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Prints no longer stick after mmu2s upgrade  

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Prints no longer stick after mmu2s upgrade

So we'll do a quick tl;dr:

-prusa slicer, standard pla .15mm quality settings, brand new prusament pla filament

-upgraded from mk3s (ran like a flawless top) -> mmu2s

-reduced ptfe tube drag as much as possible

-switched to steel hot end

-ran preflight calibration all over again

-(non-stop prints keep pulling off the bed mid print)

-made sure nothing is lower than the nozzle

-completely replace hot end assembly, swapped in steel nozzle, got a textured print bed

-re-ran pre-flight calibration

-still same issue

-Tried: decreasing slicer layer height, used the printer's tune flow rate up


I'm completely stumped... I have no clue what I can do at this point other than rip the mmu2s off the thing and go back to when it ran without issue. I'm open to any help, I can video tape the thing and link the video, try out any test print. For starters I have pictures of one of a dozen attempts at a benchy, started printing just fine if not a little bit of an elephants foot (should have helped bed adhesion), then I hear a pop 30 mins in and the thing is off the bed, I hit pause print and took the pictures. I can only find success stories and minor struggles with the mmu2s, what did I do wrong here? I can't even get a single filament print to work, let alone a please!


This topic was modified 2 years ago 2 times by alex.l23
Posted : 24/08/2019 5:02 pm
New Member
Topic starter answered:
RE: Prints no longer stick after mmu2s upgrade


It appears it might have been a burr on the nozzle or a loose heater block. 

After finding cases of hardened steel nozzles with burrs on the end causing extruded plastic to twist back around and stick to the outside of the tip I've replaced the steel nozzle with the original brass nozzle. Either while changing it, or during a previous swap, I loosened the heater block from the heat break, causing a wobbly nozzle end.

Further testing required, but the lesson for today is always make sure you retighten everything you work on!

Posted : 26/08/2019 3:01 am