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    RRF 2.03 pressure advance causes 20% overextrusion

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    • jschallundefined
      jschall
      last edited by

      Does Duet configure the trinamics in rising edge or falling edge mode?

      With PA at 1.0, as counted by a python script analyzing the output of my Saleae (assuming rising edge mode):

      fwd_count 6334445
      rev_count 5157566
      net_count 1176879
      mm 2979.440506

      Slicer says 2.48m filament use. Duet web interface confirms, says the file has 2481.7 mm filament use.

      Next up, PA at 0.0. If this comes out correct, it will be incontrovertible proof that there is a firmware issue with PA causing overextrusion.

      1 Reply Last reply Reply Quote 1
      • jschallundefined
        jschall
        last edited by

        The python script: step_counter.py.txt
        The data with PA: https://drive.google.com/file/d/16LW2Xb2MWsUTvyCdSjDqBvFwDXq1xOuR/view?usp=sharing

        1 Reply Last reply Reply Quote 1
        • jschallundefined
          jschall
          last edited by

          Ah, the TMC 2660 doesn't have a falling edge mode, only rising edge and both edges. I misread the datasheet.

          1 Reply Last reply Reply Quote 1
          • jschallundefined
            jschall
            last edited by jschall

            With no pressure advance: https://drive.google.com/file/d/1oFvrJnxZc6fvLlGZqTdCqO7GB4Zfzdy_/view?usp=sharing

            Python script output:
            fwd_count 1942964
            rev_count 961423
            net_count 981541
            mm 2484.913924

            2.48m, dead on what the slicer expected.

            Proof positive that PA causes overextrusion and that this is a firmware bug, NOT a mechanical or configuration issue.

            CCS86undefined 1 Reply Last reply Reply Quote 2
            • jschallundefined
              jschall @Phaedrux
              last edited by

              @Phaedrux said in RRF 2.03 pressure advance causes 20% overextrusion:

              Why 8x microstepping on the extruders?

              What is recommended?

              Vetiundefined 1 Reply Last reply Reply Quote 1
              • Vetiundefined
                Veti @jschall
                last edited by

                @jschall

                x16 with interpolation enabled.

                also your thermistor config is wrong.

                Your bed is 4138 which is the default and very likely wrong.
                Your hotends are 4388
                So you might be printing at the wrong temperature.

                E3D uses 104-GT2 thermistors which is B4725 C7.060000e-8

                jschallundefined 2 Replies Last reply Reply Quote 0
                • jschallundefined
                  jschall @Veti
                  last edited by

                  @Veti said in RRF 2.03 pressure advance causes 20% overextrusion:

                  @jschall

                  x16 with interpolation enabled.

                  also your thermistor config is wrong.

                  Your bed is 4138 which is the default and very likely wrong.
                  Your hotends are 4388
                  So you might be printing at the wrong temperature.

                  E3D uses 104-GT2 thermistors which is B4725 C7.060000e-8

                  Set to 260C/120C. Seems fine to me.

                  20200830-134609.jpg 20200830-134510.jpg

                  1 Reply Last reply Reply Quote 1
                  • jschallundefined
                    jschall @Veti
                    last edited by

                    @Veti

                    I've done more research and 4725 is the wrong B value. The right number is 4267. I might update my config to match, I don't fully trust the thermal camera's accuracy and it doesn't make sense that the hotends and bed are different when the bed uses the same thermistor.

                    But I'd need to do some verification on that change regardless.

                    1 Reply Last reply Reply Quote 1
                    • jschallundefined
                      jschall
                      last edited by

                      Regarding underruns: I'm running the file again now to determine if there are any, but it is most of the way through and there have been no underruns.

                      1 Reply Last reply Reply Quote 1
                      • Vetiundefined
                        Veti
                        last edited by

                        @jschall said in RRF 2.03 pressure advance causes 20% overextrusion:

                        I've done more research and 4725 is the wrong B value. The right number is 4267.

                        No its B4725 and C7.060000e-8 if you Specify B and C you switch to the Steinhart–Hart equation which is more accurate over a wider temperature range.

                        This is documented here
                        https://duet3d.dozuki.com/Wiki/Connecting_thermistors_or_PT1000_temperature_sensors

                        jschallundefined 1 Reply Last reply Reply Quote 0
                        • jschallundefined
                          jschall @Veti
                          last edited by

                          @Veti
                          Thanks, will correct that, then.

                          1 Reply Last reply Reply Quote 1
                          • jschallundefined
                            jschall
                            last edited by

                            https://gist.github.com/jschall/98f9459590cfad6bbe413f3b49c266eb

                            No underruns.

                            1 Reply Last reply Reply Quote 1
                            • botundefined
                              bot
                              last edited by

                              Well, this is interesting thank you for doing this.

                              *not actually a robot

                              jschallundefined 1 Reply Last reply Reply Quote 0
                              • jschallundefined
                                jschall @bot
                                last edited by

                                @bot said in RRF 2.03 pressure advance causes 20% overextrusion:

                                Well, this is interesting thank you for doing this.

                                Any suggestions where to go from here?

                                1 Reply Last reply Reply Quote 1
                                • Vetiundefined
                                  Veti
                                  last edited by

                                  please do upgrade to the latest firmware.

                                  even if there is a bug in 2.03 i doubt that we will see a rrf2 bugfix.

                                  so it would be good if you could retry this in rrf3.

                                  1 Reply Last reply Reply Quote 0
                                  • jschallundefined
                                    jschall
                                    last edited by

                                    Ok, I need to upgrade anyway.

                                    1 Reply Last reply Reply Quote 1
                                    • Edgars Batnaundefined
                                      Edgars Batna
                                      last edited by Edgars Batna

                                      I had analyzed this issue multiple times before as well and 2.05.1 had only minor improvements related to PA. Based on my findings something happens on the step generation level, probably CPU running out, causing moves to be done before reverse motion (there is some code in there that basically aborts moves before they are done, you'd need to analyze it yourself as I've wasted more time than I'd like already and I have no means of analyzing stepper control). I eventually gave up using PA on my printer as it ALWAYS overextrudes for me and I've ruled out every mechanical issue, too.

                                      I think that it will get worse, if you upgrade to 3.x, as it probably uses more CPU.

                                      jschallundefined DocTruckerundefined 2 Replies Last reply Reply Quote 1
                                      • jschallundefined
                                        jschall @Edgars Batna
                                        last edited by

                                        @Edgars-Batna said in RRF 2.03 pressure advance causes 20% overextrusion:

                                        I had analyzed this issue multiple times before as well and 2.05.1 had only minor improvements related to PA. Based on my findings something happens on the step generation level, probably CPU running out, causing moves to be done before reverse motion (there is some code in there that basically aborts moves before they are done, you'd need to analyze it yourself as I've wasted more time than I'd like already and I have no means of analyzing stepper control). I eventually gave up using PA on my printer as it ALWAYS overextrudes for me and I've ruled out every mechanical issue, too.

                                        Interesting. How did you come to your conclusions? Did you ever write them up?

                                        Edgars Batnaundefined 1 Reply Last reply Reply Quote 0
                                        • DocTruckerundefined
                                          DocTrucker @Edgars Batna
                                          last edited by

                                          @Edgars-Batna said in RRF 2.03 pressure advance causes 20% overextrusion:

                                          I think that it will get worse, if you upgrade to 3.x, as it probably uses more CPU.

                                          Think the main changes for RRF3 were around making it more configurable at runtime, currently making the jump myself. Guess there are more advance features available, but not sure if CPU use will be effected. Interested to learn more there.

                                          Running 3 P3Steel with Duet 2. Duet 3 on the shelf looking for a suitable machine. One first generation Duet in a Logo/Turtle style robot!

                                          1 Reply Last reply Reply Quote 0
                                          • Edgars Batnaundefined
                                            Edgars Batna @jschall
                                            last edited by Edgars Batna

                                            @jschall Yeah, I created various topics, but it wasn't easy separating printer from firmware, as my build wasn't as polished back then. It was mostly treated as a printer hardware issue. Just look at topics created by me and you'll see multiple threads.

                                            This is the latest one: https://forum.duet3d.com/topic/16840/printer-refuses-to-do-a-certain-print

                                            I added detailed logging to the firmware in the meantime and wrote a program which counts how much extrusion the movement planning actually wants to command and it added up. The only thing left were the step interrupts themselves and the barely understandable second part of DriveMovement::PrepareExtruder (PA step computation) in the code. Without means to analyze stepper signals I stopped debugging.

                                            jschallundefined 1 Reply Last reply Reply Quote 1
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