Belt material is wrapped around a small diameter mandrel. Instead of cutting the belt to length, the material is then continued to be wrapped around the mandrel, forming a belt material overlap, and held under tension. An ultrasonic welding horn is then traversed across the width of the belt overlap. As this horn is traversed across the overlapped joint, the horn not only joins the belt material wrapped around the mandrel but, as the trailing edge is held under tension, the horn also separates or severs the trailing edge of the material from the welded seam.