Request for change to G30



  • Hi,

    G30 by itself probes at the current X,Y and sets Z to the probe trigger height.

    To get the probe to the desired X,Y position I use a G1 command with the X,Y values needed taking into account any X,Y probe offset.

    It would be a bit simpler and more consistent if we could do G30 X### Y### and have the firmware do the math for us taking into account any X,Y probe offset.

    Thanks.

    Frederick



  • Duet G30 already has X and Y defined. What are you requesting different than what G30 does now?



  • You have to use a P probe point always to get the offset take into account so that the probe ends up on the X/Y position in the G30 command. 150/150 is the center of the bed here.
    G30 P0 X150 Y150 Z-99999 S-1

    No idea if the result is really the same as doing manually G30 X150-probeoffset Y150-probeoffset because of using P0 ?
    Or should I do a G30 after that again so I don't need to do the math myself and have the result I want. That is "When the probe is triggered, set the Z coordinate to the probe trigger height." ?
    If I am required to do two steps I would like to have a option to probe the center of the bed or any other position without having to do the offset math myself to have the probe at the define position and not the nozzle.



  • @Danal said in Request for change to G30:

    Duet G30 already has X and Y defined. What are you requesting different than what G30 does now?

    A G30 without a P parameter ignores the X,Y parameters. I would like it to use them, as I said, for a bit more simplicity and consistency.

    Frederick



  • @Scachi said in Request for change to G30:

    You have to use a P probe point always to get the offset take into account.

    Understood. I am simply suggesting that G30 without a P parameter also accept X,Y parameters just for a bit more simplicity and consistency.

    Perhaps there is a reason why this cannot be done but I cannot think of such a reason.

    Frederick



  • @fcwilt said in Request for change to G30:

    A G30 without a P parameter ignores the X,Y parameters. I would like it to use them, as I said, for a bit more simplicity and consistency.

    Aha, got it.

    So the proposal is: Honor XY on G30, without P, and apply probe offset. This implies a G31 has been previously executed to set the probe offset.

    You didn't ask... but... yeah, I'd vote YES for that change.

    =========================

    Meanwhile, you can do a very similar thing, no math on your part, by the same numbers you put in the G31 X Y in a M206. Such as:

    M206 Xnnn Y-nnn  ; Same values as G31 in the config file. (Or possible same values with opposite signs, I haven't tried this)
    G30 Xxxx Yyyy    ; Spot where you want the probe to touch, not the nozzle.
    M206 X0Y0        ; Don't forget to remove the offset
    

    Not quite as easy, particularly from the command line. Still, no math, and available now.



  • @Danal said in Request for change to G30:

    Aha, got it.

    Meanwhile, you can do a very similar thing, no math on your part, by the same numbers you put in the G31 X Y in a M206. Such as:

    I had not thought of that and it is rather clever.

    Frederick


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