The loose clamp sometimes referred to as the clamp die, is the moving block used to grip the tube with the bend former during bending. It has a machined form corresponding to the bend former. The amount of gap between the former and the clamp when in the closed position will depend on the thickness of the tube. It is permissible to have a slight pinch on this item to improve grip. The clamp should never be permitted to crush the tube onto the mandrel, especially the ball type. This practice will almost certainly result in damage to the balls and mandrel linkage.