2020 / Ender 3 Filament Guide With Runout Sensor

thingiverse

I like having a filament guide, but I wanted it to also act as a filament runout detector and apply some tension to the filament so I don't get backups on my spool, which can cause tangling. I started with this: https://www.thingiverse.com/thing:2917932 Print this thing so the hole is on z, standing up, and the arm lays flat. I designed it so that it doesn't need supports to print. You might have to drill out the filament hole, particularly if you get a lot of elephant foot or overextrusion on your printer. You'll need to put a limit switch in it, the filament should trigger the switch when it is not empty. Wire the base and the nc connector to the gnd / control pin of your octoprint server pi. I had to drill out the holes to handle 2mm width bulges in the cheap PLA I use. To observe and react to the switch, I used an octoprint plugin called Filament Sensor Reloaded: https://plugins.octoprint.org/plugins/filament_sensor_reloaded/ Alternately if you aren't using octoprint, I guess you plug it into your display controller acc pins and add it to marlin, but you're on your own there. I used a cheap limit switch I had on hand, these are similar: https://www.amazon.com/Cylewet-20Pcs-Switch-Arduino-CYT1093/dp/B076GM7JQP I'm planning on making an adaptation of this part for my flsun cube but I'm just going to make a different part since I have new limit switches with rollers which might be better for the minimal backpressure. I'll also redesign this thing so that it uses a piece of bowden tubing with a notch cut out of it for the guide. If you're going direct to i/o then using a direct switch is noisy, so you either have to set a delay of 5000ms or make a less noisy circuit with a drop down 1k resistor and a 10K resistor tied to nc and 3.3v to c. Connect the 1k resistor to the i/o and the 10k to gnd. It will make way less noise and you can use sane delay values. I probably should put a mount on it for an LED so we've got visual feedback on the state of the switch, but this was designed to be as simple as possible.