Calibration Bed

I use it to calibrate my auto leveling bed on a 400x300x300 bed size

In marlin, by default ALB use 9 points. It is not enough in some cases

You need to change this variable :

MESH_NUM_X_POINTS 5 // Don't use more than 7 points per axis, implementation limited
MESH_NUM_Y_POINTS 5

It's a 25 points mesh. Best results for printing