CORE One MMU3 Filament Blobs around Gear
Hi everyone,
I recently installed the MMU3 on my Prusa Core One and I’m struggling with a recurring issue during filament unloading. After a short while, the filament tip tends to wrap itself around the extruder gear. It then gets jammed between the gear and the main plate, which blocks the unloading process.
This happens with different filament brands and regardless of which slot the filament comes from, so it doesn’t seem to be filament-specific.
Another thing I noticed: my extruder gear has a bit of play and can move slightly from left to right. I suspect that it might be sitting too far to the right, which creates a small gap on the left side where the filament tip could catch. I’m not sure though – some amount of play is probably normal.
Has anyone else experienced this issue? Are there known causes or fixes (e.g. gear alignment, retraction settings, mods)?
Any advice would be much appreciated!
Thanks in advance,
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RE: CORE One MMU3 Filament Blobs around Gear
1 pic
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RE: CORE One MMU3 Filament Blobs around Gear
Seems there could be a bind or heavy resistance of some type while unloading. It appears it isn't tripping the sensor to stop the unload and the gear keeps unloading. May need details on filament type, heat etc.
Some things to check from my experiences with MMU unloading. Redo the nextruder Filament sensor calibration. Is the idler too loose or too tight? The correct filament and nozzle temperature is being used. The heat break fan is running at correct RPM. Do the fan checks. Check the menu settings are correct for the MMU. Make sure the magnet holder for the MMU based filament sensor is in place correctly and moves smoothly.
Does this happen when ejecting after reaching the end of a roll of filament? Is there a kink on the end of the filament used for winding? Kinks can cause drag or jams an mess up the unloading.
I use a Modified main plate that encapsolates the filament better. https://www.printables.com/model/1165633-mk4mk4s-with-mmu-main-plate-with-improvements I used PC-CF to print it. It will need something better than PETG. There are a few variations. You need the MMU based one.
RE: CORE One MMU3 Filament Blobs around Gear
Also make sure the PTFE tube from the MMU to the Nextruder is the correct length and the correct length choice is set in the CoreOne menu settings.