bed not level - mesh bed leveling does not compenstate
 
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Elbkind
(@elbkind)
New Member
RE: bed not level - mesh bed leveling does not compenstate

I fixed this with some steel springs instead of the 6mm spacers under the heatbed. The fine tuning takes a while, but the results are good.

Napsal : 25/09/2020 8:54 pm
mafredri
(@mafredri)
Active Member
RE: bed not level - mesh bed leveling does not compenstate

When BML doesn’t seem to be doing the right compensation, two things can help:

  1. Pre-heat the bed and let it sit at target temp for 5 minutes before performing BML
  2. Pre-heat the PINDA/MINDA probe to 35C before BML
  3. Combine 1. & 2.

Granted, these are my experience from my MK3S, I don’t have a Mini, so can’t guarantee it’s applicable.

The reason 1) can help is that the heat bed will expand during heatup and there’s no guarantee it won’t keep doing it after hitting target temp. The firmware assumes the bed does not change shape which can lead to wrong compensation. Similarly for 2) the heated bed will heat up the PINDA probe during BML which means that first and last point can be probed at vastly different PINDA temps and firmware does not calibrate for the lower spectrum (<35).

Some people don’t seem affected by these things though, YMMV.

Napsal : 26/09/2020 4:12 am
bobc
 bobc
(@bobc)
Reputable Member
RE: bed not level - mesh bed leveling does not compenstate
Posted by: @mafredri

When BML doesn’t seem to be doing the right compensation, two things can help:

  1. Pre-heat the bed and let it sit at target temp for 5 minutes before performing BML
  2. Pre-heat the PINDA/MINDA probe to 35C before BML
  3. Combine 1. & 2.

Granted, these are my experience from my MK3S, I don’t have a Mini, so can’t guarantee it’s applicable.

The reason 1) can help is that the heat bed will expand during heatup and there’s no guarantee it won’t keep doing it after hitting target temp. The firmware assumes the bed does not change shape which can lead to wrong compensation. Similarly for 2) the heated bed will heat up the PINDA probe during BML which means that first and last point can be probed at vastly different PINDA temps and firmware does not calibrate for the lower spectrum (<35).

Some people don’t seem affected by these things though, YMMV.

If you did have a Mini, you might realise steps 2 is not possible, the MINDA does not have a temperature sensor. This has been the subject of a lot of discussion in the Mini forums.

Good point about the bed temp though. I have a delay in my start gcode which helps a little.

Napsal : 26/09/2020 8:21 am
Martin Majewski
(@martin-majewski)
Trusted Member
RE: bed not level - mesh bed leveling does not compenstate

It’s nearly the end of 2020, we have FW 4.2.1 and still MBL is not compensating for the poorly machined bed. I cannot use the entire bed, not even get the 1. layer calibration to stick on the right hand side of the bed. ☹️

 

 Cheers,

 Martin

-- www.martinmajewski.net --Printables:printables.com/@MartinMajewski
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Napsal : 30/10/2020 12:50 pm
SquishinStix
(@squishinstix)
New Member
RE: bed not level - mesh bed leveling does not compenstate

I'm here in 2025 to say the same thing...mesh bed visualizer in Octoprint says my max variation is 0.2mm - auto bed leveling should easily be able to account for this, and yet I have good squish in some places and low adhesion in others if I do a large print. SO FRUSTRATING. I've spent time leveling it with a mod down to 0.1mm variation and removing the G29 bed leveling command with better results, but it doesn't last from sheet to sheet and print to print!

Napsal : 12/07/2025 1:40 pm
3Delight
(@3delight)
Moderátor Moderator
RE: bed not level - mesh bed leveling does not compenstate

You have to calibrate every time you change the sheet, unless you've stored it in the memory.  To be honest I always do a full recalibration whenever I change sheet.

Napsal : 12/07/2025 3:09 pm
SquishinStix
(@squishinstix)
New Member
RE: bed not level - mesh bed leveling does not compenstate

I know that - and I have my z-offset stored for my various sheets and it works fine. That's not the problem. 

The problem is that even though the sheet is "flat" to within 0.2mm, the mesh bed leveling does not properly account for it. If I set the Z-offset perfect for the left side of the bed, it's way too high for the right side. If I set the Z-offset perfect for the front of the bed, it's way too high for the rear of the bed. It's a compensation issue. In fact, I've manually leveled the entire bed such that I can print a giant square with a perfect first layer by removing the mesh leveling from the g-code, then if I run the bed analyzer in Octoprint it will find 0.4-0.6mm of variation and if I print the same g-code adding back in the mesh leveling it compensates incorrectly and prints a bad first layer on a level and flat sheet. 

Napsal : 12/07/2025 3:30 pm
Arklan
(@arklan)
Trusted Member
RE: bed not level - mesh bed leveling does not compenstate

I have a mini from the early days.

I did the silicon tube mod for the bed and used octoprint to level it to about 0.02. I still leave the default start gcode, so g29 does run every print. I only use one single sheet, but it's been reliable and stable for me over time, including normal seasonal variations and whatever else. here's the mod link - some of it's outdated I'm sure. https://github.com/bbbenji/PMSBLM

Napsal : 12/07/2025 8:31 pm
SquishinStix
(@squishinstix)
New Member
RE: bed not level - mesh bed leveling does not compenstate

I've done this mod using custom TPU spacers and has it to within about 0.1mm across the whole bed earlier this week, and got a flawless first layer across the whole bed...without mesh leveling... 

Napsal : 12/07/2025 11:03 pm
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