It’s happened to me three times now on large prints, wasting a lot of filament…
The problem is that the filament run out sensor only detects the presence of filament, not its movement. So, if by chance the filament breaks somewhere between the filament sensor and the extruder the printer will just keep on printing without any actual filament. Unfortunately, like I’ve said, this has happened to me three times now.
The problem is that filament spools are not perfect… sometimes the manufacturer tangles the filament on the roll… sometimes the filament springs off the spool… when any of that happens the filament gets knotted and jammed BEFORE the run out sensor. The extruder keeps extruding but can’t advance the filament, so the filament breaks right before the extruder. All the while, there’s still filament within the run out sensor, so it never stops the print, and the printer keeps on “printing” without laying down any plastic. If the break happens far into a print there’s no way to resume where you left off… without some sort of advanced gcode editing, that is.
So, I guess I’m asking if there’s a motion detecting run out sensor available, or one that’s in the works. Because right now I’ve been pretty annoyed with both filament manufacturers and a certain Creality filament sensor.
I’ve had that same problem in the past a couple times. I usually unroll carefully a few turns on the roll to see if it has a snag on it. I think it was my fault once before when I opened the roll and it unwound a little and I didn’t notice the tangle when I rolled it back up… I can see if there is a tangle in the roll and unroll it a little and fix it if it’s not too far in.
I get most rolls from Ender, Creality and they are wound very well so there is no tangle issue that I’ve had recently. Not to say it’s a good Idea to check on it during a print.
As far as I know there is no motion sensor for this machine just the filament detector thingy. Mine is not working anymore anyways…
A good filament NEVER has this issue. I tested hundreds of spools.
It often happens, without your noticing, that the end of the filament goes under one of the coils when you put it away and this causes the filament to knot on the spool.
This is a very real problem when printing engineering filaments of unusual rigidity. I’m talking polycarbonate and PET-CF (not PETG-CF). But it’s a slightly different case.
These filaments are so stiff the reverse bowden path may take a turn that is a tighter radius than the filament can do and it snaps inside the bowden, often past the sensor.
BigTreeTech has a filament runout sensor with a tachometer wheel turning with the filament. You must have your K1 rooted to be able to tell it to look for pulses from the sensor not just stop when the switch goes off once.
Unfortunately it looks like the BTT sensor has only one pulse sensor, so if the filament breaks, it will still think it’s ok for awhile as retracts push the filament the wrong way but the sensor still counts that movement. However as the filament gets used up past the retract distance that will stop, just later than ideal.
I haven’t tried it yet but I’m going to add that sensor and see.
I can see if there is a tangle in the roll and unroll it a little and fix it if it’s not too far in.