Cutting-off tool
Cutting-off or parting tool: This tool is made for dividing bars of metal into different lengths. The form and dimensions are here shown.
Stock: 7 × 7⁄8 × 7⁄16 in. tool steel.
Bevel one end. Place the other end in the fire and heat about 1 in. Place the fuller on the anvil. Put the top fuller on this, then put the steel between the two fullers about 1⁄2 in. from the end. Using the sledge hammer, drive down so that the centre thickness will measure 1⁄8 in. Draw the lump left on the end to 1⁄8 in. thickness, the same width as the tool. The drawing shows that the clearance on this tool is one half the thickness of the cutting edge, or 1⁄16 in. This clearance must be put on as shown in the drawing, otherwise the tool will not clear while doing the cutting. Finish up as shown in the sketch. Harden and temper in the same way as you did the round nose tool. Cutting off tools are made with the shoulder all on one side. (See [sketch] and see article on [tempering steel].)
XXV
HOW TO HARDEN, SOFTEN, AND STRETCH STEEL
ANNEALING OR SOFTENING OF STEEL
All steels that are worked under hammers and heated to any degree of temperature, when finished should be softened by heating, so that the unequal strains caused by the working of the metal may be neutralized. When the work is entirely finished it is placed in a furnace or forge fire and heated red hot. Then the fire is either withdrawn from the furnace, or the blast is shut off from the forge, and the metal is allowed to cool off as the fire goes down. This softens the metal and saves it from the danger of unequal strains.
Hard or high carbon steels are treated in a different way. The metal is heated red hot, then it is placed in a box filled with slack lime. The lime completely covers the piece. The cold air is prevented from striking it and cooling it off too quickly. When no lime is at hand wood ash can be used.