EMPLOYEE STATED DURING THE PROCESS OF THREADING CYLINDER SHAFT BACK INTO CLEVIS ON WEIGH-BIN AT THE LOADOUT, THE 15"" CRESCENT WRENCH HE WAS USING SLIPPED OFF CYLINDER SHAFT ALLOWING HIS RIG HT HAND TO STRIKE A PIECE A 2"" ANGLE IRON. EE SUSTAINED LACERATION TO BASE OF HIS RIGHT THUMB REQUIRING 6 SUTURES.