Relay box for use with Octoprint

thingiverse

I'm using Octoprint on a Raspberry Pi and wanted a way to switch my printer on/off remotely because I work in a different building than the printer. The printer can now be preheating while I walk over, or I can switch it off if it's finished printing and I'll be gone for a while before I get over there or I want to collect my print but leave the cooling fan running for a bit. Plus, I fancied a fun project. This box sits between the mains power and the printer PSU. Internally, the live mains cable goes via a switch and a relay module in parallel - that way I can turn it on remotely but then keep it on via a physical switch or, if I'm local, just use the switch. Neutral and earth pass straight through (though there's also a take-off from neutral for the neon lamp). The relay module is readily available on eBay/Amazon/Aliexpress etc. I've also used a small SPST switch with neon, an old IEC lead, an IEC connector, and a small connector block. Hardware is 10mm M3 machine screws for the lid, two tiny self-tappers for the IEC connector, and a rubber grommet for the IEC lead. I'm using this plugin in Octoprint to toggle the relay, which is connected to one of the Pi output pins: https://plugins.octoprint.org/plugins/psucontrol/. The Octopod mobile app also supports this plugin, so you'll be able to turn on/off via your mobile/tablet. Note that I'm in the UK where we have fuses in our mains plugs, and therefore this does not have or need a fuse. If you're building this elsewhere it'd be prudent to modify the STL/wiring to include a panel mounted or inline (inside) fuse or use a fused IEC socket.