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Extruder acceleration/jerk and tuning

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Tuning and tweaking
extrusion tuning extruder acceleration extruder jerk
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  • undefined
    Ringo1508 @deckingman
    last edited by 29 May 2019, 17:36

    @deckingman said in Extruder acceleration/jerk and tuning:

    As @Phaedrux says, the max speed should be set for the maximum travel speed (e.g. I use 350mm/sec for non-print moves but usually print at around 90mm/sec). Personally, I calculated the maximum attainable speed based on the maximum acceleration that the motors will give me for the mass and bed size and set that in config.g. So it's nice and high and won't limit what I do with my slicer.

    You could add a step between 7 and 8 - set maximum accelerations for moves rather than axes - see M204 https://duet3d.dozuki.com/Wiki/GCode#Section_M204_Set_printing_and_travel_accelerations. This can actually be useful on a per-print basis rather than being in config.g though.

    Sorry to dig up an old thread @deckingman but I'm hoping to keep this all in one thread so if someone finds it searching for the same reason I did, this info will be here too!

    @deckingman, how did you calculate the "maximum acceleration that the motors will give me for the mass and bed size"?

    I'm just now diving into the black arts of tuning and I have no idea how to tune acceleration, feedrate (speed?) and jerk.

    The EMF calculator says that I'll start losing torque on my X/Y axis around 254.8mm/s so I was going to set M203 X and Y to 250mm/s (max speed) and then M204 T to 250mm/s (max travel speed) as you suggested (if I understood you correctly on this.) I just have no idea how to figure out max acceleration.

    undefined 1 Reply Last reply 29 May 2019, 19:01 Reply Quote 0
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      deckingman @Ringo1508
      last edited by deckingman 29 May 2019, 19:01

      @ringo1508 said in Extruder acceleration/jerk and tuning:

      @deckingman, how did you calculate the "maximum acceleration that the motors will give me for the mass and bed size"?

      It's a long, long time since I did the calculations but I used a spread sheet to do the calcs. This was later updated and improved upon by user @wilriker and he posted it online somewhere. Sorry but I can't off hand find a link. Maybe he'll see this post and jump in or if not, try sending him a PM.

      Basically it comes down to Force = Mass X acceleration so if you knowe the mass and the force, you can calculate the acceleration..............................

      ....................As I'm in a generous mood, I've just dug out my old spreads sheet which went something like this:

      Quoted holding torque = 59N.cm at max current.
      Assuming 85% max current is used then torque becomes 50.15 N.cm
      Take 70% fudge factor for loss due to micro stepping gives 35.61 N.cm
      Use 50% fudge factor for loss at speed gives 17.8N.cm
      Pulley diameter = 12mm, so radius =6mm (0.6cm)
      So available force = 29.7 N
      X carriage mass at that time was 1.67Kgs
      So acceleration becomes 29.7 / 1.67 = 1.77m/sec^2 or 17,767 mm/s^2.
      But assume only 10% of this for a single micro step then becomes 1,777 mm/s^2

      As I said, there were lots of fudge factors in the calculation and some things missing but IIRC the result was a conservative estimate. @wilriker did a better job of the calculations than I managed.

      Once you know the maximum accelerations, then the maximum attainable speed (assuming an initial velocity of 0) can be calculated from sqrt(2 x acceleration x length\2). The length would be the diagonal across a rectangular bed or the diameter of a circular bed.

      HTH

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

      undefined 1 Reply Last reply 29 May 2019, 19:11 Reply Quote 1
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        Ringo1508 @deckingman
        last edited by 29 May 2019, 19:11

        @deckingman awesome!! Thank you so much.

        1 Reply Last reply Reply Quote 0
        • undefined
          wilriker
          last edited by 29 May 2019, 19:25

          For completeness here's the link to my online Maximum Acceleration Calculator. 🙂

          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

          1 Reply Last reply Reply Quote 0
          • undefined
            deckingman
            last edited by deckingman 29 May 2019, 19:29

            @Ringo1508 I told you @wilriker would likely step in.

            @wilriker Thanks man (uel). 👍

            Edit. Manuel - you should put a link yo that in the Wiki (if you haven't already).

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

            undefined 1 Reply Last reply 29 May 2019, 19:30 Reply Quote 0
            • undefined
              wilriker @deckingman
              last edited by 29 May 2019, 19:30

              @deckingman said in Extruder acceleration/jerk and tuning:

              @wilriker Thanks man (uel). 👍

              If you summon me I come. 😂

              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 29 May 2019, 19:33 Reply Quote 1
              • undefined
                deckingman @wilriker
                last edited by 29 May 2019, 19:33

                @wilriker said in Extruder acceleration/jerk and tuning:

                @deckingman said in Extruder acceleration/jerk and tuning:

                @wilriker Thanks man (uel). 👍

                If you summon me I come. 😂

                I must stop polishing that old lamp..........

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

                undefined 1 Reply Last reply 29 May 2019, 19:39 Reply Quote 0
                • undefined
                  wilriker @deckingman
                  last edited by 29 May 2019, 19:39

                  @deckingman said in Extruder acceleration/jerk and tuning:

                  I must stop polishing that old lamp..........

                  😂

                  I put a link to the calculator at the wiki entry for M201 - though I must admit that it feels a bit strange to "promote" my own tools in the official GCode documentation.

                  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 29 May 2019, 20:06 Reply Quote 2
                  • undefined
                    deckingman @wilriker
                    last edited by 29 May 2019, 20:06

                    @wilriker The Wiki is there for the benefit of the entire community. You have made your tool avaible, also for the benefit of the entire community. Therefore it is right and proper that there should be a link to your tool in the Wiki.

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

                    1 Reply Last reply Reply Quote 2
                    • undefined
                      dc42 administrators @mrehorstdmd
                      last edited by 30 May 2019, 08:04

                      @mrehorstdmd said in Extruder acceleration/jerk and tuning:

                      1. M593 to cancel ringing- does it affect retraction tuning?

                      No, it doesn't.

                      The M566 jerk setting affects how well M593 works. High jerk settings make M593 less effective, or totally ineffective.

                      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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                      • undefined
                        DocTrucker
                        last edited by 30 May 2019, 08:11

                        Not mentioned fine tuning of extrusion temp in that original list. It would seem logical to go for linear/non linear extrusion correction checks as soon as your happy with extrusion temp and e-steps/mm.

                        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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