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

[TehStranger]

Hi all,

I recently installed my 8x12 upgrade for my i3v and I would like to have ABL calibrate the entire bed instead of just the 9 points for 8x8 sized bed, how would I go about this?

Thanks.

[Roxy]

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?

[jasay]

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.

[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.

[Roxy]

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

I will give that a shot.

Thanks.

OK... You are running the enhanced code! Then by specifying something like: G29 n 4 or G29 n 5 you will get more points.

[TehStranger]

OK... You are running the enhanced code! Then by specifying something like: G29 n 4 or G29 n 5 you will get more points.

That's all I have to do? won't it try to home more points on the X axis too though? Sorry I'm still learning all this code

[Roxy]

Oh! Yes, it will do a n x n grid. We will have to make a small change if you want more points in one direction than the other.

[TehStranger]

Oh! Yes, it will do a n x n grid. We will have to make a small change if you want more points in one direction than the other.

alright, where do I start?

[Roxy]

alright, where do I start?

Well... You just go into the G29 code in Marlin_main.cpp and make some changes. But if you want somebody else to do that you should probably explain why it is beneficial to have more points taken on one axis than the other.

[TehStranger]

Well... You just go into the G29 code in Marlin_main.cpp and make some changes. But if you want somebody else to do that you should probably explain why it is beneficial to have more points taken on one axis than the other.

It isn't beneficial it's just that my bed is 8x12 8 being the X axis so I can't really have it do more points. I don't need someone to do it I just need to be pointed in the right direction

Thanks