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    How to tune/calibrate heater feedforward?

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    • oliofundefined
      oliof
      last edited by

      RRF 3.4 has a new feature, heater feedforward. How do I determine the heater feedforward value(s) I need to set for my machine (and given filament)?

      <>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>

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      • Phaedruxundefined
        Phaedrux Moderator
        last edited by

        This is what I was told by DC42:

        heat the nozzle and let the temperature stabilise. Then commence extrusion at a fast rate (as fast as the extruder can reasonable manage without skipping) and watch the temperature. If there is an initial drop, then increase the feedforward. What you are looking for is either the temperature remaining steady, or rising by a small amount followed by a drop below target of a similar amount. When extrusion stops the reverse will happen, i.e. with no feedforward the temperature will rise and then gradually return to target.

        If you give that a try and it seems to work well I will add that to the M309 entry.

        Z-Bot CoreXY Build | Thingiverse Profile

        o_lampeundefined 1 Reply Last reply Reply Quote 1
        • demonlibraundefined
          demonlibra
          last edited by

          What length of filament is enougth for this test?

          Phaedruxundefined 1 Reply Last reply Reply Quote 0
          • Phaedruxundefined
            Phaedrux Moderator @demonlibra
            last edited by

            @demonlibra said in How to tune/calibrate heater feedforward?:

            What length of filament is enougth for this test?

            How much filament does it take at max flow to impact the thermistor reading?

            Z-Bot CoreXY Build | Thingiverse Profile

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            • o_lampeundefined
              o_lampe @Phaedrux
              last edited by

              @phaedrux
              I always assumed this feature would help with dual tool printers to heat up the idle tool from standby-temp to working temp before toolchange?
              Being able to look ahead was the reason for the dual gcode stream concept?

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              • dc42undefined
                dc42 administrators @o_lampe
                last edited by

                @o_lampe said in How to tune/calibrate heater feedforward?:

                Being able to look ahead was the reason for the dual gcode stream concept?

                One of the reasons.

                The purpose of heater feedforward is to better maintain an even nozzle temperature in high flow rate extruders, by anticipating the additional heat needed when the flow rate increases, instead of waiting for the temperature to drop before power is increased.

                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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                • demonlibraundefined
                  demonlibra
                  last edited by demonlibra

                  @phaedrux said in How to tune/calibrate heater feedforward?:

                  @demonlibra said in How to tune/calibrate heater feedforward?:

                  What length of filament is enougth for this test?

                  How much filament does it take at max flow to impact the thermistor reading?

                  Aluminum V6, heater 40 W, nozzle 0.4 mm, maximum flowrate around 10 mm3/sec.

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