Burning the FP's

[Holtzman]

An FP with the stock gearbox has an optimal efficiency of about 100 rpm. With your two 2:1 reductions your getting about 25 rpm at your arm, or about 150 degrees a second.

Does that correspond with the actually performance you were getting? If so, at that speed, the FP would be stalling with very little actual load. It might be fine with the weight of your arm, but stick a tetra a few feet out, and say hello to the magic smoke.

I would suggest that you try just switching up the sprockets on your arm first, before any major rebuilds. Try two 4:1 reductions, instead of your current two 2:1 reductions. That will give you a little more manageable 6.25 rpm at your arm, or about 37.5 degrees per second and 4 times as much torque.