Auto_Bed_Leveling: Enhanced G29 command

[peonking]

I tried to make the bed very leveled, in hope that the correctional matrix wont bring the nozzle too high on the left side. However that had no affect on the result.

From the topology, I do see the bump along column 3 and 4.

Doing a 2x2 probing would skip that bump, but nozzle still goes too high on the left side.

[Roxy]

I don't think you want to skip the bump. The fact is that it is there. It is going to affect the print. My vote would be to look for a flatter piece of glass.

But with that said... The Mesh Bed Leveling is advancing fast. In a few months you may not even care.\

[peonking]

I understand that the bump would affect the print.

What i don't understand is why, when probing just 4 corners, the nozzle still raises too much on the left side.
4 points probe assume a flat surface, and I'd expect the nozzle lightly touches the side and scrapes the middle as it moves from right to left. But that's not what I'm seeing.

[inventabuild]

How do you know it raises too much on the left side. Is the filament not sticking to the bed or is it fatter on the left side than the right side?

Marlin will fit the best plane possible through the four points, but one of the corners on the left side could be lower than the other corners so you don't have a perfect plane; hence Marlin will printa higher on part of the left side due to the low corner there.

Or maybe Roxy or someone could troubleshoot from a different angle.

[peonking]

Here is how I test it.
At the end of ABL, the probe will be at the top right corner.
1, G1 Z0 sends nozzle back to the nozzle's coordinates and moves the nozzle towards the bed. It stops right above the bed. I can slip i business card under the nozzle and it would feel very snugged.

2, Then send G1 X0 sends the nozzle towards the top left corner. I could see the gap between the nozzle and bed widen. By the time it stops, i can slip the card between freely, without resistance. There is even a visible gap between the card and the nozzle.

3, Then I send nozzle to bottom left corner. The gap is the same as (2).

4, Lastly i send the nozzle to bottom right corner. As it travels, the gap is visibly shrinking. By the time it stops, the card is snug with the nozzle and bed.

[beerdart]

ABL question.

I have RC3 up and running. Is there a way to store ABL to EEPROM and have it recalled for the print?

[Roxy]

Yes. You would just change the M500 and the M502 code in Configuration_Store.cpp to save and restore it. It should only be a few lines of code to do that . You would probably want to delete the one line at the start of G28 that clears the correction matrix so that did not happen any more.

There is already a thread here on how to do it: http://3dprintboard.com/showthread.p...trix-to-EEPROM

[beerdart]

Looks like RC3 has a different marlin_main.ccp

Yes. You would just change the M500 and the M502 code in Configuration_Store.cpp to save and restore it. It should only be a few lines of code to do that . You would probably want to delete the one line at the start of G28 that clears the correction matrix so that did not happen any more.

There is already a thread here on how to do it: http://3dprintboard.com/showthread.p...trix-to-EEPROM

[Roxy]

Looks like RC3 has a different marlin_main.ccp

Yes, and in fact, ConfigurationStore.cpp is much altered from that example. But you should be able to figure out where to splice in. And if you can't, you can switch to Mesh Bed Leveling which inherently stores the values in EEPROM. I'm currently working on a fancy, and automatic Mesh Bed Leveling. You can also wait for that to be available.

[adamfilip]

Yes, and in fact, ConfigurationStore.cpp is much altered from that example. But you should be able to figure out where to splice in. And if you can't, you can switch to Mesh Bed Leveling which inherently stores the values in EEPROM. I'm currently working on a fancy, and automatic Mesh Bed Leveling. You can also wait for that to be available.

Is there a beta we can try. out. Mesh levelling is awesome