268 



APPLIED SCIENCE 



The double-cut files are used fop all kinds of hand-work. The 

 teeth of a rasp are entirely separate. They are round on the 

 top and are formed by raising with a punch, small portions of 

 stock from the flat surface of the file flank. The rasp is used 



FIG. 127. File Cuts. 



(a) Single cut. (6) Double cut. 



(c) Rasps. 



for removing large quantities of stock quickly and will work 

 well on soft metals and even on wood. When a good job is 

 wanted a rasp must be followed up with a file of finer grade. 



Files are made convex, i.e., rounding, as shown in Fig. 

 128, for three reasons : (1) to overcome the effect of the spring 

 down or bending of the file due 

 to the pressure of the hands in 

 making a cut; (2) to overcome FIG. 128. Shape of File, 

 the spring or warp caused by 



heating and hardening the file when made; (3) to make the 

 file bite or cut with only a few teeth in the middle of its length. 



Figure 129 shows the end view of sections of files. A is the flat 

 file, B the hand, C the square the most commonly used D 

 the triangular or 3-square, E the half-round, and F the round. 



