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    Pressure Advance messing with travel moves

    Tuning and tweaking
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    • gnydick
      gnydick last edited by

      @dc42

      I noticed that when I have pressure advance enabled, my travel moves are slowed down, not just extruding moves. I believe this shouldn't be the case, correct?

      gnydick dc42 JohnOCFII 3 Replies Last reply Reply Quote 0
      • gnydick
        gnydick @gnydick last edited by

        @gnydick I increased the accel and jerk on the extruder, and now it's not happening.

        1 Reply Last reply Reply Quote 0
        • gnydick
          gnydick last edited by

          Also, I don't think the calibration technique we've been using is valid. When I find the setting where there are no noticeable transitions, my prints end up not being dimensionally correct and slightly misshapen. For example, the maker's muse torture egg, all of the shells are stuck to each other when I use PA but separate when I don't.

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          • dc42
            dc42 administrators @gnydick last edited by

            @gnydick said in Pressure Advance messing with travel moves:

            @dc42

            I noticed that when I have pressure advance enabled, my travel moves are slowed down, not just extruding moves. I believe this shouldn't be the case, correct?

            You are right, pressure advance should only affect moves in which there is both extruder motion and XY motion.

            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

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

              @dc42 so, you'll look into it? Just because I increase extruder accel and jerk to fix it doesn't mean it's OK.

              Disabling PA also fixed the travel speed.

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

                @gnydick said in Pressure Advance messing with travel moves:

                @dc42 so, you'll look into it? Just because I increase extruder accel and jerk to fix it doesn't mean it's OK.

                Disabling PA also fixed the travel speed.

                Can you post a video showing the effect? Are absolutely sure that it is pure travel moves that are affected? Do you have anything unusual such as wipe-while-retracting configured in your slicer?

                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

                1 Reply Last reply Reply Quote 0
                • JohnOCFII
                  JohnOCFII @gnydick last edited by JohnOCFII

                  @gnydick What slicer are you using? I'm seeing a very odd slow down when I slice files with Slic3r. Pressure Advance was active, but not sure it is related. I'll re-do that print without PA.

                  I notice I also had wipe with retract active. I can turn that off too.

                  Related, the simulation time is about what I would expect, but the actual print time is 1.5 times as long as I would expect. The hot-end seems to pause or at least really slow down often.

                  gnydick 1 Reply Last reply Reply Quote 0
                  • gnydick
                    gnydick @JohnOCFII last edited by gnydick

                    @johnocfii I'm using slic3r also, also with wiping, but no matter what the move is, a wipe isn't anything special, it's just a travel along the path of the object.

                    I'm 100% sure it's not the slicer as disabling PA fixes it. I realize that disabling a feature can make up for a bad setting from the slicer, but it's just not so in this case.

                    JohnOCFII 1 Reply Last reply Reply Quote 0
                    • JohnOCFII
                      JohnOCFII @gnydick last edited by JohnOCFII

                      @gnydick Well, based on my testing, using Pressure Advance together with the experimental "wipe while retract" definitely cause the actual print time to be much longer than the simulated print time when using Slic3r PE version 1.41.2+

                      • Simulated print time: 1:02
                      • Actual print time: 1:37

                      Same model, no wipe with while retract and no Pressure Advance:

                      • Simulated print time: 1:04
                      • Actual print time: 1:07

                      I started doing testing with and without PA and with and without the wipe while retract option. I can also test with S3D.

                      I'm testing with this model: https://www.thingiverse.com/thing:1363023

                      I'm using the following firmware and DWC:

                      Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
                      Firmware Electronics: Duet Ethernet 1.02 or later + DueX5
                      Firmware Version: 2.02(RTOS) (2018-12-24b1)
                      Web Interface Version: 1.22.6

                      gnydick 1 Reply Last reply Reply Quote 0
                      • gnydick
                        gnydick @JohnOCFII last edited by

                        @johnocfii the reason why it's happening, I'm theorizing, is because the wipe happens at travel speed, so there's a negative extrusion while moving fast, so it thinks it's an extrusion move that needs to be smoothed.

                        JohnOCFII dc42 2 Replies Last reply Reply Quote 1
                        • JohnOCFII
                          JohnOCFII @gnydick last edited by JohnOCFII

                          @gnydick Could be. It was suggested that I may need to tweak my settings too. In particular, Extruder Jerk. This is on a CoreXY machine:

                          ; Axis and motor configurations
                          M350 X16 Y16 Z16 E16 I1                             ; Configure 16x microstepping with interpolation
                          M92 X200.40 Y200.32 Z1600.0 E820.0                  ; Set steps per mm - 1/9/2019 - osh
                          M566 X1000 Y1000 Z30 E20             			 ; Set maximum instantaneous (jerk) speed changes (mm/min)
                          M906 X1000 Y1000 Z1000 E800 I50                     ; Set motor currents (mA) and motor idle factor in per cent
                          M201 X3000 Y3000 Z20 E1000          			; Set accelerations (mm/s^2)
                          M203 X24000 Y24000 Z900 E3600       			; Set maximum speeds (mm/min)
                          

                          John

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

                            @johnocfii Yeah the extruder jerk and accel look pretty low.
                            Try 3000 E Jerk and 8000 E Accel

                            Z-Bot CoreXY Build | Thingiverse Profile

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

                              @phaedrux said in Pressure Advance messing with travel moves:

                              @johnocfii Yeah the extruder jerk and accel look pretty low.
                              Try 3000 E Jerk and 8000 E Accel

                              Thanks - I'll raise them up. That seems like quite a leap. Is there some good guidance on settings?

                              Phaedrux 1 Reply Last reply Reply Quote 0
                              • dc42
                                dc42 administrators @gnydick last edited by

                                @gnydick said in Pressure Advance messing with travel moves:

                                @johnocfii the reason why it's happening, I'm theorizing, is because the wipe happens at travel speed, so there's a negative extrusion while moving fast, so it thinks it's an extrusion move that needs to be smoothed.

                                Yes, wipe-while-retract might confuse pressure advance. How does it behave if you turn off wipe-while-retract?

                                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

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

                                  @johnocfii I should mention that those settings are for a Titan Aero. Direct drive 3:1 with slightly larger than pancake motor. So it's a very responsive system. These settings may not be ideal for a bowden tube system, I'm not sure.

                                  From my point of view, the extruder isn't moving much mass at all and it's not traveling very far compared to the other axis, so short quick moves and direction changes aren't as big of an impact as they would be on the other axis. So my settings are high to eliminate any artificial extruder speed limits. It's speed and response will be dictated by the other algorithms at play and the physical limitations of the motor.

                                  If you notice any grinding or skipping with those settings tone them down, but for best responsiveness I think you'd want them on the higher end than the lower end.

                                  It may also be worth mentioning that I'm not using the slic3r wipe on retract function since I'm using firmware retraction.

                                  Z-Bot CoreXY Build | Thingiverse Profile

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

                                    @dc42 I did an actual print last night, and the print time was 1:22. I did a simulation last night, and it was 1:20. But then I did 3 other simulations of the file with and without PA and with and without wipe while retracting, and all had the same 1:20 simulation time. At that point, I shut off the printer (and Duet and went to bed). I just powered up the printer (a RailCore 300ZL) and simulated that file again. Today's simulation showed up at 1:04.

                                    So -- color me confused. Not sure which simulation value is valid. I did not change config.g between simulation runs.

                                    In the mean time, I'm going to increase the extruder jerk and acceleration, which will probably invalidate future tests. For now, I will keep wipe while retracting turned off. I may do some other PA vs. non-PA tests, and will post results if I find the simulation time varies greatly from the actual print time.

                                    Thanks,

                                    John

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

                                      @phaedrux I'm using the Bondtech BMG but my stepper is not a pancake. I'll work my way up on the settings. Appreciate the education!

                                      FYI - here's am image link of my Y-carriage/extruder.

                                      https://imgur.com/Yh9vgY4

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                                      • deckingman
                                        deckingman @JohnOCFII last edited by deckingman

                                        @johnocfii If it's any help, I'd concur with @Phaedrux that your extruder jerk at 20mm/min is extremely low. I have Bondtech BMGs with Bowden tubes of about 150mm. My E jerk is 3600 mm/min and acceleration is 3,000 mm/sec^2.

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

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

                                          @deckingman Thanks for the confirmation. Mine is a direct setup (for all intents and purposes -- about 40mm between the BMG and my E3D-v6 hot-end).

                                          I'll start with your settings and see how it goes!

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                                          • JohnOCFII
                                            JohnOCFII last edited by JohnOCFII

                                            I revised my extruder settings as suggested above to the following and also disabled the wipe while retracting setting in Slic3r.

                                            1. The simulation estimate is now accurate to the actual printing time.

                                            2. Speed of the print is inline with what I'd expect.

                                            Thanks to all for your guidance.

                                            ; Axis and motor configurations
                                            M350 X16 Y16 Z16 E16 I1                                         ; Configure 16x microstepping with interpolation
                                            M566 X1200 Y1200 Z80 E3600                                 ; Set maximum instantaneous (jerk) speed changes (mm/min)
                                            M906 X1000 Y1000 Z1000 E800 I50                         ; Set motor currents (mA) and motor idle factor in per cent 
                                            M201 X3000 Y3000 Z20 E3000                                 ; Set accelerations (mm/s^2)
                                            M203 X24000 Y24000 Z900 E3600                           ; Set maximum speeds (mm/min)
                                            
                                            deckingman 1 Reply Last reply Reply Quote 0
                                            • deckingman
                                              deckingman @JohnOCFII last edited by

                                              @johnocfii Glad it worked out for you.

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

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

                                                @deckingman

                                                But by @JohnOCFII changing his configuration, the problem is just being avoided, not fixed. The fact that PA makes any changes on a wipe, a move with no extrusion, but may have retraction, is incorrect.

                                                bot deckingman 2 Replies Last reply Reply Quote 0
                                                • bot
                                                  bot @gnydick last edited by

                                                  @gnydick said in Pressure Advance messing with travel moves:

                                                  @deckingman

                                                  But by @JohnOCFII changing his configuration, the problem is just being avoided, not fixed. The fact that PA makes any changes on a wipe, a move with no extrusion, but may have retraction, is incorrect.

                                                  PA is not a perfect system. For that matter, wipe-while-retract, and all the other slicer tricks are even FARTHER from perfect... so which do we prioritize? Generalized PA algorithm wins every time for me. Please don't change a thing 😛

                                                  *not actually a robot

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

                                                    @gnydick said in Pressure Advance messing with travel moves:

                                                    @deckingman

                                                    But by @JohnOCFII changing his configuration, the problem is just being avoided, not fixed. The fact that PA makes any changes on a wipe, a move with no extrusion, but may have retraction, is incorrect.

                                                    I'm not arguing with the fact that if PA is being applied to non extrusion wipe moves, then it ought not too. Take that up with the firmware author, not me - I'm just an end user like you.

                                                    But @JohnOCFII s extruder jerk setting was much too low regardless of whether PA was being used or not.

                                                    Having said that, many settings interact with each other. So for example, too low an extruder jerk will have adverse effects when using PA. Also, you may run into problems with too much retraction after enabling PA (because the two things do much the same) and should reduce retraction. That's just the way things interact with each other.

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

                                                    gnydick 1 Reply Last reply Reply Quote 1
                                                    • gnydick
                                                      gnydick @deckingman last edited by

                                                      @deckingman gotcha, just making sure 😉

                                                      1 Reply Last reply Reply Quote 0
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