[MrForbes]

Might work...but I didn't crunch the numbers! Sounds reasonable.

As Adam mentioned, play it safe. If that reduction gives you 25% or less motor loading, and you have factored in the losses in the transmission (figure up to 50% torque loss to friction with a 3 stage planetary), then it should be fine. But also keep in mind that if the arm can travel to it's stop and the motor is still powered, the motor will smoke. You need to make sure the control system has limit switches, etc. or build in some type of "clutch". We had a clutch type system on our 2009 robot on a part that was driven by a small BB motor and gearbox--it powered a V belt for the last reduction stage, and the belt would slip when it reached the end of travel. We had no problems with that little BB motor either!