H2C filament not loading from ams + slow extrusion?

Bambu Lab H2 Series Bambu Lab H2C
1

Hey guys, I’ve got an issue with my H2C that I’m hoping you can help with.

I’ve got a fairly new H2C and it’s already giving me issues. For some reason, after a couple of weeks of prints, it now won’t load the filament from ams for location 1. I’ve tested the others with and they have no issues.

I’ve contacted Bambu and I’m trying to work with them but it’s going slow.

things I’ve done is:

  1. Opened up extruded to check for clogs (clean)
  2. Swapped the filament loader motor in the am btwn spot 1 and 4, same issue.
  3. Tired multiple different filament, same issue.
  4. Connected another ams 2 pro, it would load some spots ok, but failed in spot 3.
  5. Cold pulled both left and right bozzles, same issue

Also, I feel that it’s extruding very slowly/weak because whenever I’m trying to load/unload rolls, it takes over 4+ minutes to do so. The purging of the filament takes 2+ minutes each time and it does it twice. It also tends to get backed up and at the end glob up around the tip of the nozzle vs making clean swirls. Possibly because it’s extruding too slowly and building up?

any idea is what else I can check? I just really need this working soon for a project and it’s killing me waiting for the Bambu responses.

2
  1. Disconnect your PTFE at the AMS and where it enters the toolhead
  2. Feed a loose piece of filament (preferably PETG) into the AMS end and see how easily it pushes through the whole path. If you encounter any significant resistance, there’s your problem.

I also recommend everyone with feed issues print out the AMS PTFE “helpers” that go at the back of the AMS units to help make a more gentle transition, those can make a big difference in some cases.

3

Thanks! will try it out now… great tip and makes a lot of sense as a easy way to find if tehre is a blockage. I’m more worried that there is something off with the extruder but it’s great to have more crossed off the list.

Well, I guess it’s something else other than the feed path. Ran some PETG from one end to the other on the right path, no uptick in the drag, all consistent throughout. I should also mention that the left nozzle feels like it’s extruding slowly so I’m thinking it’s more and more something with the extruder now.

4

Just out of curiosity, are you using the 4 to 1 adapter that comes with the H2C? There is a small rubber piece near the exit that causes loading issues. If I can find it there’s a video on YouTube but he basically uses a small Alan wrench to remove it.

5

I am and I’ve tried it without before and it still didn’t work. But I’ll test again.

also, tried doing a print with 4 colors, 1 in the ht, 3 in the ams avoiding spot 1 and it failed to load anyway.

I’m going to take apart the extrudeR again and see if I missed something the first time.

6

Ok, to validate that take the lid off the printer, disconnect the PTFE from the extruder and feed some loose filament directly into the extruder and try to print something.

7

Thanks!

So I’ve printed a benchy and it worked. Quality seems ok as well.

Whats super frustrating is that now spool 1 is working fine to load up but now spool 3 is having the same issue as spool 1 used to have and is not loading.

I’ve also tested with and without the 4 to 1 adapter, no change

I’ve tested with multiple nozzles, multiple cold pulls to clean them just in case, still have loading issues.

Any idea what could make it move from spool 1 to spool 3? Or other things to check? I’m not sure if it’s the extruder but I just have no idea what it could be a this point.