MANUFACTUPvE OF FROST SCREWS. 



161 





b'lG. 118.— Frost screws used by the 

 German army. Measurements 

 in mm. 



36. s 



rod, the shank is formed, the hammer being used at first vigor- 

 ously and afterwards more Hghtly. The chisel head of the 

 screw, which has become somewhat turned up by striking 

 against the front of the mould, 

 is then once more sharpened, 

 and the partially finished screw 

 cut off with the hand-chisel on 

 the front of the anvil. In mak- 

 ing blunt screws a piece of the 

 bar, about ^ an inch in length, is 

 left projecting beyond the mould. 

 The end of the shank is rounded 

 off and the thread cut upon it 

 by means of a screw-cutting 

 machine, which is dropped into 

 the cross channel. A practised 

 smith is said to be able with this mould to produce about 100 

 screws per hour. In form- 

 ing the thread only one 

 screw-cutting machine is 

 required, as, of course, it 

 will take any ordinary size 

 of screw. 



The advantages of well- 

 manufactured screwed shoes 

 are so many that this 

 method deserves preference 

 over any other. The ob- 

 jections that screws are lost, 

 broken, etc., can usually be 

 referred to carelessness in 

 manufacture and the use of 

 bad materials. The use of 

 screws is one of the best 

 methods of roughing. A 

 set of sharp and blunt 

 screws and a small key 

 should be supplied with 

 each set of shoes. 



The screws shown herewith are those most commonly used 



L 



i^..lL.^ 



Fig. 119.— Mould for making screws. Army 

 pattern for field use. 



