I just purchased a hardened steel gear assembly and hardened steel nozzle. After installation, I can’t get the filiment to extrude. It behaves like a blockage, but I’ve cleared the nozzle twice with a heat gun. Without the nozzle the filament goes through fine and it looks like there’s enough purchase on the filament. I’ve tried a cold pull and about every other tactic I can think of but can’t get the filament to go through the nozzle. The only thing I can think of that makes sense is that the temperature isn’t registering correctly and the hotend is cooler than it says it is. The heat sink remains barey warm, but I’ve brushed the nozzle on the outside with filament, and the filament melts, so I have to think it’s heating up.
This nozzle has worked, and worked quit well with the previous gear assembly. I know the filament is making it into the nozzle, it’s just not extruding. Is there some secret method of clearing that I might not have tried? I’ve tried the heated wrench method, the cold pull, and tried feeding the filament by had with heated to 250. (I’m using PETG.)
I can push the needle all the way through from the top, which I checked prior to the last failure. But when feeding in it only goes so far and gets stuck, and the extruder rattles a bit like it’s slipping on the filament. I’m at my wit’s end.
Is it possible the thermister sensor is blocking the filament? Maybe that little sensor wire is the problem??? Maybe it’s solar flares??
I’m not very well versed in precisely how to set the thermisterf sensor. I’s there some kind of description of how to do it? How are you supposed to bend the end? Is it an L or a V? Yes I’ve reseated the connected like dozens of times. The control panel report 250. I’ve tried getting it up to 300 but it didn’t help. Is it possible that the sensor is actually blocking the filament? I bent it at 90 degrees but maybe I should keep it close to the side. I just reset the grease, but I kept the themister relatively clean… basically because I really don’t know what to do.
Got a bit more data. The blockage in 36 mm up from the end of the nozzle. So it’s only a couple of millimeters in from the top of the heat sink. Has to be something about temperature. It’s just not getting hot enough.
If you have a small hex wrench and a pair or two of pliers try finding one that will fit in the heatbreak. Heat it with your preferred heating method and holding it with pliers push gently down through the heatbreak.
Alternatively you could plug it in wihtout mounting it, and then heat it to 200-240 and do the same thing. Just don’t burn your fingers.
You’ve confirmed the blockage. Just gotta unstick it man.
The heatsink itself isn’t overly hot first up when loading, and if it melts at the tip it should be working.
With the nozzle heated do the gears work when you press the extrude feed? Can you get the filament to load by using the external spool? Just a wild thought, strip the extruder down as you may have a stray bit of filament stuck there.
I’ve stripped the extruder down twice since installing it and it seems fine. It’s one of those with the angled gears of hardened steel. The teeth look odd but they seem to mesh OK. I have an asbestos oven glove but because it’s woven it’s still a little hot using the hotair gun. I have lots of good pliers. I kind of have a pliers addiction.
One question about this procedure with the wrench, which I’ve done before: Does it push all of the material out or does it leave a residue? I have tried this several time with the unit plugged in, and couldn’t get anything to extrude which was what led me to the notion that it wasn’t getting hot enough, but if the temperature is not distributed evenly when plugged in (but concentrated at the bottom) then that would explain why it didn’t work while still plugged in.
Also, about the sensor, I had this notion that the cutter arm could be activated without discrimination and that’s what was blocking things. Is that something that would happen if the sensor is bad?
I also super-aggravated myself by losing that damn pin which I thought was right in front of me so I ordered a hundred of the things. I might have to calm myself down by actually actupuncturing myself.
We’ve all been there, 3d printing demands patience of a saint at times (my dogs tend to leave me alone). Going by the wiki is my best advice, but probs like yours throws it a little and it takes a keen eye to spot the cause.
I’ve used the allen key a few times and found it awkward as I don’t have a vice handy in the print room (its on the list). I’m a bit unorthodox and just go with the blow torch method and watch the world burn (and filament gunk). The best option is to have a few spares and throw a fresh one on and deal with the blocked ones later.
The sensor can be fickle, I’ve had a tiny bit of filament cause a “blocked nozzle” code. It isn’t a complicate item and you can usually see if there is something not right. The cutter either works or doesn’t, I’d disregard it at the moment. One other area often overlooked is the buffer spring on the back of the printer, that can raise the same type of issues if the spring isn’t seated correctly.
I have found that “clearing the shaft” is not that easy. It requires multiple tries, at least with PETG filament, and the “cold pull” method doesn’t really work with that stuff. It’s too sticky. I’ve also found that a big saddler’s needle (US size 3, UK size 10) for sewing leather works better than the wrench because you can use either the eye end or the pointy end depending on exactly what you’re doing. The pointy end will go far enough down so as to minimize the amount left in the shaft and you can jiggle it around and pump it. The eye end is good for cleaning off the sides of the shaft. Takes several reheatings. I also used knipex pipe pliers to hold the head sink with the handles held by a tight elastic band. Knipex pliers are pretty expensive but Amazon has a cheaper version of the same thing. A small vice would work too. Work it from both ends until it’s pretty clear.
(Also, use a piece of foam or something for a pin cushion. The little acupuncture needle that comes with the set is nearly invisible to older eyes when laid flat on the table.)
OK I have completely cleared the nozzle and shaft and tried to load the filament, but it won’t load. It just “chatters.” I know the gear assembly advances the filament when the nozzle and heat sink are removed, so I still have no idea what the problem is. Just for the heck of it I removed the two screws holding the heatsink and nozzle (do you call this the “hotend” ?). Now when I hit “retry” it starts lowering the whole “hotend” into the chute, so the gear assembly is working. But there is still something hung up inside the “hotend” shaft. I have no idea how to clear it. I thought it was clear!
What the deuce is going on???
I should mention that the other thing I did was to replace the toolhead cable with the “new and improved and robust” version recommended. I don’t know if that makes a difference, but givenn the fact that the filiment seems “stuck” I can’t see how that would matter.
There was only about 20 mm of filament in the hotend and it pulled right out. That’s the point where cold filament stops, so it appears that the upper part of the “shaft” isn’t getting hot enough to melt the filament. The tip is certainly hot, even with the slicone wrap on it. Too hot to touch. But something isn’t kicking in. Could it be a problem with the new toolhead cable? Maybe I plugged it in wrong? But it seems like if that was the case the hotend wouldn’t get hot at all.
If you take the hotend off and hold it towards the light can you see through it? Like just a tiny point of light on the other end. If the extruder is extruding without the hotend on, and you can see there isn’t anything in the hotend and the thermistor shows it’s getting hot then the only thing left I can think of is the hotend isn’t lining up with the extruder correctly. I’ve never heard of this happening and I didn’t know it was possible but it’s the only other thing I can think of. Did the parts you replaced all come directly from Bambu? Also when you’re doing these tests how hot are you setting the nozzle?
I didn’t try to see through it, but I tested it with the needle from the top and it clears all the way to pointy end of the nozzle. I can probe with the needle all the way, and don’t feel any ridges on the way down. However, if I take a piece of cold filament I can only push it in about 15 mm before it stops, so I assume this is because the shaft is sort of funnel-shaped, and when the filament reaches this point it should be hot enough to deform into the funnel. But that’s not happening.
I ordered the extruder mechanism on Aliexpress, but the hotend itself was directly from Bambulab. Moreover, it has worked with the older extruder mechanism, so it was at least good then. Ironically I used it to print the gear extraction tool. As for “lining up” it appears to be dumping the filament into the right hole, but it just gets no farther than when I push the filament in by hand (about 15 to 20 mm).
I’m pretty sure the upper part of the hotend is not getting hot for some reason. I think the temperature reading is for the lower part, but the filament never gets that far. Pulling out the piece that was stuck in the hotend the southern end of the stick doesn’t look deformed at all… like it hasn’t been heated up.
Again, besides the gear assembly the only other thing I’ve changed is the toolhead cable, which I bought directly from Bambulab. My next action will be to pull the back off and make sure the toolhead cable is plugged in properly. If it is, I don’t know what’s wrong.
Can you post a picture of the hotend showing the heater and thermistor in place? If the heater is flat against the nozzle and the printer is showing the nozzle is the temp you set it at I don’t think it’s possible for just the tip to be hot. The heat should radiate through such a small surface pretty fast. What temp are you setting it to?
