*) 



WHEEL -CUTTINU. 



WHEEL-CUTTING. 



j under the conical point, and the point t be then dropped into 



it, the distance moved over by the plate, and also by the wheel which 

 is screwed ur otherwise fixed on to the end of the arbor c, w ill lie 

 irt of a circle. The cutter having been adjusted to ouch a dis- 

 tance from the centre of the arbor e as is required to cut a proper 

 depth into the wheel, the o]>eralion of cutting is pert'orim-d by bringing 

 down the slide i which carries the cutter-arbor by the lever /, the 

 arbor being carried round by the band which panes round the pulley 

 j, and a wheel similar to a lathe-wheel, which the operator keeps in 

 motion by the foot acting on a treadle in the same way as in a common 

 lathe. As soon as the cutter has passed through the thickness of the 

 wheel, the pressure is taken off the lever by which the cutting-frame 

 or slide has been depressed, and it is brought back to the position it 

 had before by the spring H, the plate is shifted one division, and the 

 operation of cutting is repeated. It will be perceived that any number 

 can be cut from each circle, provided the required number is an 

 aliquot part of the divisions in the circle used : thus, on the i-iivl, of 

 860, by passing over two divisions between each cutting, 180 will IK' 

 cut ; three divisions, 120 ; four divisions, 00 ; and so on. 



In some engines the edge of the dividing-plate, ur rather a rim just 

 within the edge on the under side of the plate, has a screw cut upon it, 

 into which a tangent-screw is made to act ; and the head of this screw 

 consists of a small wheel, or dividing-plate, reuioveable at pleasure, in 

 order to substitute mother of a different number. By such an arrange- 

 ment as this just described, not only may any number (even I'lin.e 

 numbers) be cut, but the plate itself may be divided. The cutting of 

 wheels, or rather shifting the plate by the screw, would take too much 

 time for ordinary wheel-cutting ; hence the numbers most in use are 

 drilled in the plate as above described. A great many ingenious 

 methods are resorted to in wheel-cutting for the purpose of cutting 

 odd numbers, for moving the plate over any number of divisions rapidly 

 without the possibility of making a mistake, the details of which our 

 limits will not allow us to go into : what we have said above we deem 

 sufficient to illustrate the principle. It is necessary here to observe 

 that the cutter, previous to commencing to operate, should be adjusted 

 so that a plane passing through the centre of its cutting-edge, and 

 parallel with its sides, should pass also through the centre of the arbor 

 on which the wheel is fixed ; otherwise the teeth will not be cut in 

 straight to the centre, and will have the appearance of being bout 

 on one side. It is also necessary that the downward motion of the 

 slide containing the cutter-arbor should be perfectly at right angles 

 with the plane of the wheel. We have hitherto spoken of the wheels 

 as being screwed to the arbor c, 'but we have also said the arbor e is 

 hollow, for the purpose of receiving the axes of the wheels to bo cut. 

 This hollow arbor is, in fact, capable of receiving end-pieces, which arc 

 firmly fixed therein ; and it is on these latter pieces that the wheels 

 which have no axes of their own, but simply a hole through them, are 

 screwed. But when the wheel to be cut is already fixed on an axis, 

 the hollow arbor is used with an apparatus shown in the figure, which 

 we shall now describe : 1, 1, part of a very firm bar attached to the 

 lower frame, and extending horizontally across the centre of the engine- 

 plate, the extremities of which bar terminate in two pins or pivots : 

 2, 2, one of which is not seen, extending a short distance beyond the 

 edge of the dividing-plate ; on to these pins are hooked two pieces, 8, 8, 

 which, at their upper ends, past through slits in the piece of iron, 4, 4, 

 which has a screw, 5, passing through its centre. (In all this apparatus, 

 except the screw, 5, there must be no nice fitting, but perfect freedom.) 

 The screw 5 has a centre, either male or female, by which it presses 

 down the hollow cone y ; but the foregoing apparatus, called the gal- 

 lows, will be best understood by describing the mode of putting on a 

 wheel having an arbor in it : Remove the gallows ; on to the end of 

 axis e drop a flange x, a little less in diameter than the circle which 

 corresponds with the bottom of the teeth to be cut : through the centre 

 of this flange drop the longer part of the arbor of the wheel , t.. ).. 

 cut, so that the wheel rate on the flange r ; then over the wheel drop 

 the flange or collar x" (of the same diameter as x) ; over the shorter 

 put of the axis of wheel K- place the hollow cone y : bring the gallows 

 over the cone ; screw down screw 5 just sufficiently tight to hold the 

 gallows in its position, but not to set the wheel w fast; reumxe the pin 

 k from the plate p p, and cause the latter to revolve rapidly by the hand 

 or otherwise ; the wheel w will in all probability be far from con 

 with the plate, as will also the centre of cone ri. With the hand .-lip 

 the wheel if or conn y, or both, is may be required, together with the 

 upper flange jr 1 , as nearly concentric with the plate p p as the hand and 

 ye will enable you in one or two Hvcouds to do; next slide Hi. 

 so as to bring the jcrew 8 to a convenient distance from the wheel , 

 and set fast by screw 7 ; then by revolving the plate rapidly, and 

 gradually bringing the end of 8 to the edge of wheel w, it will be got 

 perfectly concentric ; next screw down 5 sufficiently tight to | 

 the wheel from moving, and net fast screw 5 by tightening nut 9 : the 

 cotter being then adjusted so is to cut the teeth a proper depth, the 

 cutting proceeds as before described. This operation of netting the 

 wheel perfectly concentric will not occupy an experienced hand more 

 than fifteen seconds. 



Of ike Cutltrt, and tlit mode of making and viiny them. The 

 vary with the nature of the work to be done, and much >l 

 harm* good one* and well adapted for the purpose. The first kind we 

 shall describe k used for the commonest work, that is, merely for cut- 



ting spaces whose sides are parallel through their whole length (in 

 which case the teeth have to be rounded up afterwards), and the cutter 



ly a circular disc of steel with teeth on its edge, similar to a 

 circular saw, the two sides being slightly undercut, as seen in the sec- 



. 1 : this allows the cutter to pau freely through the metal 



No. l. 



without clogging, which it would do were the sides parallel. These 

 teeth in the cutter are sometimes made with a file by hand, but they 

 are much better made in the engine. Cutters of this description are 

 generally tempered HO low, after having been hardened, as to allow of 

 the teeth being renovated with a 8-square file when they become dull, 

 and answer the purpose well enough for common purposes. A better 

 sort of cutter, and more lasting, is made with from six to sixteen or 

 eighteen teeth, as in No. 2, which gives a side-view and section : these 



So. 2 



are left very hard, being tempered only to a light straw-colour, and are 

 sharpened with emery and oil on a metal mill or lap ; these take much 

 longer making than those first described. When these consist of not 

 more than six teeth, each tooth is generally relieved in direction shown 

 in section No. 3, but not on the sides, by which means the cutter frees 

 itself better, and cuts on its sides to the very root of its tooth, which 

 can be kept sharper and in much better working condition than the 

 foregoing. 



Cutters are also made having but one tooth, others with two, three, 

 and four ; but these are more frequently used when the teeth are to 

 be cut and rounded up at one operation, in which case the side view 

 and section No. 3 will represent the form in which they require to be 



No. 3. 



n 



made to produce the necessary curve for the wheel-teeth ; and great 

 nicety is required to produce two curves on each side of the cutting- 

 tooth exactly similar, for unless they are so, the teeth in the win < 

 therewith will have a very unsightly appearance. 



It will be necessary to say a few words on the different kinds of work 

 to which the various cutters above described are applicable. N,.. 1 is 

 used, when tempered low, for soft metal, such as gold and brass and 

 gun-metal ; if left hard, they should be sharpened with oilstone dust or 

 very fine emery, and they can then be used for harder metals, such as 

 iron and steel. No. 2 may also be used for the same purposes, but 

 when used for the harder metals should have a greater number of teeth, 

 from 20 to 30 not being too many in a cutter of three-quarters of an 

 inch in diameter. In general, the harder the metal to be cut the 

 greater the number of teeth required in the cutter; and will 

 metals, such as steel aud bell-metal, it is requisite to keep tin 

 well supplied with oil, and in all cases where hard metals are under 

 operation the cutter should have a slow in ILTS with from one 



to six teeth may revolve from 10,000 t.> L'u.i 



cutting the softer metals, aud those \\ith In i . L'O t, ,-il, i',,,,,, ;,000 to 

 8000 or 10,000 ; in fact, cutters with few teeth cannot be used for tin- 

 harder metals with advantage, and the others should not have more 

 than from 60 to 100 revolutions in a minute. These obsci 

 apply to cutterx whoKi- diameter is about three-quarters of an ineh ; it 

 the cutters are larger, they in tut have a proportionably ICRI nun 

 revolutions. Cutters are con.. steel, and indeed 



for all the metals, having very fine teeth, from '200 to 300 in the inch ; 

 but the use of thorn is now almost obsolete : in fact, the process 

 approximates very closely to filing, and such cutters may be regarded 

 as circular files. One great disadvantage is that the keen edges are 

 soon lost, aud they cannot be renovated without softening. 



Wheel-cutting is one of those operations in which much depends 

 upon the manual dexterity and judgment of the operator ; for it some- 

 times happens that steel, one of the hardest metals, may be cut with a 

 more rapid motion, and a less number of teeth in the cutter, than 



