Good point, I should have included that.
One of them is driving a 24" arm with 12 pounds on the end. It also has a gas shock to counterbalance the weight, so the effective weight should be lower. Without the gas shock, it’s 24 ft-lbs of torque /2 on the chain = 12 ft-lbs. Probably lower than that once the gas shock is added in. 1/2" hex shaft.
The other one is driving a wrist, and I’m not 100% sure what we’re looking at for torque on that. But it’s certainly less than the arm, so if the arm is fine the wrist should be fine.
We will look into doing 70:1, not sure if we’ll have enough output torque then. Potentially dumb question: if 70:1 isn’t enough, would 210:1 (10:1, 7:1, 3:1) be worse or better for gear failure? I know it’s three stage which means the torque on the end is worse, but the output stage would be 3:1, which is the strongest from what I understand.