In further demonstrating hardening and tempering of tool steel, the making of a flat cold chisel will be considered. The principles involved are about the same in all hardening and tempering.
CHAPTER VII.
Making a Flat Cold Chisel—Spring Tempering—Welding Steel—Case Hardening—Coloring Steel—Annealing—Making a Scratch Awl—Making a Center Punch—Making a Hand Punch—High Speed Steel—Annealing High Speed Steel.
Exercise No. 17.—Flat Cold Chisel.
Fig. 109.
A good cold chisel is an indispensable tool in a shop, and one that is very much abused. Therefore, it should be made with the greatest care. In the forging of a good chisel a piece of ⅝-in. octagonal tool steel, from 75 to 95 point carbon, is used. The piece is cut six inches long. In doing this the bar may be nicked with a chisel. The nicked part is then set over the outer edge of the anvil. A chisel with a handle is set on the nicks and given a good blow with a sledge hammer, shearing the piece from the bar. See [Figure 109]. This method of cutting is quite dangerous, so care must be taken. Perhaps, a less dangerous method, tho not so practical, is to heat the bar red and cut the piece off with a hot chisel and sledge, or on the hardie, if one has no helper. The end is then hammered. See [Figure No. 110].
