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

    Slow hotend heating near target temp

    Scheduled Pinned Locked Moved
    Firmware installation
    4
    14
    2.1k
    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.
    • pkmundefined
      pkm
      last edited by

      Hello,
      Since I switched to the new heating controller in 1.15, I often notice the hotend heating very slow when the temperature is 5-10C below the target.
      Sometimes it takes 2-3 minutes to go from 230C to 238C!
      I use autotuning and save the results. Did that a few times.
      What could be the problem?

      1 Reply Last reply Reply Quote 0
      • Jackalundefined
        Jackal
        last edited by

        Have you tried 1.17e or 1.18RC2?
        There has been some changes to hotend tuning.

        1 Reply Last reply Reply Quote 0
        • pkmundefined
          pkm
          last edited by

          Yep, I just installed 1.18RC2, and before that I had 1.18beta and 1.17 something.

          1 Reply Last reply Reply Quote 0
          • burtoogleundefined
            burtoogle
            last edited by

            Here's something I discovered recently… e3d v6 hotend was heating up quickly all the way to the target temp and then I had to change the hot end fan. The new fan seemed to shift a lot more air than the old one and, subsequently, the hotend struggled to reach the target temp. I swapped the fan again to one that wasn't quite so aggressive and everything's back to normal again. Maybe your hotend fan is cooling the hotend too much?

            1 Reply Last reply Reply Quote 0
            • pkmundefined
              pkm
              last edited by

              If it matters, that's what the autotuning put to config-override.g recently
              M307 H0 A290.3 C1404.5 D1.0 S1.00 B0
              M307 H1 A722.7 C248.3 D10.0 S1.00 B0

              1 Reply Last reply Reply Quote 0
              • pkmundefined
                pkm
                last edited by

                I have e3D Volcano.
                Not sure about the fan, it's been the same for a long time. And that tiny 30mm fan just can't blow too much…
                Also, the hotend heats up really fast (24V 40W heater), but only up to 5-10C below the target temp, then the curve just gets flat.

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

                  @pkm:

                  Also, the hotend heats up really fast (24V 40W heater), but only up to 5-10C below the target temp, then the curve just gets flat.

                  That indicates that auto tuning has over-estimated the hot end gain. Try reducing the A parameter in the M307 H1 command by 10 or 20%.

                  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
                  • pkmundefined
                    pkm
                    last edited by

                    Thanks, I'll try that!
                    IIRC autotuning said that the hotend would reach 750C at full PWM. Hard to believe, actually.
                    Also interesting that the dead time is 10s for hotend but 1s for bed… Does it make sense to decrease D to 2s?
                    I'll also try to measure average PWM at work temp.

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

                      10s for the hot end is higher than normal, it's usually about 5s.

                      1s for the bed is extremely low. Is it a silicone heater with the thermistor embedded in the element?

                      If it's a Duet WiFi that you have, try auto tuning with firmware 1.18RC2 and see whether it gives different results. Leave out the P parameter in the M303 command (it's no longer needed), but choose the T parameter to allow for up to 10C overshoot.

                      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
                      • pkmundefined
                        pkm
                        last edited by

                        Those were settings from 1.18RC2 autotuning…
                        I just tried once again:

                        [[language]]
                        11:39:33M307 H1
                        Heater 1 model: gain 745.5, time constant 250.1, dead time 10.0, max PWM 1.00, mode: PID
                        Computed PID parameters for setpoint change: P6.0, I0.024, D41.9
                        Computed PID parameters for load change: P6.0, I0.235, D41.9
                        11:10:55Warning: Heater 1 appears to be over-powered and a fire risk! If left on at full power, its temperature is predicted to reach 765C.
                        Auto tune heater 1 completed in 328 sec
                        Use M307 H1 to see the result, or M500 to save the result in config-override.g
                        11:07:05Auto tune phase 3, peak temperature was 211.1
                        11:06:52Auto tune phase 2, heater off
                        11:05:32Auto tune phase 1, heater on
                        11:05:26M303 H1
                        Auto tuning heater 1 using target temperature 200.0C and PWM 1.00 - do not leave printer unattended
                        
                        

                        I think this might explain something:
                        Computed PID parameters for setpoint change: P6.0, I0.024, D41.9
                        This is exactly when the problem occurs, for example changing the temp from 230C to 238C is very slow.
                        So why is I 10 times less for a setpoint change?

                        1 Reply Last reply Reply Quote 0
                        • pkmundefined
                          pkm
                          last edited by

                          The average PWM is 0.333 at 235C which corresponds to A650…

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

                            So use A650 in your M307 command. I suggest you also try reducing D in M307 to about 5, because I don't believe that 10 is the correct value. If this causes the temperature to oscillate, then increase D towards 10 again. Reducing D will reduce the response time of the PID control.

                            The I parameter is lower for a setpoint change because using a large I parameter usually results in a large overshoot. If the gain is set correctly then the set point will still be reached quickly.

                            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
                            • pkmundefined
                              pkm
                              last edited by

                              Thanks David.
                              I did a few tests and M307 H1 A650 C200 D5.0 B0 proved to work well enough.
                              Not sure why autotuning was a bit off.

                              1 Reply Last reply Reply Quote 0
                              • pkmundefined
                                pkm
                                last edited by

                                I think you can adjust autotuning to more agressive temperature rise, even if it leads to a small overshoot.

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