Clamp it with bolts and plates, placing the die in the slot to support any part which does not require to be closed. To open the slot of a quadrant or link that has closed in being hardened:

Take two keys having an equal amount of taper upon them, and place them together so that their outside edges are parallel. In sert them in that part of the slot which requires to be opened, and holding a hammer against the head of one key on one side of the link, drive in the Other key with a hammer on the other side of the link. After the key is driven as far in as the judgment suggests, measure the width of the slot, so that, if the operation was not performed to a sufficient extent on the first at-tempt, the operator may judge how much to essay at the second, and so on. To prevent, as far as possible, a slot link or quadrant from altering its shape in the process of hardening: Fit into the slot, at various parts along its length, pieces of iron of the same diameter as the die intended to work in the slot, and in quenching the quadrant, immerse it endwise and vertically.