Ender 3 Optical Runout Sensor Holder (Offset adjusted)

thingiverse

Thanks to the ingenious creator of this simple optical filament runout sensor holder, which cleverly utilizes the ubiquitous 3-wire optical end-stop sensor as a filamenet runout sensor. A small piece of PTFE tube is inserted into each end of the holder and the board screwed on top. Users of the Ender 3 will need to flash a bootloader and firmware to add support for the sensor if it hasn't already been done, as the stock firmware doesn't have this capability. This design mirrors the original exactly except I've offset the top half to align the filament holes with my standard extruder. The creator's original design seems to employ a metal type extruder; possibly this or the Z-axis offset caused the misalignment issue. If your filament entry hole in the extruder lines up almost perfectly with the left screw of the Z-axis nut, then this part will provide a straight filament path. However, if your filament entry hole falls between the Z-screw and the left Z-screw nut, the original part is likely to perform better.