Klipper macros for drying filament using the heated build plate of a 3D printer

filament_dryer.cfg

; An idea for using the heated bed of a 3D printer as a filament dryer.
; Adds GCODE command: START_DRYER TIME=T TEMPERATURE=C
; (T is time in seconds, C is bed temperature in Celsuis)
; To stop drying early, use STOP_DRYER.
; Also defined some utility macros: DRY_PLA, DRY_PETG and DRY_ABS.
; Edit these with your own preferred defaults.

[gcode_macro START_DRYER]
description: Start the heated bed filament dryer.
gcode:
    {% set ChamberTemperature = params.CHAMBER | default(25.0) | float %}
    {% set BedTemperature = params.TEMPERATURE | default(50.0) | float %}
    {% set DryTime = params.TIME | default(14400) | int %}
    ; turn the heaters on, however you do that.
    M140 S{BedTemperature}      ; Sets the print bed temperature without waiting.
    M141 S{ChamberTemperature}  ; [OPTIONAL] Sets the enclosure temperature.
    ; then finally,
    SET_GCODE_VARIABLE MACRO=DRYER_STATUS VARIABLE=time_remaining VALUE={DryTime}
    SET_GCODE_VARIABLE MACRO=DRYER_STATUS VARIABLE=bed_temperature VALUE={BedTemperature}
    SET_GCODE_VARIABLE MACRO=DRYER_STATUS VARIABLE=chamber_temperature VALUE={ChamberTemperature}
    UPDATE_DELAYED_GCODE ID=DRYER_TIMER DURATION=1

[gcode_macro STOP_DRYER]
gcode:
    ; Turn off heaters etc. here
    M140 S0 ; Disable bed heater
    M141 S0 ; [OPTIONAL] Disable enclosure heater/fan
    SET_GCODE_VARIABLE MACRO=DRYER_STATUS VARIABLE=time_remaining VALUE=0
    UPDATE_DELAYED_GCODE ID=DRYER_TIMER DURATION=0    ; Stop the timer.
    M117 Drying Stopped

[gcode_macro DRYER_STATUS]
variable_time_remaining: 0
variable_bed_temperature: 0
variable_chamber_temperature: 0
gcode:
    {% if time_remaining > 0 %}
        M140 S{bed_temperature} ; Reset bed temperature (prevents timeout)
        SET_GCODE_VARIABLE MACRO=DRYER_STATUS VARIABLE=time_remaining VALUE={time_remaining - 1}
        M117 Drying {time_remaining}
    {% else %}
        STOP_DRYER
    {% endif %}

[delayed_gcode DRYER_TIMER]
gcode:
    UPDATE_DELAYED_GCODE ID=DRYER_TIMER DURATION=1
    DRYER_STATUS

[gcode_macro DRY_PLA]
gcode:
    START_DRYER TEMPERATURE=50 CHAMBER=25 TIME=14400

[gcode_macro DRY_PETG]
gcode:
    START_DRYER TEMPERATURE=55  CHAMBER=30 TIME=18000

[gcode_macro DRY_ABS]
gcode:
    START_DRYER TEMPERATURE=65 CHAMBER=40 TIME=14400

akash191095 version works for me, running current git klipper etc... as of 3 august 2025

Nice macro set, but I wanted a better display on the timer, so I used this:

{% if time_remaining > 0 %}
        M140 S{bed_temperature} ; Reset bed temperature (prevents timeout)
        SET_GCODE_VARIABLE MACRO=DRYER_STATUS VARIABLE=time_remaining VALUE={time_remaining - 1}
        {% set hours_remaining = time_remaining // 3600 %}
        {% set minutes_remaining = (time_remaining % 3600) // 60 %}
        {% set seconds_remaining = time_remaining % 60 %}

        M117 Drying {hours_remaining}:{minutes_remaining}:{seconds_remaining}
    {% else %}
        STOP_DRYER
    {% endif %}