A SCRAPER OPERATOR WAS REMOVING THE CENTER EDGE FROM 657 #16. ONE BOLT WOULD NOT COME OFF SO A WELDER WAS CALLED TO CUT IT OFF. THE WELDER WAS LAYING UNDER THE SCRAPER TO CUT THE NUT OFF. WHEN THE BOLT WAS CUT OFF IT CAUSED THE CUTTING EDGETO FALL ON HIS FOOT CAUSING THE DAMAGE.