Filament consistently jamming on retraction
I've had an issue come up that is now happening 100% of the time on single-filament prints with PLA (haven't tried on other materials). When the print is done and it attempts to retract the filament, it will always get jammed inside the extruder. It makes it past the gears, but as you can see in the photo, the tip gets an odd tail that goes to the side, which then blocks it from getting pulled through the hole at the top of the extruder, and requires me to cut the filament off above the extruder and pull the small bit out from the inside.
The prints all complete perfectly. I noticed that the filament settings had been set for the "standard" filament, rather than the settings I use for multi-filament prints. So I did a print with the MMU2S settings, but got the exact same result. Are there any ideas as to what might be creating these odd tails? Thanks!
Filament consistently jamming on retraction
Update in case anyone is interested. I took the front part of the extruder off so I could get a good view of the filament path. I didn’t see anything glaringly off, but I blew out some small bit of filament and put things back together. Not sure if it was one of those bits or if something had been misaligned, but it’s back to extracting normally again.
This should solve the issue...
Ok, common problem. It's your idler sensor. Although I have been running MMUs on two printer successfully over 2.5 years I occasionally stumble upon myself. Exactly what happened to me. I have the advantage of a soldered LED to the idler sensor which is lightyears more accurate than the display. In your case the sensor triggers too early and releases the filament to the MMU gears. Hence ripping the filament tips. These tend to get caught easily either in the plastic body parts (double cone) or in the chimney.
So, simple advice: Do the LED mod and adjust the idler correctly or just adjust the idler by pure luck.
Cheers,
Michael