MMU2S upgrade for MK3S with standard E3D heatbreak?
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MMU2S upgrade for MK3S with standard E3D heatbreak?  

JP Powers
Eminent Member
MMU2S upgrade for MK3S with standard E3D heatbreak?


So, before I pull the trigger on buying a MMU2S upgrade for my MK3S, I'm hoping for some input to avoid any unnecessary trouble.

I had a lot of jamming issues with my MK3S earlier this year that started after upgrading to the MK3S. The end result/solution involved changing the extruder motor, heatsink fan, and most importantly the heat break. The Prusa heat break has an extra gap inline for the MMU2S, but a lot of users suffering jams have solved it by changing to the standard E3D heat break and that's helped solve my problem as well.

Fast forward to today and I now have a number of projects I'd like to work on that would benefit from getting a multi-material upgrade. I've been debating between the MMU2S and a Mosaic Pallette 2. Ultimately, I'd prefer the MMU2S for my Prusa due to how it functions. I mostly am interested in utilizing very different materials and worry the Pallette's splicing method won't work well for it (there is little information I've seen about this and it appears to mostly be for mixing different colors of the same/very similar polymers). However, I do have a FLSun QQ-S delta printer as well and being able to potentially move the Pallette between the two has a certain appeal. The majority of my projects right now would mostly revolve around multi-color PLA so either would work, I just have a lot of ideas that would benefit from mixing PLA, PET-G, and dissolvables and I worry the Pallette might not be able to splice those together well.

Once I solved the jamming issue with my Prusa it's been pretty damn solid. I'm genuinely concerned about the MMU2S introducing new problems, specifically those that might be caused by the things I had to do to work around issues the printer itself had. I understand adding any form of multi-material support will potentially (or quite likely) introduce it's own issues, my concern is those issues being in conflict with previously solved "regular" printer issue solutions. I'm not opposed to swapping the heat break back to the Prusa one, but I'd hate to go through a weekend of building out the upgrade to just spend a week or two with problems that result in switching back to the standard E3D heatbreak then having poor performance from the MMU2S.

I appreciate any insight/suggestions anyone can provide!
Posted : 30/08/2019 4:47 pm
Peter L
Honorable Member
RE: MMU2S upgrade for MK3S with standard E3D heatbreak?

You will most likely have to switch back to the Prusa heatbreak. The reason Prusa uses a nonstandard heatbreak is specifically so the MMU works properly.

Posted : 31/08/2019 10:52 pm
Eminent Member
RE: MMU2S upgrade for MK3S with standard E3D heatbreak?

Alternative to Prusa MK 3 Custom Heat Break

I have a MK2.5S that was upgraded from a MK2.5 and in turn from a MK2.  I added a MMU2S about 3 months ago and have had some good and bad luck getting filament to load all the way to the hot end.  I traced the problem eventually to the size of the tip at the end of the filament that was formed during a previously unload.  The tip diameter measured slightly over 2mm in diameter.  The bottom of the heat break measures exactly 2mm and would not allow the filament to load past the cold end of the heat break.  I think this is why Prusa has a modified heat break (2.2mm ID from Standard 2.0) on the MK 3 but since I upgraded from earlier versions of the i3 I still had the standard E3D heat break.    That having been said, I took a different approach from Pursa and sourced some PTFE tube that had a 1.9mm ID and used it for the heat break liner instead of the 2.0mm standard PTFE ID tube.  The result is a Filament tip of 1.9MM.  I also increased the cooling cycle to 3 in the Sli3er. The filament now loads the next time through the heat break PTFE tube without any difficulty all the way to the hot end tip since the heat break tube diameter of 2mm is comfortably larger that the filament tip.  I have printed a number of Multimedia files without any difficulty and without sourcing a non-standard heat break.  Here is what I sourced:

Posted : 28/12/2019 6:24 pm