FT-2020 i3 Prusa Filament Runout Sensor

thingiverse

This is a mechanical filament sensor for FT-2020 i3 Prusa 3D Printers that works well with most 1.75 mm filaments. I prefer this end stop setup over optical sensors, which could fail due to clear filament color, and it uses a positive mechanical displacement switch. You can purchase end stop sensor switches and cables from: https://smile.amazon.com/gp/product/B01FX8SR8A or https://www.biqu.equipment/collections/switch-sensor/products/5pcs-lowest-price-black-mechanical-endstop-without-the-wheel-for-reprap-ramps-1-4-3d-printer-with-independent-packing or other similar places. (Most printer kits have 1 or 2 extra, so check your leftover parts bin). To mount the switch, use 2x M3 x 10 socket head cap screws with nuts on the opposite side. Check the switch with some spare filament to ensure it's working properly. You may need to slightly bend the switch arm out 1 mm to guarantee the switch is closed when filament is in the guide. Some mechanical adjustments are expected here as switches and part prints vary. The Fusion 360 file included allows for customization if desired. To enable firmware changes in Marlin, add the following lines in the "Configuration.h" file: # define FILAMENT_RUNOUT_SENSOR if ENABLED(FILAMENT_RUNOUT_SENSOR) # define FIL_RUNOUT_INVERTING true // set to true to invert the logic of the sensor. # define ENDSTOPPULLUP_FIL_RUNOUT // Uncomment to use internal pullup for filament runout pins if the sensor is defined. # define FILAMENT_RUNOUT_SCRIPT "M600" endif Be sure to set "#define FIL_RUNOUT_INVERTING" to TRUE - by default it is false. The switch shown is normally open configuration. If your setup is NC, this statement would be false. More details can be found in the diagram here: http://www.smidgeindustriesltd.com/reprap/mech_endstops.png Also un-comment and enable servos with this line in the servo section: # define NUM_SERVOS 3 The switch cable will need to be re-pinned per the photos - swapping RED and BLACK wires. Plug the revised cable into the SERVO3_PIN as shown, with the RED wire oriented as shown. Note: This switch can also be used with OctoPi, see details noted in this Thingiverse post here: http://www.thingiverse.com/thing:2147179