This self-made tool is used to bulge small hollow forms, such as tubing, outward from within. Tap the shaft just above the clamped tang end with a small hammer held in the left hand. With each blow of the hammer, the end inserted in the tube vibrates, the ball kicks upward, each time making a bump appear on the tube wall. By watching the position where the bumps appear, and moving the tube accordingly, the bulging can be controlled. The effect of this tool’s action is exactly as if a repousse punch had been used on the open work.
