How do I set more calibration points for Auto Bed Levelling?

[TehStranger]

Things have changed based on the version of the firmware you are running. But the first step in all cases is to edit your Configuration.h file to set the

#define AUTO_BED_LEVELING_GRID_POINTS 3

higher. Maybe 5?

It is already set to 5 but it actually homes in 9 different spots.

Assuming marlin firmware, find this section of configuration.h and change the "170" for y to something more appropriate for your 12" bed, e.g. "270".

//===========================================================================//============================= Bed Auto Leveling ===========================
 //===========================================================================


 . . .


   #define AUTO_BED_LEVELING_GRID


   #ifdef AUTO_BED_LEVELING_GRID


     #define LEFT_PROBE_BED_POSITION 15
     #define RIGHT_PROBE_BED_POSITION 170
     #define FRONT_PROBE_BED_POSITION 20
     #define BACK_PROBE_BED_POSITION 170

This will change the overall bounds of the autolevel function and the firmware will recalculate the points in the middle, but will not change the number of points. To do that you can add a "N" command to your gcode. Something like G29 N4 will do 4 points in each axis (16 total). I'm not aware of a way to do uneven number of points in X&Y e.g. 3x4 points.

I will give that a shot.

Thanks.