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[SOLVED] Underextrusion at 0.1mm but not at 0.2mm layer height

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  • undefined
    llamazen @Phaedrux
    last edited by llamazen 11 Apr 2018, 23:10 4 Nov 2018, 23:06

    @phaedrux Here it is.

    AI3M_03_RetractionCalibration.gcode

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    • undefined
      llamazen
      last edited by 4 Nov 2018, 23:14

      I did a test print today with 0.075mm^3 extra prime after retraction and it printed OK.

      It's weird though because I never had to use it before. I got the number from the E3D nozzle diagram for my 0.4mm nozzle.

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      • undefined
        deckingman @Phaedrux
        last edited by 5 Nov 2018, 08:36

        @phaedrux said in Underextrusion at 0.1mm but not at 0.2mm layer height:

        ..............................
        You can combat this a little bit by setting the extruder to a higher microstepping. I find anything over 64 causes hiccups. .........................

        Just a "for info". The extruder moves much faster when doing retract/unretract than it does during normal print moves and that's what causes the hiccups. So if you are able to retract at slower speed, then you can push the micro stepping up a bit further. The step pulse frequency limit is about 200,000 so if you take the steps per mm, multiply that by the micro-stepping then divide the result into 200,000 it'll give you maximum extruder speed that you can use.
        HTH

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

        undefined undefined undefined 3 Replies Last reply 5 Nov 2018, 15:36 Reply Quote 0
        • undefined
          Phaedrux Moderator @deckingman
          last edited by 5 Nov 2018, 15:36

          @deckingman thanks for that Ian.👍

          Z-Bot CoreXY Build | Thingiverse Profile

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          • undefined
            llamazen @deckingman
            last edited by 5 Nov 2018, 22:24

            @deckingman @Phaedrux Sorry guys, I don't quite understand what you're saying. I currently set the microstepping of the extruder to 16 interpolated.

            As far as I know, this sets the microstepping 256 virtual steps. I have tried setting removing interpolation but the motor gets noisy and whiny like it did with the cheap drivers.

            undefined undefined 2 Replies Last reply 5 Nov 2018, 23:51 Reply Quote 0
            • undefined
              Phaedrux Moderator @llamazen
              last edited by 5 Nov 2018, 23:51

              @llamazen So the idea is that if the print move asks the extruder to move a distance shorter than the minimum distance of a single microstep the extruder motor won't move at all.

              Z-Bot CoreXY Build | Thingiverse Profile

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              • undefined
                deckingman @llamazen
                last edited by 6 Nov 2018, 07:51

                @llamazen I see where you are coming from and why. Unfortunately in this instance the term "interpolation" is a bit misleading (in fact, it's a lot misleading). ☺

                All it means is that when it is used, the driver chip will divide the micro step pulse into 16 smaller step pulses. But, it's always 16 smaller step pulses. The step pulse from the Duet is an on or an off, a 1 or a zero, a high or a low. There is no in between. I'm not sure what happens inside the firmware but I'd imagine there will be some sort of rounding happening. So if the calculated movement amount required say 10.6 micro-steps, then it would be rounded up to 11 pulses. Conversely, if the calculation resulted in 10.4 micro-steps then it gets rounded down to 10 pulses. Whatever happens, it's always a whole number of micro step pulses. So "interpolation" doesn't give any better positional accuracy. From a positioning point of view 16x micro-stepping with interpolation is exactly the same as 16X without interpolation and the only way to get finer resolution is to use higher micro-stepping.
                HTH

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

                undefined 1 Reply Last reply 6 Nov 2018, 08:02 Reply Quote 0
                • undefined
                  llamazen @deckingman
                  last edited by 6 Nov 2018, 08:02

                  @deckingman OK got it. I'll do a print with 64 and 256.

                  Thanks guys for the input.

                  undefined 1 Reply Last reply 6 Nov 2018, 08:06 Reply Quote 0
                  • undefined
                    deckingman @llamazen
                    last edited by 6 Nov 2018, 08:06

                    @llamazen said in Underextrusion at 0.1mm but not at 0.2mm layer height:

                    @deckingman OK got it. I'll do a print with 64 and 256.

                    Thanks guys for the input.

                    Stick with 64 to start with. At 256x you'll likely run into the maximum step pulse frequency of 200,000 Hz that I was talking about (unless you use very low retraction speed). Run M122 during the print and check for any reported hiccups which should zero or near zero.

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

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                    • undefined
                      deckingman
                      last edited by 6 Nov 2018, 08:09

                      If you let me know the steps per mm @16x, I can calculate the maximum extruder speed that you can use for retraction at any other micro-stepping (or you can do that calculation yourself using the info I posted earlier).

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

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                      • undefined
                        DocTrucker @llamazen
                        last edited by 6 Nov 2018, 08:38

                        @llamazen Sorry, I've diverted from the original subject to something that I had measured on a recent test. I think it is probably best that I spin that off to a another post that I will write now. I doubt what I am seeing will directly effect your work, but I suspect it may have a little to do with retraction and advance settings.

                        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!

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                        • undefined
                          OBELIKS @deckingman
                          last edited by 9 Nov 2018, 07:49

                          @deckingman said in Underextrusion at 0.1mm but not at 0.2mm layer height:

                          @phaedrux said in Underextrusion at 0.1mm but not at 0.2mm layer height:

                          ..............................
                          You can combat this a little bit by setting the extruder to a higher microstepping. I find anything over 64 causes hiccups. .........................

                          Just a "for info". The extruder moves much faster when doing retract/unretract than it does during normal print moves and that's what causes the hiccups. So if you are able to retract at slower speed, then you can push the micro stepping up a bit further. The step pulse frequency limit is about 200,000 so if you take the steps per mm, multiply that by the micro-stepping then divide the result into 200,000 it'll give you maximum extruder speed that you can use.
                          HTH

                          So with 850 steps/mm at 16x that would mean 14,7mm/s?

                          P3Steel Toolson mk2 - Duet 2 WiFi --> RatRig V-Core with Duet WiFi 1.03
                          Original Prusa i3 MK3S

                          undefined 1 Reply Last reply 9 Nov 2018, 08:28 Reply Quote 0
                          • undefined
                            deckingman @OBELIKS
                            last edited by 9 Nov 2018, 08:28

                            @obeliks said in Underextrusion at 0.1mm but not at 0.2mm layer height:

                            @deckingman said in Underextrusion at 0.1mm but not at 0.2mm layer height:

                            @phaedrux said in Underextrusion at 0.1mm but not at 0.2mm layer height:

                            ..............................
                            You can combat this a little bit by setting the extruder to a higher microstepping. I find anything over 64 causes hiccups. .........................

                            Just a "for info". The extruder moves much faster when doing retract/unretract than it does during normal print moves and that's what causes the hiccups. So if you are able to retract at slower speed, then you can push the micro stepping up a bit further. The step pulse frequency limit is about 200,000 so if you take the steps per mm, multiply that by the micro-stepping then divide the result into 200,000 it'll give you maximum extruder speed that you can use.
                            HTH

                            So with 850 steps/mm at 16x that would mean 14,7mm/s?

                            No, sorry I didn't make that clear. I should have said, if you have the steps per mm at 16x, then first divide by 16 to get whole steps then multiple by the new steps per mm. If you have already got the steps per mm at the desired micro-stepping, you simply divide that into 200,000. So with 830 steps per mm, you can go up to 241 mm/sec. You'd need to go to 256x micro-stepping to get as low as 15. Sorry.

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

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                            • undefined
                              OBELIKS
                              last edited by 9 Nov 2018, 09:57

                              OK, that makes more sense.

                              P3Steel Toolson mk2 - Duet 2 WiFi --> RatRig V-Core with Duet WiFi 1.03
                              Original Prusa i3 MK3S

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                              • undefined
                                wilriker
                                last edited by 9 Nov 2018, 11:24

                                Or use my Extruder Microstep Calculator. Just enter steps/mm (@ x16) and look at the Max Retraction Speed (mm/min) column of the result table that will give you these values for all available microsteppings. 😉

                                For this case you can simply ignore all other input fields and result columns.

                                Manuel
                                Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
                                with probably always latest firmware/DWC (incl. betas or self-compiled)
                                My Tool Collection

                                undefined 1 Reply Last reply 9 Nov 2018, 11:34 Reply Quote 1
                                • undefined
                                  deckingman @wilriker
                                  last edited by 9 Nov 2018, 11:34

                                  @wilriker I'd forgotten that you'd done that.

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

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                                  • undefined
                                    llamazen
                                    last edited by 11 Nov 2018, 13:33

                                    Back to the original topic. I finally found some time to play with the printer again and tried your suggestions.

                                    I have forced the steps per mm to 64 and did a test print. It did not fix the problem but the extruder motor was louder.

                                    I have printed 2 hollow test-cubes next to each other. There were no signs of under extrusion but the retraction cylinders looked bad.

                                    Finally I have decided to just use the extra prime amount for the time being. It gives me the good results inspite of my reluctance to use it.

                                    Thank you for your input. I learned a lot about the finer details of extruders.

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