Questions about How Auto Bed Leveling Works

[Roxy]

Thanks very much Roxy, it's cool to see how the code creates this matrix of measurements. The amount of work to implement auto bed leveling in the Marlin Firmware must have been extraordinary!

Are the measurements taken every time a print is starting up as part of the normal printing routine or are they done only when you want?

If it is automatic/included in every print start-up sequence, does it measure while the bed is hot?

Whoever did the original work was a truly gifted individual. It was a lot of work.

There was somebody here exploring the possibility of saving the bed correction matrix in the EEPROM so it doesn't have to be constructed at the start of each print. I don't know where in the process that work is. Or if it will see the light of day. It really isn't that hard to do. All the support routines for the EEPROM and default settings is in place to do it.

So right now... You just do a G28 and a G29 at the start of each print and the correction matrix is generated and used during the entire print. I have my Slicer Start Up GCode wait until the bed is up to temperature before doing the probing. That seems to help accuracy (at least for me). And I have the nozzle coming up to temperature during the probing. That works out pretty good for me.