Migrating MMU3 from Mk3S+ to Core One? - General discussion, announcements and releases

RE:

What-ever — Mon, 13 Oct 2025 11:10:12 +0000

When I upgraded my Mk4 to an Mk4S I do not remember having to upgrade any part for the MMU.

Assembly manual for the upgrade :
https://help.prusa3d.com/manual/original-prusa-mk4-mk3-9-to-mk4s-mk3-9s-upgrade_2186

The Y axis upgrade is not important.
The LCD upgrade is only the faceplate (cosmetic) so not important

The Nextruder upgrades :
Nextruder faceplate (With the Mk4 name) , mostly cosmetic but the Core One has its own face plate so no problem?
The Part Cooling Fan : the new part cooling fan is re-used in the Core One so no problem expected.
A high flow nozzle is installed , for the MMU a normal flow nozzle is advised
Check the bowden couplers as Prusa advises here :
https://help.prusa3d.com/guide/1-conversion_793793#898178

Upgrading connectivity , these parts are also used on a Core One.

So my conclusion was : If you already have the filament detection parts updates on your Mk4 the MMU should also work on the Core One
The printable parts for this update can be found here :
https://www.printables.com/model/531604-mmu3-printable-parts/files
Inside the folder : CORE ONE & MK4 & MK3.9 Nextruder parts - R2
So if you have the parts for this upgrade (it does use a few NON printable parts) it should work

The Core One nextruder upgrade is doen in this assemblt manual step :
https://help.prusa3d.com/guide/9d-core-one-nextruder-mod_111779
So you can check if you have all NON Printable parts.

The only question I have is if the original Buddy Board to MMU3 cable is long enough.
But the conversion kit does not have a new cable so I guess it is long enough.

(Edited to add Cone One nextruder assembly manual)

RE: Migrating MMU3 from Mk3S+ to Core One?

Koos — Tue, 30 Sep 2025 10:03:10 +0000

I have the same question

Migrating MMU3 from Mk3S+ to Core One?

Patronics — Mon, 11 Aug 2025 05:16:23 +0000

I think it's finally time to bite the bullet and replace my old Mk3S+ with a new Core One. I already have the MMU3 unit for my Mk3, and I'd like to transfer that over to the Core One. I was surprised to find there doesn't seem to be any official instructions for that transition, though there are instructions for transferring the MMU3 from the Mk3S+ to a Mk4, and from a Mk4 to a Core One.

The instructions for the Mk4 to Core One transfer mention that "Core One is only compatible with the latest versions of the MMU3 units, specifically those used on the MK4/S". So does that mean there's no viable upgrade path? The comments on that page seem to imply the only difference is the color and size of the fittings, which can be replaced. Though I know the wiring harness is different for the Mk3 as well, but that can likewise be replaced. I suspect that those items, in addition to the MMU3 Conversion Kit for Core One might be the only parts I need? Maybe also a new PTFE tube? Has anyone else attempted this particular process? Is there anything else I'm overlooking, or some fundamental issue making this upgrade impossible?

Thanks in advance!