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After upgrade from MK3 to MK3S+ can't get good bed contact  

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peterpop
(@peterpop)
Member
After upgrade from MK3 to MK3S+ can't get good bed contact

So I recently bought this MK3 second hand. After some fiddling and calibration I got it to run quite decent. I decided to upgrade it to MK3S+ and when I received the package I printed the necessary PETG parts. They were pretty much flawless.

During the upgrade I took the liberty of also removing all the smooth rods for cleaning and replaced all the LM8UU bearings with new ones.

I ran the wizard (and several times since), did the first layer calibration, cleaned the sheets with dishwasher soap and IPA. No matter what I do I can't seem to get consistent adhesion. Two heatbeds came with the printer. A textured one (the default I think) marked TL-21 and a smooth golden one marked PA-11. I got the good results on the textured before the upgrade.

My latest test after the upgrade I did on the smooth one (because I wondered if the coating on the other had somehow been affected - though I can't see how). The final first layer calibration looked quite good (didn't take a picture) with the z value dialed to -1.735 (which is a bit higher than I had it before, but this was where I could place the PINDA and not have it touch the paper).

I printed the Bed level test and I don't really know what to make of this result. Some places are ok, some places have nothing and some places are just mangled.

Filament is missing someplaces - mostly on the right side.

 

In the top left corner a part has broken off while the rest looks ok.

 

The same on the top center square.

In the lower left square a missing edge but otherwise ok.

The center looks pretty ok to me.

But all the right squares has problems.

How should I proceed from here?

Is there THE BEST way to dial in the Z offset to completely eliminate that as a problem. Are there test prints that can expose any problems that could explain why it is so hard for me to get proper adhesion after the upgrade?

Another thing I noticed when doing the manual check after reattaching the bed carrier was that my bed is curving upwards in the middle across X ever so slightly. I guess the mesh bed leveling should handle that.

Posted : 14/01/2026 11:19 pm
Ruebarb
(@ruebarb)
Estimable Member
RE: After upgrade from MK3 to MK3S+ can't get good bed contact

I've had my Mk3S for 6 years, the pinda probe would move over time until I finally used purple thread locker. Had to reestablish my z offest too many times. Thier zip tie method to get the generic placement, but you need then run live z tests to dial it back in in. I used a different file to get the live Z, never found the built in very good. See below.

https://forum.prusa3d.com/forum/prints-troubleshooting/failed-first-print-fix-for-petg-benchy-that-shifted-after-a-couple-layers-on-textured-sheet/paged/2/#post-777727

Posted : 05/03/2026 2:09 pm
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