DIY direct drive mount

[EarthLife]

5 hours ago, Robindonne said:

Interesting!   I have for some months some items in my wishlist.  Time to dive in this project is what keeps me from ordering.   Last thing i remember was planning to stack two harmonic drives to  get to a high resolution….. 

€ 139,35 | Harmonische Drive CSF-25 Reducer Lager 20*85*18.5Mm Voor Csf CSG-25 Draaikrans Zengkun China
https://a.aliexpress.com/_vTjDFw

£98 for a harmonic drive such as that particular sounds like a good price !   They don't mention backlash levels, but I've seen other manufactures elsewhere state 'zero backlash', which is interesting as I never knew that.

DIY'ability, backlash, stiction, simplicity, smoothness, cog'less, linear-torque, reaction speed etc were the reasons I decided on a direct drive, I don't have any experience of using harmonic drives. Robot designers seem to really like them, I'm assuming it's what's used in industrial robot arms. Any level of backlash free gearing makes accurate position sensing easier as well.