Filament Sensor

thingiverse

Having finally succeeded in catching my printer before it runs out of filament, I decided to take action. I discovered the "Filament Sensor"-plugin for OctoPrint and chose a microswitch to handle detection for me. This is the result; It's attached right before my extruder, allowing me to use nearly every last scrap of filament I have lying around. Edit: Previous problems with the RPi not booting were caused by connecting 3V3 and GND with a 1k resistor between them. Miraculously, it still worked, but the RPi didn't boot. After rewiring as described, it functions as intended. How I Designed This Stuff I Had Lying Around So, I have a lot of electronic junk lying around, so I figured I could use some of it for this. Among the junk, I had: Many meters of thin cable strips Microswitches Resistors with varying values Dupont connectors 3D Design I created a rough model of the microswitches I planned on using and then designed a holder around them. The lever on the switch needed a slight kink to make it pick up a better signal, which is completely okay by me. Circuits.io didn't have an RPi model, so you'll just have to use your imagination here Circuit To connect a button to my RPi3, I had to create a small circuit to avoid messing things up. You need a current-limiting resistor (R1) on your input pin, so you don't damage your RPi. Then, you need a pull-down (R2) to make the pin LOW by default. Next, connect one lead from the switch between the resistors and the other to a 3.3V supply. Note: Don't use 5V; apparently, the RPi doesn't like that! I used a pin-out I found on Google to figure out which pins were GND and 3.3V on my RPi and chose GPIO 21 for the input signal. If you can't figure out how this should map over to your RPi, you might want to reconsider doing this... R1: 1k R2: 10k