264 



APPLIED SCIENCE 



tool steel 8 in. long. After the chisel is forged (hammered 

 in a hot condition) to the required shape, the end is hardened 

 by drawing the temper (heating) to a purple color. There 

 are three elements to be considered in making a good chisel, 

 namely, shape, temper, and cutting edge. Chisels must be 

 forged and tempered at a low heat, as a high heat will burn 

 the steel (burn the carbon out of the steel). 



v y 



(a) (&) (c) (d) (e) 

 (a) Flat Chisel (Side View). 

 (6) Flat Chisel (Front View). 



(c) Flat Chisel with Curved Edge. 



(d) Cape Chisel (Side View). 



(e) Cape Chisel (Front View). 



(/) (0) (A) () (J) 

 (/) Gouge Chisel. 



(0) Diamond-Point Chisel. 

 (h) Round-Nose Chisel. 



(1) Side Chisel (Front View). 

 (j) Side Chisel (Side View). 



FIG. 124. Chisels. 



Chisels made for use in the pneumatic hammer are longer 

 than hand-driven chisels. The shanks are fitted to the 

 holder or socket in the hammer and the chisel head should 

 be tempered to keep it from upsetting. Ordinary chisels 

 should never be used in the pneumatic hammer. The flat 

 chisel (Fig. 124, a and b) is the form most commonly used. 

 The cutting edge is generally drawn out about Y% in. wider 

 than the stock from which it is made and then ground to an 

 angle of 60. For cutting soft metal the angles should be 

 less; 30 for lead or Babbitt metal (a soft mixture of metals), 



