Filament runout sensor box - ender 3 metal extruder

cults3d

This is a remix of remixes. My stock Ender 3 extruder didn't last very long and I upgraded to a metal extruder with dual drives. this has the entry point for filament with ~+8mm in z and ~-3mm in Y. autonumous did a remix covering that, looks like he has the very same extruder. Another issue with the original design seems to be unfilled spaces next to the sensors roll which at 1.2 mm are dangerously close to standard filament width. Sebastiandruckt did an elegant version (https://www.thingiverse.com/thing:4813860) that takes care of that. Unfortunately errors in the mesh kept me from basing my remix on his version. But I clipped the redesigned holders from his model and glued them onto the body of autonumous' model. Hoping this will be the combo that serves my needs. About the key. I included the version from the source but I'm not using it myself. For one, things sit rather tight as it is. Now the key is supposed to seal the switch at its place and make sure it won't over time slip down and thus bring the sensor in an "always off" - error state. Unfortunately Pushing the key in brought my sensor into an "always on" - error state which is definately worse. "always on" simply means the sensor will not alarm you to a filament runout situation, defeating the purpose of having a sensor installed. "always off" - however means the sensor and then the printer or printhost will remind you in a strong way that something is not right. And when the spool is not empty you just know the sensor is having a problem. YMMV but if you see problems, this is one possible source. I added the FreeCAD source to this but it's just blobs. Runs nicely here, I took a felt tip marker and put 12 stripes on it and by the marks the filament left on those stripes you see it runs just in the middle, as it should. The stripes help showing the filament's move. Now, all it would take is a cheap little camera chip and some logic to register movement and we have a smart sensor which gives alarms when the filament is struck.