -<table summary=""> - <tr> - <td class="center sm bold">By Her Majesty's</td> - <td class="ctr"> - <img src="images/ad300a.png" alt="" width="155" height="75" /></td> - <td class="center sm bold">Royal Letters Patent.</td> - </tr> -</table> - -<hr class="r10" /> - -<p class="center xxl">CUNNINGHAM AND CO.,</p> - -<p class="center bold arial">480, NEW OXFORD STREET, LONDON, W.C.,</p> - -<p class="center lg bold gesperrt">ORNAMENTAL WOOD</p> - -<p class="center xs">AND</p> - -<p class="center ">METAL CUTTING MACHINES,</p> - -<p class="center xs">AND</p> - -<p class="center xl">DRILLING APPARATUS.</p> - -<hr class="r10" /> - -<p class="center sm bold">ADAPTED FOR LADIES' USE.</p> - -<div class="figcenter" id="ad300b" style="width: 210px;"> - <img - class="p0" - src="images/ad300b.png" - width="210" - height="350" - alt="" /> - </div> - -<blockquote> - -<p class="sm"><span class="bold">Useful to the following Trades</span>—Organ Builders—Cabinet -Makers—Pattern Makers—Chair Makers—Gun Case Makers—Marqueterie -Makers—Toy Maker—Jewel Case Makers—Carvers—Cutlers—Leather -Cutters—Engravers—Jewellers—Chandelier -Makers—Electrotypers—Stereotypers—&c.</p> -</blockquote> - -<hr class="r10" /> - -<p class="center sm bold">Will cut Brass a Quarter inch thick with ease.</p> - -<p class="center xs">The working of the Machine is very simple, and can be learnt by an -amateur in five minutes.</p> - -<hr class="r10" /> - -<table summary=""> - <tr> - <td class="ctr"> - <img src="images/ad300c.png" alt="" width="149" height="150" /></td> - - <td class="center"><span class="sm">Patentees of the</span><br /> - <span class="xl arial bold">CAM ROLLER BUFFING,</span><br /> - <span class="sm">FOR</span><br /> - Preventing Noise in Machinery.<br /> - <hr class="r10" /> - <span class="sm"><i>See ENGINEER, Jan. 24th, 1868.</i></span></td> - </tr> -</table> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_291" id="Page_291">[291]</a></span></p> - -<p class="center bold gesperrt lg">W. J. CUNNINGHAM <span class="smcap">AND</span> CO.</p> - -<p class="xs">Beg to call the attention of the Public to their newly-invented -Ornamental Wood and Metal Cutting Machine. Its extreme simplicity of -construction precluding the possibility of speedily getting out of -order, having no springs, and its peculiar adaptability to all kinds -of fret-work render it at once an acquisition and an indispensability -where accuracy, expedition, and high finish are required. The working -is exceedingly easy, requiring no more exertion than an ordinary -Sewing Machine for ladies' use, and making as little noise. Its great -utility, combined with neatness of construction, fits it not only -for the workshop, but the drawing-room of the amateur. The saw takes -the place of a pencil in the hands of the operator, enabling him to -produce the most elaborate artistic designs in wood-work. Box or other -hard texture woods, 1 inch thick, are as readily sawn through as the -finest veneer; metallic plates of ⅛ inch thick are also speedily -pierced. Magnificent specimens executed by this machine, which have -been universally admired for their extreme delicacy and perfection, -and acknowledged to be unrivalled, may be seen at the inventor's -address. The length of stroke of the saw can be varied to the work -in hand. A simple mechanical contrivance is attached for blowing the -sawdust from the saw whilst working, also a Circular Saw.</p> - -<p class="xs">An equally valuable invention is W. J. C. & Co.'s <span class="smcap">Patented -Drilling Apparatus</span> which is with the greatest advantage combined -with the Sawing Machine, enhancing and enlarging its range of -usefulness, or it may be adapted to a lathe, or as a distinct machine. -Its great advantages over the ordinary lathe for drilling purposes -must be apparent when by the addition of this apparatus to a 5 inch -centre lathe the operator is enabled to drill in the centre of three -or more feet, and the drill being vertical and worked by leverage, -greater accuracy and facility is ensured. For ornamental purposes it -surpasses all hitherto contrived methods, not being limited to one -centre around which to describe curves, angles, circles, or any other -mathematical figure, the operator is at perfect liberty to describe -every conceivable device the fancy can dictate.</p> - -<hr class="r10" /> - -<p class="center bold">Advantages and Capabilities of this Machine.</p> - -<p class="center sm"><i>This Machine can be adapted to any Lathe, see page 131.</i></p> - -<blockquote class="xs"> - -<p>This Machine has a Circular Saw.</p> - -<p>This Machine has a Vertical Saw.</p> - -<p>This Machine has a true Parallel Motion.</p> - -<p>This Machine has no Springs whatever.</p> - -<p>This Machine has a Bead and Moulding Apparatus.</p> - -<p>This Machine has a Planing Apparatus.</p> - -<p>This Machine has a Drilling and Grooving Apparatus.</p> - -<p>This Machine has a Kinography that will engrave hundreds of -different patterns on wood or metal.</p> - -<p>This Machine will cut Spirals and Ovals.</p> - -<p>This Machine has a Pentagraph, for reducing, enlarging, and -cutting on the face of wood any drawing from paper or fret-work.</p> -</blockquote> - -<p class="center sm"><i>Circulars and all particulars on application.</i></p> - -<hr class="r10" /> - -<p class="center bold">Every kind of Materials, viz., Saws, Fret Patterns, Fancy Wood Drills, -Cutters, &c., kept in stock.</p> - -<hr class="r10" /> - -<p class="center">MANUFACTURERS OF TURNING LATHES.</p> - -<p class="center sm">AND ALL KINDS OF MECHANICAL TOOLS.</p> - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_292" id="Page_292">[292]</a></span></p> - -<p class="center bold xl">MOSELEY AND SIMPSON,</p> - -<table summary=""> - <tr> - <td class="ctr"> - <img src="images/ad302a.png" alt="" width="199" height="200" /></td> - - <td class="center"><span class="smcap xs">Late</span><br /> - 17 & 18, KING ST.JOHN MOSELEY & SON,<br /> - <span class="bold lg">17 & 18, KING ST.</span><br /> - <span class="xs">AND</span><br /> - <span class="bold sm">27, BEDFORD ST.,</span><br /> - <span class="sans xs">COVENT GARDEN,</span><br /> - <span class="gesperrt sm">LONDON, W.C.</span><br /> - <span class="xs bold">ESTABLISHED 1730.</span></td> - - <td class="ctr"> - <img src="images/ad302b.png" alt="" width="201" height="200" /></td> - </tr> -</table> - -<hr class="r10" /> - -<p class="center lg gesperrt">LATHE AND</p> - -<p class="center xl">TOOL MANUFACTURERS,</p> - -<p class="center sm">&c., &c.</p> - -<hr class="r10" /> - -<p class="center sm bold">PRICE LIST OF LATHES.</p> - -<blockquote class="sm"> -<p>Turning Lathe, Iron Frame and Bed planed true, Wood Tool Board, Iron -Cone Mandrel, Cylinder poppet head, Rest and two Tees, Turned Grooved -Wheel Crank, Treadle complete with 3 Chucks:—</p> - -<table summary=""> - <tr> - <td class="tab1 right">No. 1.</td> - <td class="tab1">3½</td> - <td class="tab2">inch centre,</td> - <td class="tab3">and 2 foot</td> - <td class="tab1">6 inch</td> - <td class="tab5">Bed</td> - <td class="tab1">£10</td> - <td class="tab4">10</td> - <td class="tab4">0</td> - </tr> - <tr> - <td class="tab1 right">" 2.</td> - <td class="tab1">4½</td> - <td class="tab2">"</td> - <td class="tab3">" 3 "</td> - <td class="tab1">Bed</td> - <td class="tab5"></td> - <td class="tab1">12</td> - <td class="tab4">12</td> - <td class="tab4">0</td> - </tr> - <tr> - <td class="tab1 right">" 3.</td> - <td class="tab1">5</td> - <td class="tab2">"</td> - <td class="tab3">" 4 "</td> - <td class="tab1">"</td> - <td class="tab5"></td> - <td class="tab1">15</td> - <td class="tab4">15</td> - <td class="tab4">0</td> - </tr> - <tr> - <td class="tab1 right">" 4.</td> - <td class="tab1">5</td> - <td class="tab2">"</td> - <td class="tab3">" 4 "</td> - <td class="tab1">"</td> - <td class="tab5"></td> - <td class="tab1"></td> - <td class="tab4"></td> - <td class="tab4"></td> - </tr> - <tr> - <td></td> - <td></td> - <td colspan="4" class="left"> - with Brass Pulley and Slide Rest</td> - <td class="tab1">21</td> - <td class="tab4">0</td> - <td class="tab4">0</td> - </tr> - <tr> - <td class="tab1 right">" 5.</td> - <td class="tab1">6</td> - <td class="tab2">inch centre</td> - <td class="tab3">and 4 feet</td> - <td class="tab1">Bed</td> - <td class="tab5">with Slide Rest complete</td> - <td class="tab1">25</td> - <td class="tab4">0</td> - <td class="tab4">0</td> - </tr> - <tr> - <td class="tab1 right">" 6.</td> - <td class="tab1">7</td> - <td class="tab2">inch centre,</td> - <td class="tab3">6 feet</td> - <td class="tab1"> Bed,</td> - <td class="tab5">self-acting, and</td> - <td class="tab1"></td> - <td class="tab4"></td> - <td class="tab4"></td> - </tr> - <tr> - <td colspan="6" class="center">Screw Cutting leading Screw, and 22 Change Wheels - </td> - <td class="tab1">40</td> - <td class="tab4">0</td> - <td class="tab4">0</td> - </tr> -</table> - -</blockquote> - -<p>For Lathes of other descriptions, Estimates are furnished on -Application.</p> - -<hr class="r10" /> - -<p class="center bold">TURNING TOOLS.</p> - -<blockquote class="sm"> - -<table summary=""> - <tr> - <td></td> - <td class="tab4">s.</td> - <td class="tab4">d.</td> - </tr> - <tr> - <td>Chisels for Soft Wood, the set of 6 handled</td> - <td class="tab4">8</td> - <td class="tab4">0</td> - </tr> - <tr> - <td>Gouges</td> - <td class="tab4">9</td> - <td class="tab4">0</td> - </tr> - <tr> - <td>Tools for hardwood and metal, handled and ready for use, per dozen</td> - <td class="tab4">15</td> - <td class="tab4">0</td> - </tr> - <tr> - <td>Drills handled</td> - <td class="tab4">0</td> - <td class="tab4">7</td> - </tr> - <tr> - <td>Arm Rests Handled</td> - <td class="tab4">2</td> - <td class="tab4">6</td> - </tr> - <tr> - <td>Callipers from</td> - <td class="tab4">1</td> - <td class="tab4">0</td> - </tr> - <tr> - <td>Turner's Squares from</td> - <td class="tab4">6</td> - <td class="tab4">0</td> - </tr> -</table> -</blockquote> - -<p class="center">All Kinds of Chucks, Cutters, &c., made to order.</p> - - -<p class="transnote p4">Transcriber's Note:<br /> - -1. Page 38, Bunhill-row, Covent-garden and Charing-cross seems to be -an old-fashioned way of writing.<br /> -2. All references to illustrations have been linked for ease of use, as the paragraphs are mostly extremely long, - and illustrations have been moved to end of paragraphs to facilitate smooth reading.<br /> -3. This table of contents has been created by the transcriber to aid the reader.<br /> -4. Footnote 20, Page 183: Footnote marker is missing.<br /> -5. Page 238: starting the 3rd table, there is a fraction 33-1/14. This has been changed this to 33-1/16, as it seems to be a mistake.<br /> -6. Spelling errors such as guidepiece, sawgates, swiveljoint, tongueing - and whiteing have been retained as they are in the original. -7. Discrepancies with 3/4-inch and 1/4in. have been retained as in the original. -8. <span class="bold">Inconsistencies with images:</span><br /> - -a. Page 22: Fig 31D is incorrect in the book as E. Changed to 31D and removed fig. no. on the image.<br /> -b. Pages 36 & 38: numbers 53-56 are repeated.<br /> -c. Page 74: It seems the reference (Fig. 126) should be Fig.116.<br /> -d. Page 89: There is no Fig. 137 or a reference to it.<br /> -e. Page 99: The number 9 on the image is back to front. There does not seem to be a Fig. 148, although it is referred to (page 98)<br /> -f. Page 98: Fig. 148 is incorrectly numbered on the image as 143.<br /> -g. Page 100: There is a 2nd reference to Fig. 149, which it seems has to be an illustration of a pattern, but there is no 2nd Fig. 149. It seems the Fig. nos. mentioned in the reference s/b 150 to 153.<br /> -h. Page 104: The illustration is incorrectly numbered as 153 (should be 156).<br /> -i. Page 107: The number 9 on the image is back to front.<br /> -j. Page 111: The number 6 on the images is back to front.<br /> -k. Page 112: Fig. 166 incorrectly numbered as 165.<br /> -l. Page 141: There is no Fig. 204. ( assumed to be the top image above Fig.205)<br /> -m. Page 159/160: Number repeat for Fig. 229.<br /> -n. Page 160: There is no Fig. 230. Possibly the 2nd no. 229.<br /> -o. Page 178-184: Numbers 246-255 are number repeats.<br /> -p. Page 185/6: There is no Fig. 257, but no reference to it either, so it is assumed this wast an omission by the author.<br /> -q. Page 189: There is no Fig. 261, although it is referred to on page 189. The reference has been changed to Fig. 262, which it pertains to.<br /> -r. Page 201: Fig. 284 is out of sequence, it appears on page 209.<br /> -s. Page 207: It seems the reference should be to Fig. 290, not 296 which has no L in the figure<br /> -t. Page 231: Fig, 319 is referred to, but there is no Fig. 319. Presumably the first figure on Page 233<br /> -u. Page 236: Illustration top un-numbered, presumably 4.<br /> -v. Page 278: Figs, 422/3 is referred to, but there are no Figs. 422/3. Based on extensive research, comparing two different copies of a matching -edition, and correlation of illustrations with the text, it appears that -the inconsistencies in numbering within the book make it seem that -something is missing. The images are in fact Figs. 420 and 421.</p> - - - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of The Lathe & Its Uses, by Anonymous - -*** END OF THIS PROJECT GUTENBERG EBOOK THE LATHE & ITS USES *** - -***** This file should be named 60819-h.htm or 60819-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/6/0/8/1/60819/ - -Produced by Karin Spence, Curtis Weyant and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from scans of public domain works at the -University of Michigan's Making of America collection.) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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