Redesign, 36mm question.

[jgannon]

In another thread, Dr. Joe said that the 36mm may fail with repeated use with as little as 100in-lbs of torque. You want to use two, so you safely have 200in-lbs at your disposal. A 5ft arm that weighs 15lbs and is uniformly distributed weighs 0.25 lb/in. Integrate from 0-60, and you get 450in-lbs. You'll need to add more to that, because your weight is not uniformly distributed (due to your gripper at the end), and you'll have to add 60*(tube weight) to account for actually manipulating a game piece. Roughly estimating, I'm thinking that the 11:30 reduction is cutting it way too close to be safely operating your arm. A bigger sprocket at the top (the IFI 60 or 72) may work, but as others have mentioned, you still have the backdriving problem. My team is taking our chances with that, but you may not want to.