Filament runout sensor for Tevo Tarantula (and others) by corruptfile

Last crawled date: 3 years, 1 month ago

Quick and dirty filament runout sensor. I will be leveraging a RPi3 for this, but there are tutorials on how to wire a runout sensor to the MKS board. This is for 1.75mm filaments only.
For this, you will need:
Raspberry Pi running Octoprint
I am running Marlin 1.1.5. YMMV if you are running something else...
2x M4x10 socket head cap screws
2 M4 T-nuts (like the ones the printer came with) -OR-
2 M4 threaded inserts (I used McMaster-Carr P/N 94510A040
A microswitch. I used an OMRON SS-5GL2T (https://www.amazon.com/ELECTRONIC-COMPONENTS-SS-5GL2T-MICROSWITCH-ROLLER/dp/B011N9VGV8)
2 pieces of 1.75mm filament cut to ~20mm
2 conductor cable
Heatshrink
Female jumper or some other connector to hook up to the GPIO pins
(optional) 2 t-nuts to direct mount this to the frame if desired.
(optional) some sort of connectors for quick disconnection of the cable.
The physical assembly should be straight forward for the assembly. If you are not using the press inserts, you just drop the tnuts in the back of the rear clamshell and tighten up. Might be a good idea to do this before mounting to the printer to allow you to tighten the nut in and have it swage into the plastic. I never used that method so I'm not sure!
Solder one conductor of your cable to the relay COM/GND. The other should be soldered to the NO terminal (you can use the NC terminal too, and just change it in Octoprint). Use heatshrink to protect your connections and offer some strain relief. Place the switch in the housing and use the 2 pieces of filament to secure the switch. Depending on your printer performance, you may need to drill (use a 5/64" bit) it out a tad.
After the assembly is done, you will need to wire it to your RPi. I am using the RPi for remote on/off as well, so I opted to build an enclosure for the relay to live. Also, I used a breadboard with a GPIO extension board for ease of wiring. This is totally optional and you can get away with wiring directly to the GPIO header on the RPi. Connect one conductor (doesn't matter which) to your switching pin (I used Pin 24 (BCM8/CE0) for signal) and the other to a ground pin (pin 20 or 25, for example). Congrats, now you are wired.
In Octoprint, download and install the "Filament Sensor Reloaded" plugin. After it is installed, change the pin to 24 (or whatever one you used), leave debounce at 250ms, leave switch type to Normally Open (unless you wired your switch NC!), select board mode, and deselect "Pause print when out of filament". In custom g-code, add the following:
M600 X0 Y0 Z5
This will start the filament change process (M600) and send the print head to home. Follow the prompts on your LCD to complete the filament change.
No more partial rolls!