How to make a Cold chisel using Forging ?

 1. Heat one end of the octagon steel bar.

 2. Forge chamfer on head.

 3. Heat other end, forge to flat taper, and then cut off excess metal. 

 4. Turn the chisel a quarter turn and , holding the shank horizontally, hammer the narrow           sides to make them parallel. Alternate the blows, four or five on the wider surface ,               then four or five on the narrow surface, and so on until the chisel is in the shape                    desired.

5. Heat treat and then grind.

Tools used : (1) Anvil, (2) Hammer, (3) Flat Tong, (4) Flatner, and (5) Foot-rule

Hardening and Tempering : 

After the chisel is forged the next operation is annealing. Heat the chisel to a cherry red (a little hotter than dull red) and cool very slowly ordinarily in the air. Annealing serves to relieve , the setup by forging and to give the steel an even, close-grained structure. 

The next step is hardening. Heat the cutting end to a cherry red about 50 mm back from the cutting edge and quench the steel vertically in cold water to a depth of about 25mm moving the chisel up and down during this operation. This movement is to avoid having too sharp a line between the hardened and unhardened portions. If this is not done the piece is liable to crack at the water line. Plunge the whole chisel under water and quickly back nearly out, i.e., out to the 25mm portion that must be left in the water. Remove the chisel from water and dip into the tempering oil. 

Tempering is the next operation. Remove the chisel from the oil bath and polish with a piece of emery cloth. Heat the cutting edge over a flame until the color of the cutting end becomes purple tinged with blue and then cool very slowly in air. 

Finally, grind the cutting edge to the shape and angle desired.