What Is the Bambu Labs Skill in text-to-cad? Complete CLI Guide

The Bambu Labs skill provides a command-line interface to validate, package, and send G-code files to Bambu Lab 3D printers using FTPS file transfers and MQTT printer control, enabling automated printing workflows from text-to-cad generated models.

The Bambu Labs skill in the earthtojake/text-to-cad repository bridges the gap between AI-generated CAD models and physical fabrication. This skill module enables direct integration with Bambu Lab 3D printers through a secure CLI workflow that handles file preparation, encrypted upload, and printer job management. By implementing both FTPS transport and MQTT messaging protocols, the skill transforms raw G-code into ready-to-print jobs without manual slicer intervention.

Core Functionality of the Bambu Labs Skill

The skill provides a self-contained automation pipeline that manages the complete handoff from generated G-code to physical print.

G-code Validation and Packaging

Before transmission, the skill validates input files using inspect_gcode_file to verify file size, MD5 checksums, and proper .gcode extensions. For advanced workflows, the skill integrates with the external bambox CLI through build_bambox_pack_command and build_bambox_validate_command to generate Bambu-compatible .gcode.3mf project files that include material profiles and printer settings.

Secure File Upload via FTPS

The upload_ftps function establishes implicitly-TLS FTP connections to transfer validated G-code directly to the printer's internal storage. This implementation uses the printer's access code for authentication, ensuring encrypted transport of print files over the local network without exposing plaintext credentials.

Printer Control through MQTT

Once files are uploaded, the skill communicates through the publish_mqtt function to execute printer commands including start, stop, cancel, and clear errors. The subscribe_mqtt_reports capability enables status monitoring and confirmation of command execution, creating a bidirectional control channel for job management.

Serial Number Discovery

The discover_printer_serial function extracts the device's unique serial number from its TLS certificate during the initial connection. This identifier is cached and used in subsequent MQTT commands to address the correct device, eliminating the need to manually specify serial numbers for repeated operations.

Key Implementation Components

According to the source code in earthtojake/text-to-cad, the skill architecture separates planning from execution to ensure safety and repeatability.

Main Script Architecture

The core implementation resides in skills/bambu-labs/scripts/bambu_lan_print.py, which defines the orchestration logic. Key builder functions—including build_send_plan, build_print_control_plan, and build_clear_error_plan—assemble JSON payloads describing intended actions. These plans serve both dry-run previews and actual execution workflows.

Dry-Run Safety Mode

All network actions operate behind a dry-run mode by default. Real FTPS uploads and MQTT commands require the explicit --execute flag and a valid access code. This design prevents accidental print starts during testing and allows users to preview exactly what files and commands would be transmitted before committing to physical operations.

Practical CLI Usage Examples

The Bambu Labs skill exposes several command modes for different stages of the print workflow.

Packaging G-code with bambox

Convert plain G-code into a Bambu-specific project file using the packaging command:

text-to-cad bambu-labs package \
    --gcode part.gcode \
    --bambox-profile p1s-0.4 \
    --filament PLA \
    --execute

Omit --execute to preview the packaging plan without creating the .gcode.3mf file.

Uploading and Starting Prints

Send validated G-code to the printer and immediately start the job:

text-to-cad bambu-labs send \
    --gcode part.gcode \
    --host 192.168.1.42 \
    --access-code 12345678 \
    --action start \
    --handoff plain \
    --execute

This command invokes upload_ftps to transfer the file, then publishes an MQTT gcode_file command to begin printing.

Managing Active Jobs

Control running prints using the control subcommand:

# Cancel a running print

text-to-cad bambu-labs control \
    --host 192.168.1.42 \
    --access-code 12345678 \
    --action cancel \
    --execute

# Clear printer errors after resolving the cause

text-to-cad bambu-labs clear-error \
    --host 192.168.1.42 \
    --access-code 12345678 \
    --execute

Source Code Structure

The skill implementation spans three primary locations in the repository:

• skills/bambu-labs/scripts/bambu_lan_print.py — Core logic for FTPS upload, MQTT messaging, bambox integration, and TLS serial discovery
• skills/bambu-labs/SKILL.md — User-facing documentation defining CLI options, parameters, and safety procedures
• tests/python/skills/bambu-labs/test_bambu_lan_print.py — Comprehensive test suite verifying dry-run plan generation, error handling, and protocol interactions

Summary

The Bambu Labs skill enables automated fabrication workflows in text-to-cad by:

• Validating and optionally packaging G-code via inspect_gcode_file and bambox CLI integration
• Uploading files securely through implicit-TLS FTP using upload_ftps
• Controlling printer state through MQTT commands via publish_mqtt and subscribe_mqtt_reports
• Discovering printer identity automatically using discover_printer_serial from TLS certificates
• Operating in safe dry-run mode by default, requiring explicit --execute flags for physical actions

Frequently Asked Questions

How does the Bambu Labs skill handle security when connecting to printers?

The skill uses implicitly-TLS FTP (FTPS) for all file transfers, encrypting both credentials and G-code payload during transmission. The upload_ftps function requires the printer's access code for authentication, and the discover_printer_serial function validates the printer's identity by extracting the serial from its TLS certificate, preventing connections to unauthorized devices.

What is the difference between plain G-code and bambox-packaged files?

Plain G-code contains only movement instructions, while bambox-packaged files (.gcode.3mf) include embedded material profiles, printer settings, and metadata required for Bambu Lab's native workflow. The build_bambox_pack_command function generates these project files when the --bambox-profile flag is specified, ensuring compatibility with Bambu's slicer ecosystem.

Can I use the Bambu Labs skill without executing actual printer commands?

Yes. The skill operates in dry-run mode by default, generating execution plans through functions like build_send_plan without transmitting data. Real FTPS uploads and MQTT commands only occur when you append the --execute flag to your CLI command, allowing safe testing of workflows before physical deployment.

What protocols does the skill use to communicate with Bambu Lab printers?

The skill implements two primary protocols: FTPS (FTP over implicit TLS) on port 990 for encrypted file uploads via upload_ftps, and MQTT over port 8883 for printer command and control via publish_mqtt. These protocols enable both the transport of print files and real-time job management without requiring cloud connectivity.

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