Gearbox for mechanism or appendage

[IKE]

500:1 is probably a bit slow if the plan is to mate it to a CIM motor. At free speed, it would go down to 9 RPM or about 7 seconds per revolution. At peak power, it would be about 13 seconds per revolution. An arm sweeping 120 degrees would be between 2.5 and 4 seconds which would seem pretty slow.

The 125:1 & 250:1 arms have me pretty intrigued.

Are you measuring efficiency as "Actual speed / theoretical free speed"?

Richard Wallace and some others might be able to help you with a more accurate efficiency method that you could do.

A string and spool winch with a weight and stopwatch could probably be pretty effective way of measuring efficiency at several torque levels.