DEV version auto bed leveling

I've successfully gotten the bed leveling routine to work.

But after using G32... the Z height gets adjusted but when I travel the nozzle around the bed the Z height varies by as much as .2mm.

Even if my steps per mm were off in the firmware all areas of the bed would be off together... but they are not. I have even tried probing a 5 X 5 grid... but is still doesn't work.

What could I be missing?

How accurate is auto bed leveling supposed to be?


  • Accuracy depends on printer type and bed. It just puts a median plane from measured points to correct rotation of bed. It does not correct bumps and it does not correct geometry errors in delta printers, which is the main source for deltas to not get a flat surface. Assumptions are here 120° between pillars, exact same diagonal length and steps per mm, the 2 diagonals per axis exact parallel. Even an error of 0.1mm can cause the effector going up and down depending on position. And such precision is nearly impossible to build.  So there are many screws in eeprom variables you can modify to improve this kind of error. Not that you will ever get a perfect surface but you can normally get close enough to be able to print first layer.

    At that stage you can use G33 to add a distortion map that will fix the remaining bumps at the bottom (you decide at which height the effect starts to vanish in settings). If you use that please use dev version from yesterday which has some fixes for distortion correction.
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