Mechanics' Magazine, MUSEUM, REGISTER, JOURNAL, AND GAZETTE No. 854.] SATURDAY, DECEMBER 21, 1839. [Price 3d. WHITELAW'S MACHINE FOR GRINDING THE RIMS OF PULLIES. Printed and Published for the Proprietor, by W. A. Robertson, No. 166, Fleet-street. Gentlemen, Mr. Edward Sang, in his paper on the Progress of Exactitude in the Manufacture of Machines, has given you an account of the latest improveiments made on the turning, planing, and screwing machines. But besides these machines there is the grindstone, which has been fitted up of late, so as to do certain kinds of work in an expeditious and accurate manner, and from some experience which I have had in working it, I am of opinion that it might be applied to a greater variety of work, and much more extensively than it has ever yet been. I will first give you an account of a machine planned by me for grinding pulleys or drums truly cylindrical on the rim, which has been much in use during the last eighteen months. After I have described the first machine, I will give you an idea of another machine, which has never yet been brought into practice, for grinding pulleys, &c. round on the rim; and then you will, I believe, be of opinion that grinding machines might be used to great advantage in factories where mill-gearing is made. The Fig. 4, (opposite page,) is a side elevation of a machine for grinding drums or pulleys of a truly cylindrical shape, or, as it is called, straight on the rim, and fig. 5, is a ground-plan of the same machine. The parts which are seen in both figs. are marked by the same letters in the one fig. as in the other; a a is the grindstone, and b b is the pulley which is to be ground. pulley bb is fastened upon the mandril cc, this mandrel is fixed into the spindle dd at the one end, and it works into a plummet block e at the other end. The speed of the grind-stone is 180 revolutions per minute, and the pulley bb makes 130 revolutions in the same time; the stone and pulley revolve in the same direction, in order that the parts in contact may rub upon each other at the combined speed of their circumferences. There is a small shaft fff, which, means of the mitre wheels fixed upon it, gives motion to the screws g 9, 99, I, I, in connection with the plummer blocks, into which the spindle d d and the mandril cc work. As the plummer-blocks slide upon the rails h, h, h, which form part of the framing of the machine, in a similar manner as the parts of a sliderest move, and as all the screws marked gg have the same pitch of thread, the spindle and the mandril are shifted at once, either from, or towards the grindstone, and keep always parallel to its shaft, if the handle or wheel a is moved by hand. Upon the end of the shaft of the grindstone, a bevel pinion i is fixed, and this pinion gears into the wheel k k, fixed upon the shaft 1. The shaft is bored out to fit the shaft m m, which is turned parallel the whole of its length, so as to slide through the shaft / easily. There is a feather fixed into the shaft 1, which fits the groove planed into the shaft mm, so that this shaft can slide through the shaft ; but it cannot revolve unless the shaft carry it round. Upon the end of the shaft m m a small crank n is fixed; as this crank has a perpendicular position in the figs. it is not so distinctly seen. The crank pin has a brass on it, which slides into a groove running in a perpendicular direction in the part o o. As two sets of the bushes in the part oo work upon journals cut into the spindle dd, if the grindstone revolve, the spindle d d and the mandril cc will work endways, at one time in one direction, then in another, so as to bring an end of the pulley bb past a side of the stone, once for every half revolution of the crank shaft; and, in this way, the pulley and the stone, as they wear, keep perfectly cylindrical. It will be evident that the mandril and the spindle have no ruffs, and they are turned parallel at the parts which slide and revolve into the plummer-blocks. The bracket pp, which supports the crank-shaft, is fixed upon the two plummer-blocks for the spindle dd, and, on this account, if they are moved, from or towards the grindstone, it is carried along with them. The pulley q, which drives the spindle dd, is connected to it (the spindle) in a similar way as the shaft m m is connected to the shaft 7, and the part of the bracket pp, seen in the ground-plan passing nearly round this pulley, keeps it always at its proper place. The small rod t to guide the part o o, and keep its groove GRINDING THE RIMS OF PULLIES. always in a perpendicular direction. S is the pulley which drives the grind stone. 195 ground, it is shifted back from the stone and still kept revolving, then a stick with a little emery and oil on it is pressed against the pulley, and this gives it a fine polish. A grindstone for finishing pulleys is not anything like so expensive to make as a turning lathe: it does incomparably more work, and it does it as well as any self-acting lathe; besides, when the iron is hard, which is frequently the case in thin pulleys, a lathe is good for nothing, and this makes no difference in a grinding machine: a grinding machine Fig. 4. The machine now described grinds fifteen pulleys of 18 inches diameter by 5 inches broad, in a day, working ten hours; now this is a great quantity of work, considering the very moderate speed at which the parts are driven. When a pulley is finished, if a planed malleable iron straightedge is applied on be rim parallel to its axis, it touches the ley in every part. After the pulley is both ends, for the bush of the crank-pin to work into, the crank-pin can easily be taken away by unscrewing the nut which holds it to the crank, and then the spindle d d will not be wrought endways by the motion of the crank. When the ends of a pulley are to be ground, the crank-pin is taken away and a pincing screw is fixed upon the rod rr, which acts upon the part oo, so as to press the spindle d d on end, the one way or the other, as required; then if the pulley is shifted past the side of the stone, the pincing screw will press its end against the stone, and, if the machine is kept in motion, the end of the pulley will be ground. Having the crank forked answers another purpose; it allows the pin to be shifted further from, or nearer to, the centre of its shaft, in order to give a longer or shorter range to the motions which the crank gives to the spindle and mandril. A machine for grinding drums should be made wider than the one shown in the sketch, at the place where the stone and the pulley to be ground work, in order to get the ends of a long drum ground, when they are not finished in the turning lathe, at the time the drum is chucked, to get its eye bored out. Perhaps the simplest way of finishing the ends of a pulley which is bored out in the eye, is to do it in the lathe when it is on the chuck. When a pulley is finished, and it is to be taken out of the machine, or when a rough pulley is to be put into the machine, the cutter t is driven out, and then the mandril cc is drawn on end by means of the handle u, after the key which holds the pulley upon the mandril is slackened. Any of the plummer blocks which guide the spindle dd and mandril ce can readily be taken away, and a larger or smaller one put in its place; by this means a spindle or mandril to suit any sort of job may be used. The stone is covered in by means of a wooden box, so that the water used in grinding may not be thrown about the workshop. The machine shown in figs. 1, 2, and 3, (see front page) is for grinding pulleys round on the rim; in all the figs. the same letters point out the same parts. a a is the grindstone; bb is the pulley to be ground; this pulley is fastened upon the mandril or spindle cc. When a pulley to be ground is put upon the mandril cc, or when a finished pulley is to be taken off this mandril, the pincing screw d is slackened, and then the ruff into which it is screwed gets loose upon the mandril; after this the mandril is drawn on end, so far as that a pulley may either be taken off, or put upon it, by taking hold of the pulley e which gives motion to the mandril. The two screws ffff work into nuts fixed into the bracket gggg, and by moving the handle or wheel h, the pulley to be ground is pressed against the stone, or shifted away from it as is wanted. The bracket gggg has two pins or gudgeons ii fixed on it, and the frame 11mm turns upon these pins as a centre. When a pulley is to be ground very flat on the rim, the plummer blocks kk are shifted as close to the rail marked mm as they can get, by turning the handle n. The closer that the plummer blocks, into which the mandril cc works, are brought to the rail 17, the pulley will be ground with the more curvature on its rim. The shaft oo is set in motion, by means of the bevel wheels p and q ; this shaft has an eccentric r upon it, which, by means of the connecting rod s, gives motion to the frame 11mm. By slackening the pincing screw t, the eccentric may be shifted along the shaft o o, and by slackening the pincing screws u and v, it may be shifted along the rod ww, so as to give as much travel to the frame 11 mm as is required. As the frame lmm is always in motion, it might perhaps be better to have a guide round the pulley e, in order to keep the belt on it. After the plummet blocks kk are brought to the place on the rails of the framell mm, which gives the pulley its required curvature, the machine is set in motion, and the pulley is pressed against the stone by means of the handle h. In order to get a very large pulley put into, or taken out of the machine, the rail a must be taken away, by unscrewing the bolts which fix its ends. In the bracket gggg, each of the parts which hold the pins i i has a slit in it, so that, by unscrewing the nuts y y, the pins may be shifted to any end of the slits. One of these slits is seen in fig. 2; it has a check round it to receive a shoulder formed upon the pin. In the frame 11mm each of the parts which hold the bushes for the pins ii, has a slit formed, so that the bushes can be fixed on either end of it; there GRINDING THE RIMS OF PULLIES. are cutter holes placed so that the bushes can have other positions, besides at the ends of the slits. When the bushes are not fixed at any of the ends of the frame Il mm, a gib, as shown in fig. 2, is passed through a set of cutter holes; after this the brasses are brought up against it, and fixed by means of the same cutter which fixes them at the ends of the slits. By having the slits for the pins in the bracket gggg, and the slits for the bushes in the frame 11m m, allows the rails upon which the bracket g ggg slides, as well as other parts of the machine, to be made much shorter than they could be made without them, and some sizes of pulleys could not be ground at all without these slits. The use of the slits in the bracket g g g g is to allow the mandril c c in every position to work clear of the part of this bracket, which has an upright direction fig. 1. The cutter holes in the frame 1 m m must be fitted, so that, in whatever place in the slits the bushes are shifted to, the rails Il and m m will have an upright position, in a view, as per fig. 1; and when the pins i i are shifted to the different ends of the slits, in the bracket gggg, from what they are shown in the figs., these rails of the frame 11mm must have an upright position, in a view, as per the side elevation. It will be seen that fig. 3 is not a complete end view, but is only inter.ded to show some of the parts. If the smallest speed of a cone was made in the form of a pulley, with a flanch cast inside of its rim close to one end; and then, if the next larger speed was cast without arms,but having two flanches, one at each end of its rim, the parts now spoken of could be fixed together so as to form a cone of two speeds, by means of bolts passing through the flanch on the small speed, and one of the flanches on the large speed. On the principle now explained, a third speed could be fixed upon the cone, then a fourth, and so on, till the required number of speeds was put upon it. In a cone having a great many speeds, the largest speed should be cast with arms and a centre, the same as for the small speed. A cone of this construction could be ground upon a machine, as last described, by separating it into speeds, and grinding the smallest one first; then the second smallest speed could be ground after it was bolted upon the smallest speed, and 197 so on, grinding one speed after another, Report of the Committee of the Society Your committee, having attentively considered the drawing and description of this machine, are of opinion that it will produce the required effect. They imagine, however, that there is a considerable defect in the arrangement of the relative positions of the grindstone and of the drum or pulley to be ground. The communication is one of very high merit, and relates to a subject every day becoming more important; the committee, therefore, consider it worth while to criticise minutely the point referred to. In Mr. Whitelaw's arrangement the axes of the drum and of the grindstone are parallel to each other. Two inconveniences result from this:-In the first place there is created a tendency in the drum to follow the motion of the grinder, which causes an undue, though not very considerable, strain on the band or belt which leads the drum. In the next place, there is a tendency to streak the Surface. It is true that arrangements are made to shift the drum length-ways upon the stone, so as to equalize the wear, and to shift the positions of the streaks, but this, in the opinion of your committee, will merely palliate, not effectually correct, the evil. If the axes were placed at right angles to each other, both of these evils would be removed; and if, in addition, the motion of one or other shaft were reversed at intervals, a surface would be produced superior both in general accuracy and in finish. The streaks then would cross each other ob liquely on the drum, and the ultimate result would be a very flat surface; of this, one of your committee has had abundant experience. Mr. Whitelaw's proposed method of rounding pulleys would, no doubt, answer perfectly; indeed, there appears to be no distinction in principle, and as little in practice, between the machine for giving a straight, and that for giving a circular outline; here, also, the cross |