R 408.14244 Hammer die keys.

Rule 4244. (1) A hammer die key and shims shall be made from a grade of material which does not crack or splinter when treated. A die key shall project not more than 3 inches in front or in back of the ram or die. (2) A head of a key shall be kept free of mushrooming and splitting by grinding off any flaring. (3) A head of a manual key driver shall be kept free of mushrooming by grinding or machining. A cutting torch shall never be used for this. A driver shall be suspended from a securely fastened beam with chain or cable of sufficient size to handle the weight of the driver plus a safety factor of 5. Chain, cable and fasteners shall be kept free of twisted, bent or elongated links. A driver shall be made of steel that will not chip on impact. (4) A pneumatic key driver is recommended. The driver shall be made of steel that will not chip on impact.