InMoov bicep rotGear/rotWorm replacement (lower ratio) *experimental*
I didn't like the idea of using continuous-rotation servos in my InMoov project, but was unhappy with the ratio in the standard InMoov rotGear/rotWorm, so I created my own. This is very experimental (call it alpha)- so I'm looking for feedback!
More info here: http://mhespenh.ninja/replacement-worm-gearset/
What is it?
This is a 2.5:1 drop-in replacement for the stock InMoov rotGear and rotWorm (and a spacer). This will rotate the big gear once every 2.5 rotations of the servo, so a normal 180° servo going end-to-end will rotate the big gear ~72°. I don't know exactly what the ratio on the stock gears are, but it appears to be around 15:1.
gearSpacer goes between rotGear and rotTit, tabs face towards the rotGear (flat side towards rotTit)- you can glue the spacer to rotGear if you want. [See second photo]
This will only fit in the bicep- I'll upload a version for the shoulder soon.
A few disclaimers
- I have done very little testing of these gears, so use at your own risk! Please provide feedback if you use them!
- You will lose a LOT of stall torque with this setup by virtue of the gear ratios, so this is a conscious trade-off: Speed for power. (IE: you can easily rotate the servo-end by turning the big-gear, which you can't (easily) with the stock setup).
- This gear train is way more sensitive to friction/sloppy printing than the stock setup, so you need to have your printer working well to get this to run smoothly.
Update history
- 06 June 2015: Initial commit
- 07 June 2015: Uploaded corrected STLs (previously were oriented incorrectly, otherwise unchanged)
- 07 June 2015: Added gearSpacer as a shim to force gear and worm into alignment when under pressure of arm hanging off it.