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Re: Worm gears
Our team used a McMaster-Carr steel and cast iron worm gear set on last year's robot arm. We used one of AndyMark's nanobox's and a CIM to drive it. This drove a bicycle sprocket and chain to another larger sprocket mounted directly to the arm. Our worm gear set alone did not backdrive and with all the reduction we had very good control and speed, plus plenty of power. The system gave us no problems at all and we didn't even give a thought to efficiency since we had more than enough torque
We did notice some severe action when going from full up to full down, so we spring loaded the arm to reduce the "slam" factor. The arm was balanced by the springs when horizontal, so we actually drove the arm both up and down from horizontal. It worked quite well, and our rookie team was able to hang more than its share of tubes.
Though the weight of the steel.cast iron gears is greater than the plastic, I think I would go with them again, particularly on a drive system. I know the plastic gears work well in the garage door application, but I want to see some data on durability in our robot applications.
Dr. Bob
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