Rotary hemming units are used to roll form a hem or turn-up on the edge of the fin. A set of pinch rolls pull the material through the machine and are operated by a dancer arm controlled motor. This motor runs at the same speed as the fin machine that provides a smooth supply of material up to the fin machine. It is used with the spacer plates, which can be setup to run a variety of fin sizes to match the tooling in fin machine.