First tests of my #modulecnc axis are done. New coupler working very well 
“Stl” files available on thingiverse.
You know when you put things in quotes like that, it means the opposite of what you’re saying, right? So by saying “stls” you’re saying, they’re not really STL formatted files, they’re something else.
I didn’t knew that. English isn’t my native language so I can make mistakes sometimes. Eeveryone can. Necessary files are on thingiverse. Is that ok for you @ThantiK ? Nevertheless thank you for this suggestion.
No worries, any file repository is great. 
I’d expect that coupler to be quite elastic around its rotational axis, which would lead to “a bit” of backlash under load. Have you tested it with e.g. a z-axis that needs to lift some weight?
@Thomas_Sanladerer actually means a lot of backlash. I see what you did there, lol. It actually might be better off in the z direction as the resistance toque is more or less constant, as long as he’s not lifting to much. If he’s just lettering the bed one layer at a time, it might be ok. It probably does need more rigidity though, which should be a simple matter of adding more columns or thickening the ones he has
Is there any reason you didn’t try a traditional “love-joy” connector. With the new flexible filaments the internal compression piece could be printed.