Filament stuck at several points

Bambu Lab P Series Troubleshooting
1

Hey guys!

I am having a rather troublesome issue for quite a while now. Totally random, sometimes my filament gets stuck either right before the toolhead or somewhere in the middle. The feeder keeps on working but nothing is being fed any further. Once I’m in a print with several filament changes, this can get quite annoying, because the print requires me to manually push the filament a little bit into the feeder for it to continue to feed. I have a video of it via this link.

While having a multicolor print, most colors work, but there is most often one that stops before the toolhead.

I noticed something though: When I cut off a larger piece of the filament, then the next filament swaps for this filament work well, but then the problem starts again after a couple of swaps. Also, the filament gets stuck at the same place of the role (not the tube), as if the filament gets damaged at one time and the damage stays at the same place. Almost like the wheels that grab onto the filament at the start of the toolhead damage it somehow (it makes a certain sound while starting to feed (only occationally) and then I know that from now on I have to help it push) and that damage stays although I can’t see it even after thorough inspection of the filament.

I have tried most of the stuff.

  • Changed the filament cutter
  • Changed the filament (some work better than others)
  • Changed the position of the filament from e.g. A1 to B3 (sometimes this does the trick, sometimes not, but not possible while in a print. I have two AMS)
  • Lubed everything that needs lubing
  • Checked all tubes and changed some
  • Dried filament (didn’t make any difference)
  • Cleaned the cogs/wheels that grab the filament in the toolhead
  • Changed to nozzle

Let me know your thoughts on this. I can’t find the error, wherever I look… Watch the video, it helps understanding.

And thank you all for your help. I hope that someone here can find a solution to this problem.

2

one, what video? there is not one. 2, you may want to change out your pfte tube.

3

Press on the word “link” in my text. That will lead you to a download page to download the video. (I can’t upload the video straight away here).
I have tried changing the PTFE tubes, but still the same problem.

4

Did you replace ALL the PTFE tubing? Do you have large radius loops of the tubing. That gets to be important if you have multiple AMS devices. with tight curves the filament is going to rub the tubing with more pressure than if the loops are big.
I keep a spare package of the tubing. Not the pre-cut option but the one that is one long coil of tubing.
You refer to feeder. Are you talking about the primary feeder in an AMS?

5

Well, it has been a while since I changed the PTFC tube that goes all the way down to the toolhead, but I can’t see any damage to it. I changed it maybe 6 months ago.
I will provide some pictures of the tubing.

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6

ohhhhhhhhhhhhhh okay i will take a look. also, what filament is this that you are using?

7

so with that video, I would say one print a cardboard spool adapter, 2, I would see if your feeder funnel(the part where the filament goes in) looks damaged, because over time, they will wear down, as they are only plastic

8

The filaments I use in the picture are Sunlu Mint green and Elegoo Green (can’t remember the exact name of the green right now).

9

Spool adapter doesn’t make any difference at all, unfortunately. Also, I once installed an adapter onto the feeder tunnel without success.

10

The issue is in every pic you post.
Cardboard works, just needs help. That’s why tapping moves it along for a bit. Big tip if the spool is working without an adaptor would be if it’s rewinding and you see big loops and the spool isn’t moving.

Just print adaptors for the spools you’re using.

A mention about PTFE tubes. I don’t know what you meant by not seeing wear. If you’re looking at the outside it would be awhile before the wear actually is visible for you to see. If you look at each end and the hole looks larger than a new tube, it’s time to replace. Depending on filament that could be 1 month or 6 months.

I don’t know what this means. A spool adaptor goes around the spools edges and often needs to be designed for the spool in use. Sunlu had a run of spools that were too small, and Elegoo uses cardboard that is a little slick on the edges, and can be bent.
None of those adaptors go into the feeder.

11

Thanks for your effort in explaining, @R3d-Five. What I mean with a feeder adapter is this: AMS Feeder Funnel Saver Protector Filament Guide by eds_3d_shop MakerWorld: Download Free 3D Models . Apparantly, it is called a feeder funnel and not an adapter.
Now, the grey filament in the video is Polyterra (again cardboard) but I use a spool adapter to it. This is the one I use: https://makerworld.com/en/models/17376-polymaker-polyterra-bambu-lab-ams-cardboard-spool?from=search#profileId-16171
I am still not convinced that the spools are the issue due to one reason:
Occationally, when the spool gets all the way through the tubes and ends up in the toolhead, the machine makes a strange sound and it won’t continue to feed without a manual slite nudge (too much will rewind the spool). Once I get nudge it with just the right amount of force, the filament gets caught and proceeds. After it is time again for that exact filament in a multicolor print, on the exact same place where I forced it to move, it doesn’t want to feed it further. Depending on how much filament was used in the previous round, it stops earlier than before, but at the spools exact point (it doesn’t go as far as before because parts of the spool have been used in the printer). Once the printer gets the filament down to where that place of the spool is, the spools works again (sometimes I cut off a larger part of the spool to prevant that part from not feeding the filament further). Sadly, this happens from time to time and I get the exact same problem again. When it happens is random, some filament is more prone than other.
It is so hard to explain in text and easier to show in a video, let me know if there is a part you don’t understand.

12

All good and that is one of the spool adaptors.

As for the rest I’m still thinking it’s the spool OR maybe a crossover you haven’t caught. They can be tricky.

The weight of the spool as well as the circumference is what helps the spool. I’m sure you know that. I’m not trying to talk down here, so bear with me.

In my experience this has happened when the spool slips (it will make a noise) or a crossover (tangle if you will) prohibits the feeding. Usually not a noise there as the AMS will just retract.

I get what you’re saying about random. I’ll give you a few things to try or investigate, as well as maybe another cause.

Notice the spool next time. Does it have straight edges or are they warped? Do they make contact with all the internal rollers (front back) and do they spin freely? Is there any debris inside the AMS (desiccant spilling out is a great cause of irritation) that’s impeding the rotation? That can be intermittent as well. Is it one slot (I think you cleared that one but just incase).

When you have time take the AMS apart. Inspect the 4 tubes that lead from the feeder to the hub. Look at the inner diameter and see if there’s wear. Look at the motor on the hub. There is a plastic part that crosses and holds the motor shaft stable. Is that cracked? If so there are a few on MW that you can print and replace it with. Hold onto the screws.

Since you use cardboard spools inspect the feeders and their gears. Has debris gotten into them. If so you can remove them and blow them out with compressed air, or disassemble the feeder tube from the body and clean that way. Be careful as there is a wire or ribbon cable (can’t remember which) connecting the feeder to the motor in the housing.

I forgot to mention, before you do any taking apart, listen to the hub and feeder motors carefully. Any grinding or strange sounds could mean they are the culprit and need to be replaced. Not often the feeders themselves but I have heard of the motor wearing and causing issues.

From there carefully inspect the PTFE tubes from the AMS to the buffer or hub. If using a 4way splitter be sure the tubes are seated and the ends are cut straight with a cutter, not scissors. Also look for bends that are binding filament as well. Don’t think that’s it but good practice.

That’s my advice. I may be and could be wrong but what you describe sounds like simple interference or spool issues. Aside from what I’ve suggested I don’t see the AMS itself as the issue.

Also for the feeding issue try this.

There are a few on the site that work. I’ve tried a lot of them. This one printed in PTEG or ABS has been the one that works best for me.

Sorry for the wall of text.

13

okay, i really dont know then sorry

14

I will make some adjustments, add adapters and get back to you with the results :slight_smile: Thanks thus far. And I really don’t mind the wall of text. It is rather helpful than having to guess what someone wants to say by just some sentences. A pedagogical approach is always welcome. (I am a teacher, hence I’m all for that!) :disguised_face:

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15

question, how long did you dry the filament for, and how old is the filament?

16

About 3 months and I dried it for 8 hours

17

okay i really dont know then sorry

18

I’ll piggyback off of what @R3d-Five has said about spools and is a good project.
These printers and AMS units are pretty well engineered and while they do have some issues, it is worth being aware of what BL says and factor it into ones thinking. BL discourages the use of cardboard spools. They didn’t yank that out of thin air. It is based on lots of hours runtime in AMS devices. But there are perfectly valid reasons for buying spools from different manufacturers, many of which come on various types of paperboard. Me included.
The trouble with paperbord, cardboard, fiberboard is that it is a moisture magnet and it bends. I tried the printed spool adapters and was dissatisfied with them.
What I did was found a filament winder/rewinder on Printables put a motor on it and rewind paper spooled filament onto BL spools.

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19

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I’ve finally managed to pinpoint where the problem with the filament occurs, but not what actually causes it. Right at the point where the AMS grabs the filament, the filament gets damaged. See the picture. I can see the usual bite marks from the feeder when it pulls the filament down, but at the very tip, after it has gone all the way through, the filament gets damaged.

This damage is severe enough that the filament jams and the AMS can’t feed it any further. The softer the filament is, the more frequently the problem happens. With PolyTerra it occurs more often compared to, for example, Sunlu. When it happens, I hear a sort of “hard retraction sound,” but it doesn’t occur every time.

Why is the filament getting chewed up like this?

20

When you load a roll and stick the filament in the funnel you say it hangs at that location and won’t go any further?
It could be getting hung up in the PTFE that is below the bottom. If you have never had to disassemble your AMS, there is a lot going on under the bottom of the AMS. Lots of opportunity for trouble.