[DaveL]

Most of our lifting arms have been pneumatic. But when I first became a mentor, we didn't know how to do pneumatics and we used a motor to power our arm in 2012.
I learned 2 things really fast; 1) don't rely on your motor's bearings for arm support and 2) any arm faster than full range of motion in under 3 seconds is very dangerous and unlikely to be accurately controlled by humans.

In the off season, we went and rebuilt that arm with a 250:1 Banebots transmission and a 2:1 sprocket reduction. (500:1 total reduction).

We learned the arm is so stiff, we needed to run the motors to move it. What's going to happen when a robot hits it or your robot runs into a wall?

We are trying AM's 50:1 transmission with a 5:1 sprocket on a 2 foot arm (250:1). This transmission has large steel gears that should back drive if hit. Hope that's slow enough without running it at 3 volts!