INJURED WAS USING 6 POUND HAMMER TO POUND A DRIVE SHAFT INTO POSITION ON A MACK WATERTRUCK. THE END OF THE DRIVE SHAFT DROPPED AND WHEN INJURED SWUNG HE CAUGHT HIS THUMB BETWEEN THE END OF THE DRIVE SHAFT AND THE HANDLE OF THE HAMMER CAUSING A INJURY TO HIS RIGHT THUMB, EMPLOYEE IS A CONTRACTOR WORKING FOR AJM CORP.