passing_slicer_variables.md

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Passing Slicer Variables to PRINT_START

This section will demonstrate passing temperature variables to PRINT_START.

This method can be used for other slicer variables too, not just temperatures / heating commands.

• The available variables are not always published, however, so you sometimes need to dig around to find the names of them.
• SuperSlicer recently introduced 📄support for custom variables.

Passing Temperatures

By default, slicers will put heating commands either entirely before or after PRINT_START. You have to pass the temps TO PRINT_START in order to control when they happen. For example I don’t want my nozzle to heat until the very end so it’s not oozing during QGL, mesh etc.

If you don’t use a chamber thermistor, just remove the chamber stuff.

Example macro:

This macro is a template.
You will have to add things like G32,QUAD_GANTRY_LEVEL,BED_MESH_CALIBRATE, or whatever other routines that you need to run during your PRINT_START.

[gcode_macro PRINT_START]
gcode:        
    # Parameters
    {% set bedtemp = params.BED|int %}
    {% set hotendtemp = params.HOTEND|int %}
    {% set chambertemp = params.CHAMBER|default(0)|int %}
    
    G28
    # <insert your routines here>
    M190 S{bedtemp}                                                              ; set & wait for bed temp
    TEMPERATURE_WAIT SENSOR="temperature_sensor chamber" MINIMUM={chambertemp}   ; wait for chamber temp
    # <insert your routines here>
    M109 S{hotendtemp}                                                           ; set & wait for hotend temp
    # <insert your routines here>
    G28 Z                                                                        ; final z homing

This would now be run like PRINT_START BED=110 HOTEND=240 CHAMBER=50. Chamber defaults to 0 if not specified.

Slicer Start G-code

Don't split any of these lines.

SuperSlicer

(3 lines)

M104 S0 ; Stops PS/SS from sending temp waits separately
M140 S0
PRINT_START BED=[first_layer_bed_temperature] HOTEND={first_layer_temperature[initial_extruder]+extruder_temperature_offset[initial_extruder]} CHAMBER=[chamber_temperature]

Prusa Slicer

(3 lines)

Prusa Slicer doesn’t support chamber temp.

M104 S0 ; Stops PS/SS from sending temp waits separately
M140 S0
PRINT_START BED=[first_layer_bed_temperature] HOTEND={first_layer_temperature[initial_extruder]+extruder_temperature_offset[initial_extruder]}

Cura

(1 line)

PRINT_START BED={material_bed_temperature_layer_0} HOTEND={material_print_temperature_layer_0} CHAMBER={build_volume_temperature}