stock roll are not shown mounted to the frame 94 at opposite ends of the supply shaft 96 are a photoelectric sensor 112 and retroreflector 114 for detecting when the amount of remaining stock material on the roll 98 has become low the low stock level sensor 112 is positioned at a radial distance from the shaft 96 and directs an optical signal towards the retroreflector 114 which in the absence of an object lying in the optical path 116 is directed back to the sensor for detection by the sensor when a partially full roll of stock supply material 98 is on the shaft 96 it interrupts the optical path and thus can be detected by the sensor when the amount of stock material on the roll 98 becomes low the diameter of the stock roll becomes small and ceases to interrupt the optical path 116 allowing for the detection by the sensor 112 of the low level of stock material available the sensor 112 generates a signal which is supplied to the controller 32 fig2 indicating whether the supply of stock material is below a determined level a separate photoelectric sensor 118 and corresponding retroreflector 120 are also mounted to the frame 94 for detecting the end of the stock material or end of web the sensor 118 is positioned at a location between the stock.