Abstract: The limited working region of a numerically controlled machine can be filled to maximum capacity with multiple strips of workpiece stock by providing one or more workpiece holding units each of which has opposed vertical walls between which two or more strips of workpiece stock may be disposed. An expansion device is actuated between the walls to generate outwardly directed forces against the walls and the two or more workpieces. The expansion device has a wedge that is elastically pushed between a plurality of laterally movable jaw pieces to force the jaw pieces apart.