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mmu2s can't unload filament !!!!  

Active Member
mmu2s can't unload filament !!!!

Hello !

I have a Prusa i3 MK3S+ with a MMU2S installed. For a good while everything was working fine. Here and there I had problems with loading and unloading  but every time I got it working again.

Now my problem is that I have all 5 slots installed with filament but only the first two are working as they should. The third sometimes and the forth and the fifth sometimes don't load and don't unload as they should. I already have checked the alignment of the gears and cleaned the gears inside the MMU2S. 

What I noticed is that sometimes, when I try to unload a filament, it won't as it is somehow stuck (this is what I think) inside the extruder gears. I had been checking the filament sensor status, it said that it would be empty.

Does there exist somehow a checklist or procedure, which when followed correctly resolves all the issues ????

Thanks for any help !

Kind regards !

Posted : 02/04/2022 2:49 pm
Prominent Member

I am not aware of a checklist but then problems can have a lot of different sources. Here are some points I would check. If you have already made sure that the 5 extruder gears are perfectly aligned, also checked with filament acutally in place.

  • Are all 5 extruder gears not only aligned but also cleaned from plastic remains in the gears? (slipping)
  • Are the two screws pressing down the idler equally strong screwed in, ie pressure applied the same left and right?
  • If you have the idler not engaged and all channels loaded at the MMU, try to move the filament manually to the extruder. do all 5 channels feature the same low friction? Change the channels manually with the 3 buttons on the MMU and also check if the selector aligns perfectly well for each channel.
  • Are all idler wheels easy going without higher friction at channels 3-5?
  • Switch the type of filaments you are using around, 1->5, 5->1 etc., is the pattern still the same with 1-2 working reliably and 3-5 sometimes failing?
  • Are the filament tips of all 5 filaments good or stringy, too thick (high friction) etc?
  • At which point of loading/unloading exactly does it fail, is it when the tip is midway in the extruder tube or at another point?

PS: If you have resolved the issue in the meanwhile already, what was the problem?

This post was modified 2 years ago 3 times by Thejiral

Mk3s MMU2s, Voron 0.1, Voron 2.4

Posted : 09/04/2022 10:26 am