Had a go at bolt hobbing tonight. I’m pretty pleased with the outcome although the dimensions aren’t quite right for the i3 wades.
This is the first time I’ve understood hobbing a bolt on a lathe. All it took was one photo.
Glad to be of service!
Looks like 3mm?
M3 tap for 3mm filament.
The reason i ask is i see some people are using a 5mm tap and say they prefer it.
I will try both and report back. I would expect the 3mm to give better traction on the filament and a more consistent feed as it will have more teeth in contact.
Ya i have no experience in doing this, just reporting what i had read in case you didn’t see it. Although i would like to know for future use, thanks
The 5mm tap probably gives more room for slop in the alignment of the hobbing with the filament, considering standard washers aren’t a very small quantized step for spacing.
Good point @Tony_Olivo I’m fortunate to have access to a lathe to make the bolts to suit so i can try a few different sizes and see how well they work. calibrating the e-steps on the extruder might get tedious!
Also, the thread pitch of the tap should be what puts more or less teeth in contact with the filament, not the diameter.
@richard_dorfner This is very true. M3 fine thread is 0.35mm pitch whereas M5 fine is 0.5mm pitch.
AHhh, was not aware of that so Yup. 
Always something new to learn!