Filament runout sensor Prusa Mk2 style extruder

thingiverse

I needed a runout sensor I could mount directly to the top of an MK2 style extruder body. I wasn't happy with the ones that were available, so I came up with this one myself. It's inspired by the new MK3S filament sensor setup. It uses a steel ball for the filament to ride on, ensuring the filament won't kick the sensor off when unloaded. The ball housing has a fin that triggers an optical sensor. The ball housing needs to be printed in black for it to trigger the sensor properly. The ball is a tight fit, and I use PETG filament; I press the ball in with pliers. When the filament is absent, there's a 8x3mm round magnet on the back that pulls the ball forward. The sensor is held in place with two M3x8mm screws. There's also a spot on the holder for an M3 nut, and you can use a screw to hold it tight to the body. You can use the filament sensor body to open the idler door enough to get your filament in. Any 3mm screw over 5mm long should work. I'm using this on a mini Rambo board, but you can use it on anything that has open pins. I have this one connected to pin 30, which is the X max endstop pin - works great. In configuration.h for Marlin 1.1.9: #define FILAMENT_RUNOUT_SENSOR #if ENABLED(FILAMENT_RUNOUT_SENSOR) #define NUM_RUNOUT_SENSORS 1 // Number of sensors; up to one per extruder. Define a FIL_RUNOUT#_PIN for each. #define FIL_RUNOUT_INVERTING false // Set to true to invert the logic of the sensor. //#define FIL_RUNOUT_PULLUP // Use internal pullup for filament runout pins. #define FILAMENT_RUNOUT_SCRIPT "M600" #define FIL_RUNOUT_PIN 30 #endif Pins MiniRambo: // Limit Switches #define X_MIN_PIN 12 #define X_MAX_PIN -1 #define Y_MIN_PIN 11 #define Y_MAX_PIN 24 #define Z_MIN_PIN 10 #define Z_MAX_PIN 23 Affiliate links: Steel ball I used: https://www.amazon.com/Aobbmok-10Pcs-Chrome-Bearing-Spheres/dp/B078X3SZQJ/ref=sr_1_4?keywords=10mm+Chrome+Steel+Bearing+Balls&qid=1558199078&s=gateway&sr=8-4 Magnet I used: https://www.amazon.com/gp/product/B07B3SDRCP/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 Optical sensor I use: https://www.amazon.com/gp/product/B076D2NV26/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 Parts needed: 1x Sensor housing 1x Ball holder; USE BLACK FILAMENT, PETG is best. 1x 10mm steel ball 1x 8x3mm round magnet 2x M3x8mm screw 1x M3x5-20mm screw Unload load video: https://youtu.be/sS5E81eAdL4 Assembly video: https://youtu.be/lbYrFWREhaA youtube.com/ChrisRiley