Getting the drive system right for the field sorter has been our focus for the last month. Originally we felt that we could adapt a portable 18V electric drill to power the sorter but discovered that the high speed, relatively low torque of a drill motor was not well suited for attaching a drive pulley to drive the round belt and rollers. We started looking for an inexpensive DC motor with the specs that we needed. First we tried a small rotisserie motor ($59.99) which had adequate torque but turned at 50 RPM, which would have taken a very large pulley to step up the speed of the rollers. Next we found a little DC motor with high torque that turned at 192 RPM ($14.75). It was a surplus auto seat motor with a metric worm gear shaft. We have mounted it on the frame and put a 2" pulley on it to drive the round belt. In a test using a fully charged Makita 12V drill battery the motor ran the roller sorter for an hour without loading any clams on the rollers. Next we run the clams.