TECHNICIAN WAS HELPING MECHANICS WITH CHANGE OUT OF SHOVEL BUCKET TEETH, WHILE HOLDING PIN DRIVER IN PLACE, HE WAS STRUCK BY A VERY SMALL PIECE OF METAL WHICH CHIPPED OFF PIN DRIVER WHEN IT WAS STRUCK BY SLEDGE HAMMER, PIECE OF METAL ENTERED RIGHT WRIST, PENETRATED ARTERY, AND LODGED AGAINST BONE IN LOWER ARM.