Question about trigger height BL-Touch

  • Hello, I have following question for my Tevo Delta printer:
    In your docs under calibrating a delta printer I read
    "When you have established what the trigger height is, set the Z parameter og the G31 command in config.g to that value."
    In your docs under mesh bed calibration is
    "find the G31 command and enter your trigger height as a negative value in the Z parameter (ex. G31 X0 Y0 Z-.43)".

    Is the Z value now positive or negative in G31?

    Thanks for the answer

  • Hi,

    For my Hypercube using a BL-Touch i'm using a positive value.

    ; Z-Probe offsets
    G31 P25 X22.9 Y37.1 Z2.0                 ; Z probe trigger value, offset in relation to nozzle. And trigger height adjustment

  • @mloidl said in Question about trigger height BL-Touch:


    Thanks mloidl, but it's still unclear for me.
    In your case, (sorry for my english) the Z value would be the height of the BL touch above the nozzle.
    But if the G31 Z value is the nozzle height, it should be negative.
    Your answer is in the Delta Calibration manual as corrct, but in the mesh grid manual it's negative.

    OK, I'm an old man and maybe I miss something 😉

  • Hi,

    i too have a TLM with Duet.... and i am using

    G31 P25 X0 Y10 Z2.059 ; Configura el valor de activacion P50, y los offsets desde el Nozzle

    This web help me...

  • I followed the same instructions as mentioned by @peirof.
    Especially the chapter (Find Z-Offset).

    I, then entered the value which i got from the duet in the config file.

  • Thanks mloidl and peirof,
    I will enter a positive value like peirof has, around 2mm.
    G31 X0 Y0 Z-2.395 P25

    But anyway, then the mesh grid manual is wrong and should be corrected:
    "Once you are satisfied with your trigger height result (should be between 0 and 1mm, depending on your printer), open your config.g file (this can be found in your DuetWebControl), find the G31 command and enter your trigger height as a negative value in the Z parameter (ex. G31 X0 Y0 Z-.43)"

  • administrators

    If the G31 Z parameter is positive, that means the probe triggers before the nozzle touches the bed. Example: IR sensor, inductive or capacitive sensor, BLTouch. If it is negative, that means the probe triggers when the tip of the nozzle is below the normal position of the bed surface. Examples: Smart Effector, Precision Piezo, FSRs under the bed supports.

  • @dc42 Thanks,
    Now It makes sense, I din't care about the capacitive sensor yet.
    But the smart effector is already here 😉

    Sorry for some stupid questions, I'm a newbee.
    There is more to come...


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