Abstract: Employee #1 was being shown how to operate a Farrel 4620 crack mill machine, 1910-20 model, that flattens scrap rubber into a sheet. It has an emergency trip wire 68 in. from the floor across the top and sides of the rollers and a belly bar across the front of the rollers. Rollers are 3 to 4 ft wide and run at 140 feet per minute. Employee #1 was instructed by a coworker to stand back and watch the process. The coworker started to feed scrap ("wig wag") into the machine and jogged to a point where the tail had to be placed under or on top of the front of the sheet to complete an end-to-end round sheet. Employee #1 placed his hand on the tail end to help it catch. He got his hand caught in the nip point under the material and was pulled into the machine. The coworker hit the trip wire to stop the machine. Employee #1 was transported to hospital, where his left arm was amputated between the wrist and elbow.