Filament runout sensor - hotend tube fitting edition (one piece of tubing, not two)

Last crawled date: 4 years, 3 months ago

Note: Please don't mind the gruff looking lid, I had some over-extrusion and never re-printed because the lid worked fine.
I looked at the other filament runout sensors out there, and I had gripes with all of the current designs I could find. While many of them are really well made, none of them satisfied me.
What I have here is a filament runout sensor made to fit an M10(1.0 thread) tube fitting for Bowden tubes, just like the one used on many hotends. This is because I did not want the tube to slide back and forth during retractions, and the fitting will hold it still.
Furthermore, I wanted a filament sensor that needed a single piece of tubing with only slight modification instead of two pieces placed into the housing. So I spent quite a few prints getting the distance JUST RIGHT so the switch is triggered by filament running into a tube that's been cut open and releases once the filament leaves.
Optionally, you can even mount this to your extruder frame just by drilling out the filament feeding hole and adding a way to seat a tube in there with no movement during retractions. For me, I used a different tube fitting and drilled it out to very snugly fit a tube so the tube needs to be gripped very tight to be moved. This then allows me to feed my filament directly into my extruder frame via tube so it meets no resistance other than the movement mechanism.
Parts needed:
A piece of Bowden tube(regular and Capricorn should both work)
A knife or other way to slice open a piece of your tube
A microswitch like this one: https://www.ebay.com/itm/10pcs-Micro-Roller-Lever-Arm-Open-Close-Limit-Switch-Kw12-3-PCB-Microswitch-Hot/123803444289?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
Keep in mind, this housing is designed for that specific one. I cannot guarantee that any other shape of switch will work.
Some basic soldering stuff to attach the wires to the sensor like any other sensor out there
A M10 Bowden fitting with a 1.0mm thread pitch(this is the one the MK8 hotend on the Ender 3 uses for instance, it is an extremely common fitting, you probably have one)