Bed Leveling Failed on CoreONE upgrade - Assembly and first prints troubleshooting

RE: Bed Leveling Failed on CoreONE upgrade

Jürgen — Mon, 16 Feb 2026 11:27:17 +0000

Posted by: @jennyhsieh623gmail-com
When I encountered the error I originally thought the problem was that the printer thought wrong. Turns out I under tightened the back screws of the heatbed with the lock nuts.

When I encountered this post I originally thought that it gave rather strange advice. Turns out it was just link spam in the making, right?

RE: Bed Leveling Failed on CoreONE upgrade

jennyhsieh623@gmail.com — Mon, 16 Feb 2026 02:39:49 +0000

When I encountered the error I originally thought the problem was that the printer thought wrong. Turns out I under tightened the back screws of the heatbed with the lock nuts.

RE: Bed Leveling Failed on CoreONE upgrade

hyiger — Fri, 09 Jan 2026 23:54:12 +0000

Posted by: @stanleyb
I'll suggest one more thing: sometimes it's worth switching to manual Z-axis movement and going all the way down to Z=275. If the motors whine, it means the bed has mechanically leveled. Maybe this will help someone.

Or just run Z Alignment Calibration from the UI.

RE: Bed Leveling Failed on CoreONE upgrade

StanleyB — Fri, 09 Jan 2026 23:22:24 +0000

I'll suggest one more thing: sometimes it's worth switching to manual Z-axis movement and going all the way down to Z=275. If the motors whine, it means the bed has mechanically leveled. Maybe this will help someone.

RE: Bed Leveling Failed on CoreONE upgrade

Colin8 — Mon, 27 Oct 2025 23:10:43 +0000

I fixed the problem on my printer. When the bed comes all the way up to touch the nozzle, the screw heads that attach the rear center lead-screw nut were contacting the counterbored holes in the rear bed stop. I removed the bed stop and could see very light, silver colored drag marks in the counterbores. After opening up the counterbores a bit with a Dremel tool, all the bed leveling problems went away. This also explains why using multiple print sheets or lowering the nozzle slightly helped some people resolve the bed leveling failure at the right rear location.

RE: Bed Leveling Failed on CoreONE upgrade

SgtCaffran — Mon, 23 Jun 2025 05:11:21 +0000

Thanks for checking. Make sure to mention this to Prusa support!

RE: Bed Leveling Failed on CoreONE upgrade

HonzaJaros — Mon, 23 Jun 2025 02:15:35 +0000

Mind blowing, that’s might be it!!

I put calipers to one. 40mm and it fits between thread teeth. Then without adjusting the calipers I moved it to on other leadscrew and it doesn’t fit, so is the third one 😱😱😱

RE: Bed Leveling Failed on CoreONE upgrade

SgtCaffran — Sun, 22 Jun 2025 21:33:51 +0000

For the people who experience an unleveled bed and have to resort to placing a shim, check out this topic:

https://forum.prusa3d.com/forum/prusa-core-one-hardware-firmware-and-software-help/skewed-xy-plane-z-rods-heatbed/

Seems that there are cases where one of the Z motor spindles has a slightly different pitch. This problem might be related to an unleveled bed and bed leveling failures, even though the frame looks square.

RE:

Brian — Sun, 08 Jun 2025 12:24:40 +0000

Some have printed a shim and placed it below that lead screw at the bottom so when it homes at the bottom it's correct. I imagine you could attach something to the bottom of that lead screw as well.

Others have had luck by just loosening a screw at the back of the baseplate and pulling it up and retightening. I'm not sure which one because I didn't have a C1, but that what I've read.

RE: Bed Leveling Failed on CoreONE upgrade

HonzaJaros — Sun, 08 Jun 2025 11:56:53 +0000

I would like to add some information to the topic.

I have problem with TXT sheet yesterday a could not get pass the 49 points (25 ok) so I tried to find what is happening.

with support got this https://help.prusa3d.com/article/uneven-bed-31111-core-one_856294

unfortunately no difference. so I grab my old Raspberry PI with octoprint and ran bed levelling visualisation and got 2.6mm difference in bed level. that is the culprit why my printer didn't passed the test.

so this is what I found.

when I do Z calibration. the left Z lead screw keeps the bed to high. prusa support told me I have to follow the link mentioned above.

but I went different way:

I just manually lowered my left Z lead screw turning it by hand anticlockwise till it shows it is flat.

the problem is, when the bed hits the bottom, I have to do it again. Prusa support wasn't able to tell me how to fix that my left side is higher.

but I still having this Z issued when it suddenly starts printing higher.
I can print the same model, same filament and same sheet on my MK4 and it's perfect. the sheet is clean 100%. you can actually see how the filament drops from higher level

no idea who is the fix here :((