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    Problem with fluctuation at high-ish temperatures

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    • darookeeundefined
      darookee
      last edited by

      I'm trying out colorFab_XT which needs to be printed at around 240°C, until now I only needed about 220-225°C and these temperatures are stable.

      When heating everything up the nozzle stays at 240°C but as soon as the print starts, the temperature will drop to 230-225°C. When pausing the print the temperature will recover after a short time and, when pausing the print long enough, will be stable throughout the rest of the print.

      What can I do to get a stable temperature right from the beginning?

      This is from my config{,-override}.g:

      M305 P1 T100000 B4388 R4700 H0 L0
      M307 H1 A244.3 C136.2 D12.3 S1.00 B0
      
      

      The temperature drops with and without using a fan 😕

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      • dc42undefined
        dc42 administrators
        last edited by

        Your dead time value of 12.3 seconds is very high. Try 6 or 8 seconds. If the temperature starts oscillating, you've set it too low.

        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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        • darookeeundefined
          darookee
          last edited by

          Thanks! I set the dead time to 8 and started a print, it is now much more stable and drop much slower when the fan is turning on. May decreasing the dead time make it even more stable? Can I change the values while printing to test ist out?

          The parameters of my M307 where written by M500 after successfully doing a PID tune - is there anything that may have gone wrong here?

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          • dc42undefined
            dc42 administrators
            last edited by

            The dead time measurement is the least accurate part of the PID tuning process. The value you get seems to vary somewhat with the M303 S parameter you use, which isn't right. So I'm looking at an improved way of measuring it in the next release.

            Reducing the dead time further may help, but if you go too low then the temperature will oscillate. You can adjust it while you are printing, if you don't mind the possibility of ruining the print if it does oscillate..

            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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