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Unread 11-03-2013, 16:14
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Re: Nightmare Repairs At Competition

Quote:
Originally Posted by AdamHeard View Post
Curious, can you post the gearing spec on your arm? Every reduction + motor.

Then also the distance to CG of the robot from arm pivot, and the weight of the non-arm portions of the robot?

For random knowledge, the trick of dropping a tooth will work in a pinch on most gear setups, but you introduce a LOT of backlash and I wouldn't recommend it for high speed systems w/ lots of loaded direction change.
Sure, I'd be happy to. We are well aware that we heavily exceeded a reasonable load on an aluminum pinion.

Input: CIM
Gear Reductions: TB3 Reductions (15:60, 14:50, 14:50) followed by two custom reductions (20:84 20:84). The pinion that failed was the final 20 tooth pinion. TB3 gears are steel as is the first 20T pinion, only the final 20T pinion was aluminum. No, that isn't backwards.

The arm failed both times when attempting to hang. Hanging hooks are roughly 2 feet from the pivot point. Base weight is about 75 pounds. I would say the CG is probably six inches forward of the pivot point (yes, it's far back).
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Last edited by Chris is me : 11-03-2013 at 18:12.
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