Tevo Tornado Filament Runout Sensor and Guide

thingiverse

After I installed a BLTouch onto my Tornado, I had a leftover limit switch that I always intended to repurpose as a filament runout sensor. I finally got some time to work on this project, but because space is limited on my machine between the extruder and the spool, I decided to integrate a rudimentry filament guide into the design of my limit switch housing (see photos). I decided to make this a single piece design (not including the lid, which is attached using two M3 screws), so support is required. Even so, it only took about 3.5 hours to print on my system at 0.1mm layer height. The hole on the outfeed side of the switch arm was meant for a piece of PTFE tubing running between the switch and the extruder, but this ended up making the manual release on the extruder difficult to use and I have since removed the PTFE tubing except for a very short length at the extruder entrance. I've included a STEP file of the design if anyone wants to improve on it. The wires for the old Z-axis limit switch were too short, so I had to extend them to allow full travel of the carriage in the Z direction. For the firmware update, I followed Michael's guide here: https://youtu.be/gwHpXaj_6xE My version of firmware was a little older than the one in the video, and because of the connector used on the Z-axis limit switch cable and the version of board I have, I had to connect it to Servo 2 in place of Servo 3, but it all worked out without issue.