160 



WINTEK SHOEING. 



as given above. Before cutting the thread, which is performed 



with the machine shown in fig. 116, the screws are heated with 



charcoal and the end of the 

 shank filed off square. The 

 screw is then grasped between 

 the claws (a) and the slide-rest 

 (h) advanced until the shank 

 engages the die {c, d) and the 

 latter begins to cut ; the gradu- 

 ating screw (c) serves to fix the 

 position of the two portions of 

 the die, so that the shanks of 

 the screws may be of equal 

 thickness. The thickness of the 

 shank is about -|- an inch, the 



thread is on Wliitworth's scale, for saddle horses a trifie smaller, 



say, -/g- of an inch. 



In England and Denmark screws with a concavity on either 



Fig. 115.— Screws (full size) provided 

 with AVliit worth thread. 



Fig. 116. — Screw-cuttiug machine. «, claws for grasping screw ; b, slides for adjusting the 

 cutting parts of die, c and d; e, set screw for determining the thickness of the finished 

 shank. 



face are also used (fig. 117). In the German army screw^s are 

 largely employed. The shank is about -J- an inch thick and 

 about I" inch long, the screw being formed of square 

 steel bar a trifle more than ^ an inch on either 

 face. The process is as follows : — A mould, speci- 

 ally designed for field use (fig. 119), is carried. The 

 steel bar is first raised to a white heat and the 

 chisel edge roughly sharpened on the beak or horn 

 screw with con- of the auvil by means of the hand-hammer. The 



C3.VG sides 



steel rod is then laid in the hollow part of the 

 mould, so that the chisel head rests against the front. With 

 the help of the forging hammer, and by continually turning the 



