AIDS TO GARAGE EFFICIENCY.
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Two of Our Mechanic Readers Contribute Details of Some Useful Devices They Have Employed for Securing Efficiency.
SOME extremely useful hints to the garage mechanic are embodied in a letter from "KR." of Bath, and each of them. is accompanied by a clear and informative sketch. They are all concerned with extra fittings .and gadgets, the possession and use of which is a great help to the man who has to _do the _best he can with somewhat sparse equipment which the usual every-day garage affords, but every one of them is well worthyof the notice of the machine or bench hand in the most advanced and modern .workshop.
The first of. these hints refers to a vice-fitting to enable thin objects, always difficult to hold securely and without damage in tlffi machine vice, to be gripped efficiently. The device consists
of two strips, accurately cut at the top te a neat square shoulder, so as to hold the work without tilting it. These strips are kept apart at the bottom by a block, as shown, secured by a couple of screws which pass right through from one strip to the other as well as through the block. By the substitution of narrower or wider blocks, work of varying width may be dealt with. Equipment of this kind is most useful in connection with work which has to be milled, ground or shaped.
The sketch above shows a simple form of stop to regulate the depth of a bored hole. Useful at all times when a hole has to be bored, it is patticularly valuable in connection with repetition work. It is assumed that the hole is being bored in the lathe, the boring bar being held in the Slide rest. Into the front of the rest a setscrew should be fitted and furnished with a lock-nut. The setscrew is set so that its head is at a measured distance from the point of the tool, the distance depending, of course, on the depth of the hole and the length of the bar. Raving set it, lock it by means of the lock-nut, and go ahead with the boring. When the head of the screw comes against the work the hole is bored to the correct depth.
A useful safety guard for the setscrew of a lathe-dog is the subject of the next sketch. A cap of suitable dimensions is bored to fit the boss on the dog rather tightly. The outside is neatly turned and knurled, and the cap is then slit at one side, the slit being terminated by a small drilled hole, as shown. The fitting 'can be forced over the neck of the carrier after tightening the screw on the work, and there is then nothing to catch the fingers or clothing.
When a hole has to be bored out with bar and cutter on the vertical drill, the usual method of steadying the lower end of the bar is a bush fitted into the centre of the table. Should there be no hole in the latter large enough to serve this purpose, an arrangement such as that shown in the fourth of these sketches can be rigged itp, and will be found to act as a satisfactory substitute. The necessary parts consist of four packing blocks, with a washer, which has a
tole into which the bar fits, sandwiched 'n between them as shown. The work is aid on to the top of this edifice, and clamped down in the usual manner. In the sketch a double-ended .cutter shown, but for odd jobs it is often more convenient to use a single-ended one,
adjusted to the exact size of the hole which is to be bored. Correct fitting is most important, as any slackness will cause the cutter to chatter and result in uneven and over-sized bores KEYWAY-CUTTING is an operation which has its special difficulties, and they are emphasized in the case of the garage hand who has not much in the way of machine-tool equipment on which he can draw. Yet it frequently happens that keywayis have to be cut, or widened, or otherwise repaired, generally at short notice. Often a new shaft is delivered without the keyways having been cut, or, again, a job will come in for repair and one of the parts required will be a new shaft, easy enough to make in the lathe, and a straight-forward job altogether but for that keyway in the end, for which the mechanic has no tools.
The usual garage machine-tool equipment is confined to the lathe and drill— nothing more, and in such cases the knowledge of how to use the former machine as a keyway cutter cannot fail to be of interest. We have no doubt, therefore, that many readers will appreciate the following hint from " of Cleckheaton, describing howhe manages to do this class of work on an ordinary lathe and in quite an efficient manner.
In his letter he starts by assuming that a keyway I-in. wide by 4-ins. long has to be cut. The first thing to do is to drill a series of holes, touching one another, for the full length of the key nay. Then procure an old drill which has been broken close to the shank and grind its cutting end dead square. Back off the two lips, as is done with an end mill or recessing drill. Put this tool in the lathe chuck and mount the shaft in the tool-holder of the top slide rest, packing it up carefully until the centre of the shaft is in line with the centre of The lathe, and the proposed key• way faces the chuck in which the im provised end mill is held. Clamp it securely in that position. Now, by using the top slide to feed the shaft up to the tool, and the cross slide to traverse across the tool, the keyway can readily be cut to the required depth and length. Emphasis must he placed on the import. since of drilling the holes exactly in line.