Bambu Lab Server

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Overview

Complete MCP server for Bambu Lab 3D printers (P1P, P1S, X1C, A1, A1 Mini). Connects over local MQTT for real-time control and monitoring, with FTPS file upload and X.509 certificate signing to bypass firmware authentication restrictions.

25 tools covering print control, status monitoring, camera, AMS filament management, temperature, LED control, and more.

Background

In January 2025, Bambu Lab pushed firmware updates requiring authentication for local LAN printer control, breaking all third-party tools — OctoPrint, Home Assistant integrations, custom scripts, everything.

Community researchers extracted the X.509 certificate and private key from the Bambu Connect desktop application, restoring third-party access. This MCP server builds on that work to provide comprehensive printer control through Claude.

Key references:

• Hackaday: Bambu Connect's Authentication X.509 Certificate and Private Key Extracted — the article that started the workaround
• OpenBambuAPI — reverse-engineered MQTT protocol documentation
• bambu-node — TypeScript library for Bambu printers

Features

• Local MQTT control — Print, pause, resume, stop, speed profiles, G-code execution
• Real-time status — Continuous caching from MQTT reports with cached + fresh status tools
• Camera control — Start/stop recording and timelapse
• AMS management — Change filament trays, unload filament
• FTP file upload — FTPS upload to printer SD card (port 990)
• X.509 signing — Bypass firmware auth restrictions with certificate signing
• Temperature control — Set nozzle/bed temps with safety limits
• Object skipping — Skip failed objects without stopping the print
• Speed profiles — Silent, Standard, Sport, Ludicrous (or raw percentage)
• LED control — Chamber and work lights
• Safety validation — Blocked G-codes, temperature limits, path traversal prevention

Quick Start

Prerequisites

• Node.js 18+
• Bambu Lab printer on your local network
• Developer Mode enabled on the printer (recommended — Settings > LAN Only > Developer Mode)

Install

git clone https://github.com/schwarztim/bambu-mcp.git
cd bambu-mcp
npm install
npm run build

Option A: Developer Mode (Recommended)

Enable Developer Mode on your printer, then configure with your LAN credentials:

# Grab these from your printer screen:
#   IP Address:    WLAN → IP
#   Access Code:   WLAN → Access Code (8-digit)
#   Serial Number: Settings → Device → Serial Number

Add to ~/.claude/user-mcps.json:

{
  "mcpServers": {
    "bambu-lab": {
      "command": "node",
      "args": ["/path/to/bambu-mcp/dist/index.js"],
      "env": {
        "BAMBU_LAB_MQTT_HOST": "192.168.1.100",
        "BAMBU_LAB_MQTT_PASSWORD": "YOUR_ACCESS_CODE",
        "BAMBU_LAB_DEVICE_ID": "YOUR_SERIAL_NUMBER"
      }
    }
  }
}

Developer Mode gives the most reliable experience. All MQTT commands are automatically signed with X.509 certificates.

Option B: Browser Login (No Developer Mode)

If you don't want to enable Developer Mode (e.g., to keep Bambu Handy working), you can authenticate via browser login instead:

npm run setup

This opens Firefox (used instead of Chrome to avoid Google SSO bot detection), lets you log into your Bambu Lab account, and auto-discovers your printers. Credentials are saved to ~/.bambu-mcp/credentials.json and loaded automatically — no env vars needed.

Note: Token is valid for ~3 months. Run npm run setup again to refresh.

Then register with Claude Code (no env vars required):

{
  "mcpServers": {
    "bambu-lab": {
      "command": "node",
      "args": ["/path/to/bambu-mcp/dist/index.js"]
    }
  }
}

Limitations without Developer Mode: Printing .3mf files via project_file command requires Developer Mode. .gcode files and all other commands (stop, pause, resume, status, speed, G-code, camera, AMS) work without it.

Tools

Cloud API (4 tools)

Tool	Description
get_user_profile	Get Bambu Lab cloud account profile
list_printers	List all printers registered to cloud account
get_printer_status	Get printer status via cloud API
sign_message	Sign message with X.509 certificate for firmware auth bypass

Print Control (7 tools)

Tool	Description
printer_stop	Stop the current print immediately
printer_pause	Pause the current print
printer_resume	Resume a paused print
printer_set_speed	Set speed via profile (silent/standard/sport/ludicrous) or percentage
printer_send_gcode	Send G-code command (dangerous commands blocked)
printer_print_file	Start printing a file from printer SD card
skip_objects	Skip specific objects during multi-object prints

Status & Info (3 tools)

Tool	Description
printer_get_status	Request full status push (temps, progress, AMS, fans, etc.)
printer_get_cached_status	Return last cached status (no pushall — use for frequent polling)
printer_get_version	Get firmware and module version info

Camera (2 tools)

Tool	Description
camera_record	Enable/disable camera recording
camera_timelapse	Enable/disable timelapse recording

AMS & Filament (2 tools)

Tool	Description
ams_change_filament	Change to a different AMS tray (0-3)
ams_unload_filament	Unload current filament from extruder

Hardware (3 tools)

Tool	Description
set_temperature	Set nozzle or bed temperature (with safety limits)
set_nozzle	Set nozzle diameter for profile selection
led_control	Control chamber/work LED lights

Connection & Upload (3 tools)

Tool	Description
mqtt_connect	Connect to printer via local MQTT over TLS
mqtt_disconnect	Disconnect from MQTT
ftp_upload_file	Upload .gcode/.3mf/.stl to printer via FTPS

Architecture

Claude Code / AI
    |
    v
Bambu Lab MCP Server
  |-- Cloud API (bambulab.com)
  |-- MQTT Client (port 8883, TLS)
  |-- FTP Client (port 990, FTPS)
    |
    v
Bambu Lab Printer (P1P/P1S/X1C/A1)

How It Works

1. MQTT connects to the printer over TLS on port 8883 using the LAN access code
2. Status reports are continuously cached as they arrive on the MQTT report topic
3. Commands are sent on the MQTT request topic with sequence IDs for response matching
4. FTP uploads files to the printer SD card over FTPS (port 990)
5. X.509 signing uses the extracted Bambu Connect certificate for authenticated commands

Configuration

Environment Variables

Variable	Required	Description
BAMBU_LAB_MQTT_HOST	For MQTT	Printer IP address
BAMBU_LAB_MQTT_PASSWORD	For MQTT	LAN access code
BAMBU_LAB_DEVICE_ID	For MQTT	Printer serial number
BAMBU_LAB_MQTT_PORT	No	MQTT port (default: 8883)
BAMBU_LAB_MQTT_USERNAME	No	MQTT username (default: bblp)
BAMBU_LAB_COOKIES	For cloud	Session cookies for cloud API
BAMBU_LAB_BASE_URL	No	Cloud API base URL
BAMBU_LAB_USER_ID	No	Bambu Lab numeric user ID (for signed MQTT commands)
BAMBU_LAB_APP_CERT_ID	No	Override the built-in X.509 cert ID
BAMBU_APP_PRIVATE_KEY	No	Override the built-in X.509 private key
BAMBU_APP_CERTIFICATE	No	Override the built-in X.509 certificate

Finding Your Printer Info

• IP Address: Printer screen → WLAN → IP
• Access Code: Printer screen → WLAN → Access Code (8-digit)
• Serial Number: Settings → Device → Serial Number

Security

X.509 Certificate

This server includes the publicly extracted X.509 certificate from the Bambu Connect desktop application. This is not a secret — it was publicly disclosed in January 2025 and is embedded in every copy of Bambu Connect.

All MQTT commands are now automatically signed with RSA-SHA256 using this certificate. This is required by post-January 2025 firmware — unsigned commands are rejected with error 84033543. No Developer Mode required for basic commands (stop, pause, resume, speed, G-code).

The certificate can be overridden via BAMBU_APP_PRIVATE_KEY and BAMBU_APP_CERTIFICATE environment variables if Bambu Lab rotates credentials. Set BAMBU_LAB_USER_ID (your numeric Bambu Lab user ID) for full compatibility — find it via the cloud API's /v1/design-user-service/my/preference endpoint.

Safety Features

• Blocked G-codes: M112 (emergency stop), M502 (factory reset), M500/M501 (EEPROM), M997 (firmware update), M999 (restart)
• Temperature limits: Nozzle max 300C, bed max 120C
• File validation: Only .gcode, .3mf, .stl uploads allowed
• Path traversal prevention: No .. or absolute paths in FTP uploads

Best Practices

1. Keep printers on a separate VLAN
2. Rotate LAN access codes periodically
3. Never commit .env files (already in .gitignore)

Acknowledgments

• Community researchers who extracted the X.509 certificate — making this possible
• OpenBambuAPI — reverse-engineered MQTT protocol docs
• Shockedrope/bambu-mcp-server — speed profile concept
• DMontgomery40/mcp-3D-printer-server — multi-printer platform inspiration
• bambu-node — TypeScript Bambu library
• Bambu Lab — for making excellent printers (even if the auth lockdown was rough)

License

MIT — see LICENSE for details.

Disclaimer

Not affiliated with or endorsed by Bambu Lab. Use at your own risk.