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    More strange pressure advance behaviour

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    • deckingmanundefined
      deckingman @dc42
      last edited by

      @dc42 said in More strange pressure advance behaviour:

      @deckingman, no there isn't any update.

      Did we ever establish whether slic3r generates GCode with a uniform extrusion rate for curves?

      Not really. Going through the gcode file for those test cylinders, what is for sure is that the extrusion amount can differ but there are no changes to feedrate. I'll have to do some maths on the XY coordinates but I'm pretty sure I did it before and discovered that the reason the extrusion amount varies is that the segment size can vary. I'm pretty sure the change in E amount corresponded with a change in XY of the same magnitude.

      Most of the time, the segment size is constant for any given arc but at seemingly random points in the file, odd segment sizes appear (for segment size read E amount). I think at one point you or I decided that change in segment size would lead to a change in direction that was sufficient to trigger pressure advance (but my memory is hazy on that so it could be a Red Herring).

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

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      • jmjcokeundefined
        jmjcoke
        last edited by

        Try Kisslicer 1.62. S3D just sits there on me desktop, Like a $149 bill.

        Joshua Coke

        Trick Laser Metal Max with Smart Effector
        Duet Wifi
        Zesty Nimble
        Mosaic Pallette+
        At work
        Renishaw AM250/400/ RenAM500M/500Q Powder Bed Fusion (Metal 3D Printers)

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

          @jmjcoke said in More strange pressure advance behaviour:

          Try Kisslicer 1.62. S3D just sits there on me desktop, Like a $149 bill.

          I currently use Slic3R. I did try S3D but for me it was hopeless with more than 2 colour objects and also the fact that essentially I have a number of completely different machine configurations. Fortunately, I managed to get a refund within the 30 day period.

          Ref Kissslicer - yes it might be worth a try but again, I'd need the Pro version to do 5 colour objects which, means parting with more hard earned for something that might, or might not work.

          The BIG problem with all this is that are we starting to tread the path that Duet Firmware will only work with certain slicers? IMO the perfect slicer has yet to be developed and they all have their vagaries and "issues". So to my mind, the firmware ought to work independently of which slicer was used to generate the gcode. I'm not saying it should produce perfect prints - that would be impossible. But it ought to carry out the movement commands that are embedded in the gcode file, regardless of how imperfect those commands might be.

          I don't think the Duet team would want to go down the road of "Please buy our boards, they are the best (but they only work with certain slicers)". That's likely to put quite a few people off buying the product, despite that fact that their favourite slicer may not generate the best gcode.

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

          T3P3Tonyundefined 1 Reply Last reply Reply Quote 0
          • deckingmanundefined
            deckingman
            last edited by

            OK, so I just installed KISSlicer in order to take a quick look at it. It only lets me configure a printer with up to 4 extruders - I have 5. So that's not going to be any good.

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

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            • T3P3Tonyundefined
              T3P3Tony administrators @deckingman
              last edited by

              @deckingman you are right about us wanting it to work with all slicers. I guess people are asking about the slicers as a potential variable. Does this weird shifting happen in square profile columns?

              www.duet3d.com

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              • deckingmanundefined
                deckingman @T3P3Tony
                last edited by

                @t3p3tony said in More strange pressure advance behaviour:

                @deckingman you are right about us wanting it to work with all slicers. I guess people are asking about the slicers as a potential variable. Does this weird shifting happen in square profile columns?

                Hi Tony,

                I think you may be confusing this thread with another. It's not a weird shifting thing. This is just about using highish levels or pressure advance, as is required by the Diamond hot end. The issue is only when doing arcs, and is somewhat random in that it doesn't always do it. (Actually, there is another issue related to using pressure advance with multiple extruders and that isn't random - it always does it). However, in this case, even with a single extruder it is random. It manifests itself in erratic carriage movement, and random short pauses resulting in some weirdly shaped circles. Printing a test file which consists of nothing but various different sizes of cylinder, shows this randomness. i.e. for any given layer, one or more or none of the cylinders will exhibit the behaviour but on the next layer, it might be the same cylinder, or a different cylinder, or no cylinders that exhibit the problem.

                The gcode file that Slic3R generates shows that randomness in terms of segment size. Generally the segments are consistent for any given circle but now and then, there is an odd one which is larger, followed by a small one and that pattern my be repeated for a few moves before reverting to equal segment sizes.

                So the consensus seems to be that it is the non-prefect gcode that is initiating the problem hence the suggestions to try different ones. The trouble is, none that I have tried support 5 extruders so I'm stuck with Slic3R. Short term, I could use a different slicer but then long term, I won't be able to print using 5 extruders. As things are, I can print with 5 extruders (as long as I don't use pressure advance).

                The thing is, up until October, I had always had the problems with pressure advance and multiple extruders but using a single extruder was problem free. This is a new issue which started some time between October and January. Same printer, same slicer, same config etc but different firmware.

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

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                • burtoogleundefined
                  burtoogle
                  last edited by

                  Cura can handle up to 8 extruders.

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

                    @burtoogle said in More strange pressure advance behaviour:

                    Cura can handle up to 8 extruders.

                    Thanks. I'll give it a try when I get the opportunity. Just out of curiosity, why do other slicers impose limits on the number of extruders? I guess Slic3R must have a limit but just to see what would happen, I tried setting the number of extruders in Slic3r to 100 and it all seemed to work. Not that I'd ever use that many but I'm just curious as to why there is a hard limit with some slicers.

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

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                    • Knaudlerundefined
                      Knaudler
                      last edited by Knaudler

                      hello

                      also have one model with PA problems
                      with 1.21 or 2.0(RTOS)RC2b (using newest beta for duet wifi)

                      normaly I use 0.4 (on my CR-10 - 50cm Bowden) for really smooth surfaces
                      but this thing makes really problems
                      without PA and nothings else, it works

                      with PA or Coasting, extruder doesnt work any more from layer 10
                      maybe it goes backwards and printing only air

                      https://www.thingiverse.com/thing:2917556

                      make the pulley with Fusion 360
                      want to test - in S3D the preview looks good - the outer line only one line without gaps
                      test with S3D (newest)
                      slow/fast, only 0.1PA
                      with a lot of different jerk settings

                      extra test with cura (newest) because S3D may not make good code ?

                      nothing works
                      M122 is ok no underruns

                      only without any PA or coasting this thing ist printing clean

                      maybe you can test ?
                      my speed is 60mm and outline 20%
                      2 Perimeter 0.4, 3 Bottom layer - no infill (for this test)
                      layer 0.1 or 0.12 mm

                      so I think its good to aktivate PA only via gcode (variable processes) for long smooth lines

                      excuse the bad english

                      greetings from Hamburg

                      dc42undefined 2 Replies Last reply Reply Quote 0
                      • dc42undefined
                        dc42 administrators @Knaudler
                        last edited by

                        @knaudler, I'll add this to my list to test, next week if I can.

                        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

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                        • dc42undefined
                          dc42 administrators @Knaudler
                          last edited by dc42

                          @knaudler, can you confirm that it was M572 pressure advance that you were using, not some sort of "pressure advance" feature in the slicer? If so, please provide the GCode files that you are trying to print, that gave problems when you enabled pressure advance.

                          You also said "with PA or Coasting, extruder doesnt work any more from layer 10". So enabling coasting in the slicer had the same effect? If so, this isn't a firmware problem, it is a slicer problem.

                          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

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                          • Knaudlerundefined
                            Knaudler
                            last edited by

                            hello

                            thats why I checked with Cura
                            I have to look for the right file...

                            last 30h print I had problems with loosen wifi connectivity on duetwifi
                            if there is a short wifi break (AP update), all client reconnect only duet never 😞
                            but thats something for other thread.

                            maybe I can check with anet A8 and Marlin in next days
                            looking for gcode ...

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                            • Knaudlerundefined
                              Knaudler
                              last edited by

                              hhmm

                              now with BondTech extruder AND 1A for Stepper it works,
                              same gcode with a lot very short, fast retracts (GT2 idler)
                              pressure advance 0.1 with FW 2.0
                              before only used 800mA - maybe not enough for 80mm/sec retract ?
                              on 15V

                              with BondTech now max retract speed is 60mm/sec
                              first test ok

                              Knaudler

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                              • deckingmanundefined
                                deckingman
                                last edited by

                                I'm wondering if there is any point in me raising this issue yet again but here goes...........

                                So on another forum, I have now established that although slic3r generates uneven segment sizes, seemingly at random, the extrusion rate itself does not vary. To illustrate:

                                Here is a sample of "problem" gcode.....

                                G1 X246.350 Y203.493 E0.06750
                                G1 X245.357 Y203.301 E0.06755
                                G1 X244.373 Y203.062 E0.06765
                                G1 X242.926 Y202.622 E0.10103
                                G1 X241.976 Y202.271 E0.06763
                                G1 X241.044 Y201.877 E0.06763
                                G1 X239.687 Y201.208 E0.10104
                                G1 X238.807 Y200.709 E0.06763
                                G1 X237.951 Y200.170 E0.06756
                                G1 X237.122 Y199.592 E0.06754

                                Calculating the move distance from the XY coordinates we get these segment lengths...

                                1.0113916155476
                                1.01260900647782
                                1.5124182622542
                                1.01276897661806
                                1.01185967406551
                                1.51294745447422
                                1.01163283853384
                                1.0115616639632
                                1.01060625369129

                                Dividing the extrusion amount by the segment lengths we get the following extrusion rates.....

                                0.066789163526362
                                0.066807622258179
                                0.066800304202502
                                0.066777321937563
                                0.066837331038475
                                0.066783548695757
                                0.066852317781633
                                0.066787821649257
                                0.06683117163911

                                Therefore the theory that it is changes in the extrusion rate that causes pressure advance to trigger, doesn't explain the behaviour I am seeing (unless changes of extrusion rate to the 4th decimal place are considered significant).

                                To summarise.......

                                A value of 0.4 or 0.5 pressure advance is required by my printer/hot end to cure over/under extrusion at the start and end of longish moves at anything other than slow print speed. If I try to print cylinders, circles or arcs using that amount of pressure advance, (with a single extruder) it will sometimes trigger, seemingly at random, multiple times during an arc move. This is visible and has been captured on video and a link to that video has been provided (as have the stl files, the gcode files, and the configuration files as well as M122 diagnostic reports). This multiple triggering of pressure advance causes the print head to falter and jerk leading to ruined prints.

                                Coincidentally, the gcode generated by slic3r randomly has uneven segment sizes for any given arc, but the extrusion rate itself does not vary. I can't help think that might be a clue as to the cause - we have seemingly random changes to segment length, and we also have seemingly random triggering of pressure advance......

                                Also, this behaviour (with a single extruder), was not apparent prior to firmware updates around January this year. Although since July of last year, I have had similar problems when using multiple extruders.

                                Over the last 12 months, I have changed just about every setting that has been suggested or that I can think of. I've updated the firmware multiple times. I've generated multiple reports, made numerous videos, and carried out extensive testing in order to provide as much information as possible. Yet still the problem persists with no sign of any cure being forthcoming. Getting just a tad fed up now.............

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

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

                                  This is on my list to look at for the 2.01 release.

                                  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

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

                                    Hi Ian, please can you provide the links to a GCode file generated by slic3r that exhibits the problem shown in your video, and your config.g file.

                                    EDIT: I've just found a link to https://drive.google.com/drive/folders/0B_MwtHtQR_Zvd1BSd1RKSFYwbTQ in an older post of yours. Do those correspond to the video that you posted?

                                    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

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

                                      @dc42
                                      Hi David. Sorry that it took a while but yes, those files are the ones and that folder is still on my google drive and shared. My config.g has changed somewhat since then due to changing the Titan extruders for Bondtech ones and one or two other changes that I've made.

                                      For info, I've raised the uneven segment length as an issue on slic3r GitHub but I doubt if anything will come of it as it doesn't seem to affect print quality (as long as pressure advance isn't used).

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

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                                      • dc42undefined
                                        dc42 administrators
                                        last edited by

                                        Thanks. Are you able to reproduce the problem using a cylinder sliced in vase mode?

                                        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

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                                        • deckingmanundefined
                                          deckingman @dc42
                                          last edited by

                                          @dc42 said in More strange pressure advance behaviour:

                                          Thanks. Are you able to reproduce the problem using a cylinder sliced in vase mode?

                                          I don't think I've ever tried that but I'll give it a go to see what happens. I have no time to do it this weekend though. However, I'm taking a bit of break from my day job next week, so I should have a fair amount of time to do some more testing from Tuesday onwards.

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

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                                          • deckingmanundefined
                                            deckingman
                                            last edited by

                                            I've had a quick look at this. I can't use vase mode on those test cylinders because they are multiple. So I've created a tapered cylinder which will give me circles of differing radii. I've sliced it firstly with zero infill, 3 perimeters and no top, and secondly in spiral vase mode (single perimeter, no top, constantly varying Z). Looking through the gcode files, both look like they have unequal segment lengths for any given circle. I'll print them both with highish pressure advance enabled (probably won't manage it over the weekend but I'll do me best) and report back. I'll do them with a single extruder to start with, and again using multiple extruders.

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

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