Bambu X1 Carbon & AMS - Extruder cannot grab filament

Bambu Lab X1 Series Bambu Lab X1C
1

I love my BX1C, it’s been working hard over the past couple of weeks/months. Today, I had my first show stopping issue, which I have began troubleshooting, but am struggling.

Printing using PLA from the AMS. I load the spool, and the AMS pushes the filament right though to the extruder. It then retracts all the way back to the AMS, and tries again. This cycle is repeated 3 or 4 times, after which it throws an error on Orca/Bambu Studio “Extruding filament failed. The extruder might be clogged”. I try to manually pull the filament from AMS side but it is gripped, I cannot pull it. I press the retry button on the printer screen and the cycle repeats, the only way I can break the cycle is to turn it off at the main switch whilst the AMS is retracting, then I can manually remove the filament.

So that is the problem.

I moved the roll to another AMS slot. The problem persists.

I tried multiple combinations of various filaments (PLA/PETG and rolls) and AMS slots, the problem persists.

I removed the hot end, and the extruder, dismantled and cleaned as per the Bambu guidance. There were no clogs, broken pieces of filament or anything else causing a blockage. There was a clear line of sight from the extruder in to the nozzle out. I cleaned and brushed all the components, everything felt free. I reassembled, and tried to load the filament. The above problem persisted.

I loaded an offending spool onto the external spool holder. I “loaded” and gently pushed the filament as per the screen prompt. The filament loaded and purged through the hot end.

I examined all the PTFE routes. The only thing that I found (and I was looking very critically), was the OD of the inlet tube into the extruder was slightly chewed up (nothing I considered abnormal). I snipped 5mm off the end with my tube cutter and reassembled. The problem persists.

So my conclusions. The problem is at extruder level. It is as if the filament approaches the inlet of the extruder, where the tensioner gears and pully grips, but there is not enough force from the AMS to overcome the tension. I have never fiddled with the spring tensioner tension.

I have trawled the community, and have seen this issue occasionally crop up, but people seem to be able to cure it by cleaning components and tidying up PTFE routes, both of which I have already tried.

Does anyone have any suggestions / experience?

Are the extruders considered consumables? As I say, it’s been working hard the past few months.

Apologies for the essay, I just like to troubleshoot as much as possible before I ask for help!!!

Look forward to hearing from you.

Gray

2

I understand that you are facing a filament feeding issue, but can you clarify where the filament stops and retracts?
Can you confirm that it is at the extruder inlet?

Why do you conclude that it is at the extruder level? Didn’t it work without the AMS?
Do you have extra PTFE tubes?
What do you mean by working hard? PA?

1 Like
3

Check your buffer and spring
https://wiki.bambulab.com/en/x1/troubleshooting/hmscode/0700_4000_0002_0004

4

Hi, thanks for your reply.

Apologies for not being clearer.

The filament is pushed from the roll in the AMS, all the way to the extruder, but doesn’t actually enter the extruder. I think the printer recognises it hasn’t gone in, so the AMS pulls the filament back, and respools it back onto the roll, then it tries again.

I say it’s at extruder level because when I use the external spool, I can manually help the filament by gently pushing it. It’s strange because for the past few weeks, we have been printing flawlessly.

I don’t have any extra PTFE tubing.

By working hard I mean its been printing 24 hours a day for the past few weeks.

Thanks again for your reply.

1 Like
5

Many thanks for the link. I’ve checked the spring and it slide freely, it looks like the “normal” position. I’ll keep my eye on it when I “load” a filament.

The link did mention spool tangling. I’ll get a length of filament that isn’t on a spool, and see if it feeds.

Thanks again for the reply.

1 Like
6

Hi,

Ok. The X1C extruder and nozzle will not be affected by printing PLA, even in a 24/7 schedule.
Please try and confirm:

  1. Remove the X1C top glass and disconnect the PTFE tube.
    Heat the extruder to the printing temperature and manually feed the filament into the extruder.
    Use the display controls to extrude and retract, and observe if it is moving freely → If so, the extruder and nozzle are likely working correctly; try the second step. Otherwise, let me know so I can share the procedure to verify and fix the issue.

  2. If the extruder+nozzle set is correct, check the PTFE tube connecting to the extruder.
    Take a careful look (using proper light) for any sign of wear and bends that may affect the filament path. If faulty, acquire a set of PTFE tubes from BL, or if you go with 3rd party ones, ensure that has the correct diameter. While waiting for the order delivery, you may also verify the next step.

  3. If the PTFE tube is in good condition, verify the PTFE path, starting with the tube curvature on the extruder inlet. The PTFE tube curvature at the extruder inlet can cause the exact problem you are dealing with. For testing, keep the top window open and use the AMS. Select an AMS filament and press the option Load Filament. The printer will heat up and feed the filament afterwards. If it fails to load, it will retract and feed again; at that time, using your hand (better with gloves) and with care, try adjusting the PTFE tube inlet curvature. You may need to repeat the process a few times. Observe (or record) the loading behaviour.

  4. If the manual adjustment fixes the filament load, you have a few options. Many users rely on a PTFE printed adaptor (check MakerLab or other repository) that ensures an “optimum” path for loading filament. In my experience, it helps, but it is not ideal. Another solution (it works for me) is to adjust the length of the PTFE tube inside the printer. For this purpose, you have a PTFE tube fitting inside the rear printer. Note that the max tube length relates when the extruder is at the right front corner.

If the issue persists, please share your findings.

3 Likes
7

Hello sir, many thanks for your prompt reply.

I continued my trouble shooting this morning. There seems to be a random nature of the failures. I tried many filaments in various slots, and there was no pattern in terms of failure. As part of my trouble shooting yesterday, I had already done your “Step 1”, and I found everything ran freely.

There is a sensor in the top of the extruder, that switches when it sees filament. I could trigger this sensor and it showed that filament was present, as per the green spot on the extruder diagram on the printer screen and orca. So I was pretty sure I didn’t have a faulty sensor.

I started taking an interest in the buffer sensor and spring. Although the spring was seated correctly, and the buffer was actuating as described, the PTFE tube between the buffer and printer, was slightly angled as it came out of the AMS hub, and when I say slight, I MEAN slight.

Anyway, I straightened it’s path, and repeated the filament load procedure. I couldn’t get it to fail. It loaded every time. I am going to monitor it, and keep trying to see if the path has fixed the problem. I shall report back.

If this does appear to have been the problem, I will be surprised it is as sensitive to this as it appears. It’s not like the PTFE tube was kinked or has a mega tight radius. I’m also surprised I haven’t seen this before. The set up has not changed, so I must have been on the limit. My google searching has show numerous gizmos designed to straighten this path, so maybe it is an issue.

So, back to your reply, assuming we have bottomed this out, it is down to PTFE path. I’ll keep my eye out and report back.

Thanks for your support on this, much appreciated.

Gray

1 Like
8

The buffer can be sensitive if the slide doesn’t get the full travel. In normal operation it needs to push all the way for the extruder to take the filament. Feeding from the external spool takes this out of the equation, which made me suggest this. Anyhow, glad you found the problem :slight_smile:

9

I’m not counting my chickens yet!!!

Thanks for pointing me at the buffer arrangement.

Fingers crossed!!!

It has given me good training in dismantling extruders and hot ends!!!

10

I liked @JayZay 's systematic troubleshooting suggestions :+1:

It seems you have it solved, but I was about to ask if you have tried swapping out an entire hotend assembly?

image

As you say, there are loads of “cable tidy” models, but this printed perfectly with standard PLA settings and is working for me: Cable Tidy - X1- P1S - P1P by KobaRiley - MakerWorld

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image1000×1124 71 KB

1 Like
11

Sit rep…

It appears the issue was the PTFE tube routing immediately out of the AMS hub. A slight “off-straight” was enough to either make it slightly more awkward to push the filament through, or more likely in my eyes, interfere with the operation of the buffer arrangement.

I printed one of the suggested guides to ensure straight entry and exit of the PTFE though the hub and everything seems to work fine. I cannot replicate the issue.

Many thanks for all your help and ideas, it really is much appreciated. It’s great to have a supportive community like this, rather than some of the toxicity we see on other platforms. Hopefully I can help other users if they face the same issue. I guess it’s often the case where the solution is relatively simple and worth pursuing before you start spending money of replacement parts.

I’ll mark this issue as solved.

THanks again everyone, back up and running!!!

Gray

3 Likes
12

I have the same issue it seems, but I can’t figure out what you did to make it work again:/

And I keep seeing at the back that my buffer spring keeps being pushed and gets small once the filament gets to the extruder, and then the filament goes back and tries again. If anyone can help, it would be greatly appreciated!