This project provides a standalone, automated exhaust fan controller for Bambu Lab 3D printers running inside an enclosure. It uses an ESP32 to connect directly to the printer's local MQTT broker to monitor print status and automatically trigger a 12V PWM exhaust fan (like a Noctua) when a print starts.
Key Features:
- 🏠 Fully Local & Standalone: Connects directly to the printer's Port 8883 MQTT broker.
- 🧠 No Home Assistant Required (but supported): Runs its own internal logic and local web dashboard.
- 🛡️ Safe JSON Parsing: Uses ArduinoJson V7 directly within ESPHome to parse massive Bambu payloads without consuming excessive memory.
- 🎚️ Auto/Manual Override: Web UI allows you to toggle the fan manually or let the automation take over.
- 🔌 No soldering necessary: Eliminates the need for soldering or complicated wiring with careful hardware selection.
- ESP32 Controller: Acebott QA007/009 ESP32 Max (Arduino Uno form factor)
- This board removes the need for buying multiple other components virtually eliminating the hassle of additional wiring.
- Screw Terminal Expansion: Arduino Uno Compatible Screw Shield
- Exhaust Fan: Noctua NF-A8 12V PWM
- Other 12V PWM fans should work, but may not fully stop spinning when PWM is 0%.
- Power Supply: 12V DC Barrel Power Supply (Option 1 | Option 2)
- Enclosure: YOOPAI 3D Printer Enclosure
- As far as I'm aware, all sizes use the same 70mm diameter port.
- Window Vent: Dryer Vent Window Kit
- You may of course print your own.
- Exhaust Attachment: Fume Extraction for YOOPAI Enclosure (Requires 4x M3x60mm screws)
- Cut and strip the wires on the extra extension cable provided in the Noctua fan box.
- Attach the Screw Shield to ESP32 board.
- Wire the fan to the screw terminals as follows:
- Red Wire (12V Power):
Vin - Black Wire (Ground):
GND - Blue Wire (PWM Signal):
GPIO33 - Yellow Wire (Tachometer/RPM):
GPIO32
- Red Wire (12V Power):
=========================================================
WIRING SCHEMATIC
=========================================================
[ 12V DC Wall Adapter ]
|
| (Plugs into DC Barrel Jack)
v
+-------------------------------------------------------+
| ACEBOTT ESP32 + SCREW SHIELD |
| |
| [Vin] [GND] [IO33] [IO32] |
+------|-----------|------------------|----------|------+
| | | |
| (Red) | (Black) | (Blue) | (Yellow)
| 12V Power | Ground | PWM | Tach/RPM
| | | |
v v v v
+-------------------------------------------------------+
| |
| NOCTUA NF-A8 12V PWM FAN |
| |
+-------------------------------------------------------+
- For reference the Acebott Documentation can be found here.
You need three things from your printer's network settings screen (or Bambu Studio):
- Printer IP Address (e.g.,
192.168.1.50) - Access Code (8-digit code acting as the password)
- Serial Number (e.g.,
01P00A...)
Bambu printers use a self-signed certificate for their MQTT broker on port 8883. You must extract this to allow the ESP32 to trust the connection.
Run this from a Linux terminal (replace <PRINTER_IP>):
openssl s_client -showcerts -connect <PRINTER_IP>:8883 < /dev/null 2>/dev/null | sed -n '/-----BEGIN CERTIFICATE-----/,/-----END CERTIFICATE-----/p' > bambu_cert.pem
(Optional) Test the connection from your PC:
mosquitto_sub -h <PRINTER_IP> -p 8883 -u bblp -P <ACCESS_CODE> -t "device/<SERIAL_NUMBER>/report" --insecure --cafile bambu_cert.pem --ciphers "DEFAULT:@SECLEVEL=0" -d
Create a new device in ESPHome and paste the following configuration. Make sure to update the IP, Access Code, Serial Number, and Certificate.
esphome:
name: bambu-exhaust-fan-esphome
friendly_name: bambu_exhaust_fan
esp32:
board: esp32dev
variant: ESP32
# Enable Web UI
web_server:
port: 80
# Enable built-in ArduinoJson library
json:
globals:
- id: printer_is_running
type: bool
initial_value: 'false'
# Virtual switch to toggle between Auto (MQTT) and Manual control
switch:
- platform: template
name: "Automated MQTT Control"
id: auto_mode
optimistic: true
restore_mode: RESTORE_DEFAULT_ON
# Fan PWM Output
output:
- platform: ledc
pin: GPIO33
id: fan_pwm
frequency: 25000 Hz # Standard for PC Fans
fan:
- platform: speed
output: fan_pwm
name: "Enclosure Exhaust Fan"
id: bambu_fan
# Fan RPM Tachometer
sensor:
- platform: pulse_counter
pin:
number: GPIO32
mode: INPUT_PULLUP # Required for open-collector tachometers
name: "Exhaust Fan Speed"
id: fan_rpm
unit_of_measurement: "RPM"
update_interval: 2s
filters:
- multiply: 0.5 # 2 pulses per revolution
# Printer Status
text_sensor:
- platform: template
name: "Printer State"
id: printer_state_sensor
icon: "mdi:printer-3d"
# Local Bambu MQTT Connection
mqtt:
broker: "192.168.1.50" # REPLACE with Printer IP
port: 8883
username: "bblp"
password: "YOUR_ACCESS_CODE" # REPLACE with Access Code
client_id: "esphome_exhaust_controller"
skip_cert_cn_check: true # Required to bypass Bambu's self-signed TLS cert
discovery: false # Prevents ESPHome from spamming the printer's broker
# REPLACE with the contents of your bambu_cert.pem
certificate_authority: |
-----BEGIN CERTIFICATE-----
MIIDXTCCAkWgAwIBAgIEX...
...
...
-----END CERTIFICATE-----
on_message:
- topic: "device/YOUR_SERIAL_NUMBER/report" # REPLACE with your Serial Number
then:
- lambda: |-
// The 'x' variable holds the raw MQTT payload string
std::string payload = x;
// Fast-fail: Only parse if "gcode_state" is actually in this payload
// This saves the ESP32 from parsing useless delta updates
if (payload.find("\"gcode_state\":") != std::string::npos) {
// Use ESPHome's built-in ArduinoJson wrapper
auto doc = json::parse_json(payload);
auto root = doc.as<JsonObject>();
// 1. Check if the "print" object exists
if (root["print"]) {
JsonObject print_data = root["print"];
// 2. Check if the "gcode_state" key exists inside "print"
if (print_data["gcode_state"]) {
// 3. Extract it as a string
auto state = print_data["gcode_state"].as<std::string>();
// 4. Evaluate it
if (state == "RUNNING" || state == "PREPARE" || state == "PAUSE") {
id(printer_state_sensor)->publish_state("RUNNING");
id(printer_is_running) = true;
} else if (state == "IDLE" || state == "FINISH" || state == "FAILED") {
id(printer_state_sensor)->publish_state("STOPPED");
id(printer_is_running) = false;
}
}
}
}
# 4. Trigger Fan logic based on state, obeying the Auto/Manual switch
- if:
condition:
switch.is_on: auto_mode
then:
- if:
condition:
lambda: 'return id(printer_is_running);'
then:
- fan.turn_on:
id: bambu_fan
speed: 100
else:
- fan.turn_off:
id: bambu_fan