Bed_Mesh magnified to points off the bed

[Pentheus]

Basic Information:

Base Ender 3 (2018) FrankEnder
MCU / Printerboard: Manta E3EZ, CB1
klippy.log (1.1 MB)

klippy.log

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Describe your issue:

…
In this case I believe the printer.cfg file might well be needed, but I did not post it, as per request, please ask if you need it.

When I send bed_mesh command, it executes, but… the X gaps between points are exaggerated, way beyond what fits on the bed, so the first point is correct, the second point is in the middle fo the bed, the third point is off to the far right, and the (Should be a last point) is off the bed completely out into the matrix. Printer halts with a Move out of bounds error.

So, I cannot figure out why/ which setting is the culprit to expand the points beyond what is specified in the bed_mesh min/max settings. If my bed is set to 10,210, the points sought by the mesh are something like 10, 280. It is exponential, so changing the settings to less, only cause the mesh to compensate to a larger size for the new settings.

This has tripped me up in the past, and now I want to know why it is happening as much as how to fix it. I want to be able to troubleshoot this for the far future.

Thanks in advance.

[Sineos]

Understanding X and Y Axes Limits and Homing

The X and Y Axis Klipper needs to know from its printer.cfg settings how far the X and Y axes can safely move without hitting the printer’s frame. It also needs to know where the origin (X=0 / Y=0) is. This origin is the beginning of the usable printer bed. In the following, we assume a Cartesian printer that follows the conventions of a Cartesian Coordinate System. This is also the reason why it is a quasi-standard to define the origin as the left-front corner of the bed. This way, all logic…

[Pentheus]

Thank you Sineos. Here is what I have so far:

1. If the bed_mesh was (say 200mm). It would take the measurement points (for example 5, 5) further than the printer would allow (for example 250mm), (50mm) past the right side of the bed, and generate an error for:
   ‘Move out of bounds x 250, y…’

2. By taking away the probe offset (50mm) from what is the bed_mesh (200mm), minus the probe offset (50mm) for a total of (150mm) And, the point distance exaggerations stops, within a 1mm tolerance. First half of the problem solved.

Second part of the same problem, (I believe they are related):

3. When the bed_mesh map is being created, The Probe offset is on the left of the nozzle, like your diagram above. Now, the bed_mesh would put the nozzle off of the right side of the bed, so the probe can measure on the edge. This would leave the probe at the edge of the bed, and nozzle out in mid-air. (as intended, I believe)

4. The boundary of the position_max needs to relax to let the nozzle past the edge of the bed, lest the bed_mesh cannot complete. Or, the position_max will need to be increased in order to allow for the nozzle to move past the edge of the bed, so the Probe can take the final reading. (All while avoiding the exaggeration issue previously experienced in the beginning.)

Point 4 is still untested, until I am better educated about the matter, and can test it out. I have a bed_mesh that is working on ¾ of the bed for now. I think your answer shows the final step I was missing. I am grateful, yet exhausted from my efforts.