Configuring the chamber heater with a higher dead-time

  • Hi!

    I'm trying to set-up a 3D printer with a heated chamber. Since it is heating very slowly, it needs quite a bit of time before increasing temperature.

    However, with the maximum setting for M307 dead-time (60 secs), I'm not able to make it work, the heater doesn't heat quickly enough.

    Check the code below:

    ; Chamber
    M141 H2                                   ; Assign chamber heater to heater 0
    M143 H2 S100                              ; Set temperature limit for heater 0 to 120C
    M307 H2 A50 D60 B1                        ; use bang-bang control for the chamber heater with 60 seconds dead time
    M305 P2 T97968 B4630 C9.486166e-8 R4700   ; Set thermistor + ADC parameters for chamber

    Is there a way to either increase the dead-time or disable the protection for this heater?


  • administrators

    What happens if you try to set a dead time longer than 60 seconds?

  • I gave up trying to monitor chamber temp and controlling the heater by chamber temperature. Instead I've fitted the thermistor to the heater heatsink itself, and just set the heater to a temperature which will give me the 40 deg C chamber temp I want.

    Since it rarely varies, if I set the heater to 80 deg C my chamber reaches 40 deg C, given that the bed temp is a constant for abs printing also.

  • @dc42:

    What happens if you try to set a dead time longer than 60 seconds?

    When I send:

    M307 H2 D60
    ```Everything looks good, and sending M307 H2 shows that the dead time is set to 60 seconds.

    M307 H2 D120

    Same does for 61\. I believe the max configurable is currently 60, but a higher value could solve our heating problem.
    Thanks for your support!

  • administrators

    You need to increase the time constant too because the firmware checks that the time constant is at least twice the dead time.

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