Mesh bed compensation questions



  • Hello everyone,

    until now my printer is running fine excluding getting my first layer right sometimes.

    My idea:

    setting up a PINDA including temp compensation and mesh bed leveling.

    What i have done:

    -Connected the PINDA signal to the Z-probe in (got 5V from the expansion header)
    -Connected the PINDA temp sensor to E1 thermistor 2
    -Checked the trigger hight according the guides with different probe temperatures and calculated C
    -Define my grid
    -Defined my homing scripts (homing Z is done at the middle of the bed and with G30 to set an Z0 datum)

    This is what i set up in my config:

    Z-Probe
    M308 S2 P"e1temp" Y"thermistor" T100000 B4138 A"Probe" ; Configure extruder 2 temp input as thermistor on pin e1temp PINDA
    M558 P8 C"^zprobe.in+zprobe.mod" H3 F120 T10000 ; set Z probe type to switch and the dive height
    G31 P1000 X24 Y-21.5 Z1.260 H2 S25.4 C0.00758 ; set Z probe trigger value, offset and trigger height
    M557 X34:186 Y31.5:174.5 P3 ; define mesh grid

    homing scripts and complete config g attached

    No comes the point I don’t understand.

    When doing my mesh compensation, I receive different outcomes.

    The height differences between the probe points stay the same but the initial point the height map is built from varies.
    When I got the version with initial point I probed my Z0 datum (this is also the point I home and set my trigger height) the print runs perfectly. If I got the other versions the nozzle height is off….

    As i understand the Z height in the map should be close to zero where the nozzle was homed.

    Good version: (homing point marked with the cursor)
    c25a5e55-a1b7-4207-b834-7723bd8b18b5-image.png

    Wrong version:
    cd12b172-7555-4783-864b-caafcf11d41f-image.png

    I tried different ways to generate my map but i cannot find a pattern that is reproducible.
    1.
    G28
    G29

    G28
    G30
    G29

    G28
    Home Z
    G29

    Your help is appreciated! Please tell me just that I’m thinking wrong and messed it up 🙂

    Greets DerGulli

    p.s. please be patient as im new with reprap (;

    Files:
    homez.g homey.g homex.g homeall.g config.g



  • Forgot:

    I am printing with:
    -duet wifi
    -RepRapFirmware for Duet 2 WiFi/Ethernet 3.1.1 (2020-05-19b2)
    -Version von Duet WiFi Server: 1.23

    Greets


  • Moderator

    Have you tested the repeatability of your probe by doing repeated G30 S-1?



  • Yes i did,

    and it looks kinda wired to me. If i do it always at the same spot the readings are nearly 100% accurate but after moving the printhead and poing back to the same position it can happen that the distance changes.
    I am really tired about this and i tried a lot.
    I think i just try an bl touch as i have some laying around.

    Greets ther gulli


  • Moderator

    @DerGulli said in Mesh bed compensation questions:

    If i do it always at the same spot the readings are nearly 100% accurate but after moving the printhead and poing back to the same position it can happen that the distance changes.

    Sounds like backlash to me.



  • Hi,

    thanks for your thoughts, never tought about that. Today i will give it a try with the bl touch. I checked the mechanics and it looks "ok". If all not helps i will order an anti bachlash nut and try again.

    Best regards

    DerGulli



  • Hello,

    just installed by Bl Touch, my leveling now is consistant. Maybe by sensor had some issues.

    Thanks

    Greetings DerGulli


  • Moderator

    @DerGulli said in Mesh bed compensation questions:

    Maybe by sensor had some issues.

    I'm not familiar with PINDA enough to say, but glad to hear you're getting good results with the BLTouch.


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