What is the true repercussion for the object from automatic bed level correction in the 3D-Printing?

[Kazuyuki]

What is the true repercussion for the object from automatic bed level correction in the 3D-Printing?
I have a simple question. The automatic bed level correction forms the first layer along the unevenness of the bed, ensuring adhesion to the bed. That works fine, but the 1st layer must has unevenness.
And, where does the unevenness that seems to be absorbed or not in the other layers?
Could you please show me the way of? I post some case as follows.

1. The unevenness is absorbed in the first (few) layers and then remaining layers are flattened.
2. Or, if I use “raft” in the bottom, the unevenness is absorbed only in the “raft” ?
3. No. All layers has same uneven from the bottom to the top, followed the unevenness of the head.
4. Or, are there any other methods?

[brent113]

Effect on printed materials through automatic level adjustment

Great discussion, fun read. The answer is both 1) and 2) are possible, depending on how you have the firmware set. In practice, without doing anything, the answer is 1). If you want 2) you will need to adjust the mesh as the way Snapmaker stores the mesh is incompatible with Marlin’s M420 Z Fade Height. Z fade height gives funny results when the mesh values are very far away from 0. Snapmaker uses the mesh values around 6-7mm because it combines both the bed unlevel characteristics and also …

[dstarke]

@Effect on printed materials through automatic level adjustment

If you move this into M206 and out of M420 I believe you can drive the nozzle to negative coordinates if you’re careless, crashing into the build plate.

I have actually crashed my nozzle into the print bed once when I tried out the M420 fade out. I really hope that they disable that function in the future to prevent such mistakes or just make it work. Fortunately, the replacement print sheet was delivered within one week

[Kazuyuki]

Thank you brent113 & dstarke! The current answer is 3,that’s in the firmware; all layers has same uneven.
I have to jack up my searching skill, sorry. But, I’m grad to know there is another person in community have a same question. Thanks again.

[brent113]

@Kazuyuki

I have to jack up my searching skill, sorry.

Ha, nah…I just remembered posting that. Struggled a bit to find my own post