Popular Science Monthly
��769
��Boring a Hole in Glass
WHILE the Wimshurst static ma- chine is one of the most easily constructed mechanisms of its kind, no doubt a good many amateurs are pre- vented from constructing it through the mistaken notion that the glass plates are difficult to drill. This is by no means the case, provided one has
���/y^ J Arrangement for boring hole in glass by means of a lathe
access to a lathe. The difficult part is not in cutting the disk, since any good glazier can do that; but in cutting the hole in the center, for fitting the hub on the machine.
Excellent results can be obtained with the following scheme: Into a piece of copper tube C, Fig. 2, the size of the hole wanted in the glass, drive a block of wood W. This must be a driving fit. Then screw a 5/16-in. wood screw 5 ex- actly in the center of the wood block, as shown, and cut off the head. In order to hold the screw in place, it is advisable to tin the shank of the screw and the edge of the copper tube, and fill it with solder, as shown at L, Fig. 2. This is our boring tool. Next, make a bracket {B, Fig. i), that will slide on the lathe- bed plate. This may be made of wood. Place a center in the chuck and slide the bracket B against it, so as to mark the exact center. Remove the bracket from the lathe, and with a pair of dividers, draw a circle the size of the plates which are to be bored.
Drive two nails on this circumference, as shown at N, N, Fig. 3. Now replace
��the bracket in the lathe, and place the boring tool in the chuck as shown in Fig. I. Place the glass plate on the nails N, N. If all this has been carefully done, the plate will be perfectly cen- tered. Now move the bracket so that the glass plate just touches the boring tool, and exert a gentle pressure with the tailstock.
The cutting is done by applying oil and emery. Since the copper is very soft, the emery becomes embedded in the tube and thus forms an excellent cutter. A rather slow speed is desirable. The best way to apply the emery is to put it in an oil-can with a rather large opening and squirt it into the cut.
It is well to relieve the pressure from time to time to allow the emery to work into the cut. By this means a very clean hole can be cut, and the result will well repay the trouble involved in the mak- ing. — E. C. Meilloret.
Making Shrinkers
IN making the part shown in the illus- tration, much time, as well as steel, may be saved by shrinking on the piece A. Make the shrinkers from a piece of extra-heavy i-in. pipe, having the required outside diameter. The use of pipe obviates the cost of making shrinkers, and a i-in. drill just cleans out the hole. Cut the pipes into the required lengths, leaving a little extra for facing, and then drill them. When a long pipe is drilled and then cut up, a burr is left at each end, which is difficult to remove.
In Fig. I is shown a device, which is very handy for shrinking a piece to be located at some special point. A piece of steel, which has been drilled out and hardened for use in hammering on the shrinkers, is shown in Fig. 2. It will not crack or splinter like an ordinary piece of pipe. — C. Anderson.
��/5p//^ Bushinq
����Device for shrinking a piece of piping into place on a shaft
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