Wait time parameter for M558

  • Hi dc42,

    would it be possible to add a paramater for a wait time after travel to a probe point and befor probing?

    I have a FSR setup for bed probing, and they have to settle for 1-1.5s after travelling because of vibration from the fast move to probing point so the short time and long time running average values are equal at the begin of probing. The sensitivity is high, so the vibrations trigger the Z-probe pin and without the wait time often the probing aborts at the beginning because of triggered pin. With the wait time its sensitive and reliable.
    FYI: The FSRs are connected to a PCB with an ATmega8. It's calculating the averages over a short and long period of time and generates the trigger condition.

    I think the parameter would be convenient to other users who are using FSRs.

    My work around is like this (bed.g):

    G1 X-69.28 Y-40.00 Z5 F3500
    G4 P1500
    G30 P0 X-69.28 Y-40.00 Z-99999 H0.01; X tower
    G1 X0 Y-80 Z5 F3500
    G4 P1000
    G30 P1 X0 Y-80 Z-99999 H0.0		; between X and Y towers 0.01
    G1 X69.28 Y-40.00 Z5 F3500
    G4 P1000
    G30 P2 X69.28 Y-40.00 Z-99999 H-0.02; Y tower

    But it would be nice to discard the G1 and G4 commands if there would be a configurable wait time.


  • Hi,

    may I raise this question again?

    I can't do a workaround with grid bed compensation.


  • administrators

    I have just defined a parameter S in the M558 command to specify a Z probe recovery time. I hope to squeeze it in to release 1.17.

  • Thank you very much.

  • Hi David,

    I tried it out, but it's not exactly what I suggested.
    You added a timeout for the next probing after triggering the Z-probe.
    I asked for a wait time befor probing (after travelling).

    At the moment I have to work around the very first probe point. Z-probe is triggered because of the vibration of the travel move to the first point. I do this with a G1 to the first point and a G4 to wait, like befor. But I have to adjust the G1 move if I change the grid (G29), bcause the first probe point will change. same with G30.
    For the parameter in M558 Rxx i have to measure how long the longest travel move is after Z-probe and add the wait time (G30).

    Maybe you can change the parameter to a simple wait time befor probing? Then there is less calculation and the problem with the first probe point dissapeares.


  • Hi David,

    I tried again with 1.17RC1 and now its perfect. Thanks.

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