LATCHES, LOCKS, AND FASTENINGS 



109 



CLAMPING SHOES AND PLUGS 



Fig. 167. — Plug may mar the 

 shaft • to the extent that dis- 

 assembling might be impossible. 

 The smooth surfaces of the hole are 

 scored. 



Fig. 168.— The 60-deg. point 

 does not always line up with the 

 bottom of the thread. 



Fig. 169.— a fiat filed or milled 

 on the shaft is an improvement. 

 But the cup point of the screw bites 

 into the flat, and, once a ring is 

 made into the flat, it is hard to get 

 clear of it when the held member 

 must be moved to either side. 



Fig. 170. — A further im- 

 provement is a brass plug 

 making a loose fit with the 

 inside diameter of the 

 threaded hole. 



Fig. 171. — A variation 

 of the preceding construc- 

 tion is obtained by 

 making the plug a press 

 fit in the screw. 



Fig. 172. — Here the 

 side in contact with the 

 shaft makes a full fit, 

 achieved by inserting a 

 reamer into the hub bore 

 and constantly feeding 

 the clamping screw while 

 the reamer is turning. 



Fig. 173. — This is simi- 

 lar to the construction 

 shown in Fig. 172, a tap 

 being used instead of a 

 reamer. 



Fig. 174. — When a 

 longer clamping surface is 

 desired, a slot similar to a 

 key way is cut into .the 

 retaining member. 



Fig. 175. — This construction facilitates 

 the removal of the plug but can be used 

 only when the diameter of the clamping 

 screw is large enough. Freedom of the 

 internal fillister head screw permits the 

 plug to assume its natural position against 

 the shaft. 



Fig. 176. — This shows 

 another method of removing 

 a plug, by first removing the 

 clamping screw and then 

 inserting a small screw to fit 

 the tapped hole. 



Fig. 177. Fig. 178. Fig. 179. 



Figs. 177-179. — In these modifications of the clamping plug, the shoe is assembled after the clamping screw is 

 screwed through the hole. In Figs. 177 and 179, the shoe is retained by spinning or riveting, whereas in Fig. 178 a 

 pin through the hub of the shoe engages the circular half-round groove near the end of the screw. In each case, the 

 shoe bears against the shoulder of the screw. 



