PRINT_START Macro Example (Advanced)¶

This is an advanced PRINT_START macro for StealthChanger using klipper-toolchanger-easy. This version includes smart QGL selection, tool detection, and other optimizations.

klipper-toolchanger-easy provides a PRINT_START macro by default. This advanced example shows enhanced features beyond the basic implementation. For a simpler version, see the Minimal PRINT_START Example.

Features:

Smart QGL tool selection (uses single tool for QGL if only one tool is used)
Automatic tool detection based on slicer parameters
Optimized startup sequence

Common StealthChanger Variables¶

The PRINT_START macro uses several variables that slicers pass to indicate which tools will be used and their temperatures:

Tool Selection Variables¶

TOOL - The initial tool number to use for the print (e.g., 0, 1, 2). This is the tool that will be selected first and used to start printing.
TOOL_TEMP - The target temperature for the initial tool specified by TOOL.

Multi-Tool Temperature Variables¶

For prints using multiple tools, slicers pass additional temperature parameters:

T0_TEMP - Pre-heat temperature for tool 0 (if it will be used in the print)
T1_TEMP - Pre-heat temperature for tool 1 (if it will be used in the print)
T2_TEMP - Pre-heat temperature for tool 2 (if it will be used in the print)
T3_TEMP, T4_TEMP, T5_TEMP, etc. - Additional tool temperatures as needed

These T{n}_TEMP variables are only passed if the slicer detects that multiple tools will be used in the print. The macro uses these to:

Determine how many tools are being used (for smart QGL selection)
Pre-heat tools in the background while the initial tool is heating

Bed Temperature Variable¶

BED_TEMP - The target bed temperature for the print.

How Slicers Pass Variables¶

Slicers automatically detect which tools/extruders are used in a print and generate the appropriate T{n}_TEMP parameters. For example:

Single tool print: Only TOOL, TOOL_TEMP, and BED_TEMP are passed
Multi-tool print: TOOL, TOOL_TEMP, BED_TEMP, plus T0_TEMP, T1_TEMP, etc. for each tool that will be used

The macro detects which tools are used by checking for the presence of T{n}_TEMP parameters, allowing it to optimize behavior (e.g., using the single tool for QGL instead of switching to T0).

[gcode_macro PRINT_START]
description: "Initialize toolchanger, home, QGL, and prepare for printing"
gcode:
    # Initialize toolchanger
    INITIALIZE_TOOLCHANGER

    # Stop tool probe crash detection during startup
    STOP_TOOL_PROBE_CRASH_DETECTION

    # Determine which tools will be used in this print
    {% set initial_tool = params.TOOL|default(0)|int %}
    {% set tool_count = 1 %}
    {% for tool_nr in printer.toolchanger.tool_numbers %}
        {% set tooltemp_param = 'T' ~ tool_nr|string ~ '_TEMP' %}
        {% if tooltemp_param in params %}
            {% if tool_nr != initial_tool %}
                {% set tool_count = tool_count + 1 %}
            {% endif %}
        {% endif %}
    {% endfor %}

    # Set bed temperature
    M140 S{params.BED_TEMP|default(60)|float}

    # Home all axes
    G28

    # Determine if we should use T0 or the single tool for QGL
    {% if tool_count == 1 %}
        # Only one tool is being used - use it for QGL instead of switching to T0
        T{initial_tool}
    {% else %}
        # Multiple tools - always use T0 for QGL
        T0
    {% endif %}

    # Heat nozzle to 150C for QGL (softens any leftover filament)
    M109 S150

    # Run Quad Gantry Level
    QUAD_GANTRY_LEVEL

    # Re-home Z after QGL
    G28 Z

    # Stop heating (actual tool will be selected and heated next)
    M109 S0

    # Optional but recommended: Clean nozzle (uncomment if you have a _CLEAN_NOZZLE macro)
    # _CLEAN_NOZZLE

    # Optional but recommended: Calibrate bed mesh (uncomment if needed)
    # BED_MESH_CALIBRATE

    # Pre-heat tools that will be used in the print
    {% for tool_nr in printer.toolchanger.tool_numbers %}
        {% set tooltemp_param = 'T' ~ tool_nr|string ~ '_TEMP' %}
        {% if tooltemp_param in params %}
            M104 T{tool_nr} S{params[tooltemp_param]|float}
        {% endif %}
    {% endfor %}

    # Select the initial tool for printing
    {% if params.TOOL is defined %}
        T{params.TOOL|int}
    {% else %}
        T0  # Default to T0 if not specified
    {% endif %}

    # Heat the initial tool to printing temperature
    M109 S{params.TOOL_TEMP|default(220)|float}

    # Restart tool probe crash detection
    START_TOOL_PROBE_CRASH_DETECTION

    # Optional but recommended: Prime the nozzle (uncomment if needed)
    # Adjust coordinates and extrusion amount to match your printer setup
    # G92 E0                    # Reset extruder
    # G1 Z0.2 F3000            # Move to prime height
    # G1 X10 Y10 E5 F1000      # Prime line (adjust X, Y, and E values as needed)
    # G92 E0                    # Reset extruder again

Parameters¶

Required: - TOOL - The initial tool number to use (e.g., 0, 1, 2) - TOOL_TEMP - The temperature for the initial tool - BED_TEMP - The bed temperature

Optional (for multi-tool prints): - T0_TEMP, T1_TEMP, T2_TEMP, etc. - Pre-heat temperatures for tools that will be used in the print

Example Usage¶

Single tool print:

PRINT_START TOOL=0 TOOL_TEMP=220 BED_TEMP=60

Multi-tool print:

PRINT_START TOOL=0 TOOL_TEMP=220 BED_TEMP=60 T0_TEMP=220 T1_TEMP=230 T2_TEMP=250

What This Macro Does¶

Initializes the toolchanger (INITIALIZE_TOOLCHANGER)
Stops tool probe crash detection
Detects which tools will be used in the print (based on TOOL parameter and T0_TEMP, T1_TEMP, etc.)
Sets and waits for bed temperature (M140 / M190)
Homes all axes (G28)
Smart QGL tool selection:
If only one tool is being used, uses that tool for QGL (no unnecessary tool change)
If multiple tools are being used, uses T0 for QGL (standard behavior)
Heats the QGL tool to 150°C for QGL (softens any leftover filament)
Runs Quad Gantry Level (QUAD_GANTRY_LEVEL)
Re-homes Z after QGL
Optional: Cleans nozzle (if _CLEAN_NOZZLE macro is uncommented)
Optional: Calibrates bed mesh (if BED_MESH_CALIBRATE is uncommented)
Pre-heats other tools if T0_TEMP, T1_TEMP, etc. are provided
Selects the specified TOOL and heats it to TOOL_TEMP
Restarts tool probe crash detection
Optional: Primes the nozzle (if priming code is uncommented)

Customization¶

If you need to customize the PRINT_START macro:

Do not override it - Instead, modify the macro in stealthchanger/macros.cfg
Use hooks - klipper-toolchanger-easy may provide hooks for customization
Common additions:
Nozzle cleaning (_CLEAN_NOZZLE)
Bed mesh calibration (BED_MESH_CALIBRATE)
Prime lines or purge sequences
LED status indicators

For multi-tool prints, T0 is used for QGL and Z homing to ensure accurate tool alignment. For single-tool prints, the macro uses the single tool for QGL to avoid unnecessary tool changes.