Hollowing Out Soft Wood.

Fig. 93.

Fig. 94.

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, whichpasses 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 atFigs. 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.

Figs. 96, 97, 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 areessentially 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 befoursuch 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.

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 likec, 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. 100shows 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 atany 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.

Figs. 100, 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)impossiblycarved. 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 ofcutting 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. 103will 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.

Fig. 102.

Figs. 103, 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 likeFig. 104will 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 placedinsideand notupona chuck, unless you have to work upon thewholeexterior 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 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 allface 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. 106is 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 ata, 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 thesame 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 nuteis 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."

Figs. 105, 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.

Pearis tough and screws well.

Appleis little inferior.

Ilexorevergreen oakis sufficiently hard and tough and will be found quite satisfactory. Elder of large size is good, and screws well.

Sycamorescrews 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 byputting 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 theEnglish 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 orcorososwhich 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.

Figs. 1, 2, 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 ata. 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 eachend; 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.

Figs. 108, 109.

This is done, as already described, by the regular soft woodturners 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 topouteredge 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.

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—

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. 1is a plan of a 4-inch chuck.Fig. 2is a vertical section of the same.Fig. 3is a view of the outside of the chuck, andFig. 4is a separate section of the principal parta, a, taken through the linez, z(Fig. 1).

InFig. 2,a, ais this piece,b, b, has the spiral cut on it which actuates the jaws 1, 2, 3 (Fig. 1),c, cscrews on the piecea, ato keepb, bin its place andd, dis the plate which screws on the mandrel, andwhich is fixed toc, c, by three countersunk screws, one of which is shown in section.

Figs. 1, 2, 3, 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 whichrather scrape than cut, as described in detailing the process of hollowing out boxes and similar work.

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 specialformsof 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 bebrought 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 inFig. 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 inFig. 111.

Figs. 110, 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,thetool 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 inFig. 112.Fig. 113is 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 sidenext to the work—thesoleof the tool inFig. 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 theresistancewhich the tool meets with, and the best form and position is thuspractically 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.

Figs. 112, 113, 114, 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 thatbothcutting edges come into action, one on the face and one on the side of the cut, a condition explained in the Appendix asessentialto 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 sufficientthickness, 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 alongcutting edge, such as would be used if it were intended to scrape the whole depth of the side. Abroadshaving is not to be thus aimed at, nor is theinside onlyto 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 turningtool, 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 inFig. 117, to be applied as gauges over the ends of the tool, orsolidpieces 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!

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