Detached-cutter Holders.

PLAN ANGLE WITH SECTION ANGLES

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 inFig. 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 theV-shaped groove.Fig. 10has 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 inFig. 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 withoutundercuttingthe 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,—soround-nosed tools belong properly to the double-edged class, and are open to great objections unless carefully formed on this principle.

Illustration No. 5.(13, 14)

This is illustrated inFig. 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 takenfrom 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 inFig. 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 from1/32to 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.

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.(15, 16)

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, inFig. 15,the point of the tool being at A, the slope must be made in the direction A, B; while, inFig. 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."

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 winMust forge thick and grind thin,"

"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.

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 rathermorethan 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 werelessthan 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 strapthan 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.

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 cuttingflyingin 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 betweentwo 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.

Fig. 400is 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 byFig. 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, (seeFig. 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. 401is 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.

Figs. 401, 402.

These two castings, 401 and 402, are bolted together with two bolts and nuts through the holes 5 and 6, as shown inFig. 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 holebored 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.

Figs. 403, 404, 405, 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 45/6waves 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 ofFig. 407is 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,

producing on each revolution of the lower mandrel one wave, and one-fifth of another wave, requiring six revolutions to complete the pattern.

Fig. 407.

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.

Fig. 408is 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. 408.

Fig. 409is 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. 409.

Fig. 410is 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. 410.

Fig. 411is 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.

Fig. 411.

Fig. 412. 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.

Fig. 412.

Fig. 413. The whole of this pattern produced by the upper mandrel making 3⅗ revolutions to one of the lathe, producing 18 wavesacross each other with slide-rest movement for the middle rim.

Fig. 413.

Fig. 414illustrates 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. 414.

Fig. 415illustrates a rosette of 24 waves with the slide-rest movement.

Fig. 415.

Fig. 416. Another illustration of a rosette of 24 waves, rather more sharp than inFig. 415, with slide-rest movement and 9 divisions of the circular movement of the eccentric chuck, giving it a pleasing circular waved appearance.

Fig. 416.

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. 417.

Fig. 418illustrates 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.

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. 419is one illustration with an eccentric chuck on the lathe mandrel.

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 alwayscentral, and only the slide carrying the pin to receive the rod must move eccentrically.

Fig. 420, also 422.

Fig. 421, also 423.

Figs.420and421, 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 cuttinginto the wood.Fig. 420is a section, andFig. 421a 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 anddies in the lathe, using steel wire of the necessary size. This I manage easily, and keep the wire straightby 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.

Figs.422and423are 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,ovalswith 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. 424.

Fig. 425the same asFig. 424, with the patterns laid across each other by turning the circular movement of the chuck 12 divisions.

Fig. 425.

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 theovalis 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. 426.

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. 427.

Fig. 428, is also from an oval template, it is finer than 427, but is done in the same way by the template makingninerevolutions to oneof the lathe mandrel.

Fig. 428.

The above are a few specimens of the oval, but sufficient to drawattention 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 alreadydescribed, 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. 429.

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. 430.

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. 431.

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 usedon the opposite side of the lathe bedto the roller against the template, and therefore reversing the pattern, that is, the projections of the pattern are the hollows of the template, andvice 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.

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