An overhead crane was being used with a four leg chain to assist in opening a door to a precast form. The hooks from the rigging equipment were attached to the side of the form. As the crane trolley traversed to the side, the trolley made it to its maximum allowed distance. The crane operator stopped operating at that time. A second employee saw the rigging go slack and placed his hand on the hook to remove it from the form. As he had the hook in his hand, the trolley moved back towards the center on its own while the employee s hand was still on the hook. His middle finger was smashed between the hook and the form, amputating his middle fingertip from the middle of the fingernail to the tip.