Simple 1.75 mm filament-out sensor

youmagine

Update: Check out this improved design for a filament run-out sensor at https://www.youmagine.com/designs/improved-filament-run-out-sensor. The simplest possible filament out sensor is incredibly easy to use - the filament keeps the switch lever pressed down. When the filament runs out, the lever pops up and contacts open/close. You can easily connect it to a switch input on your printer's controller board to pause the print until you swap filaments and restart. The switch fits snugly into its slot. A screw holds the switch firmly in place. Insert some filament, push the switch into the slot until it clicks, then tighten the screw to secure the switch. Pull out the filament and you should hear the switch click. Put the filament back and the switch should click again. That's it - wasn't that easy? This design can be easily modified to fit any lever-type microswitch you have on hand. I designed this in two pieces - the main body sits atop my printer's 1" PIR foam cover, secured by antirotation spikes that keep it from turning. The nut is attached inside the printer enclosure. This device creates minimal friction, so your extruder shouldn't experience any issues pulling filament through it.