[AdamHeard]

Last night we experienced a weird failure on our arm while we were tuning a PID loop.

We have two 42mm 256:1s on our shoulder joint with further reduction after that. One Fischer price and one banebots.

We were tuning, and therefore some oscillation of the arm was unavoidable.

After some test, we found the arm couldn't move. At all. We removed the chain and found the BB gearbox could spin, the FP one was jammed. We disassembled both and looked inside. The BB was fine, the FP however had sheared about 1/3- 1/2 of the teeth off each of the brass planetary gears in the final stage and had jammed shut. We replaced the damaged gears (The sun and carrier were fine), closed it up and it worked.

What was interesting about all this is that the Double-D joint was fine in both boxes, and had no more backlash than our untouched gearbox.

We found that the BB motor PWM had become loose, so we never gave current to the motor, and therefore were putting to much strain on the FP gearbox. This is just a guess, any insight would be appreciated as we hope this does not ruin this season if it has the potential to reoccur.