Hey all, so I have an issue that keeps ruining prints. Every so often (and fairly frequently lately) filament will refuse to unload (using AMS) to the point where it is jammed in there hard and no amount of assistance by hand can budge it. I end up having to cancel the print and try and uncouple a tube from behind the printer (even though it is under massive tension) cut the filament then retract it by hand.
The result is always that the filament is stuck in the extruder. I have no idea how this keeps happening and whether I need to buy replacement parts for extruder internals (owned the printer for 2 years now) but I can’t let it keep going on as it’s wasting time and money.
My filament is kept inside the AMS and isn’t brittle or anything, I’m really not sure what is going on in there but it’s really frustrating
To better understand what’s going on and help identify the root cause, could you clarify the following:
What filament brand, material, and diameter are you using when this occurs?
(Some filaments swell or soften more than others, which could affect unload reliability.)
Have you noticed if this only happens with specific spools or materials, or is it random?
Does the filament unload properly if you manually trigger an unload from the AMS when the printer is idle, or is the problem only during/after printing?
Have you inspected the PTFE tubing for wear, deformation, or internal friction, especially at couplings and sharp bends?
When the filament gets stuck, is it inside the extruder gears, hotend, or further back in the tube between AMS and toolhead?
Have you ever cleaned or replaced the extruder gears, filament cutter, or the filament sensor assembly inside the toolhead?
(After two years of use, buildup or wear in those components could definitely affect feeding and unloading.)
Do you notice any grinding, clicking, or partial retractions before the filament gets jammed?
What’s your nozzle temperature and retraction settings for the material you’re printing?
(Too low temperatures or aggressive retraction could cause melted filament to solidify mid-unload.)
Have you run any diagnostic or calibration tools recently (e.g., filament cutter test, AMS path check)?
Are there any visible signs of wear on the filament path components, such as the cutter blade, extruder gears, or feed rollers?
It happens because of heat creep. The top of the machine is getting too hot for the filament, and when the extruder drive wheel tries to push the filament in to the hot-end, the filament “accordions”, it splooges out and you get a section of filament that is now too thick to pull back or push through. You have to take the extruder apart and cut the blob out.
There’s plenty of discussion on this in the forum. Open up the top of the machine when printing PLA, problem should disappear.
Hey, that’s a great bit of advice thanks, I will give it a go. What you described is exactly what happens, it seems to be doing it more during summer - maybe because ambient temps also warmer?
I think I’ll give the hotend a once over, maybe the fan is faulty, or thermal paste dried up etc
Absolutely. It might only take a few degrees higher ambient to get from below to above the glass transition threshold where the filament really starts to soften up. PLA has a low threshold, which makes it very susceptible to this. I use PLA for supports for PETG sometimes, it’s always a challenge to get the PLA to not jam up, because PETG likes a nice, hot build chamber but PLA does not.
I had a similar problem on a long print, was printing a single layer full plate test print when this happened(filament jammed tightly in the extruder). Turns out the part cooling fan was off for the first layer and it was set to print at a higher temp, so after a while the extruder gets too hot, and especially with low temp filament this can happen. Make sure your part cooling fan is running and can turn freely, perhaps the fan bearing is gunked up or needs replacing? Just a thought.
On my H2D, the hotend cooling fan has failed six times since I received the machine, and the part cooling fan has failed almost as many times.
The frustrating part is that when the hotend cooling fan stops working, a serious clog can develop very quickly — sometimes faster than the system seems to detect the fan failure.
This has been happening to me lately, and I’m getting pretty quick at disassembling the head and getting it back together, but I had a thought.. Do I need to tighten the screw pressing the spring against the extruder wheel all the way, or would it help to loosen it a little?
In our company we have two BambuLab X1 Carbon printers.
Everything worked fine for about a year and then the problems started… frequent head clogging and various other things.
What you’re talking about in this topic happened to me 2 times today, when the filament got stuck between the sensor and the extruder wheel.
And the amazing thing is that it happened exactly 2 times in the same place (the part I am printing is 140x140mm in size and 6mm thick (about 74 layers of 0.08mm) and exactly between 63 and 64 layers it stops printing - printing in the air.
It seems to me that the matter is not hardware related and has nothing to do with the printer or the filament, but is of a software nature…
The printer for some reason pulls out fast too much filament which is still melted and then a lump is made and it can’t be move forward or back…
Can someone parse the G-CODE file to check what it is?
You didn’t attach a file, and honestly there’s not a lot of value in digging through gcode for this type of issue until we’re farther down the troubleshooting tree. Perfectly normal gcode can have this problem, and it’s very unlikely there’s an error in the gcode itself.
What filament are you printing with?
Is the door and/or lid open or closed during the print?
