An employee was lifting a mold with a crane. He had rigged the mold using chain slings through eye bolts secured to the mold. He was operating the crane with his right hand and placed his left hand on the chain sling/top of the eye bolt. As the slings became tighter, the chains came together and pinched the end of his left thumb, causing an open fracture of his left thumb tip. His thumb tip had to be surgically amputated.