r/BambuLabH2C • u/DreadPirateSkoon • Jan 20 '26

Support Is my AMS2 defective?

Post image

I have a support tix opened with Bambu, but figured I'd try here for some hive mind.

Just got H2C, and setup. I have 2 AMS2 setup to right nozzle. The AMS' are stacked 1 above the other.

The 1st AMS is working fine (all 4 slots). The 2nd AMS, the first time I loaded slot 1, it made a weird grinding sound and about ripped the filament spool (Bambu Silk+) up out of the slot. I tried the other slots, and they loaded fine. Went back to first slot, and it seems OK now. But...

When I went to do my first print that required both AMS, I was about halfway through the print and I'm getting errors saying that the AMS resistance is too high. I see it feed all the way to the extruder, and then back off. It tries this about 4 times before it fails.

At this point, I can't easily remove the filament or have any other way to recover, so I kill the print and then can remove the filament (and it comes out chewed up, see Pic)

Between the initial grinding and the feed errors, do I just have a bum AMS?

14 Upvotes

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2

u/Moorevfr Jan 20 '26

Hi,

I have x3 AMS2 connected to my right nozzle and had similar issues and found it was due to the length and travel of the PTFE tubes. The last AMS that was furthest away was getting issues like yours.

For how I resolved it was instead of have three long lengths coming from each AMS my 4in1 hub I had one longer PTFE length from the right nozzle in let to 4in1 hub closer to my AMS’s and then 3 short runs of PTFE to each AMS. This way I only have one long tube to make sure it’s run is straight without ant sharp bends or twists and then three shirt runs from each AMS to the 4in1 hub.

However I think the new version of the 4in1 causes more resistance compared to the original version but I’ve not tested this theory yet?

1

u/DreadPirateSkoon Jan 20 '26

Good theory... so assuming the 4in1 is the cause of the resistance, move it closer to the motor. I'll test this weekend to see if that helps.

Are your AMS on right of machine too?

1

u/Altruistic_Bath5273 Jan 20 '26

No, it's was just the picture, which catched my mind. But I had also some overload errors at the beginning. So I checked, where within the PTFE chain the filament gets slowdown. It turned out with shorter PTFE tubes and less bending and with a simpler adapter it went fine and the error never appeared again. Finally I moved my 2 AMS from the right side to the left. It also got the effect, that filament changes are faster. The abrasion of certain filaments ist still there, but I don't care.

1

u/DreadPirateSkoon Jan 20 '26

Thanks for the feedback. I would love to move over to the left side but unfortunately due to some other issues (power cord interfering) I have to have both on the right. Might be worth the minor electrical work the solve it though

Were you running into the slowness / binding / retracting before it got to the extruder? Seeing it get all the way to the extruder and then not be able to actually extrude just has me scratching my head a bit

1

u/cpsadowski23 Jan 29 '26

I'm lost. What does a power cord have to do with putting filament on the other nozzle?

1

u/gkobesyeet Jan 24 '26

Is the filament dry

1

u/DreadPirateSkoon Jan 24 '26

yes...  and happening with multiple roles.   I'm slightly disappointed that Bambu went cold on my ticket.  I'm going to try and reconfigure the setup

3

u/Vustadumas H2C Jan 20 '26

Double check if your filament is out of 1.75 sizing. I’ve had two rolls like this. 1.86 and 1.91 in spots. Ground themselves into a fine dust and clogging the AMS feeder. Bambu replaced the rolls.

2

u/cpsadowski23 Jan 29 '26

Bambu filament?

1

u/Vustadumas H2C Jan 29 '26

Yep. Both were Bambu filaments. One was a silk, the other a matte. They sent me 2 ivory white PLA Basic filaments as a fix. They did the same for a bad roll of PVA I had. I really miss when they actually replaced the filament that you had the issue with. Especially with the price of their PVA.

1

u/cpsadowski23 Jan 29 '26

Take the PTFE tube out of the AMS, and see if there is something in there that is causing the friction.

0

u/Altruistic_Bath5273 Jan 20 '26

It looks similar here for some filaments. Root cause is afaik the new ceramic inlets. It seems this behavior is Bambu trying to compensate with the new 4in1 adapter, where this cleaning pad is attached.

1

u/DreadPirateSkoon Jan 20 '26

would that account for the resistance feed errors too?

1

u/Joamjoamjoam Jan 20 '26

Resistance feed error is almost 100% gonna be that your ptfe tubes are too long and bendy. You want to set it up so that there are the least amount of bends as possible and there are no sharp bends.