Runout Detector and Filament Guide for Ender 3

thingiverse

I designed this around a microswitch and 608 bearing that I happened to have lying around. It's a bit larger than some others, as I wanted it to combine both functions AND eliminate the need for any other filament guides customarily added to the E3. There are many solutions to a clear filament path, but I keep my reel holder as far to the left as possible and use an angled bracket holder (one of the first things I ever printed) to squeeze out a few more centimeters of overhang. Hopefully the pictures will help you see how it all works for me. Back to the matter at hand; the filament guide/detector thing. To assemble, screw in two M3 bolts through the bracket assembly and switch body using a drill press or impact driver. These will self-tap into the switch plate, so try not to strip the holes out. The wires from the switch are routed through the cable hole in the plate, then into the sloping guide on the rear of the same, before being secured to the bracket assembly with a small cable tie. It's just as simple to fit it to the printer: Remove the upper nut from the Z carriage at the left of the machine - no need to remove the bolt when you do this! Then push this nut into the bracket assembly. It's intentionally tight, so I recommend using a spare bolt to draw it through from the other side. The bracket can now be placed onto the machine, and the carriage bolt re-tightened. The 608 bearing is placed onto its axle, then the filament is fed through the switch, and on to the extruder in the usual way. The bearing cover disc is then put onto the bearing axle, and held in place using a short piece of filament (or a cocktail stick, or toothpick). I found my disc was a little sloppy, so I shimmed it with a printed washer I had lying around from another project. I haven't wired it yet as I'm waiting for delivery of a DuPont connector kit, but I have tested it using a multimeter, and it seems to work perfectly. Obviously, I will update this once I get the connectors! At first it was a bit noisy on retractions, but this noise has gone away as the assembly has had time to bed in and smooth the filament path. Enjoy.