Need help setting autolevel to use 3 points rather than a grid

Here is a link to the firmware that is on my printer.

It is a zonestar p802q with an inductive sensor and a new glass bed. I want to put metalic tape in 3 places on the bed so it can be leveled (via software) because the metal bed mount (thing that the screws go through before reaching the bed) bends very easily and is not easily leveled. right now it does a 3 by 3 grid. any suggestions?


  • You will need to select 3 point levelling in config.h and upload the firmware to your controller.
    Lad your existing config.h into the online firmware tool
    then in the features tab in the tool select the 3 point option and set your 3 coords to probe.

  • Here are the possible settings:


    This method measures at the 3 probe points and creates a plane through these points. If you have

    a really planar bed this gives the optimum result. The 3 points must not be in one line and have

    a long distance to increase numerical stability.


    This measures a grid. Probe point 1 is the origin and points 2 and 3 span a grid. We measure

    BED_LEVELING_GRID_SIZE points in each direction and compute a regression plane through all

    points. This gives a good overall plane if you have small bumps measuring inaccuracies.


    Bending correcting 4 point measurement. This is for cantilevered beds that have the rotation axis

    not at the side but inside the bed. Here we can assume no bending on the axis and a symmetric

    bending to both sides of the axis. So probe points 2 and 3 build the symmetric axis and

    point 1 is mirrored to 1m across the axis. Using the symmetry we then remove the bending

    from 1 and use that as plane.

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