MMU2S idler screws coming loose
I am having an issue where the two screws that secure the idler onto the stepper motor shaft are coming loose. This causes the filament to not unload on a color change. When I tighten the screws down it works for awhile but then they come loose again and the filament won't unload.
I don't want to tighten them too much as I am afraid I will crack the plastic. I did that originally when I first assembled it and had to reprint the idler.
I do find it odd that regular screws are being used as set screws.
Any suggestions on why the screws keep coming loose and how to fix the issue?
RE: MMU2S idler screws coming loose
might just be a tolerance issue between the bolt and nut. Could try replacing the nut for one of the spares. You could also apply some medium strength thread-locker to the bolt .
RE: MMU2S idler screws coming loose
Watch this 5 mins 11secs into the video!
Same issue as you have seen. This chap seems to think that heat from the idler stepper is causing the screws to slowly become loose. He reprinted his idler in polycarbonate to be more heat resistant.
RE: MMU2S idler screws coming loose
Interesting. Not sure I want to print with polycarbonate.
I found a modified version of the idler that adds a gear. I might give it a go.
RE: MMU2S idler screws coming loose
ABS or ASA might suffice, usually a bit more temperature resistant than PETG.