Mesh bed leveling interpretation help required!  

RE: Mesh bed leveling interpretation help required!

Posted by: @t-uddemar

Hi. I could really use some help interpreting my mesh bed leveling datas. I really don't understand what I'm looking at here. Did two meshes. One with the bed att room temperature (19 degrees celsius), and on with 60 degrees celsius on the bed.

19 degrees results:

0.25750 0.26750 0.30333 0.21500 0.21000 0.07167 -0.05083
0.22667 0.28250 0.29083 0.27167 0.23000 0.12417 -0.06750
0.19250 0.28750 0.29500 0.26750 0.21083 0.12000 -0.07500
0.20833 0.23333 0.27833 0.29250 0.19771 0.09167 -0.07250
0.18083 0.29583 0.31167 0.25271 0.19583 0.09083 -0.09083
0.18250 0.29167 0.30750 0.21083 0.16083 0.05417 -0.15917
0.07833 0.13833 0.12750 0.09500 0.05167 -0.06083 -0.15167

 

60 degrees results:

0.16667 0.27167 0.32500 0.29333 0.23667 0.05333 -0.14000
0.24500 0.32750 0.37167 0.34500 0.30167 0.14667 -0.08917
0.25250 0.37250 0.40833 0.36771 0.31083 0.18250 -0.04917
0.25667 0.35583 0.39917 0.40667 0.29312 0.16000 -0.04250
0.24083 0.38500 0.41917 0.35667 0.29500 0.14500 -0.07917
0.22333 0.35833 0.39833 0.30583 0.23667 0.08750 -0.15833
0.04583 0.17417 0.21583 0.17667 0.11000 -0.05667 -0.24583

Hello and welcome in the Prusaforum!

Try this tool to visualize your meshbed leveling values: http://lokspace.eu/3d-printer-auto-bed-leveling-mesh-visualizer/

Your printing bed has an irregularity of about 0.4 - 0.5mm. A fine adjustment would not be bad 👍 

RE: Mesh bed leveling interpretation help required!

@t-uddemar:

Some comments to your numbers. Your printer did a Mesh bed leveling on a grid in x and y axis which has 7 points in each direction ==> 7 by 7 is 49 points in the mesh. On every point your printer is measuring the z-level of the bed. This is possible, because in the bed there are magnets and the Mind / Pinda / what ever the name of the sensor is (it is an inductive sensor) measures the z level when the Minda is triggered. I don't know which where your settings. It is possible, that the printer is doing the measuring @ one grid point 3 of 5 times and is then calculating some average value for z level. And these are the numbers in your post. Every number is the z-level at a grid point. If you put these numbers in the tool - Karl Herbert posted a link - you get a drawing of your heated bed. The more equal your numbers are the better it is - means your surface is more plane.

You did the meshbed leveling @ 2 temperatures - about room temperature and the heated bed @ 60 °C. Suddenly there where differences between the numbers even when you look @ the same point of the grid - what happened?

Because of the increased temperature the bed is growing in x and y dimension. But it is also fixed to the carrier of the bed. Bed is fiberglass and resin, the carrier is aluminum. Bed has 9 points where it is screwed against the carrier. Fiberglass and aluminum have different coefficients of thermal expansion and this leads to deformations of fiberglass and carrier. When heating the bed (and also the carrier) both are doing some kind of deformation and that you can see in your numbers.

Below is an example of a mesh bed (3 by 3) done in octopi (visualization).

Best regards, Clemens