[Dave Astolfo] wanted to be able to let his CNC mill run by itself with the ability to monitor it remotely. The only problem with that idea is that if he checked in and saw something bad happening he needed a remote kill switch as well. He ended up killing two birds with one stone by adding extra features to an IP camera.
These Internet Protocol cameras are pretty nifty. Just plug their power cord in and they’ll connect to WiFi and start streaming video. Many of them offer features like pan and tilt, and this model even features IR LEDs for night viewing that can be switched on and off through the web interface. That’s the point at which [Dave] started his hack. He patched into the leads on the IR LEDs. They’re monitored by an ATtiny85. When he turns on the LEDs via the webpage the ATtiny85 senses it and drives a servo motor to push the ESC key on the keyboard. As you can see in the clip after the break, this will stop the milling in its tracks. We especially liked the use of LEGO Technique pieces to make the servo mount removable.