Quote:
Originally Posted by JesseK
You know the drill: video, or it's a bench grinder...
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I briefly considered this, then decided I'm not evil.
A video of it working (10:1 planetary, followed by a 33:1 cycloidal stage):
https://www.youtube.com/watch?v=ArUGM51HFVs
A video of a basic anti-backdrive test:
https://www.youtube.com/watch?v=tG_l...ature=youtu.be
I changed the design to use 1/16" pins around the periphery, and found that let me get 33:1 into a single package. I made this one all custom, but the next revision just requires a carrier plate from a 7:1 instead of the modified carrier I had to make (thanks to 649 MSET-Fish for providing 7:1 carriers!)
The noise level is high because the way I machined the housings, I neglected to centerdrill the pin holes before final drilling, resulting in holes that are all very off. The lasercut wobble gears I am using are now too large because of this, and so run very noisy. I will remake the housings next to fix the issue.
Right now I would estimate the maximum non-backdrive torque before the gears slip is around 25 foot-pounds, which is quite low, and the failure mode is that the gears go skew on the shaft as the plastic bores get larger than the shaft over time. Replacing the plastic or using some extra shims to prevent bending on the shafts should fix the issue, but we'll see.
The wobble gears will be replaced with aluminum for some more realistic torque tests soon, and then replaced with steel for the final cuts. For the immediate future, I can get slightly smaller gears lasercut to run it quieter.
As a neat sidenote, I made the offset shafts using a boring head with a backwards boring bar in the mill. At this point I can start from a bar of 3/8" round and turn it into a shaft in around 45 minutes.