Adding MMU3 to Core One, what a nighmare
I recently added an MMU3 unit to my Core One. The experience was a nightmare. Before I start getting negative I want to say I love my Core One. It is a great printer. My issues are only related to the MMU3 “upgrade”.
I ordered my Core One last December with the expectation of being to add multicolor printing with an MMU3 when it was released for the Core One. I was replacing an Bambu X1C with an AMS and hoping to do multicolor printing without the “poop”.
My assembled Core One arrived in March. It worked great out of the box. Absolutely no issues doing single color prints. Changing nozzles was a joy. Great printer.
In June, or so, Prusa released versions of the MMU3 for the Core One. I placed an order. After waiting 4 weeks without getting info about a scheduled ship date, I followed up with support via an online chat. They said there was a delay in shipping the units but they did know the cause of the delay. This was six months after my original order of my Core One. I was not a happy camper.
While looking at the Prusa site I noticed that they had an assembled MMU3 for the MK4s in stock. The also had a MK4s to Core One MMU conversion kit available. Sounded like a good path forward. I canceled my MMU3 order and replaced it the MK4s conversion option.
I assembled the kits without issue. The MMU3 was already assembled but the buffer needed to be setup. This was all external to the printer. Internally the Nextruder needs to be modified. I was a bit pissed that I had to make these changes to a new printer. Since Prusa were requiring these Nextruder changes for MK4s printers with MMU3 last year. Why weren’t those changes incorporated into my printer at the factory.
I make the Nextruder changes and fired everything up. After updating the printer and MMU3 firmware I was ready to try a print.
I tried to load the filament and was unsuccessful. I chose a spool of PLA that was 2/3 empty. The curvature of the filament was such the it would not engage with the mechanism in the MMU. This is the first time I ever encounter a problem with curves in filament. I thought, OK, old filament, try a new spool.
Nest i tried a brand new spool of dry Prusament PETG. This filament had much less curvature but it still got stuck. Initially. It was stuck feeding around the pulley in the buffer. I straightened it out and got past the blockage. Then it got stuck in the MMU. Again, more straightening needed. After many attempts, I got the filament loaded. Way too much work to load brand new filament.
At one point, I thought I would bypass the MMU and use the external spool holder. I researched how to do this and found a paragraph that said that you can do a single external spool print but the unload might fail and a manual unclogging might be needed.
Bottom line, by applying the Nextruder changes I have screwed up my printer. The MMU limits my printers to using 0.4 brass nozzle. If I want to use a different nozzle, I have to use the external spool, but that may fail during unload. Oh, and loading filament into the MMU3 is a real pain due to filament curvature.
What a mess.
I hope the engineers at Prusa who are working on their Netgen solution have access to a Bambu printer with AMS. It is a great example of how easy multicolor printing can be.