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    Pressure Advance Calibration

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    Tuning and tweaking
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    • wilrikerundefined
      wilriker @OBELIKS
      last edited by

      @obeliks What kind of extruder are you using? The Bowden setup of the P3sTE Mk2? AFAIK Bowden setups use larger PA values - and my original Anet MK8 direct extruder even needs 0.144 apparently. 😁

      Manuel
      Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
      with probably always latest firmware/DWC (incl. betas or self-compiled)
      My Tool Collection

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      • OBELIKSundefined
        OBELIKS
        last edited by

        I know, but this is a bit silly.
        I am using a cloned Titan extruder. A bad clone.
        But still, long bowdens are supposed to have around 0.2, and I have a 40cm long bowden

        P3Steel Toolson mk2 - Duet 2 WiFi --> RatRig V-Core with Duet WiFi 1.03
        Original Prusa i3 MK3S

        deckingmanundefined 1 Reply Last reply Reply Quote 0
        • deckingmanundefined
          deckingman @OBELIKS
          last edited by

          @obeliks I haven't looked at the file but I'd have thought with that test, that acceleration and instantaneous speed change (jerk) will play a big part in the results. Forget the 100mm/sec speed unless you have a genuine E3D volcano - even then, you might struggle depending on nozzle size and layer height.

          Maybe your clone just has a very low melt rate or maybe it's got a partial blockage or the filament is bulging in the heat break area causing a restriction. Suggest you try something like a test cube without any pressure advance, just to check what speed you can print at (i.e how fast can melt filament). If the melt rate equates to (say) 60mm/sec or less, then trying to print at 100mm/sec ain't gonna work - no matter what you do with pressure advance.

          Ian
          https://somei3deas.wordpress.com/
          https://www.youtube.com/@deckingman

          wilrikerundefined Phaedruxundefined 2 Replies Last reply Reply Quote 0
          • wilrikerundefined
            wilriker @deckingman
            last edited by

            @deckingman At least with my rather low print acceleration it never got faster than 83.3mm/s (I need to tune this some day) but a simple calculation of 0.4mm extrusion width, 0.2mm layer height (as generated by the script) and 100mm/s print speed this would add up to 8mm³ of filament. IIRC a V6 is able to melt about 9-10mm³/s so this should be possible at least in theory (not taking into account any counter-pressure created by not extruding into thin air but "against" a surface).

            Manuel
            Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
            with probably always latest firmware/DWC (incl. betas or self-compiled)
            My Tool Collection

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            • Phaedruxundefined
              Phaedrux Moderator @deckingman
              last edited by

              @deckingman said in Pressure Advance Calibration:

              I'd have thought with that test, that acceleration and instantaneous speed change (jerk) will play a big part in the results.

              I've noticed the same. Jerk especially seems to have a effect. The higher the jerk value, the lower the pressure advance value I need.

              In the back of my mind I've had an idea for a systematic tuning guide. What parameters to start with, and what order to proceed in, with example test models to use for consistency. Printer tuning can seem like a dark art, but really it's just a complex interactive system which so far has lacked a rigorous systematic approach to testing and verifying results. You've done more than most in experimenting and codifying the way the system interacts on your blog.

              Z-Bot CoreXY Build | Thingiverse Profile

              deckingmanundefined 1 Reply Last reply Reply Quote 0
              • deckingmanundefined
                deckingman @Phaedrux
                last edited by

                @phaedrux Yes I think it's best to tune everything else first - speeds, temperatures, acceleration, jerk etc until you get the best quality you can. Only then start playing around with pressure advance and other things. And only ever change one thing at a time (I'm not a fan of Taguchi methods). There are just too many interactions going on I've found. Oh, and make copious notes along the way.

                Ian
                https://somei3deas.wordpress.com/
                https://www.youtube.com/@deckingman

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                • bartolomeusundefined
                  bartolomeus
                  last edited by

                  For python noobs like me: I uploaded the script into a browser based python implementaition, and it outputs the gcode: http://www.skulpt.org/#

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                  • bartolomeusundefined
                    bartolomeus
                    last edited by

                    I just printed with this script two times, one with PA from 0 to 0.2, and one with PA from 0.1 to 0.3.
                    During the print I entered M572 a few times to see what the actual settings are, and I could see the values change. At the end of the second print the returned value was: M572 - Extruder pressure advance: 0.298, 0.000

                    First: what is the second output: 0.000?
                    Second: I saw nothing in the print....really nothing. No gaps tearing or anything.

                    My setup: CoreXY, E3d, Bondtech BMG, 650mm capricorn, Firmware 2.02RC1

                    wilrikerundefined 1 Reply Last reply Reply Quote 0
                    • wilrikerundefined
                      wilriker @bartolomeus
                      last edited by

                      @bartolomeus It is not gaps or tearing that you are looking for but the value where there is a consistent extrusion width.

                      Manuel
                      Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
                      with probably always latest firmware/DWC (incl. betas or self-compiled)
                      My Tool Collection

                      bartolomeusundefined 1 Reply Last reply Reply Quote 0
                      • bartolomeusundefined
                        bartolomeus @wilriker
                        last edited by

                        @wilriker ok, but I still see nothing. All layers are identical, al columns in the print turned out exactly the same. Nothing like the pictures above.

                        Phaedruxundefined wilrikerundefined 2 Replies Last reply Reply Quote 0
                        • Phaedruxundefined
                          Phaedrux Moderator @bartolomeus
                          last edited by

                          @bartolomeus 650mm Bowden tube is long. Perhaps even higher values are needed.

                          The second value reported as zero may be from a second extruder that's defined but unused?

                          Z-Bot CoreXY Build | Thingiverse Profile

                          bartolomeusundefined 1 Reply Last reply Reply Quote 0
                          • wilrikerundefined
                            wilriker @bartolomeus
                            last edited by

                            @bartolomeus That is interesting. My latest test can be seen here.

                            Regarding the second value: this is the one for the second extruder. If you did not explicitly tell RRF that there is only one (don't remember the exact command, it's the one where you assign motors to axes) then I guess it has the second extruder configured by default.

                            Manuel
                            Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
                            with probably always latest firmware/DWC (incl. betas or self-compiled)
                            My Tool Collection

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                            • bartolomeusundefined
                              bartolomeus @Phaedrux
                              last edited by

                              @phaedrux higher than 0.3? I went through my config to be sure, but there's no second extruder configured. I'll go over it again and then post my config.

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                              • bartolomeusundefined
                                bartolomeus
                                last edited by

                                0_1536956172493_IMG_20180914_221237.jpg

                                wilrikerundefined 1 Reply Last reply Reply Quote 0
                                • wilrikerundefined
                                  wilriker @bartolomeus
                                  last edited by

                                  @bartolomeus So you definitely need higher values. All layers are identical but all are identically bad. In my image at about a little above the middle layer that is how it should look like. One consistent extrusion width from left to right. No bumps.

                                  Manuel
                                  Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
                                  with probably always latest firmware/DWC (incl. betas or self-compiled)
                                  My Tool Collection

                                  bartolomeusundefined 1 Reply Last reply Reply Quote 0
                                  • bartolomeusundefined
                                    bartolomeus @wilriker
                                    last edited by

                                    @wilriker I'll give higher a go tomorrow.

                                    My config: 0_1536956692480_config.g

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                                    • wilrikerundefined
                                      wilriker @bartolomeus
                                      last edited by

                                      @bartolomeus You don't have a M584 command in your config to tell RRF that there is only one extruder (besides other things, check the documentation). That's probably why you get the value for the second (implicit) extruder.

                                      Manuel
                                      Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
                                      with probably always latest firmware/DWC (incl. betas or self-compiled)
                                      My Tool Collection

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                                      • bartolomeusundefined
                                        bartolomeus
                                        last edited by

                                        One thing I should add: in the script I changed min speed to 20.

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                                        • bartolomeusundefined
                                          bartolomeus
                                          last edited by

                                          Ok, so I had to increase PA to 1 to see a result. I really need to switch to direct drive.

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                                          • fmaundefined
                                            fma
                                            last edited by

                                            Thanks to this great script! I ran it, and found 0.1s, which is the value I was using.

                                            Frédéric

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