[FR] Pass Z homing (Z0) point to bed leveling if bed leveling requires the same point to be sampled

[Wallby]

Is your feature request related to a problem? Please describe.

No response

Are you looking for hardware support?

No response

Describe the feature you want

Hello,

I thought it might be nice if bed leveling (e.g. bilinear) would reuse the "Z homing sample" if the z homing sample is the same as a point that should be sampled for bed leveling. E.g. is a 3x3 grid is sampled, and z homing samples the center point, then bed leveling only needs to sample 8 points (instead of 9).

Additional context

No response

[thinkyhead]

Note that the Z homing point, where Z0 is established, is rarely coincident with the center of the mesh. Moreover, it is most common to home Z with a cold bed, whereas G29 should be done on a heated bed.

[Wallby]

I've reformatted this request (changed title and description). I.e. if one of the points required for bed leveling is already known from z homing.. skip the point in bed leveling.

[Wallby]

Note that the Z homing point, where Z0 is established, is rarely coincident with the center of the mesh. Moreover, it is most common to home Z with a cold bed, whereas G29 should be done on a heated bed.

I personally use bed leveling to do homing as well (i.e. the option on the LCD menu always homes and then levels).

[Wallby]

What I would like to be able to do (not sure if it makes sense though) is..

#define OVERRIDE_GRID_POINT_WITH_Z0 { 1,1 } //< i.e. instead of sampling to figure out "grid point @ {1,1}", read Z0

[Wallby]

This feature (or something alike) actually became a requirement instead of a "would be nice" when my IR probe no longer detected the bed "at the right time" (i.e. now.. it crashes into the bed, because there is a hole for a thermistor at the center of the bed).

I changed where Z0 samples (-10mm offset on the X axis now), but bed leveling still samples the same point.

[Wallby]

@thinkyhead Perhaps..

/**
 * If performing automatic bed leveling via LCD skip point GRID_POINT_TO_OVERRIDE_WITH_Z0
 * Instead use Z0 that was sampled during G28 prior to G29 (G28 is always prior to G29 when bed leveling via LCD) 
 * If Z0 does not directly coincide with GRID_POINT_TO_OVERRIDE_WITH_Z0, bed leveling will first sample all other points and then interpolate to approximate the Z for GRID_POINT_TO_OVERRIDE_WITH_Z0
 * There may not be another grid point inbetween Z0 and GRID_POINT_TO_OVERRIDE_WITH_Z0
 */
//#define GRID_POINT_TO_OVERRIDE_WITH_Z0 {0,0}

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