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MK4 main plate wearing out?  

Tom Horsley
Trusted Member
MK4 main plate wearing out?

We are told that the new MK4 nextruder main plate may need replacing after enough bazillions of filament changes. Just curious what symptoms to expect if I ever use it enough to wear it out? Be nice to recognize it instead of being confused for days.

Posted : 11/05/2024 5:24 pm
Trusted Member
RE: MK4 main plate wearing out?

You'd have problems with loading the filament. With the MMU3 I received two new FDM-printed main plates. I guess they hard more wearing resistant, otherwise I don't klnow why they would have fabricated them that way. My printer and MMU3 are currently working fine and I'm working the machine hard :-). Will let you know if I experience any troubles, but I'm pleased that I have at least one extra main plate in spare parts collection already!


Posted : 11/05/2024 5:51 pm
Estimable Member
RE: MK4 main plate wearing out?

I think that if you use your printer moderately the main plate should last a very long time before you have to replace it, if ever at all.

But the idler lever, nut and swivel on the other hand is printed out of PETG on older iterations of MK4's and MK3.9 upgrades, and will and does deform quite quickly over time because it's constantly under pressure. You can keep on top of it by occasionally checking the tension of the lever and if necessary just screwing in the adjustment screws to maintain an acceptable tension. 

I've noticed that my latest batch of MK4's purchased came with idler arms that appear to be printed out of PCCF, so I'm guessing the Prusa team know this is could be an issue and have started shipping these in PCCF instead.

I have replaced all of the idler levers, nuts and swivels and main plates on the rest of my MK4 print farm with new ones printed out of ColorFabb XT-CF20 to mitigate this issue.

Caveat here is that I print a lot and have not experienced any problems with the parts printed out of PETG, I just wanted to mitigate any future problems by implementing this preventative measure by having these parts printed out of a more durable material.

The moderate user will most likely never have an issue with the original parts printed out of PETG.

NB: The extruder upgrade parts for the MK4 MMU3 seem to printed out of PCCF as well, which seems to be working well on two of my MK4's currently.



Posted : 15/05/2024 2:51 am
Eminent Member
RE: MK4 main plate wearing out?

Main plates are in the shop now.


Posted : 20/05/2024 8:52 am
Herr Lehmann
RE: MK4 main plate wearing out?

will a another (tougher) material help to stop/slow down the wear out? I considered using a print service to print the main plate in metal. Has anyone had any experiences?

Posted : 24/05/2024 7:18 pm