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    Guide to Marlin's Fast BLTouch Probing feature on Duet

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    bltouch fast marlin probe feature rrf
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    • mwolterundefined
      mwolter
      last edited by

      Interestingly, P5 appears to be more accurate in my case. Below are five deviation tests for each P5 and P9. We're talking small fractions of a millimeter, but still. Maybe because the pin does not have to reset each time? Also the probe height can be lower with P5 at 1mm and P9 has to be 2mm or it errors because the probe can't extend. Also the P5 test is easily twice as fast as P9. IMO P5 is better as long as the machine is calibrated to reduce the chance of the pin breaking.

      P9
      Screen Shot 2020-05-04 at 9.59.01 AM.jpg

      P5
      Screen Shot 2020-05-04 at 10.01.21 AM.jpg

      Phaedruxundefined 1 Reply Last reply Reply Quote 0
      • Phaedruxundefined
        Phaedrux Moderator @mwolter
        last edited by

        @mwolter What is your M558 and G31 for those tests?

        Z-Bot CoreXY Build | Thingiverse Profile

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        • mwolterundefined
          mwolter
          last edited by

          @Phaedrux
          P5

          M558 P5 C"^zprobe.in" H1 F120 T24000
          G31 X25 Y-12.6 Z3.8 P500
          

          Here's how I'm invoking it.

          G1 Z{move.axes[2].userPosition+5} F600		; move z up 5mm
          M558 P5 C"^zprobe.in" H1 F120 T24000
          M401
          G4 P200			; pause for 200ms
          M280 P0 S60		; enable BLTouch Touch SW Mode
          G30 P0 X105 Y105 Z-9999
          G30 P1 X105 Y105 Z-9999
          G30 P2 X105 Y105 Z-9999
          G30 P3 X105 Y105 Z-9999
          G30 P4 X105 Y105 Z-9999
          G30 P5 X105 Y105 Z-9999
          G30 P6 X105 Y105 Z-9999
          G30 P7 X105 Y105 Z-9999
          G30 P8 X105 Y105 Z-9999
          G30 P9 X105 Y105 Z-9999 S-1
          M402
          M558 P9 C"^zprobe.in" H2 F120 T24000
          

          P9

          M558 P9 C"^zprobe.in" H2 F120 T24000
          G31 X25 Y-12.6 Z3.8 P500
          
          Phaedruxundefined 1 Reply Last reply Reply Quote 0
          • Phaedruxundefined
            Phaedrux Moderator @mwolter
            last edited by

            @mwolter said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

            P500

            Have you tried with P25?

            Z-Bot CoreXY Build | Thingiverse Profile

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            • mwolterundefined
              mwolter @Phaedrux
              last edited by

              @Phaedrux said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

              Have you tried with P25?

              Yes, didn't notice a difference. No difference with the accuracy or functionality (not needing M280 P0 S60). It has been P500 for a while, so left it there.

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              • PastThePointundefined
                PastThePoint
                last edited by

                Sorry to bring this back from the dead, but for those using a Duet 3 and Toolboards, this will NOT work. "Only Z probe types 8 and 9 are supported on expansion boards"

                I wasn't paying attention when I was setting everything up. When I tried to actually do a fast probe, I got the error message quoted above.

                dc42undefined 1 Reply Last reply Reply Quote 0
                • dc42undefined
                  dc42 administrators @PastThePoint
                  last edited by dc42

                  @pastthepoint said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

                  Sorry to bring this back from the dead, but for those using a Duet 3 and Toolboards, this will NOT work. "Only Z probe types 8 and 9 are supported on expansion boards"

                  I wasn't paying attention when I was setting everything up. When I tried to actually do a fast probe, I got the error message quoted above.

                  There is no reason why you shouldn't use P8 instead of P5. However, the fast probing method doesn't work on all machines, which is why we have the P9 option for BLTouch.

                  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

                  PastThePointundefined 1 Reply Last reply Reply Quote 0
                  • PastThePointundefined
                    PastThePoint @dc42
                    last edited by

                    @dc42 So, instead of attempting to use P5, I can use P8/P9 in it's place and this should function? With everything going on, I can't remember yesterday, let alone the exact details of why this didn't work, lol. But, if you think it will work, I'll give it another shot!

                    Thanks for taking the time to reply @dc42 !

                    Phaedruxundefined 1 Reply Last reply Reply Quote 0
                    • Phaedruxundefined
                      Phaedrux Moderator @PastThePoint
                      last edited by

                      @pastthepoint said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

                      @dc42 So, instead of attempting to use P5, I can use P8/P9 in it's place and this should function? With everything going on, I can't remember yesterday, let alone the exact details of why this didn't work, lol. But, if you think it will work, I'll give it another shot!

                      Thanks for taking the time to reply @dc42 !

                      I don't think that's the case. The reason this method uses P5 instead of P9 is to avoid the automatic deploy and retract commands that are inherent to P9.

                      Z-Bot CoreXY Build | Thingiverse Profile

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                      • oliofundefined oliof referenced this topic
                      • oliofundefined
                        oliof @dc42
                        last edited by

                        @dc42 said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

                        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.

                        Raising this thread because it came up in another context: Newer BLTouch probes do not autoretract anymore.

                        <>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>

                        Phaedruxundefined 1 Reply Last reply Reply Quote 0
                        • Phaedruxundefined
                          Phaedrux Moderator @oliof
                          last edited by

                          @oliof said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

                          Newer BLTouch probes do not autoretract anymore.

                          Can you point me to more details?

                          Z-Bot CoreXY Build | Thingiverse Profile

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                          • oliofundefined
                            oliof
                            last edited by

                            I don't have a source at hand, but it seems to be the case since BlTouch Smart v2.2. It definitely is in 3.1 probes (see https://github.com/MarlinFirmware/Marlin/pull/14015 -- unfortunately the originally linked video where high speed mode without stow/retract being showcased has been pulled from Youtube it seems).

                            ghost opened this pull request in MarlinFirmware/Marlin

                            closed BLTOUCH Tweaks and V3.1 new command #14015

                            <>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>

                            Herniczundefined 1 Reply Last reply Reply Quote 0
                            • Herniczundefined
                              Hernicz @oliof
                              last edited by

                              @oliof They do not autoretract during a single "multi-touch" probing move or they can do an entire 441 point mesh without retraction?

                              There are known knowns and known unknowns, things we know that we don't know. But there are also unknown unknowns.

                              oliofundefined 1 Reply Last reply Reply Quote 0
                              • oliofundefined
                                oliof @Hernicz
                                last edited by

                                @hernicz the latter.

                                <>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>

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                                • Herniczundefined
                                  Hernicz @oliof
                                  last edited by Hernicz

                                  @oliof Are you aware that the link of the pull request you posted is from May 2019 while I wrote this guide in Feb 2020? Also the pull request is for Marlin not for RepRap.

                                  I've seen Marlins HS BLTouch in action back then and because RepRap didn't have this feature I figured out a workaround (basically ported the feature). As far as I know RRF still doesn't have this feature but now you can have 2 different probing speeds in M558. Since I changed my Duet2 WiFi to a Duet 3 MB6HC using the same BLTouch, I need to put "M280 P0 S60" after every deploy comand otherwise the pin gets retracted.

                                  As far as I know this feature still only can be achieved on RepRap if you set your probe type to P5, deploy and retract manually and prevent retraction with "M280 P0 S60" if necessary.

                                  To prevent the nozzle to ram into the heatbed or give "probe already triggered..." error during a single G30 command, by default the probe type has to be P9, only switching to P5 if necessary. This is why I wrote lenghts about modular probe config.

                                  There are known knowns and known unknowns, things we know that we don't know. But there are also unknown unknowns.

                                  oliofundefined dc42undefined 2 Replies Last reply Reply Quote 0
                                  • oliofundefined
                                    oliof @Hernicz
                                    last edited by

                                    @hernicz yes I am aware of that, the Marlin Merge Request is only here as a reference to the fact that BLTouch has the ability to not forcibly retract after probing. This is in support of your work here, not against it (-;

                                    <>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>

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                                    • Herniczundefined
                                      Hernicz @oliof
                                      last edited by Hernicz

                                      @oliof Yes it has the ability (it had it back then as well), but if the firmware doesn't keep it deployed it will get retracted (at least after every probe point). On my Duet3 6HC it retracts even as a P5 I need servo commands to keep it deployed.

                                      By the way I experimented with using short dive height, sliding the pin on the heatbed with very good results. Unfortunately sliding the pin on the heatbed will eventually wear it off (how fast depends on surface), so this method is definitely not advised if you want accuracy in the long run (and don'twant to change the pin).

                                      The biggest problem with BLTouch that the pin has an unnecessary >1mm travel until it gets triggered, so @ 1mm probing speed thats 1 sec / touch. It would be nice if we would have a probe with adjustable pin deployment so we could deploy just under the trigger point of the probe and set dive height a bit more than the highest point of the heatbed (compared to Z0)

                                      In this video the probing speed is 1mm/s, but because the dive height is so short it is really rapid.

                                      https://youtu.be/Vq_Jz201ndw

                                      There are known knowns and known unknowns, things we know that we don't know. But there are also unknown unknowns.

                                      CCS86undefined 1 Reply Last reply Reply Quote 1
                                      • CCS86undefined
                                        CCS86 @Hernicz
                                        last edited by

                                        @hernicz said in Guide to Marlin's Fast BLTouch Probing feature on Duet:

                                        @oliof Yes it has the ability (it had it back then as well), but if the firmware doesn't keep it deployed it will get retracted (at least after every probe point). On my Duet3 6HC it retracts even as a P5 I need servo commands to keep it deployed.

                                        By the way I experimented with using short dive height, sliding the pin on the heatbed with very good results. Unfortunately sliding the pin on the heatbed will eventually wear it off (how fast depends on surface), so this method is definitely not advised if you want accuracy in the long run (and don'twant to change the pin).

                                        The biggest problem with BLTouch that the pin has an unnecessary >1mm travel until it gets triggered, so @ 1mm probing speed thats 1 sec / touch. It would be nice if we would have a probe with adjustable pin deployment so we could deploy just under the trigger point of the probe and set dive height a bit more than the highest point of the heatbed (compared to Z0)

                                        In this video the probing speed is 1mm/s, but because the dive height is so short it is really rapid.

                                        https://youtu.be/Vq_Jz201ndw

                                        Have you tested faster probing speeds? I didn't see a real benefit in probing so slowly.

                                        Herniczundefined 1 Reply Last reply Reply Quote 0
                                        • Herniczundefined
                                          Hernicz @CCS86
                                          last edited by

                                          @CCS86 Depends on the Z axis rigidity. Changing the probing speed will possibly develop an offset, but not necessarily affect repeatability.

                                          For those who have their threaded rod doesn't touch the motor shaft in the coupler, so their Z axis sits on a springy coupling it's definitely a good idea to probe slow.

                                          My repeatablility tests:
                                          (F2 is basically F30 you cannot go slower than that)

                                          -F2: G32 bed probe heights: 0.054 0.054 0.054 0.054 0.054 0.054 0.054 0.057 0.054 0.054 0.054 0.054 0.054 0.054 0.054, mean 0.055, deviation from mean 0.001

                                          -F300: G32 bed probe heights: 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057 0.057, mean 0.057, deviation from mean 0.000

                                          -F600: G32 bed probe heights: 0.049 0.047 0.049 0.049 0.047 0.047 0.047 0.047 0.049 0.047 0.047 0.047 0.049 0.049 0.047, mean 0.048, deviation from mean 0.001

                                          -F1200: G32 bed probe heights: 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049 0.049, mean 0.049, deviation from mean 0.000

                                          -F2400: G32 bed probe heights: 0.067 0.067 0.067 0.069 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067 0.067, mean 0.067, deviation from mean 0.001

                                          There are known knowns and known unknowns, things we know that we don't know. But there are also unknown unknowns.

                                          CCS86undefined 1 Reply Last reply Reply Quote 0
                                          • CCS86undefined
                                            CCS86 @Hernicz
                                            last edited by

                                            @Hernicz

                                            Your results are odd. I would expect that if Z stage acceleration was compressing something elastically in the coupler, the increases in speed would keep increasing the apparent offset. Not the case. It bounces around.

                                            But, you have perfect repeatability, so who cares if the offset changes? Just pick a fast speed, do a single layer test print to check and adjust the probe offset value and you are done. What is the downside? You save time every time you probe.

                                            Herniczundefined 1 Reply Last reply Reply Quote 0
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