Defining Bed mesh probe points to avoid neodymium magnets

bubblevisor

Is there a way I can define each bed mesh probe point instead of the equal spacing within the chosen G29 envelope? I am using a prusa i3 bed with neodymium magnets that mess with the induction probe hence needing to avoid the areas surrounding the magnets.

alankilian

@bubblevisor You can define the exact set of coordinates used for bed compensation using the M557 GCODE.

I guess you would do:
M557 p1 Xxxx Yyyy
M557 p2 Xxxx Yyyy
M557 p3 Xxxx Yyyy
M557 p4 Xxxx Yyyy

M557 P1 X30 Y40.5

Set the points at which the bed will be probed to compensate for its plane being slightly out of horizontal.

The second form defines the points for for G32 bed probing. The P value is the index of the point (indices start at 0) and the X and Y values are the position to move extruder 0 to to probe the bed. An implementation should allow a minimum of three points (P0, P1 and P2). This just records the point coordinates; it does not actually do the probing. See G32. Defining the probe points in this way is deprecated in RepRapFirmware, you should define them in a bed.g file instead.

Although I don't understand what this means:

Defining the probe points in this way is deprecated in RepRapFirmware, you should define them in a bed.g file instead.

It seems to conflict with other things in the Wiki.

Maybe someone else can help confirm this and I'll then go back and edit this message.

fcwilt

@alankilian

The form M557 P# is no longer supported.

From the docs:

Parameters to define G32 probe points (Cartesian/CoreXY printers only, deprecated and not supported in firmware 1.18 and later)

Pnnn Probe point number
Xnnn X coordinate
Ynnn Y coordinate

fcwilt

@bubblevisor said in Defining Bed mesh probe points to avoid neodymium magnets:

Is there a way I can define each bed mesh probe point instead of the equal spacing within the chosen G29 envelope? I am using a prusa i3 bed with neodymium magnets that mess with the induction probe hence needing to avoid the areas surrounding the magnets.

I believe you will have to make a request in the firmware section to have this ability added.

I know of know way to do it now other than perhaps specify the best grid you can and manually edit out the obvious problem grid points.

Frederick

PCR

@bubblevisor there was a solution for Users with a duet 3 and sbc for it.

bubblevisor

@fcwilt Thanks for the info. Could you explain how you would "edit out" specific problem probe points?

This is what I have in the config currently M557 X21:216 Y28:200 P4 . But I would like to adjust the position of a few of the points.

alankilian

This post is deleted!

fcwilt

@bubblevisor said in Defining Bed mesh probe points to avoid neodymium magnets:

@fcwilt Thanks for the info. Could you explain how you would "edit out" specific problem probe points?

This is what I have in the config currently M557 X21:216 Y28:200 P4 . But I would like to adjust the position of a few of the points.

Hi,

Sorry I wasn't clear.

You could view the height map in the DWC and make note of any points they were clearly incorrect and likely the result of the probe reading being influenced by the magnets.

By noting the XY position of the point you could edit the height map .CSV file and assign a Z value to that point that made sense based on the Z values of the points around it.

Frederick