Duet3D Logo Duet3D
    • Tags
    • Documentation
    • Order
    • Register
    • Login

    Blobs at every start and end of line

    Scheduled Pinned Locked Moved
    Tuning and tweaking
    blobs blob
    8
    28
    9.5k
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • dc42undefined
      dc42 administrators @Phaedrux
      last edited by

      Another thing you could try is installing firmware 2.03 and setting the jerk policy to 1 in the M566 command. That works more like Marlin does, by allowing jerk to be used where it isn't needed in theory, e.g. between a travel move and an extruding move.

      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
      • Jorgeundefined
        Jorge
        last edited by

        I updated the firmware but unfortunately it makes no difference.
        Next I will test it with a simple 8 bit board with Marlin. I hope it makes no difference because I really like the duet and the Dibond housing is milled for it...

        dc42undefined 1 Reply Last reply Reply Quote 0
        • Jorgeundefined
          Jorge
          last edited by

          I did not find the time to change the board yet but I did some coasting and restart distance tests. I set a high coasting distance and a negative restart distance until I got a fatal underextrusion at the beginning of a line but though I have a blob. So first a blob and then underextrusion for a few mm. This confuses me a lot.

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

            @jorge said in Blobs at every start and end of line:

            I updated the firmware but unfortunately it makes no difference.

            But did you also set the jerk policy to 1 ?

            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

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

              @dc42 said in Blobs at every start and end of line:

              But did you also set the jerk policy to 1 ?

              Yes, no visible difference 😞

              1 Reply Last reply Reply Quote 0
              • DanLundefined
                DanL
                last edited by

                Could it be a bowden related mechanical issue, e.g. the curvature or a slight kink or dent of the tube, a loose tube/end fitting connection, slight play in the tube-to-extruder fitting......?

                DanL

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

                  Blobs at the end of a line are typically caused by lack of pressure advance or insufficient retraction. Blobs at the start of a line are not normal. Are you sure that you don't have a positive "extra restart distance" or similar 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
                  • Jorgeundefined
                    Jorge @DanL
                    last edited by

                    @danl said in Blobs at every start and end of line:

                    Could it be a bowden related mechanical issue, e.g. the curvature or a slight kink or dent of the tube, a loose tube/end fitting connection, slight play in the tube-to-extruder fitting......?

                    I assumed something like that, too. The bowden is about 50 cm long, which is longer, than I'm used to. That's why I try made a test with a very short bowden, allowing me only to print on one corner of the print area. Again no difference.
                    Watching the tube-to-extruder fitting while printing didn't bring the enlightment, too.

                    @dc42 said in Blobs at every start and end of line:

                    Blobs at the end of a line are typically caused by lack of pressure advance or insufficient retraction. Blobs at the start of a line are not normal. Are you sure that you don't have a positive "extra restart distance" or similar configured in your slicer?

                    Makes sense. But I even set ...

                    @jorge said in Blobs at every start and end of line:

                    ... a negative restart distance until I got a fatal underextrusion at the beginning of a line but though I have a blob. So first a blob and then underextrusion for a few mm. This confuses me a lot.

                    DanLundefined 1 Reply Last reply Reply Quote 0
                    • DanLundefined
                      DanL @Jorge
                      last edited by

                      @jorge
                      I just looked at your S3D settings and you are not using the "Coast" setting.
                      For me, "Coast" is really helpful to control end blob. I know you tested Coast and Restart, but maybe look at that approach again?
                      I don't know if you have seen the info in the link below, but maybe helpful.
                      https://forum.simplify3d.com/viewtopic.php?f=8&t=2367

                      DanL

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

                        In theory, coast-to-end is a poor substitute for pressure advance, and is therefore not needed if you are using the right amount of pressure advance.

                        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 2
                        • Jorgeundefined
                          Jorge
                          last edited by

                          Finally I found the time to change the board and it did not help. Same blobs with Marlin. So it has nothing to do with the Duet or RepRap Firmware which means it must be a mechanical issue. I am kind of happy about that, because I love everything about the Duet. But now I have no idea how to solve the problem.

                          1 Reply Last reply Reply Quote 0
                          • Vetiundefined
                            Veti
                            last edited by

                            From your config

                            M305 P0 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 0
                            M305 P1 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 1

                            B4138 is the default value and very likely the wrong value for your thermistor.
                            This can give vastly incorrect temperature differences. (in the range of 40C easily)

                            1 Reply Last reply Reply Quote 1
                            • Jorgeundefined
                              Jorge
                              last edited by

                              Thank you for that clue! You were right! I had to calibrate P1 and landet at B3980. The hotend was more than 20C to hot (at 230C)! But since I tested a lot of different temperatures, this didn't help for my problem 😞

                              Vetiundefined 1 Reply Last reply Reply Quote 0
                              • Vetiundefined
                                Veti
                                last edited by

                                what is the lowest temperature that you have printed pla at?

                                1 Reply Last reply Reply Quote 0
                                • Vetiundefined
                                  Veti @Jorge
                                  last edited by

                                  @jorge said in Blobs at every start and end of line:

                                  Thank you for that clue! You were right! I had to calibrate P1 and landet at B3980. The hotend was more than 20C to hot (at 230C)! But since I tested a lot of different temperatures,

                                  how did you do the calibration?
                                  normally you find out what the thermistor is and put in the specified value for that thermistor into your config. B3980 is a very unusual value.

                                  1 Reply Last reply Reply Quote 0
                                  • Jorgeundefined
                                    Jorge
                                    last edited by

                                    I printed PLA at temperatures down to non extrusion.

                                    I have a hotend from aliexpress. There was no B Value mentioned.
                                    For the calibration I removed the filament and the bowden. Then I put the temperature sensor of my multimeter from the top into the nozzle. In the nozzle was some molten filament left, so there was a very good thermal connection to the nozzle. Then I set 230 °C and tweaked the value until the printer and the multimeter showed exactly the same value. I assume, that I eliminated any thermal transitions and tolerances this way, as I measured the temperature of the molten filament and not the heatblock or so.

                                    1 Reply Last reply Reply Quote 0
                                    • Vetiundefined
                                      Veti
                                      last edited by

                                      can you link as to which hotend you bought.

                                      but a random hotend can be a hit and miss.
                                      there could be a quality problem in any of the parts that might cause the problems you are seeing.

                                      1 Reply Last reply Reply Quote 0
                                      • Jorgeundefined
                                        Jorge
                                        last edited by

                                        Unfortunately the link is no more active. Neither to the V6 clone nor to the cyclops clone or the NF hotend.
                                        But most tests were made with the V6 clone.
                                        I already ordered a coated heatbreak from mapa refining here in Germany and a new bowden. I think the heatsink has no effect as long as the heatbreak and the nozzle are good. And I have a lot of nozzles here.

                                        1 Reply Last reply Reply Quote 0
                                        • Vetiundefined
                                          Veti
                                          last edited by

                                          @jorge said in Blobs at every start and end of line:

                                          I think the heatsink has no effect

                                          the bowden retention mechanism can have an effect. A small play can lead to retraction problems.

                                          I.e. this heatsink from aliexpress is very close to the e3d one
                                          https://www.aliexpress.com/item/32842829820.html
                                          whereas this one is using a push fit connector which can fail after some time
                                          https://www.aliexpress.com/item/32504536967.html

                                          1 Reply Last reply Reply Quote 0
                                          • First post
                                            Last post
                                          Unless otherwise noted, all forum content is licensed under CC-BY-SA