Case for Z-Endstop-Sensor as Filament Runout Detector by DorianGrey

Last crawled date: 2 years, 11 months ago

This is in fact a remix of https://www.thingiverse.com/thing:3850237 but Thingiverse doesn't support adding a thing as the ressource any more, at least for me. The parent did a wonderful job but I never really figured out how to screw the housing to the carriage and not make it totally difficult to change filament, which I do a lot.
Thus my remix, I removed the lower part supposed to get srewed and I redid the filament tube so that 2 pieces of bowden tube can be inserted into the holes to help keep a distance between the sensor and the extruder.
I considered to add a top but as it is it's easy to check if everything is nice and no dirt in the way and while it may look dangerously close I don't think there is any danger of unwanted electrical contact.
The (untidy) FreeCAD source is included so you can adapt the piece to your needs.
It was printed in PLA at 0,16mm layer but that's not that important. But turn the model on it's back before you print it.
The sensor reuses the unneeded z-endstop sensor from an Ender 3 after adding a BLTouch. But you might as well buy such a tiny switch and I guess many other printer brands use the same switches.
Wiring and Firmware:
I wired the sensor to the mainboard which is an BTT SKR mini E3 v1.2. Marlin already has settings prpared for Filament Runout Sensor, I found the specifs defined in the file
Marlin/src/pins/stm32f1/pins_BTT_SKR_MINI_E3_common.h and the FIL_RUNOUT_PIN was set to PC15 // "E0-STOP" there. No need to change this, I connected a 2-wire-cable just there and then to the left and middle pin of the sensor board. If you later discover that the logic of the sensor is just the wrong way round you can invert it by changing the connectors here (swap NO and NC)
Marlin (2.07.2 in my case) has a section for Filament Runout Sensors in Configuration.h which should have settings checked and adjusted. If you plan to use M600 you need to configure Advanced Pause ind Configuration_adv.h as well.