NOTE: The issue is not with my AMS units. I have 2 AMS units, and both of them work perfectly fine with my P1S.
The Issue: When loading filament from any AMS, filament pushes all the way to the extruder, pauses briefly, then retracts all the way back. The AMS retries multiple times before showing error: “Extruding filament failed. The extruder might be clogged. [07008007 131602]”[The extruder is ABSOLUTELY NOT clogged, as immediately before and after testing with the AMS, I can feed through the standalone PTFE and the extruder catches and extrudes the filament with zero issue. Since having this problem with AMS filament feeding, I have done multiple prints with my X1C through the rear PTFE port.]
What I Have Tried:
Bypassing AMS: Loading filament directly into the printer (bypassing the AMS) works perfectly. The filament loads into the nozzle, and printing starts as normal with perfect extrusion.
Replacing Filament Buffer: I installed a brand-new filament buffer (model SA003) from Bambu Lab, but this did not resolve the issue.
Replacing AMS Connector Board: I installed a brand-new AMS connector/interface board from Bambu Lab (the board which is inside the X1C and has the port for the filament buffer to connect to), but this did not resolve the issue.
Testing AMS Cable Ports: I tested both cable ports on both AMS units by connecting the filament buffer to each one individually. Neither resolved the issue.
Testing Different Cables: I replaced both cables connecting the AMS to the buffer and the buffer to the X1 Carbon with known working cables. This made no difference.
Testing Multiple AMS Slots: I tested each AMS slot of both AMS units. No luck.
Verified that both AMS work: Both of the AMS work perfectly fine with my P1S with perfect filament loading and perfect extrusion during prints.
Replaced Extruder Unit: I replaced the extruder unit with a brand-new one from Bambu Lab, but this did not fix the problem.
Replacing all PTFE Tubes: I replaced each and every PTFE tube, the ones on the back, the ones coming from the AMS, and the one running from the top of the extruder through the back of the machine. No luck.
Adjusted PTFE Tension: I made sure there was minimal tension in the PTFE tubes, especially in the PTFE tube running from the extruder top to the back of the machine. The arch of the tube looks perfectly fine with plenty of arch for smooth filament travel.
Firmware Updates: The printer and AMS units are running on up-to-date firmware.
Complete Factory Reset + Calibration + Device Self tests: I did the full factory reset, calibration, and self tests.
Adjusted Extruder Tension: I adjusted the extruder tension with the screw on the side of the extruder with no luck. I even modified the extruder housing to access the tension screw during operation and tested the entire range of tension settings from loosest to tightest during this back and forth filament loading attempt sequence with no luck.
Intriguing Information: At the point where the error appears on the screen, all mechanical movement in the printer / AMS stops, and at that point, filament is actually loaded all the way to the extruder. At this point, if I restart the printer and attempt a print from the AMS, the printer will continue but with severe under-extrusion. The calibration lines appear as dots and dashes rather than solid lines, and the print itself looks like absolute garbage with obvious under extrusion. Of note is that during the pre-print sequence, I can hear rhythmic clicking sounds coming from the extruder with visible movement in the PTFE tube above the extruder corresponding to each click (the clicking is not coming from the AMS). This clicking and under-extrusion ONLY occurs with filament from the AMS and never occurs when using the external spool holder.
Considering that I already replaced the AMS control board (inside the printer), the filament buffer, and the entire extruder unit, is there even anything else I can replace which would make a difference? What could the issue possibly be?
Try looking on your interface where is shows film being loaded and see if it shows the hotend as being loaded the filament runout switch could be faulty.
Is the angle similar on the P1S and the X1C where the ptfe goes in to the extruder? I’m just grasping at straws but if it gets to that point ok, and you’ve replaced most of the hardware before and after that point that might be it?
Thanks for the insight, but I’ve already tried everything to do with the PTFE tubes including replacing the one from the extruder to the back of the machine. I’ve adjusted all of the pathways to have nice smooth curves for easy filament travel.
Are you sure the ptfe is fully seated in the extruder? If it’s not fully seated it can expose the stop/ledge that the ptfe bottoms against and allow the filament to catch on it.
It’s worse because of the sharp bend in the ptfe tube as it enters the extruder forces the filament harder against the inside wall of the ptfe so if there’s a ledge it can catch on it.
When I add a new spool, I use wire cutters to cut the filament end into somewhat of a point which helps it navigate the tubing. If it catches and tries to hang, I’ve found if I reach in and manually straighten the tubing into the extruder, the filament goes right in.
If that helps you, maybe you aren’t getting clean cuts with the filament cutter?
I am sure that the PTFE is seated all the way inside the top of the extruder. I know this because I have checked and double checked, in addition to the filament always loading fine from the external spool holder.
I have also tried cutting the filament at an angle as you describe, but that did not work either.
I didn’t describe cutting the filament at an angle. I described cutting it to a point of sorts like a pencil. Cutting it at an angle won’t help if the filament happens to be rotated the wrong way but might help if rotated the right way. But it isn’t a guarantee.
Considering all you have done that is likely to address the problem, it is rather tricky to come up with further things to try.
By your description, the AMS fed filament tends to get to the start of the print head.
Make sure that this PTFE is cut perfectly straight, i.e. at 90°. Filament is very good at finding tiny gaps in the PTFE path. However, you would be able to feel that slight resistance when feeding from the rear spool.
If you do need to evercome a slight resistance as the filament enters the print head but the cut and fit into the coupler still guves extra resistance, it may be a less than perfect coupler.
The second item relates to just being a bit unlucky regarding AMS motor strength, PTFE friction and head resistance. In this case, it can help to make the straightest and shortest possible PTFE path. That also helps with filament change times.
My set-up is highly improvised and I am aware it’ll wear through the toolhead PTFE quicker than it needs to… but it has been good for 3174h so far while the top AMS has upwards of 4800h without the need for PTFE replacement.
My initial, more “traditional” set-up was only good for around 800h until the filament literally poked me in the eye.
It’s not haunted. I had this issue with ABS recently. I have quite an extended PTFE path. But, it got to the extruder fine, and the decided that it was blocked.
I blame it on heat between prints, but I also overcame the issue by pushing the filament in a little bit from the back of the printer. Doesn’t stop the issue entirely but, I didn’t have to replace anything. And it only occurred with abs.
Does it? My main suggestion is to push the filament in firmly, manually, to overcome the issue. Which is the printer thinks it is blocked when it isn’t.
The fact that you can get it to work when manually feeding filament with the external spool, is telling. The automatic feed from the AMS is not infallible, and can have all manner of obscure issues.
Another potential issue is filament quality. If there is significant changes in diameter of the filament, it can be too wide, or if it is too narrow it will be stripped by the extruder gears. If you don’t cut off the dodgy bits of filament that have been stripped, you’re left with under extrusion and build up of ■■■■ in the extruder.
I’m very sorry I can’t contribute and help you solve your problem, but Google recommended me this thread and I’d just like to say that your infographic is absolutely amazing and more people should demonstrate their issues like that.
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