MK4s + MMU3 - filament buffer bypassing for single colour printing.
Hi all,
I’m running a Prusa MK4s and have recently installed the MMU3. I use it for both multi-colour and single-colour prints. I want to simplify filament loading for when I do single coloured printing for colours that are not pre-loaded. I’m considering using a PTFE Y-junction (like those used on Bambu Lab printers) to connect 2 PTFE tubes into one: one from the buffer as normal, and the second PTFE tube connecting to a single spool holder (no buffer), and output into the MMU3. There will only ever be one PTFE tube used at once, so no jamming caused by multiple filaments, and it will only be used for a single colour print job.
Hope that makes sense?
Has anyone tried this kind of setup? Would it interfere with MMU3 operation? Any tips or potential issues you think might arise from this setup?
Thanks in advance!
RE: MK4s + MMU3 - filament buffer bypassing for single colour printing.
I Wouldn't try that option, personally, because the extruder feed 'reverse bowden' tube on the printer with MMU3, has a fairly tortuous life and adding an additional solid section with additional joints in it, is likely to cause feed problems as prints get taller.
additionally you may find the that the Y adapter inside dimensions restrict filament feeding from the MMU3 (re formed filament Tips tend to be larger than 1.75mm )
however, the simplest answer is to try your idea it will not cost a lot, and if successful, you may be able to recommend the idea
I have had MMU1, MMU2 and MMU3, over a long time... and the biggest problem I have noticed is that the ends of the PTFE tubes on the link between the MMU Feeder and the extruder, tend to get grooves worn into them, by the metal teeth inside the 'Festo' connectors. (this eventually makes the PTFE Tubes irremovable and if not replaced can actually cut the end off the PTFE tub with constant rotation)... For ages I considered trying to design rotating connector with bearings in them, but never got round to it...
then I found that Festo actually make these connectors, so I ordered some, and found that the internal dimensions were not large enough to pass 1.75mm filament... Sad...
then I found a similar product on Ali express, I ordered some and I now use one at each end of my reverse bowden tube on MMU3,
however, the extra height caused by the fittings causes collisions with tall prints, so I intend to revise the MMU3 mounting to make more space...
changing any design, is likely to have unexpected repercussions...
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility.Location Halifax UK
RE:
I wanted to achieve a similar thing, the ability to have a wildcard filament run from a dryer. I tried several styles of Y junctions and never got a satisfactory result. The biggest issue was as Joan pointed out, after the filament has been pulled back to the MMU the tips become larger than the filament itself and would jam in the Y junction.
I'm using Filamentalist rewind rollers above the printer which work great but they are not enclosed so sometimes I need to feed a single colour print from my dryer. My current solution is to have a break in the filament feeds so I run PTFE from the rollers to what is essentially a manifold, then a couple of inches below I have another manifold with PTFE to the MMU. This in itself aids loading of the MMU as I can push and pull the filament between the manifolds. Further to that, on the upper manifold I placed two PTFE connectors close together with a single corresponding connector between them in the lower manifold. One of the upper connectors is fed from the rewind roller, the other from the dryer. I can then simply pull back one filament to the air gap and feed the other through the PTFE to MMU. It saves having to remove the PTFE tubes. I use the 5th position purely because that's the side the wildcard filament is fed from, ideally I'd rather it be position 1.
So far, for my use case, it's worked a treat.
