Process for running a PID auto-tune and its results



  • I have been trying to PID auto-tune my printer (Duet3D WiFi on Wanhao Duplicator i3 V2.1) but and trying to understand how to react to the results.

    Both Bed and Extruder bring back M303 results that complain about both being overpowered, as below;

    Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 139C.
    Warning: Heater 1 appears to be over-powered. If left on at full power, its temperature is predicted to reach 572C.

    The process for running the PID tune seems different as well. In all the examples I have seen the printer will display its result at the end of each cycle and you get the result based on the average of all the cycle result.

    I am seeing the auto-tune run and then stop and produce results including the over-powered warning. So am I to take it that the auto-tune was cancelled due to the over-powered warning ?



  • That's a normal reply just advising what temp it predicts the bed and hotend "could" reach if they remained on at full power say if the mosfet failed closed.



  • Thanks for confirming.

    Following my auto-tune of both bed and extruder my bed is solid at 60 Degrees but my Extruder still overheats by about 6 Degrees over the 190 Degree test.

    I read somewhere @dc42 answered a similar question and suggested adjusting the D parameter until the temperature settles down. Is that still the best approach resolve temp fluctuations?

    ; Heaters
    ; Bed [H0 - Heater 0]
    M143 H0 S70 ; Set temperature limit for heater 0 to 70C
    M305 P0 T100000 B3988 R4700 ; Set thermistor + ADC parameters for heater 0
    M307 H0 A114.0 C410.3 D2.7 S1.0 V12.3 B0 ; PID Auto-tune Values for Bed [H0]

    ; Extruder [H1 - Heater 1]
    M143 H1 S210 ; Set temperature limit for heater 1 to 210C
    M305 P1 T100000 B3988 R4700 ; Set thermistor + ADC parameters for heater 1
    M307 H1 A547.92 C181.6 D8.7 S1.0 V12.4 B0 ; PID auto-tune Values for Extruder [H1]



  • Actually, forget that. I just ran the temp tests again on both bed and extruder and they are sitting steady at the requested temperatures (Bed = 60 Extruder = 190). I think that my PID tuning has been successful.


  • administrators

    @b0m0a0k said in Process for running a PID auto-tune and its results:

    I read somewhere @dc42 answered a similar question and suggested adjusting the D parameter until the temperature settles down. Is that still the best approach resolve temp fluctuations?

    If the temperature oscillates around the target value, increase the dead time (D) parameter. It it's slow to respond to changes in the environment (e.g. the print cooling fan turning on), you can try reducing the D parameter.

    If the temperature overshoots, increase the gain (A parameter). If it undershoots, reduce the A parameter.


 

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