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Strange Blobbing on Layer Change

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Tuning and tweaking
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  • undefined
    deckingman @Corexy
    last edited by 27 May 2020, 09:03

    @Corexy said in Strange Blobbing on Layer Change:

    Actually...this roll of PETG is a total #$%&...but mostly because I'm demanding the kind of print quality I can get from PLA and ABS I guess. I'm setting a pretty high bar there (if I say so myself), and I'm coming to the conclusion I might have to lower my standards a bit for this one.

    There have been a few threads recently by people having problems with PET-G. Even the same brand and colour seems to throw up some seemingly random variability between reels. Doing a temperature tower for every new reel might be the answer (but then again, it might not).

    What I love about the BMG is that it seems to use the same steps/mm not matter what you feed it. Which has most certainly not been the case with other single sided extruders I've had.

    I've found exactly the same thing. I patiently and carefully calibrated all 6 of mine and ended up with less than 1% spread between them. Which is within the realms of what one might expect when trying to measure 100mm of filament multiple times. It doesn't matter if I feed them PLA or PET-G or whatever. Might as well just set them all to 415 and be done with it. I tend to use 0.95 extrusion multiplier most of the time - I've found that on my machine, printed parts are surprisingly tolerant of under extrusion but very intolerant of any over extrusion.

    I think you are right. I think the BMG holds the extruder at a higher pressure, which may lead to some drooling at retract points that can be tuned out a bit with pressure advance/coast/restart/extrusion multiplier etc.

    That's my hypothesis - but I might be wrong 🙂

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

    1 Reply Last reply Reply Quote 0
    • undefined
      davidewen
      last edited by 29 Oct 2022, 13:39

      Hello everyone.

      I am getting z-seam blobs due to slight pauses at layer changes.
      This happens only on my Ender 6 running Duet.

      I primarily use PrusaSlicer, but I've also tried Cura 5.x.
      I do not get these marks on my Prusa MK3s.

      Note: both printers have the same extruder and hot end as listed blow.

      Printer: Ender 6
      Mods: Bondtech BMG direct extruder, Slice Eng Mosquito Magnum hot end.

      M115
      FIRMWARE_NAME: RepRapFirmware for Duet 3 Mini 5+ FIRMWARE_VERSION: 3.3RC2 ELECTRONICS: Duet 3 Mini5plus WiFi FIRMWARE_DATE: 2021-05-11 14:55:40

      Config.g file: config.g

      157BD65F-323B-4FD2-809A-29761A5AFAA1.jpeg

      undefined 1 Reply Last reply 29 Oct 2022, 15:18 Reply Quote 0
      • undefined
        giostark @davidewen
        last edited by 29 Oct 2022, 15:18

        @davidewen
        Hi Davide,
        Maybe you are super skilled already with all those programs , I'll just try to be cooperative.
        Is a little hard to tell for sure regarding just one possible solution.
        I use Cura and I can try suggesting something using it.

        • Try to use Cura 4.13.1. The 5.X series address some issue with concentric shapes (the width of the lines) and is removed the function of exclude tiny gaps, resulting in additional movement and extrusions. (maybe is not the case but on circular shapes could help the first point).
        • Try to use defined seam. (so , not the shortest nor the random or sharpest) . In the preview look for the best position where to place the seam. (back , front, left etc) . Try to obtain on vertical line as seam. If necessary rotate the shape. (Cura is rotation sensitive , and you can discover it looking the support lines)
        • Try to work on Wall > outer wall wipe distance. (should help to hide the seam inside the shape)
        • Try to work on Travel > disable retraction at layer change (this avoid pause and leak of materials because the pressure)
        • Try to work on Travel > combing mode on all (less retraction > less pressure changing > less leaking)
        • Try to work on Travel > disable retraction before outer wall
        • Try to work on Experimental > enable coasting . Here work on the number of the area of the nozzle. (moving without retraction should reduce the amount of material leaked for the variation of pressure. If you exaggerate with this option , or the sum of all those settings, you could generate holes instead of blobs).
        • Keep in mind that if you change layer height , all those parameters will change. To my printer ,to print at 0.3 or 0.2 is not absolutely the same.
          And you have seen by yourself with the first shape on left that emphasize the issues.
        • Keep in mind that not all the shape can use the same profile.
        • The concept is to try to avoid the numbers of retractions and keep the material's extrusion the more constant you can.
        • Then... is not exactly clear from the picture , because there are not 90 degree corners , check the belt tension. On quick and fast direction's change you can have a little of vibration of the nozzle. Or instead do not exaggerate with the speed of the print.

        I tried to inspect your picture , thanks for the high resolution.
        The lines seems good except for the seams.
        I'm optimistic that you can nail the right combo of settings.

        undefined 1 Reply Last reply 30 Oct 2022, 19:19 Reply Quote 0
        • undefined giostark referenced this topic 30 Oct 2022, 12:22
        • undefined
          davidewen @giostark
          last edited by 30 Oct 2022, 19:19

          @giostark
          Thanks for responding. I also responded to @Phaedrux on the other older post. This may be a better place to continue the conversation.

          My printers are at the office. I'll test your ideas on Monday.

          You mentioned 90° corners. These blobs are still present on those as well.
          Watching the printer, the pause between layer changes is very evident. And at the location of the pause is where the blobs occur.
          Most other posts talk about pressure advance and jerk control. I haven't done much with those settings, so I'm not very familiar with the pros/cons or the affects of making changes.

          The easiest thing for me to test will be the suggestion from @Phaedrux regarding the Z axis speed. So I will start with that.

          Cheers,
          David

          undefined 1 Reply Last reply 31 Oct 2022, 12:12 Reply Quote 0
          • undefined
            giostark @davidewen
            last edited by 31 Oct 2022, 12:12

            @davidewen
            Yep the Z in M566 could be higher. Right now I have just a delta printer and settled 800 on all 3 axis.
            You have 900 on x and y. Why so slow on z with just 60?
            David suggest the default as 600 in this post:
            https://forum.duet3d.com/topic/310/m566-what-s-a-good-number
            But someone use even 1200.

            Please if you found the solution replay here so that will be useful to us all 😀

            ps:
            I have to learn to check before the config.g and then the slicer , damn. Here the phaedrux's skill was evident!
            My advice still remain good for refinement 😉

            undefined 1 Reply Last reply 31 Oct 2022, 16:50 Reply Quote 0
            • undefined
              davidewen @giostark
              last edited by 31 Oct 2022, 16:50

              @giostark @Phaedrux ,

              Thanks for your help.
              Changing the Z Axis speed has definitely helped.

              I'm still getting a dimple at the Z-Seam, but not blobs as before.

              new numbers.
              M566 X1500.00 Y1500.00 Z600.00 E120.00 ; set maximum instantaneous speed changes (mm/min)

              6597B7F5-C67E-4A35-846F-E04FCB0749E1.jpeg CFF5A990-9E8D-45AF-897E-8A8CC5D36703.jpeg AC7BDEB0-77DF-44CC-940A-A39AF0275FD1.jpeg

              test cone (N)0.6 (L)0.36 (IF)15% (S)80 (T)250°C (F)ASA (T)9m .gcode

              undefined undefined 2 Replies Last reply 1 Nov 2022, 00:19 Reply Quote 0
              • undefined
                Phaedrux Moderator
                last edited by 31 Oct 2022, 20:46

                Increase your extruder jerk.

                Z-Bot CoreXY Build | Thingiverse Profile

                undefined 1 Reply Last reply 4 Nov 2022, 01:09 Reply Quote 0
                • undefined
                  giostark @davidewen
                  last edited by 1 Nov 2022, 00:19

                  @davidewen
                  On the Bondtech BMG I have settled E1200. Tie well the screw otherwise the gears will dent the wire.

                  1 Reply Last reply Reply Quote 0
                  • undefined
                    Norder @davidewen
                    last edited by Norder 11 Jan 2022, 01:00 1 Nov 2022, 00:59

                    @davidewen
                    How many mm is your retract in the slicer and at what speed does it run ?

                    DDA5X... 0.9° Stepper... Linearrails... Duet 2 Wifi... PT100 Board... Duet IR-Probe... Dyze Pro Kit up to 500°C.. etc
                    Thingiverse

                    undefined 1 Reply Last reply 4 Nov 2022, 01:14 Reply Quote 0
                    • undefined
                      davidewen @Phaedrux
                      last edited by 4 Nov 2022, 01:09

                      @Phaedrux
                      Sorry for the slow response. We're trying to get a big project out the door and that has been consuming time.

                      I've increased jerk in PrusaSlicer to the following;
                      X: 32
                      Y: 32
                      Z: 32
                      E: 20

                      And here are my config.g settings

                      M566 X1500.00 Y1500.00 Z600.00 E120.00			; set maximum instantaneous speed changes (mm/min)
                      
                      M203 X12000.00 Y12000.00 Z600.00 E2100.00		; set maximum speeds (mm/min)
                      M201 X1500.00 Y1500.00 Z500.00 E250.00			; set accelerations (mm/s^2)
                      
                      

                      Still getting the same results.

                      undefined 1 Reply Last reply 4 Nov 2022, 20:28 Reply Quote 0
                      • undefined
                        davidewen @Norder
                        last edited by 4 Nov 2022, 01:14

                        @Norder
                        PrusaSlicer Retraction settings;
                        Length: 0.8
                        Z lift: 0.4
                        Speed: 40
                        Min Travel: 2
                        Retract on layer: off
                        Min travel after retract: 2
                        Wipe while retracting; on
                        retract amount before wipe: 80%

                        weed2allundefined undefined 2 Replies Last reply 4 Nov 2022, 03:31 Reply Quote 0
                        • weed2allundefined
                          weed2all @davidewen
                          last edited by weed2all 11 Apr 2022, 03:34 4 Nov 2022, 03:31

                          @davidewen try retracting a little bit more...like 0.85 or 0.90! Also reduce the retraction speed to something like 25 to 30
                          Jerk values are to high!

                          https://www.thingiverse.com/weed2all/designs

                          1 Reply Last reply Reply Quote 0
                          • undefined
                            Norder @davidewen
                            last edited by 4 Nov 2022, 11:11

                            @davidewen
                            So far the settings look good.
                            If you don't have stringing or other problems with blobs or similar, then the 0.8mm retraction path is probably OK. But it can change depending on the temperature and filament and then higher values would be more suitable, which could then go up to 1.5mm.

                            That with the speed could reduce this gap at the Z-seam, as weed2all already wrote, 25-30 mm/s may be better values for you.

                            If these changes don't bring any improvements, you could enter something under "Extra length on restart". Step up there by 0.1mm.
                            This option of "Extra length on restart" is rarely used.

                            Google Translate
                            -- Original Text --

                            Soweit sehen die Einstellungen gut aus.
                            Wenn Du kein Stringing hast oder sonstige Probleme mit Kleckse o.ä., dann sind die 0.8mm Rückzugsweg wohl OK. Es kann sich aber je nach Temperatur und Filament ändern und dann wären höhere Werte besser geeignet die dann gerne mal bis 1.5mm gehen könnten.

                            Das mit der Geschwindigkeit könnte diesen Spalt an der Z-Naht verringern, wie weed2all bereits schrieb sind 25-30 mm/s gegebenenfalls bessere Werte für Dich.

                            Sollten diese Änderungen keine Verbesserungen bringen, dann könntest Du bei "Extralänge bei Neustart" etwas eintragen. Dort Schrittweise mit 0.1mm herangehen.
                            Diese Option der "Extralänge bei Neustart" wird eher selten genutzt.

                            DDA5X... 0.9° Stepper... Linearrails... Duet 2 Wifi... PT100 Board... Duet IR-Probe... Dyze Pro Kit up to 500°C.. etc
                            Thingiverse

                            1 Reply Last reply Reply Quote 0
                            • undefined
                              Phaedrux Moderator @davidewen
                              last edited by 4 Nov 2022, 20:28

                              @davidewen said in Strange Blobbing on Layer Change:

                              I've increased jerk in PrusaSlicer to the following;
                              X: 32
                              Y: 32
                              Z: 32
                              E: 20

                              Where did you change that?

                              I assume that's in mm/s?

                              Does prusa slicer now allow per move jerk settings as well as acceleration? I didn't think so.

                              Is your prusa slicer set to RepRap gcode flavour?

                              Can you share a sliced gcode file?

                              Your config file still has the limits set very low, so unless your slicer is actually sending M566/M203/M201 commands to change the limits during a print you are being limited by the config.g

                              Z-Bot CoreXY Build | Thingiverse Profile

                              undefined undefined 2 Replies Last reply 5 Nov 2022, 00:13 Reply Quote 0
                              • undefined
                                Norder @Phaedrux
                                last edited by Norder 11 May 2022, 08:55 5 Nov 2022, 00:13

                                @Phaedrux

                                Does prusa slicer now allow per move jerk settings as well as acceleration? I didn't think so.

                                The PrusaSlicer has its own jerk setting (mm/s), maximum acceleration (mm/s²) and maximum feed (mm/s)
                                for each axis.

                                DDA5X... 0.9° Stepper... Linearrails... Duet 2 Wifi... PT100 Board... Duet IR-Probe... Dyze Pro Kit up to 500°C.. etc
                                Thingiverse

                                undefined 1 Reply Last reply 5 Nov 2022, 04:46 Reply Quote 0
                                • undefined
                                  Phaedrux Moderator @Norder
                                  last edited by 5 Nov 2022, 04:46

                                  @Norder said in Strange Blobbing on Layer Change:

                                  The PrusaSlicer has its own jerk setting

                                  Where? You mean in the machine limits?

                                  Z-Bot CoreXY Build | Thingiverse Profile

                                  undefined 1 Reply Last reply 5 Nov 2022, 08:52 Reply Quote 0
                                  • undefined
                                    Norder @Phaedrux
                                    last edited by 5 Nov 2022, 08:52

                                    @Phaedrux
                                    Yes, exactly.
                                    But it is clear that the upper limit is determined by the config.g.

                                    DDA5X... 0.9° Stepper... Linearrails... Duet 2 Wifi... PT100 Board... Duet IR-Probe... Dyze Pro Kit up to 500°C.. etc
                                    Thingiverse

                                    undefined 1 Reply Last reply 5 Nov 2022, 15:46 Reply Quote 0
                                    • undefined
                                      davidewen @Norder
                                      last edited by 5 Nov 2022, 15:46

                                      @Norder @Phaedrux @weed2all

                                      Thank you all for responding.
                                      I will not be able to check settings or respond back with said settings until late next week.

                                      Cheers

                                      1 Reply Last reply Reply Quote 0
                                      • undefined
                                        davidewen @Phaedrux
                                        last edited by 7 Nov 2022, 15:33

                                        @Phaedrux

                                        Yes, I made those changes in PrusaSlicer.
                                        Are you suggesting that I make the changes in config.g?
                                        And if so, is that command M566?

                                        My current M566 is not labeled "jerk" so I just want to confirm.

                                        M566 X1500.00 Y1500.00 Z600.00 E120.00			; set maximum instantaneous speed changes (mm/min)
                                        
                                        M203 X12000.00 Y12000.00 Z600.00 E2100.00		; set maximum speeds (mm/min)
                                        
                                        M201 X1500.00 Y1500.00 Z500.00 E250.00			; set accelerations (mm/s^2)
                                        
                                        1 Reply Last reply Reply Quote 0
                                        • undefined
                                          Phaedrux Moderator
                                          last edited by 7 Nov 2022, 18:22

                                          Yes, maximum instantaneous speed changes is often called jerk.

                                          Z-Bot CoreXY Build | Thingiverse Profile

                                          undefined 1 Reply Last reply 7 Nov 2022, 19:25 Reply Quote 0
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