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[SOLVED] Heated bed PID auto tune failed.

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  • undefined
    vapvap
    last edited by vapvap 12 Mar 2018, 00:07 26 Aug 2018, 11:45

    How do I calibrate heated bed PID correctly? My attempts give errors.
    Regards.

    11:43:19 AM
    Warning: Auto tune of heater 0 failed due to bad curve fit (G=118.2, tc=794.1, td=-0.6)
    11:31:13 AM
    Auto tune phase 3, peak temperature was 85.0
    11:31:05 AM
    Auto tune phase 2, heater off
    11:22:41 AM
    Auto tune phase 1, heater on
    11:22:35 AM
    M303 H0 S85
    Auto tuning heater 0 using target temperature 85.0°C and PWM 1.00 - do not leave printer unattended

    1 Reply Last reply Reply Quote 0
    • undefined
      dc42 administrators
      last edited by dc42 26 Aug 2018, 18:51

      The problem is that the measured dead time is negative. I suggest you use the gain and time constant values given by auto tuning, but measure the dead time manually. It is approximately the time between turning the heater on and seeing the temperature start to rise significantly. It's typically 2 seconds for a hot end, somewhat more for a bed heater.

      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
      • undefined
        vapvap
        last edited by 30 Aug 2018, 23:06

        Sorry, but I'm new to these settings.
        Could you show an example of such a code command?
        I'm afraid that without you I will not deal with this.

        1 Reply Last reply Reply Quote 0
        • undefined
          dc42 administrators
          last edited by 31 Aug 2018, 07:25

          Your tuning run reported:

          G=118.2, tc=794.1, td=-0.6

          So the M307 command you need based on these values would be:

          M308 H0 A118.2 C794.1 D-0.6

          However, the dead time can't be negative. So measure the time it takes from turning the bed heater on to the indicated temperature starting to rise. For example, if it is 4 seconds, use:

          M308 H0 A118.2 C794.1 D4.0

          I have it on my work list to improve the measurement of dead time during auto tuning.

          HTH David

          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

          undefined undefined 2 Replies Last reply 31 Aug 2018, 07:37 Reply Quote 0
          • undefined
            deckingman @dc42
            last edited by 31 Aug 2018, 07:37

            @dc42 said in Heated bed PID auto tune failed.:

            I have it on my work list to improve the measurement of dead time during auto tuning.

            👍 I've always struggled in that respect with my big thick lump of aluminium tooling plate and have to manually change the auto tune value. No big deal as it's not something that needs to be done often, but it would be nice to see that improved if it's possible.

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

            undefined 1 Reply Last reply 31 Aug 2018, 07:42 Reply Quote 0
            • undefined
              dc42 administrators @deckingman
              last edited by 31 Aug 2018, 07:42

              @deckingman said in Heated bed PID auto tune failed.:

              @dc42 said in Heated bed PID auto tune failed.:

              I have it on my work list to improve the measurement of dead time during auto tuning.

              👍 I've always struggled in that respect with my big thick lump of aluminium tooling plate and have to manually change the auto tune value. No big deal as it's not something that needs to be done often, but it would be nice to see that improved if it's possible.

              Can you tell me what value auto tuning reports, what happens if you use that value, and what value you actually use to get good results?

              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

              undefined 1 Reply Last reply 31 Aug 2018, 09:43 Reply Quote 0
              • undefined
                deckingman @dc42
                last edited by 31 Aug 2018, 09:43

                @dc42 said in Heated bed PID auto tune failed.:

                @deckingman said in Heated bed PID auto tune failed.:

                @dc42 said in Heated bed PID auto tune failed.:

                I have it on my work list to improve the measurement of dead time during auto tuning.

                👍 I've always struggled in that respect with my big thick lump of aluminium tooling plate and have to manually change the auto tune value. No big deal as it's not something that needs to be done often, but it would be nice to see that improved if it's possible.

                Can you tell me what value auto tuning reports, what happens if you use that value, and what value you actually use to get good results?

                Now you've got me. I made a note in my config of the date I last ran auto tune and it was 17-08-2017, so over a year ago. Thinking about it, (and my memory is a bit hazy) I seem to remember that prior to that time, I really struggled to get a successful tune, but you made some changes which fixed the problem that I had - it was something to do with the check it makes after the heater turns off (can't remember what that check is). So now that I think about, you may have fixed the dead time issue too.

                I'll run another auto tune when I get chance - bed is hot at the moment and it'll take about 3 to 4 hrs to get down to ambient. I can say that I'm using D16.4 so that would indicate that it came from auto tune and not a post tune manual entry (I'd have rounded it to a whole second).

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

                1 Reply Last reply Reply Quote 0
                • undefined
                  vapvap @dc42
                  last edited by 1 Sept 2018, 19:00

                  @dc42
                  I'm sorry, but I think I'm doing something wrong...

                  7:43:07 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=133.8, C=839.5, D=-0.5)
                  7:30:11 PM
                  Auto tune phase 3, peak temperature was 90.0
                  7:30:04 PM
                  Auto tune phase 2, heater off
                  7:22:08 PM
                  Auto tune phase 1, heater on
                  7:22:02 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  7:21:45 PM
                  M307 H0 A83.9 C552.1 D20.0
                  6:46:16 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=83.9, C=522.1, D=-0.3)
                  6:38:16 PM
                  Auto tune phase 3, peak temperature was 90.1
                  6:38:09 PM
                  Auto tune phase 2, heater off
                  6:31:45 PM
                  Auto tune phase 1, heater on
                  6:31:39 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  6:31:15 PM
                  M307 H0 A102.6 C642.0 D17.0
                  6:22:21 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=102.6, C=642.0, D=-0.1)
                  6:12:29 PM
                  Auto tune phase 3, peak temperature was 90.2
                  6:12:22 PM
                  Auto tune phase 2, heater off
                  6:05:14 PM
                  Auto tune phase 1, heater on
                  6:05:08 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  6:04:45 PM
                  M307 H0 A102.0 C633.4 D15.0
                  5:48:31 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=102.0, C=633.4, D=-0.9)
                  5:38:47 PM
                  Auto tune phase 3, peak temperature was 90.0
                  5:38:40 PM
                  Auto tune phase 2, heater off
                  5:31:40 PM
                  Auto tune phase 1, heater on
                  5:31:34 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  5:31:22 PM
                  M307 H0 A163.0 C1031.9 D12.0
                  5:21:56 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=163.0, C=1031.9, D=-0.3)
                  5:06:05 PM
                  Auto tune phase 3, peak temperature was 90.1
                  5:05:58 PM
                  Auto tune phase 2, heater off
                  4:57:09 PM
                  Auto tune phase 1, heater on
                  4:57:04 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  4:56:48 PM
                  M307 H0 A78.8 C487.0 D10.0
                  2:26:11 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=78.8, C=487.0, D=-0.9)
                  2:18:43 PM
                  Auto tune phase 3, peak temperature was 90.2
                  2:18:36 PM
                  Auto tune phase 2, heater off
                  2:12:24 PM
                  Auto tune phase 1, heater on
                  2:12:19 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  2:12:01 PM
                  M307 H0 A141.7 C892.4 D7.0
                  2:08:46 PM
                  Warning: Auto tune of heater 0 failed due to bad curve fit (A=141.7, C=892.4, D=-0.7)
                  1:55:02 PM
                  Auto tune phase 3, peak temperature was 90.0
                  1:54:55 PM
                  Auto tune phase 2, heater off
                  1:46:39 PM
                  Auto tune phase 1, heater on
                  1:46:33 PM
                  M303 H0 S90
                  Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
                  1:45:29 PM
                  Connection established!
                  1:45:29 PM
                  Page Load complete!

                  undefined 1 Reply Last reply 1 Sept 2018, 20:10 Reply Quote 0
                  • undefined
                    deckingman @vapvap
                    last edited by 1 Sept 2018, 20:10

                    @vapvap It's the negative dead time that's screwing it up but I don't know why you are getting that. Are you starting from a low ambient or are things really hot in your part of the world?

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

                    undefined 1 Reply Last reply 1 Sept 2018, 22:32 Reply Quote 0
                    • undefined
                      vapvap @deckingman
                      last edited by 1 Sept 2018, 22:32

                      @deckingman Normal room temperature (~20C).

                      1 Reply Last reply Reply Quote 0
                      • undefined
                        dc42 administrators
                        last edited by 3 Sept 2018, 09:00

                        What happens if you use a lower target temperature such as 70C?

                        The bed needs to be allowed to cool down completely to room temperature between tuning attempts.

                        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

                        undefined 1 Reply Last reply 4 Sept 2018, 22:22 Reply Quote 0
                        • undefined
                          vapvap @dc42
                          last edited by 4 Sept 2018, 22:22

                          @dc42
                          11:20:51 PM
                          M307 H0 A181.2 C1041.0 D4.0 P0.5
                          Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
                          11:20:43 PM
                          M307 H0 A181.2 C1041.0 D4.0 P0.6
                          Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
                          10:39:52 PM
                          M307 H0 A181.2 C1041.0 D4.0 P0.7
                          Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
                          10:39:27 PM
                          M307 H0 A181.2 C1041.0 D4.0 P0.8
                          Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
                          10:38:52 PM
                          M307 H0 A181.2 C1041.0 D4.0
                          Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
                          10:21:55 PM
                          Warning: Auto tune of heater 0 failed due to bad curve fit (A=181.2, C=1041.0, D=-0.8)
                          10:05:55 PM
                          Auto tune phase 3, peak temperature was 70.3
                          10:05:48 PM
                          Auto tune phase 2, heater off
                          10:00:36 PM
                          Auto tune phase 1, heater on
                          10:00:30 PM
                          M303 H0 S70
                          Auto tuning heater 0 using target temperature 70.0°C and PWM 1.00 - do not leave printer unattended
                          10:00:00 PM
                          M307 H0
                          Heater 0 model: gain 90.0, time constant 700.0, dead time 30.0, max PWM 1.00, calibration voltage 0.0, mode PID, inverted no, frequency default
                          Computed PID parameters for setpoint change: P46.3, I0.319, D971.8
                          Computed PID parameters for load change: P46.
                          9:59:31 PM
                          Connection established!
                          9:59:31 PM
                          Page Load complete!

                          1 Reply Last reply Reply Quote 0
                          • undefined
                            dc42 administrators
                            last edited by 5 Sept 2018, 16:35

                            Try with those M307 settings. The warning message is usual when using a high-power bed heater.

                            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

                            undefined 1 Reply Last reply 12 Sept 2018, 20:55 Reply Quote 0
                            • undefined
                              vapvap
                              last edited by 12 Sept 2018, 20:16

                              This post is deleted!
                              1 Reply Last reply Reply Quote 0
                              • Phaedruxundefined
                                Phaedrux Moderator
                                last edited by 12 Sept 2018, 20:25

                                What type of heated bed is it?

                                Z-Bot CoreXY Build | Thingiverse Profile

                                undefined 1 Reply Last reply 12 Sept 2018, 20:53 Reply Quote 0
                                • undefined
                                  vapvap @Phaedrux
                                  last edited by 12 Sept 2018, 20:53

                                  @phaedrux Aluminum disc 220mm (Delta Printer).

                                  Phaedruxundefined 1 Reply Last reply 12 Sept 2018, 21:45 Reply Quote 0
                                  • undefined
                                    vapvap @dc42
                                    last edited by 12 Sept 2018, 20:55

                                    @dc42

                                    In the end, I achieved a positive value.
                                    But what to do next?
                                    After all, the "auto tune" still does not work.

                                    7:20:11 PM
                                    Warning: Auto tune of heater 0 failed due to bad curve fit (A=183.8, C=1042.4, D=0.1)
                                    7:04:11 PM
                                    Auto tune phase 3, peak temperature was 70.3
                                    7:04:04 PM
                                    Auto tune phase 2, heater off
                                    6:58:52 PM
                                    Auto tune phase 1, heater on
                                    6:58:46 PM
                                    M303 H0 S70
                                    Auto tuning heater 0 using target temperature 70.0°C and PWM 1.00 - do not leave printer unattended
                                    6:58:30 PM
                                    M307 H0
                                    Heater 0 model: gain 188.4, time constant 1070.6, dead time 5.0, max PWM 1.00, calibration voltage 0.0, mode PID, inverted no, frequency default
                                    Computed PID parameters for setpoint change: P202.9, I2.773, D710.0
                                    Computed PID parameters for load change: P2
                                    6:58:23 PM
                                    M307 H0 A188.4 C1070.6 D5.0
                                    Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 213C.

                                    undefined 1 Reply Last reply 14 Sept 2018, 21:54 Reply Quote 0
                                    • Phaedruxundefined
                                      Phaedrux Moderator @vapvap
                                      last edited by 12 Sept 2018, 21:45

                                      @vapvap said in Heated bed PID auto tune failed.:

                                      @phaedrux Aluminum disc 220mm (Delta Printer).

                                      And what is the heating element?

                                      Z-Bot CoreXY Build | Thingiverse Profile

                                      undefined 1 Reply Last reply 12 Sept 2018, 21:50 Reply Quote 0
                                      • undefined
                                        vapvap @Phaedrux
                                        last edited by 12 Sept 2018, 21:50

                                        @phaedrux said in Heated bed PID auto tune failed.:

                                        And what is the heating element?

                                        https://www.amazon.co.uk/anycubic-MK3-Round-Aluminium-Diameter-Printers/dp/B01LZ36INV

                                        1 Reply Last reply Reply Quote 0
                                        • Phaedruxundefined
                                          Phaedrux Moderator
                                          last edited by 12 Sept 2018, 22:20

                                          Ok, now is it wired as 12v or 24v? What is your power supply voltage and wattage?

                                          Z-Bot CoreXY Build | Thingiverse Profile

                                          undefined 1 Reply Last reply 12 Sept 2018, 23:49 Reply Quote 0
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