Kerf Bridge plugs into your GRBL laser's USB port and puts it on your Wi-Fi. Run it on a Raspberry Pi beside the laser, or on any PC that's already there.
Send a whole job and the bridge runs it itself, so a sleeping laptop or a dropped connection never stops a burn. It has its own web page to check on the laser from any browser, and LightBurn connects to it like any network laser.
The bridge is built in. With the laser plugged into that computer, turn on Laser plugged in by USB on Kerf's Laser tab; nothing else to install. Turn on Share with iPads on this network and the computer becomes a bridge for your iPad too.
The bridge holds the laser's USB port open, so opening and closing connections never resets the controller. It finds the laser by itself and reads its bed size and settings.
Upload a whole job and the bridge streams it to the laser itself. Close the lid, walk away, check progress later. Pause, resume and stop work from anywhere on the network.
Pass-through on TCP port 23, like ser2net. In LightBurn, add the laser as GRBL with an Ethernet/TCP connection and type the bridge's address.
Open the bridge's address on port 8023 in any browser: the laser's state and position, a big STOP button, jogging, job progress, uploading G-code and settings.
Plug the laser in and the bridge looks for it on the usual USB serial chips (CH340, CP210x, FTDI, Arduino, ESP32, STM32). It reads the bed size and full-power setting from GRBL's $$.
Whoever starts a job owns the laser until it ends. Anyone else can watch, and anyone can always stop it.
The bridge announces itself on your network (Bonjour), so apps can list it without anyone typing an IP address.
Plug a USB webcam into the Pi and point it at the bed. Watch a burn live on the bridge's web page, or full screen in Kerf. The camera is only on while someone is watching.
Give the bridge your MQTT broker and it appears in Home Assistant by itself: the laser's state, job progress, time left and the bed camera, with Stop, Pause and Resume buttons. Stop always works, so an automation can stop the laser.
With Kerf, burn a grid of dots once and the camera is lined up with the bed. After that, the camera's view sits under your design, true to size, and Kerf can find the piece you've laid down and fit your work to it.
Lasers with a GRBL controller on USB: most diode lasers (Ortur, Atomstack and Sculpfun among them) and machines converted to GRBL. If LightBurn connects to it as a GRBL device, the bridge will too. Lasers with a Ruida controller, or that only connect over the maker's own Wi-Fi, aren't supported.
Any Pi 3, 4, 5 or Zero 2 W running Raspberry Pi OS, 32- or 64-bit. The bridge uses very little; a Pi already doing something else is fine.
The bridge replaces ser2net and does the same job on port 23, plus job mode and its web page. Stop ser2net (sudo systemctl disable --now ser2net), then run the installer; or install alongside it and use port 2323 until you switch.
Almost any USB webcam: the bridge needs one that sends MJPEG, which nearly all do. Plug it into the Pi running the bridge and mount it looking down at the bed; the bridge finds it by itself. The camera works on a Pi with a 64-bit OS and on Linux PCs; the Windows, Mac and 32-bit Pi versions don't have it yet.
You need Home Assistant's MQTT broker (the Mosquitto add-on) and a Home Assistant user for the bridge to log in as. On the bridge's web page, under Settings → Home Assistant, enter the broker's address, that user's name and password, and save. A Kerf Bridge device then appears in Home Assistant with its sensors, buttons and camera. Nothing to install in Home Assistant.
Never leave a laser unattended. The bridge makes jobs reliable, not safe: stay with the laser, keep a fire extinguisher nearby, and use the STOP button or the laser's own emergency stop if anything looks wrong.
On a Pi, run the install command again; your settings are kept. On Windows, download the new version and run it in place of the old one. On a Mac, quit Kerf Bridge from the menu bar, then drag the new one to Applications and open it. Restarting the bridge resets the laser's controller, so home the laser again afterwards.