Auto tuning keeps failing

  • I have followed the instructions and every time the tuning fails for the bed and hotend heaters. I think I must be missing or not understanding something.

    Heater 0 is being tuned, phase 3 of 3
    Auto tune of heater 0 with P=0.50 S=70.0 cancelled because temperature limit exceeded. Use lower P or higher S in m303 command.

    Heater 1 is being tuned, phase 3 of 3
    Auto tune of heater 1 with P=0.47 S=240.0 cancelled because temperature limit exceeded. Use lower P or higher S in m303 command.

    It seems as if the temperature just keeps climbing until the S parameter is reached and then it fails

    This is my config file:-

    M555 P2 ; Set output to look like Marlin
    G21 ; Work in millimetres
    G90 ; Send absolute corrdinates…
    M83 ; ...but relative extruder moves
    M574 X0 Y2 Z0 S1 ; set endstop configuration (Y endstop only, at high end, active high)
    M92 X87.4890 Y87.4890 Z4000 ; Set axis steps/mm
    M906 X950 Y950 Z900 E850 ; Set motor currents (mA)
    M556 S79.5 X0.75 Y1.05 Z0.35 ; axis compensation
    M201 X500 Y500 Z15 E1000 ; set accelerations
    M203 X9000 Y9000 Z100 E3600 ; set maximum XYZ and extruder speeds
    M566 X300 Y300 Z30 E20 ; Maximum instantaneous speed changes mm/minute
    M208 X200 Y200 Z190 ; set axis maxima
    M208 X0 Y7 Z-1 S1 ; set axis minimum (adjust to make X=0 the edge of the bed)
    M305 P0 R1000 H40 L-26 X0 ; H and/or L values to set the bed thermistor ADC correction
    M305 P1 R1000 H40 L-26 X1 ; H and/or L values to set the 1st nozzle thermistor ADC correction
    M558 P1 ; Use an unmodulated Z probe or an intelligent Z probe
    G31 Z1.9 P500 ; Set the probe height and threshold

    ; ********** Single nozzle settings **********
    M563 P0 D0 H1 ; Define tool 0
    M92 E430 ; Set extruder steps per mm (single nozzle)

    ; ********** Diamond nozzle settings **********
    ;M563 P0 D0:1:2 H1 ; Define tool 0 extruder 0
    ;M563 P1 D0:1:2 H1 ; Define tool 1 extruder 1
    ;M563 P2 D0:1:2 H1 ; Define tool 2 extruder 2
    ;M567 P0 E1.0:0.0:0.0 ; single colour - extruder 0
    ;M567 P1 E0.0:1.0:0.0 ; single colour - extruder 1
    ;M567 P2 E0.0:0.0:1.0 ; single colour - extruder 2
    ;M92 E430:430:430 ; Set extruder steps/mm (multiple nozzles)
    ;M568 P0 S1 ; turn on mixing Tool 0
    ;M568 P1 S1 ; turn on mixing Tool 0
    ;M568 P2 S1 ; turn on mixing Tool 0

  • For my overpowered bed heater I had to use M303 P0.1 S140 then I had to add a B0 to the M307 to use PID mode.
    For the hotend with a 40w 24v cartridge, I used either P0.2 or P0.3 with a S250

    So, you just need to lower the P number, or raise the S number, or both.

  • I have now completed an auto tune of the hot end "M303 H1 P0.15 S210 "
    This is the result
    Heater 1 model: gain 568.0, time constant 185.4, dead time 14.0, max PWM 1.00, in use: yes, mode: PID
    Setpoint change: P4.2, I0.02, D40.8
    Load change: P4.2, I0.15, D40.8

    However, when the hot end reached the set temperature, I switched on my secondary cooling fan at 50% speed and the hot end temperature dropped dramatically and took a long time to recover.

    If this happened during a print, the consequences could be a failed print.

    This should be in the section tuning and not installation so please comment on the new thread.

  • administrators

    I didn't see a new thread, so I'll reply here.

    • Version 1.15b and earlier firmware were slow to respond if the temperature dropped more than 1C. Firmware 1.15c should respond much faster.

    • If the PID parameters generated by auto tuning don't work for you, define your own PID parameters using a M301 command in config.g. Put it after the M307 command so that it overrides the ones generated by M307.

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