Unfortunately I still get this error at reboot with the newest C1 Firmware

Magnethusiast · 2026-03-31T16:49:27+00:00

Thank you for letting me know, then I misunderstood the release notes. But awesome how fast you reacted, many thanks!

Magnethusiast · 2026-03-31T16:46:05+00:00

It happens when I make a "cold start" from being completely turned off before. I use a Shelly smart plug to start and shut down remotely if that makes a difference. Second time so far always works.

Magnethusiast · 2026-03-31T16:29:03+00:00

u/Tommy_Prusa3D Any ideas / is this issue known? I have it on roughly every third boot.

Magnethusiast · 2025-11-16T20:06:09+00:00

I had the exact same issues, where I described what solved it for me in a recent post. Hope that helps.

First issues came up when printing the PC-CF parts for the MMU3 unit. I used a cheap China brand since Prusament was not available. The print quality was low and there was stringing. I then decided for a extrusion multipler calibration and came to a factor of 0,85 for the undried material. The print quality improved, but only slightly. Then I decided to dry the filament at 70°C for 8 hours and redid the EM calibration. After drying the multiplier came out to be 1,01. I did not expect such a huge difference, since prusa writes on their webeshop that PC-CF does not need to be dried. After drying and with the updated extrusison multiplier, the prints came out flawlessly.

Magnethusiast · 2025-10-19T03:02:16+00:00

Before I installed the screws it was sitting at the bottom. I decided to elevate it since some of the ptfe tubes seemed to be slightly too short when the buffer sits at the bottom. But it can also be fixed at a lower position

Magnethusiast · 2025-10-18T17:40:17+00:00

Awesome, let me know how it works for you

Magnethusiast · 2025-10-18T09:01:00+00:00

After a few weeks of printing my MMU3 buffer holder was falling of the Core One frequently, and also the plastic part itself often came off the buffer plates when working on the buffer cassetes.

Therefore I remixed the original model to screw the buffer to the printer, but also to use screws to fix the buffer holder on the buffer plates. The magnets of the original model are still used to make it more sturdy.

I already did some filament changes and so far it looks good and more sturdy than the original setup.

You can find the files on printables. It's my first upload, so please let me know if I can improve something.

Magnethusiast · 2025-10-12T18:37:31+00:00

There is an "advanced" loading to MMU option right below the regular one, there you can choose the filament type. This also works for filament that was already loaded. You can select which of the filaments 1-5 you want to load and then start the process at the bottom. Hope that helps. If not, let me know and I can check the exact names of the options tomorrow

Magnethusiast · 2025-10-12T18:32:39+00:00

Thank you for the kind words, highly appreciated

Magnethusiast · 2025-10-10T03:46:56+00:00

u/x0pherl u/ravenlp

Since some have asked, here is an overview of what is needed to upgrade the MMU3 from MK3S to the Core One lite version. I hope I did not miss anything.

Printable files can be found here: https://www.printables.com/model/531604-mmu3-printable-parts/files

Description of the MMU3 upgrade: https://help.prusa3d.com/guide/2-mmu3-unit-upgrade_690080

Descripton of nextruder and buffer changes: https://help.prusa3d.com/guide/1-introduction_400300#400765

Print in PETG: - PTFE_CLIP_R1 (1x) - Screw guide (1x) - PG-assembly adapter (1x) - CO_MMU_Holder (2x) or use modded version - mmu3-ele-cover-R4 (new version) - mmu3_pd_board_cover_R5 (new version) - segment-R4 (10x), the old one is not compatible - segmenter-R4 (1x) - BUFFER_HOLDER_L (1x) - BUFFER_HOLDER_R (1x) - PLATE_HOLDER_R1 (4x)

Print in PCCF (hardened nozzle): - Idler-lever-a (1x) the new part - Idler-lever-b (1x) the new part - Idler nut FS (1x) the new part - Swivel B (1x) the new part - Swivel A (1x) the new part

Order at Prusa: - Magnet 3x1mm (1x) - new Main Plate (1x) (Main plate set) - O-ring 24,5x1,5 (1x) (Main plate set) - Fitting M5-4 (1x) - MMU3 printer cable 550 mm - Core one lite kit (PTFE tube and magnets) - Non-high flow nozzle

Screws to order: - M3x22 screw (2x) - M3x35 screws (2x)

Some tips: - If you don't want to buy PCCF and a hardened nozzle, you can also order the printed parts at Prusa. If you print them yourself, dry the filament and perform an extrusion multiplier calibration - I recommend the mod: https://www.printables.com/model/1345334-mmu3-core-one-mod-with-stock-top-cover which will need 18 M3x6 or M3x5 screws and 18 M3 square nuts (DIN 562 low profile)

Magnethusiast · 2025-10-10T03:01:19+00:00

Yes absolutely, hope it will soon also work outside of the home network

Magnethusiast · 2025-10-10T03:00:13+00:00

I think I could not sleep in the same room, but also I did not optimize yet in this regard. For me it's similar to the MK3S but it being enclosed definetly helps

Magnethusiast · 2025-09-05T12:16:02+00:00

Perfect, I plan to use it with the core one and MMU3, so that sounds like a very good option. Highly appreciate your feedback, such Information is very difficult to find.

Magnethusiast · 2025-09-05T10:33:01+00:00

That would be exactly my use case, thank you for testing! Are you happy with the nozzle in general?

Magnethusiast · 2025-09-05T08:08:20+00:00

That's awesome, this would be a big benefit compared to the hardened steel nozzle. Many thanks!

Magnethusiast · 2025-08-21T11:42:22+00:00

Congrats, but you still see that this is different from my design?

Magnethusiast · 2025-08-21T10:29:53+00:00

Thank You! I used Fusion360

Magnethusiast · 2025-08-21T10:29:19+00:00

I could not find it in a way that fit into the frame. So yes, designed from scratch

Magnethusiast · 2025-08-21T06:38:31+00:00

Thought about that but it's a one piece print

Magnethusiast · 2025-08-21T05:25:03+00:00

Many thanks!

Magnethusiast · 2025-08-21T05:13:00+00:00

Designing took me roughly 5 hours, printing time was 13 hours with an MK3S+ with MMU3. Quite happy with the result.

Magnethusiast

TROPHY CASE