FIG. 87.—Be sure that the tool is absolutely straight at the bottom, so as to lie flat in the tool-post.
FIG. 88.—This is the finished forged tool, and let this grow cold by itself, the slower the better. It is well to cool the tool slowly in hot ashes, to remove all forging strain. You can now grind the tool dry on a sharp emery wheel. The more you now finish the tool in grinding, the less there is to come off after hardening.
In hardening place the tool in a coke fire (hollow fire if possible) with a slow blast and heat gradually up to a white welding heat on the nose of the tool. Then dip the white hot part only into thin oil or hold in a strong cold air blast. When hardening in oil do not hold the tool in one place but keep it moving so that it cools as quickly as possible. It is not necessary to draw the temper after hardening these tools.
FIG. 89.—This tool is ground, ready for hardening. Never harden from the forging heat.
FIG. 90.—Heat the nose of the tool only up to dotted line, very slowly and thoroughly to an absolutely white welding heat, so that it shows a trifle fused around the edges, and be very sure that this fusing has gone thoroughly through the nose, otherwise the fusing effect will be taken off after the second grinding. Note the difference of the nose between this and Fig. 86.
