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 



