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Mesh probe movement optimization

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  • undefined
    j3d
    last edited by j3d 3 Sept 2021, 04:06 9 Mar 2021, 03:57

    Sorry, I should have mentioned that that diagram is viewed from the X-Z plane. Eg left/right is X and up/down is Z.

    I don't quite understand your edit @Phaedrux. If you were using a probe such as a switch or piezo sensor, you would be dragging the sensor across the bed. The diagonals that I had included would allow the sensor to clear the triggered state by still utilizing the dive height. This is important when it comes to highly warped beds, or for any sensor that requires contact with the bed.

    Edit: Oh, I think your suggestion may work for analog non-contact probes and beds with a low amount of warp, but it would fail for anything else.

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    • undefined
      Phaedrux Moderator
      last edited by 9 Mar 2021, 17:54

      OHHHHH I see now what you mean. I thought you were talking about the XY movement between points.

      Z-Bot CoreXY Build | Thingiverse Profile

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      • undefined
        DanS79
        last edited by 9 Mar 2021, 18:25

        It would be really nice if something could be done to speed up probing.

        for example,

        If I generate this mesh

        M557 X10:290 Y45:290 P21:21
        

        with these settings

        M201 X4500 Y4500 Z250 E1500                           ; Accelerations (mm/s^2)
        M203 X24000 Y24000 Z1500 E3600                        ; Maximum speeds (mm/min)
        M566 X1500 Y1500 Z120 E1500                           ; Maximum jerk speeds mm/minute
        M558 P9 X0 Y0 Z1 H2.5 F180 T12000 A5 S0.02
        

        It will take 16 minutes and 38 seconds to complete.

        A substantial portion of that time is waiting on the Z moves. Upping the M558 Feed Rate above what it already is, doesn't accomplish much as it's already well into the realm of diminishing returns.

        undefined undefined 2 Replies Last reply 9 Mar 2021, 18:33 Reply Quote 0
        • undefined
          Phaedrux Moderator @DanS79
          last edited by 9 Mar 2021, 18:33

          @DanS79 well dive speed is a bit tricky because you're then affecting accuracy. Reducing dive height to the minimum and only probing at a density that actually matters would help more. The BLtouch is pretty sensitive to dive speed. Other probe types may be less. Even so, the faster you go, the harder it is to be accurate.

          Z-Bot CoreXY Build | Thingiverse Profile

          undefined 1 Reply Last reply 9 Mar 2021, 19:41 Reply Quote 0
          • undefined
            DanS79 @Phaedrux
            last edited by 9 Mar 2021, 19:41

            @Phaedrux said in Mesh probe movement optimization:

            @DanS79 well dive speed is a bit tricky because you're then affecting accuracy. Reducing dive height to the minimum and only probing at a density that actually matters would help more. The BLtouch is pretty sensitive to dive speed. Other probe types may be less. Even so, the faster you go, the harder it is to be accurate.

            I've done several rounds of benchmark and found i could go as high as 300 without losing accuracy. Though at that speed it's frightening to watch. Dive height is about as low as i can go without risking the probe not deploying in time.

            Something like Klipper touch mode would be a nice feature to add that would speed up probing regardless of how many points are being probed.

            undefined 1 Reply Last reply 9 Mar 2021, 20:35 Reply Quote 0
            • undefined
              Phaedrux Moderator @DanS79
              last edited by Phaedrux 3 Sept 2021, 20:37 9 Mar 2021, 20:35

              @DanS79 said in Mesh probe movement optimization:

              Something like Klipper touch mode would be a nice feature to add that would speed up probing regardless of how many points are being probed.

              There actually was a post a while ago about getting that touch mode setup.

              https://forum.duet3d.com/topic/14544/guide-to-marlin-s-fast-bltouch-probing-feature-on-duet?_=1615322157391

              Z-Bot CoreXY Build | Thingiverse Profile

              undefined 1 Reply Last reply 9 Mar 2021, 21:15 Reply Quote 0
              • undefined
                DanS79 @Phaedrux
                last edited by 9 Mar 2021, 21:15

                @Phaedrux said in Mesh probe movement optimization:

                @DanS79 said in Mesh probe movement optimization:

                Something like Klipper touch mode would be a nice feature to add that would speed up probing regardless of how many points are being probed.

                There actually was a post a while ago about getting that touch mode setup.

                https://forum.duet3d.com/topic/14544/guide-to-marlin-s-fast-bltouch-probing-feature-on-duet?_=1615322157391

                I'm aware of that thread. However @dc42's post made it sound like it wasn't advisable.

                undefined 1 Reply Last reply 9 Mar 2021, 21:19 Reply Quote 0
                • undefined
                  Phaedrux Moderator @DanS79
                  last edited by 9 Mar 2021, 21:19

                  @DanS79 said in Mesh probe movement optimization:

                  made it sound like it wasn't advisable.

                  For context, this is what he said:

                  Two words of caution:

                  RRF used to keep the BLTouch deployed throughout probing sequences. Unfortunately that doesn't always work. The reason is that when the probe triggers, it retracts the pin automatically. If it is then commanded to deploy again (by using probe type P5 instead of P9), then if the print head hasn't risen enough (or the bed dropped far enough) so that the pin touches the bed and triggers again, the BLTouch enters the error state. That's why we introduced probe type 9, which keeps the pin retracted until ready to probe the next point.

                  You should not call deployprobe.g or reractprobe.g using M98. Use M401 and M402 instead, so that RRF can track the deployment state.

                  For the first point, you would need to ensure a minimum dive height to allow the pin to actually drop completely.

                  Z-Bot CoreXY Build | Thingiverse Profile

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                  • undefined
                    dc42 administrators @DanS79
                    last edited by 11 Mar 2021, 10:55

                    @DanS79 said in Mesh probe movement optimization:

                    It would be really nice if something could be done to speed up probing.

                    for example,

                    If I generate this mesh

                    M557 X10:290 Y45:290 P21:21
                    

                    with these settings

                    M201 X4500 Y4500 Z250 E1500                           ; Accelerations (mm/s^2)
                    M203 X24000 Y24000 Z1500 E3600                        ; Maximum speeds (mm/min)
                    M566 X1500 Y1500 Z120 E1500                           ; Maximum jerk speeds mm/minute
                    M558 P9 X0 Y0 Z1 H2.5 F180 T12000 A5 S0.02
                    

                    It will take 16 minutes and 38 seconds to complete.

                    A substantial portion of that time is waiting on the Z moves. Upping the M558 Feed Rate above what it already is, doesn't accomplish much as it's already well into the realm of diminishing returns.

                    @DanS79, I think the real reason for Z probing being so slow for you is that your probing speed of 180mm/min is so low. Does it need to be that low? Have you calculated the contributions to the probing time of the probing movement, the Z raise movement, and the XY movement?

                    Another option I can see is to first raise the probe by e.g. 0.5mm, then do the XYZ move to be above the next point.

                    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

                    undefined 1 Reply Last reply 11 Mar 2021, 20:40 Reply Quote 0
                    • undefined
                      DanS79 @dc42
                      last edited by 11 Mar 2021, 20:40

                      @dc42 said in Mesh probe movement optimization:

                      @DanS79, I think the real reason for Z probing being so slow for you is that your probing speed of 180mm/min is so low. Does it need to be that low? Have you calculated the contributions to the probing time of the probing movement, the Z raise movement, and the XY movement?

                      This is the default railcore config, and it would take roughly an hour and 40 minutes to finish generating the mesh for the M557 i posted above.

                      M558 P9 X0 Y0 Z1 H5 F50 T6000 A5 S0.02  
                      

                      I didn't run every possible permutation, but I decreased the drop height and increased the travel speed between points and the probing speed till I started to see a degradation in repeatability. 180 seemed to be a good compromise between speed and me worrying about crashing the machine.

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                      • undefined
                        Phaedrux Moderator
                        last edited by 11 Mar 2021, 20:45

                        180mm/min is about the limit for the BLtouch. It's pretty sensitive to speed.

                        Z-Bot CoreXY Build | Thingiverse Profile

                        undefined 2 Replies Last reply 11 Mar 2021, 20:54 Reply Quote 0
                        • undefined
                          DanS79 @Phaedrux
                          last edited by 11 Mar 2021, 20:54

                          This post is deleted!
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                          • undefined
                            DanS79 @Phaedrux
                            last edited by 11 Mar 2021, 20:55

                            @Phaedrux said in Mesh probe movement optimization:

                            180mm/min is about the limit for the BLtouch. It's pretty sensitive to speed.

                            I was able to get up to 300, but above ~220-240 repeatability started to suffer. If memory serves above 270 I had to start increasing the drop height or I'd get

                            Error: Z probe already triggered at start of probing move 
                            

                            errors.

                            undefined 1 Reply Last reply 21 Mar 2021, 18:38 Reply Quote 0
                            • undefined
                              DanS79
                              last edited by DanS79 3 Nov 2021, 21:23 11 Mar 2021, 21:23

                              For reference here's Marlin's equivalent to Klipper's touch mode.

                              https://www.youtube.com/watch?v=95N2E6JVW2s

                              I've not looked into it, but i know one member of the RailCore Community has, and he felt to properly/safely handle touch mode, error/alarm handling as it relates to probing would need to be reworked.

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                              • undefined
                                Stonebaker @DanS79
                                last edited by 21 Mar 2021, 18:38

                                @DanS79

                                ; deployprobe.g
                                ; called to deploy a physical Z probe

                                M280 P0 S10
                                G4 P200

                                wait for it to be deployed
                                as Z Endswitch i use 2000 on mesh 1000

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