Tricks of the Trade 



A simple means of driving taps by power 

 and a small vise for the work bench 



Homemade Power Tapping Machine 

 for Rapid Work 



AS it was necessary to tap several 

 xV thousand 34-in. holes in many 

 cast iron fittings some means of driving 

 the tap had to be provided. There was 

 no tapping machine in the small shop, but 



WOOD PULLEYS - 

 LOOSE ON TUBE--^ 



BAB B ITEmMTO TUBE 



-^ WOOD BASE 



Opposite revolving pulleys drive the tap in 

 either direction according to the pressure 



the foreman was equal to the occasion 

 and quickly made the tap driver shown 

 in the illustration. The shaft was made 

 from a piece of steel tube about 6 in. long 

 and ^4 in. outside diameter. Two wood 

 pulleys were fitted to this shaft, one on 

 each side of the bearing or support. One 

 of the pulleys was turned to 3 in, in 

 diameter and the other to a 2-in. diameter. 

 A countersunk washer was fitted into the 

 two outside faces of these two wheels and 

 the edges of the pipe were beaded out to 

 prevent them from slipping off. 



Before attaching the pulleys, a piece of 

 cold rolled shafting ^^ in. in diameter was 

 centrally babbited into the tube. This 

 shaft was then provided mth a central 

 hole at one end to accommodate a tap, 

 which was secured with a grub screw set 

 into a slight depression ground into the 

 tap shank. The shaft is provided with a 

 carrier or dog at each end as shown. 

 These dogs engage with the pins fitted 

 into the outside surfaces of the pulleys. 



The shaft is arranged to slide axially 

 inside the tube, the amount of the sliding 

 motion being so proportioned that when 

 one set of pins engages one of the dogs, 



the other set of pins is disengaged. 



The smaller pulley was used to drive 

 forward and the larger one for backing 

 up. It will be seen that on pressing the 

 work on the tap, the shaft is pushed back 

 and so engages the pins at the front of the 

 machine on the small pulley. Pulling 

 outward on the work draws the shaft out 

 and thus disengages itself from the pins 

 on the small wheel and immediately en- 

 gages with those on the large wheel, 

 which revolves in the opposite direction, 

 backing the tap out of the piece. 



The tube was held stationary in a 

 wooden block fastened to the bench. 

 One of the belts was crossed. The sur- 

 faces of the pins where they engage were 

 filed flat to make them act promptly. — 

 John L. Allen. 



A Homemade Bench Vise for 

 Small Work 



THE illustration shows a cheap and 

 quickly-made small vise for the 

 model maker. It is suitable for any 

 medium and light work. The vise is made 

 from two pieces of band iron 1 }.4 in. wide 

 and ^^ in. thick, with the jaw A bent as 



NfllL ID BC USED ^5 LEVEfS 



16 



Cr\P 3Cf5EW 

 PIM 



5 BRASS in 

 WflSMEe i 



y "^nOLE 



15 WOOD 5CEC 



' 5' 



WOOD WORK BENCM 



Two pieces of metal and a cap screw with 

 guide pin makes a model maker's vise 



shown and the jaw B cut straight, with 

 two holes drilled in it. The top hole is 

 13/16 in. in diameter and the one matching 

 it in the top of the jaw A is ^ in. in 



785 



