Heightmap problem



  • Hi everybody,

    I am having some trouble setting up my bltouch.
    Doing al single probe point works great. when I command a G1 Z0 the nozzle is againstthe build plate.

    But my Mesh grid compensation is where I have problems

    0_1527268062426_Knipsel.PNG

    the map is below zero point.

    I hope someone could help me out.

    Thanks,

    Stefan



  • Assuming your tool touches the bed at the centre when z=0 adjust the z component of your probe trigger height until the value of the heatmap is also 0.

    https://duet3d.dozuki.com/Wiki/Gcode#Section_G31_Set_or_Report_Current_Probe_status

    Do a few bed probes on the trot so you know what sort of tolerance your working with first.

    Edit: corrected from: "...z component of your bed compensation until the..." to: "...z component of your probe trigger height until the..."



  • Well I have tested the bltouch several times and it is within 0.08mm.

    And when I do a G30 S-1 my Z height is adjusted to the height the bltought measures.

    Then when I do a G1 Z0 the nozzle is just against the build plate, so I guess so I think I've setup everything correct, but I am wrong.

    @doctrucker said in Heatmap problem:

    Assuming your tool touches the bed at the centre when z=0 adjust the z component of your probe trigger height until the value of the heatmap is also 0.

    But does the hotend will crash in the bed when i add about 0,5mm to the Z height offset!?


  • administrators

    How are you homing the Z axis?



  • @dc42 said in Heatmap problem:

    How are you homing the Z axis?

    first i used the center of the bed, that gave me the heatmap form above.

    Now i use X 5 Y 5 and the result is getting better!
    0_1527857148988_Knipsel2.PNG

    I also used a mircometer to check the flatness of the bed.

    First I homed the printer and used a feeler gauge to make sure that the z height was correct.

    Next i mounted the micrometer and adjusted the Z height so that the micrometer read 0.

    Then I moved the printer to some point to check the height. And did the same as before. These are the results:

    X y Z

    5 5 6.42
    5 375 6.42M
    325 375 6.42
    325 5 6.42
    180 180 6.62

    The Z height indicates when the micrometer read 0. Only in the middle the bed is a bit higer.

    Is there a way to get the heatmap a bit more flat? The results are not really constant.


  • administrators

    If the results are not consistent, that's probably caused by either backlash of friction in your printer mechanics, or the bltouch not producing consistent results.

    What probing speed are you using (F parameter in the M558 command); and are you probing with the bed heater off or on?


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