Thanks for that advice, ericand. Sounds simple, and I've had zero luck finding other stuff on google...
I believe the large sprockets are 96 teeth. Connected to 16 teeth sprockets. #35 chain. the chain hasn't broken
The only problem has been that we initially usedset screws for the small sprockets. We drilled through the shaft and put screws in during the finals at GLR. The main arm is powered by the two keyand motors, the secondary arm by the window motor, and the grabber by the globe motor. The globe (at 180 rpm I think) is WAY slow, though.