Heat run away problem at high flow extrusion

  • My environments is ...

    RepRapFirmware 3.1.1
    Super volcano hotend (50W heater and silicon boot)
    PT100 sensor
    Max temperature is 350 degree celcius (M143 H1 S350)
    Titan-AERO extruder
    50mm/sec filament extrusion ( <- important )

    No problem when 300 degrees PID auto tuning

    If extrusion is performed by raising the temperature to 290 degrees from 270, the temperature does not reach 290 degrees and a heater fault occurs.

    Error: Heater 1 fault: temperature rising much more slowly than the expected 0.8°C/sec
    Resume state saved

    Warning: Tool 0 was not driven because its heater temperatures were not high enough or it has a heater fault

    It seems that a lot of heat escapes through the filament while extruding the filament.

    How to tune it? The goal is 350 degrees.

  • Moderator

    Can you post your tuned PID values?

    The phase change of the filament does have a substantial cooling effect. I think in cases like this allowing the PID auto tune to proceed while extruding filament would be beneficial.

    Do you have a part cooling fan installed? Perhaps you can simulate some of the heat loss by running the part cooling fan at full speed while doing the PID tuning.

    Once we see your tuned values we may be able to suggest alterations to manually tune to account for the additional heat loss.


  • Thank you for interesting on my issue.

    Here is my tune results.

    M307 H1 A692.0 C298.7 D5.2 S1.00 V23.9 B0

    ;;;; M307 H1 ; Volcano
    ;;;; Heater 1 model: gain 692.0, time constant 298.7, dead time 5.2, max PWM 1.00, calibration voltage 23.9, mode PID
    ;;;; Computed PID parameters for setpoint change: P14.8, I0.376, D53.9
    ;;;; Computed PID parameters for load change: P14.8, I0.909, D53.9

    0.8 degrees Celsius/second seems to be a fault trigger condition.
    Is there a way to lower it?

  • Moderator

    My understanding of the PID parameters would say you need to increase the C and D parameters, so try doubling or tripling both.

  • @Phaedrux
    OK. I'll try that.
    I was too blind to auto tuning.

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