Filament sensors are working, but doesn't stop until filament is past the nextruder gear
I upgraded my MK4S with MMU3 to a Core One, without MMU (but with the MMU nextruder mods). I have tested and calibrated both the filament sensor but the spool (in the handle) and the one in the nextruder and the calibration passes and the screen indicators reflect the correct state.
Twice now I have been printing long PETG items and run out of filament. But instead of the expected little bit of filament sticking out the end of the PTFE tube or at least from the top of the nextruder, it only stops printed once the end of the filament is past the nextruder gear so that I have to use tweezers to pull it out through the nextruder door.
What is the correct behavior supposed to be? Does it try to use most of the filament in the PTFE tube and it make some calculation of how far to run past the first filament sensor trigger? Maybe there is some tube length setting I need to change to fix that? Is there something else I'm missing here? I am planning on hooking up the MMU3 soon but haven't done so yet and have that turned off. Other ideas? Thanks.
Best Answer by darkmattermaker:
Correct behavior is: Filament sensor detects run out on the handle/side sensor first. Printer stops. Printer ejects filament so approximately 1cm is sticking out of the short PTFE tube on the side where the spool goes.
Sounds like maybe your side sensor is stuck in the "inserted" state? Mine was like that too after doing the conversion from my MK4S. It was stuck on because I hadn't pushed the magnets in the sensor in far enough. I know you said you checked this, but did you verify it shows no filament when you remove it from the side sensor?
RE: Filament sensors are working, but doesn't stop until filament is past the nextruder gear
Correct behavior is: Filament sensor detects run out on the handle/side sensor first. Printer stops. Printer ejects filament so approximately 1cm is sticking out of the short PTFE tube on the side where the spool goes.
Sounds like maybe your side sensor is stuck in the "inserted" state? Mine was like that too after doing the conversion from my MK4S. It was stuck on because I hadn't pushed the magnets in the sensor in far enough. I know you said you checked this, but did you verify it shows no filament when you remove it from the side sensor?
RE: Filament sensors are working, but doesn't stop until filament is past the nextruder gear
Thanks for the confirmation on how it should be working. I will triple check when I get home tonight and make sure the sensor is registering consistently when the filament is removed. I have checked it when yanking it back out, but maybe if I pull it through slowly toward the extruder I can see if it gets stuck. Thanks for the tip!
RE: Filament sensors are working, but doesn't stop until filament is past the nextruder gear
Running sensors calibration again should fix the issue.
RE: Filament sensors are working, but doesn't stop until filament is past the nextruder gear
Turns out that it was the side sensor arm getting stuck in the "loaded" position just as darkmattermaker suggested. The "Off" indication on the main screen made me think it was working (or at least stuck unloaded) but I think that meant something else. When I checked Info-->Sensors I could see that the value for this sensor was stuck at "2" and never moved despite hearing the ball clicking around when sticking filament in/out.
I had run the calibration process a couple of times previously and it always passed and seemed to work, but I think it was really just working with the nextruder sensor and must've just needed the side sensor as "loaded".
Thanks for the help on the debug. I still need to pull things apart to get to that piece. I remember installing that side panel being a big pain so I'm not looking forward to pulling it apart to fix it :-). But I'll get it to work.
Thanks!
RE: Filament sensors are working, but doesn't stop until filament is past the nextruder gear
I finally found time to take it apart and do some debug. I know many had issues with the magnet getting stuck and preventing the arm from pivoting. But in my case there was a flaw in the print with the "bowl" for the metal ball. So the metal ball got stuck inside the plastic part and it wouldn't move far enough despite the magnet pushing things around. A little work with the tweezers pulled out the imperfection and the ball moves freely now. Sensor up and running!