G29 not following mesh grid area properly



  • My corexy is running
    duet wifi 1.02 harware
    firmware 2.02
    wifi server 1.22
    dwc 2.05

    I cant figure out whats going on causing my mesh grind to not probe where i have it set M557 X10:345 Y-30:290 S45 It starts probing X10 Y-6.
    Y-30 is 30mm from the front of the bed and at its maximum physical travel, the bltouch is 66mm in the positive direction.
    here's my config and homing fileshomez.g homey.g homex.g homeall.g config.g
    any help would be greatly appreciated , i have been stuck on this for a few days now


  • Moderator

    Are you using a right handed coordinate system? -X to the left, +X to the right, -Y to the front, +Y to the back?

    If the probe is 66mm behind the nozzle and the nozzle can travel to -30Y only, the probe can never reach more than Y6.



  • you're correct I'm using a right hand coordinates. It doesnt stay at Y-30 when probing the front edge of the bed. when it probes g29 its moving y 24 mm. I must be missing something


  • Moderator

    Can you explain to me how the probe will physically reach -30?



  • It cant physically get there, the print head is moving Y positive, im expecting it to stay at Y-30 so it can probe the furthest forward it can. so it moving Y positive at the start of the probing its missing a part of the build plate.


  • Moderator

    Are you getting messages in the console saying it can't reach a point and is skipping it?



  • it only showed those messages when i had my probe offset backwards.



  • Your Y minimum limit is -30. Your probe offset is 66. That means, if your nozzle is in its minimum, your probe is at Y36. You want to probe at Y-30, but your probe can not reach it, so firmware will skip it and try to probe next row, moving Y+45, your probing spacing. It will be then at Y15. As your probe can not reach that either(your probe minimum is Y36), it moves another +45. So your probing should start at Y60. This is probe position, not nozzle. Nozzle will be at Y-6, as probe offset is 66.
    So, my point is, in M557 command you have to define probe coordinates, not nozzle coordinates. And probe must be able to reach those coordinates.



  • @aidar
    Ok i think i get it now, Ive been defining the mesh area by where the nozzle can go, what i should have been doing is using the probes location.
    It makes sense now how it works, just had it in my head that the dimensions were all driven from the nozzle, the firmware would take care of the offset for the mesh probing area.


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