A summarized collection of constructive threads to restart using the MMU2.
 
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John S.
(@john-s-3)
New Member
A summarized collection of constructive threads to restart using the MMU2.

Dear Community,

I purchased the original MMU, the MMU2 as well as Prusa MK2, MK3, MK3S, and MK3S+ printers.  The printers are phenomenal.  The MMU_ units are foiled with headache after headache.  I switched to Mosaic 2Pro and it does work well, but I want the MMU2 option functional.

In an attempt to reconnect the MMU2 to the MK3S is there a filtered list of threads/instructions to minimize the efforts?  Some threads in the past have indicated better bowden tube connections/sizes, wall thicknesses.  Other threads have had minor 3D printed parts for smoother feeding, etc.  However, having tried most of these, I've simply not had a successful print with the MMU2 and I'm not talking about hours of trying, I've been toying with options for months, but to no avail.  

Can someone provide a good suggested pathway to successful MMU2 prints?

Thanks.

 

Posted : 10/03/2022 2:31 pm
gnat
 gnat
(@gnat)
Noble Member
RE: A summarized collection of constructive threads to restart using the MMU2.
  • Do the IR LED mod if you haven't (thread is in the mod sub forum). This let's you get a better idea of what the IR sensor is doing either when the printer won't let you into the support menu or the state changes are too fast to register on the LCD.
  • Go in baby steps.
    • Do the extruder changes and then go back to printing as a normal non-MMU printer until you are getting through prints with no false filament runouts.
    • Use the short tubes on the back of the MMU and do a series of single tool prints using each tool until that is reliable.
    • Add in your filament management (e.g. buffer, rewind spools, etc..) and repeat the single tool prints through all the tools.
    • Do a series of 2 tool prints that test all the combinations of the tools (e.g. 1-2, 1-3, 1-4, 1-5, 2-3, 2-4, etc..).
    • Now do the same for 3 tools.
    • 4 tools
    • Finally a 5 tool.
  • Replace the PTFE tubes with something better. Either a higher quality like the Capricorn XS ($$$$) or a larger ID. The ID tolerances in Prusa's tubes are terrible and they like to kink if you aren't careful.
  • Eliminate friction. Replacing the PTFE entries on the back of MMU and the entrances and exits of the buffer with pass through festos is a good step as the factory setup is way too easy to crush the tube without realizing it.
  • Keep any curves in the PTFE to a minimum and make them as gentle as possible.
  • Bind (without pinching) the long tubes together in a bundle so that they prevent each other from moving. This is especially important during unloads.
MMU tips and troubleshooting
Posted : 14/03/2022 2:46 pm
John S.
(@john-s-3)
New Member
Topic starter answered:
RE: A summarized collection of constructive threads to restart using the MMU2.

Thank you, I'll go thru these.  Appreciate it. 

Posted : 14/03/2022 3:01 pm
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