[Joe Johnson]

350 in-lbs is nothing to sneeze at. And remember that it takes 100's of such cycles to fail the joint.

As others have mentioned, you potentially have some control via software that can help you keep from exceeding this output from the motor side.

Clutches and springs can help you from the arm side.

One way to drive through a spring. Think of a spring in general terms. One Year to save weight, we replaced a section of our arm drive chain with Spectra cable. This cable is very strong (nearly as strong as steel) but it was much much springier. Thing of that.

You can also think of perhaps using #25 chain to drive your arm vs. #35. If my memory serves me well, #25 chain breaks at 800 lbs or so rather than 3500 lbs or more for #35 chain, if you use a half inch sprocket radius for the output of the gearbox, the chain will break before the gearbox gets damaged -- not fun but at least you'd be alive again quickly.

Finally, you can back calculate what force on your arm will cause the joint to see 350 in-lbs or more. Is it reasonable that such a force would occur? If so, would it be enough to cause an instant failure or just a slight widenning of the bowtie. The second you can live with if it doesn't happen too often, the first one is something to worry about.

Joe J.