Spool entaglement alert sensor

thingiverse

This sensor detects when the entire roll has become tangled (lifted off the back rollers since the whole roll is pulled forward) and alerts the operator by stopping the print instantly. Designed to fit seamlessly with the spool holder found at https://www.thingiverse.com/thing:2864118. An added feature allows you to switch off the sensor when removing or replacing spools, eliminating any annoyance caused by the beeper, siren, e-stop, power cut, or pause print. To secure the switch in place, slide it onto the mounting posts and use your soldering iron to melt the ends of the posts. You can wire the switch to the input of a WebRelay at https://www.controlbyweb.com/webrelay/, which allows you to automatically cut power to your printer when necessary. With Prusa printers, this feature will even detect power failures and allow you to resume printing seamlessly. Moreover, you can use the WebRelay to trigger web requests whenever there is a change in input or relay status, enabling you to send notifications to your home automation system. For instance, I use this feature to play a siren sound, take a picture with my IP security camera watching my printer, and then send an email. Alternatively, you can use the e-stop plugin for OctoPi and wire the switch to that input; however, I'm not confident that the print will be stopped or paused in time before the spool topples over completely during a move. Video: https://youtu.be/9HhrPmp6Skg. ** EDIT ** Before you start using this sensor, know that when the spool becomes empty (lighter), there is a possibility that the printer pulls it hard enough during a move that the switch thinks the spool is lifted. In such cases, you will need to write some debounce or delay code in your connection setup.