G-code Customization for Production Print Farms: Start Scripts, End Scripts, and Macros

Most print farm operators use slicer defaults for start and end G-code and never think about it again. For a production farm trying to maximize consistency and minimize operator intervention, custom G-code scripts in Bambu Studio can solve real problems: more reliable first layers, automatic nozzle priming, conditional bed preparation, and cleaner print-end behavior.

What Bambu Studio's G-code customization allows

Bambu Studio supports custom G-code in several locations:

• Machine start G-code: runs at the beginning of every print, before the actual job
• Machine end G-code: runs at the end of every print
• Layer change G-code: runs at each layer transition (use carefully — runs thousands of times)
• Filament start G-code: runs when a specific filament type starts printing
• Filament end G-code: runs when a filament type ends

Important caveat: the X1C and P1S run a proprietary firmware that handles many behaviors automatically (bed leveling, flow calibration, vibration compensation). Custom G-code runs alongside this automation, not instead of it. Don't try to replicate behaviors the firmware handles — extend or supplement them.

Useful start G-code for production farms

Purge line customization: Bambu's default purge line works but can leave a blob that sometimes gets dragged across the print. A custom purge line positioned more strategically, or using a wipe to clean the nozzle more thoroughly before the print starts, reduces first-layer contamination.

Temperature soak for engineering materials: for PC or nylon prints that benefit from chamber warm-up, a start script can hold the print from beginning until the chamber reaches a target temperature:

M191 S45 ; wait for chamber to reach 45°C before starting

This prevents starting a long print in a cold chamber that would cause warping on the first layers.

Bed surface preparation reminder: for operators who sometimes forget to apply adhesive to the plate before certain materials, a start script that outputs a visible message (shown on the printer display or in logs) serves as a reminder:

M117 Apply glue stick to plate for PC jobs

Consistent nozzle parking: if your farm uses automation to detect completed prints (via camera or sensors), a consistent nozzle park position at print end makes detection more reliable:

G1 X10 Y10 F6000 ; park nozzle at front-left corner

End G-code for production

Controlled cooldown: letting the hotend cool to a safe temperature before the part cooling fans reduce can help with material that benefits from slow cooling. Typically not needed for PLA; occasionally useful for PC and nylon.

Filament retraction on end: retracting filament slightly at print end prevents ooze during cooldown that can contaminate the nozzle tip before the next print:

G1 E-2 F300 ; retract 2mm at end of print

Fan behavior: the X1C/P1S handle fan off sequences automatically, but if your setup has specific requirements (always leave chamber fan on for ventilation after ABS/ASA printing), end G-code is where to put it.

What not to customize

Don't replicate firmware behaviors: bed leveling, first-layer calibration, flow calibration, and vibration compensation run automatically as part of Bambu's firmware. Adding G-code commands for these won't improve them and may conflict with the firmware's own sequence.

Don't override temperatures via G-code then re-set them: if you set temperatures in your slicer profile, don't also set them in start G-code — you'll get duplicate commands that may cause unexpected behavior.

Avoid complex conditional logic in layer G-code: layer change G-code runs on every layer — thousands of times for tall prints. Complex scripts here add significant processing overhead and can cause layer timing issues.

Managing custom G-code across a fleet

For a multi-printer farm, custom G-code should be part of your standard printer profile rather than customized per job. Store your custom start/end G-code in your machine profile in Bambu Studio, and export/import that profile to all printers to maintain consistency.

When you update your start G-code (to fix an issue or add a new feature), update the profile and re-export to all machine profiles at once rather than updating printer-by-printer.

Version your G-code: keep a simple changelog noting what changed in your start/end G-code and when. If a new version causes issues, you can identify when the change was introduced and revert it.

Testing custom G-code

Before deploying custom G-code to your full fleet:

1. Test on your canary printer (if you follow the staged firmware update approach, use the same printer for G-code testing)
2. Run 3–5 test prints with the new script, watching the start sequence carefully
3. Verify the end sequence completes cleanly without error
4. Monitor the first production jobs for unexpected behavior

Custom G-code that's wrong can cause failed prints, nozzle crashes, or require manual intervention. Test before deploying at production scale.

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Print Hive's job management and printer monitoring works alongside your custom G-code configuration — job routing and status tracking are independent of the G-code that runs on the printer, so custom scripts don't affect monitoring. Start free →