Extruder/Bed Heater Auto Tuning Process Clarification

  • Hello, I am looking for some clarification of best practice used for defining heater settings in the config.g file after a successful auto tune.

    I have successfully run M303 for both the extruder and bed heater elements. I have used M500 to save to config-override.g

    ; This is a system-generated file - do not edit
    ; Heater model parameters
    M307 H0 A103.3 C506.1 D1.7 S1.00 V22.4 B0
    M307 H1 A356.6 C267.1 D5.6 S0.50 V24.1 B0

    Is it best to remove all heater M codes from the config.g file? Or, is it best to take the auto tune results M307 settings into the config.g file?

    What about M301? M305? is it necessary?

    A little confused of what really needs to be in the config.g file.

    Thanks for the help in advance.

  • administrators

    I normally copy the M307 commands from config-override.g to config.g. You need M305 commands in config.g to set the temperature sensor parameters. You do not need M301 commands.

  • Thanks David,

    Should the M305 and M143 before the M307 like below?

    M301 H1 S0.50 ; Set heater 1 PWM limit to 50%
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C
    M307 H1 A356.6 C267.1 D5.6 S0.50 V24.1 B0

    The above is for a E3D hotend V6 with a thermistor. (M305 settings supplied by mfg)

    What if you don't have access to the settings from the manufacturer?

    What is the best method to determine the M305 settings?

    What about the use of thermocoupler (type K) or PT100 sensor?

    Or a heated bed without any info other than watts and voltage?

  • administrators

    In that example, the M301 command should be deleted. The relative order of the M143 and other M commands doesn't matter

    If you don't have a resistance vs temperature table for the extruder thermistor, or at least a B value, I suggest you either calibrate it against a thermocouple probe or get a different temperature sensor.

    There are separate wiki pages on how to configure thermocouples and PT100 sensors.

    The thermistors in Chinese bed heaters typically have a B value of 3950.

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