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Faster / Better home-z possible?

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  • undefined
    Kolbi
    last edited by 16 Aug 2020, 06:16

    In looking at a way the hasten z-probing - while increasing accuracy, I executed the following but it caused my Z0 to be offset / wonky. The first two lines are my normal routine, but I added the second to perform a slow pass - but it wasn't accurate.

    M558 P9 C"^zprobe.in" H5 F800 T8000 ; BLTouch, connected to Z probe IN pin - fast
    G30 ; home Z by probing the bed
    M558 P9 C"^zprobe.in" H5 F60 T6000 ; BLTouch, connected to Z probe IN pin - slow
    G30

    Could / Should I use the following?

    M558 F800 ; BLTouch, connected to Z probe IN pin - fast
    G30 ; home Z by probing the bed
    M558 F60 ; BLTouch, connected to Z probe IN pin - slow
    G30

    Or is there a better way to shift probing depth speed?

    Thanks,
    Kolbi

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    • undefined
      jens55
      last edited by 16 Aug 2020, 07:23

      This is how I do my Z homing.
      Note the A10 bit - this probes until two successive probe runs agree within a certain range. It does up to 10 probes. It will stop if two runs agree and it will fault out if there is no agreement within 10 runs.
      This is for a BLTouch.
      For mapping the bed, I also lower jerk and acceleration.

      M558 F2000 A1 ; set for rapid decent for one probe
      G30 ; do quick probe
      ;this is to rapidly lower the nozzle in case it is quite high
      M558 F60 A10 ; return to normal (slow) probing speed
      G30 ; home Z by probing the bed

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      • undefined
        Kolbi
        last edited by Kolbi 16 Aug 2020, 07:24

        Thanks @jens55 Just got done with a print, tested some options, and found this to work nicely. Nice use on the 'A' option - thanks for that.

        G1 X105 Y105 F6000 ; go to probe point
        M558 F1000 ; fast z-probe, first pass
        G30 ; home Z by probing the bed
        G1 H0 Z5 F400 ; lift Z to the 5mm position
        M558 F50 A9 ; slow z-probe, second pass
        G30 ; home Z by probing the bed
        G1 H0 Z5 F400 ; lift Z to the 5mm position
        M558 F200 A1 ; normal z-probe, set to normal speed
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        • undefined
          dc42 administrators
          last edited by dc42 16 Aug 2020, 07:33

          @Kolbi said in Faster / Better home-z possible?:

          Could / Should I use the following?

          M558 F800 ; BLTouch, connected to Z probe IN pin - fast
          G30 ; home Z by probing the bed
          M558 F60 ; BLTouch, connected to Z probe IN pin - slow
          G30

          Yes, there is no need to redefine the Z probe type when just changing the other parameters. Also, lifting Z between the two G30 probes (as you are now doing) is probably needed.

          Duet WiFi hardware designer and firmware engineer
          Please do not ask me for Duet support via PM or email, use the forum
          http://www.escher3d.com, https://miscsolutions.wordpress.com

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          • undefined
            Kolbi
            last edited by 16 Aug 2020, 08:02

            Thanks @dc42 , @jens55 !

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            • undefined
              fcwilt
              last edited by 16 Aug 2020, 11:03

              Hi,

              I would not be comfortable use A1 as the default setting.

              It's fine for doing your "high speed" probe but for everything else I would at least use A2. I use A5.

              Frederick

              Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

              undefined undefined 2 Replies Last reply 16 Aug 2020, 16:35 Reply Quote 1
              • undefined
                Kolbi @fcwilt
                last edited by 16 Aug 2020, 16:35

                @fcwilt Thanks Frederick!

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                • undefined
                  fcwilt @fcwilt
                  last edited by 16 Aug 2020, 16:35

                  Hi again.

                  Just FYI did you know you can force the averaging of a fixed number of readings?

                  For example A5 S-1 will cause 5 readings to be taken and the average computed.

                  Frederick

                  Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

                  undefined undefined 2 Replies Last reply 16 Aug 2020, 16:39 Reply Quote 1
                  • undefined
                    Kolbi @fcwilt
                    last edited by 16 Aug 2020, 16:39

                    @fcwilt Just so I'm square on this; when A5 is used without the S-1 switch it will conduct up to five probes or until two back-to-back probes match, and the S-1 switch will cause it to probe 5 times and then yield the average of those 5?

                    undefined 1 Reply Last reply 16 Aug 2020, 16:44 Reply Quote 0
                    • undefined
                      Kolbi
                      last edited by Kolbi 16 Aug 2020, 16:42

                      AH... got it:

                      The A and S parameters control multiple probing. Probing is repeated until two consecutive probe attempts produce results that differ by no more than the S parameter; then the average of those two results is used. However, if the number of attempts specified by the A parameter is reached without getting two consecutive results within tolerance of each other, no further probe attempts are made and the average result of all the attempts is used.

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                      • undefined
                        fcwilt @Kolbi
                        last edited by 16 Aug 2020, 16:44

                        @Kolbi said in Faster / Better home-z possible?:

                        @fcwilt Just so I'm square on this; when A5 is used without the S-1 switch it will conduct up to five probes or until two back-to-back probes match, and the S-1 switch will cause it to probe 5 times and then yield the average of those 5?

                        Correct.

                        Consider, getting two consecutive readings doesn't mean that the readings are accurate, just that they are the same, within the tolerance specified by a positive S value.

                        The downside to averaging is it takes longer.

                        Frederick

                        Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

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                        • undefined
                          jens55 @fcwilt
                          last edited by 16 Aug 2020, 16:46

                          @fcwilt said in Faster / Better home-z possible?:

                          Hi again.

                          Just FYI did you know you can force the averaging of a fixed number of readings?

                          For example A5 S-1 will cause 5 readings to be taken and the average computed.

                          Frederick

                          Thanks Frederick - did not know that!

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