January 31, 2026, around midnight, one of the AMS slots on my H2C starts to act weird and has constant issues with the pull-back filament. Before that, I heard a strange sound from it.
So, I go check everything and do some tests to find out the problem. Turns out Slot 1 has a defective gear, which causes the filament spools to be unable to roll back. After swapping it to the slot 4, my prints can finally continue.
But I did find more issues on this AMS:
1 The internal PTFE Tube of slot 1 is almost broken
2 The out PTFE tube is almost broken near the back of the AMS
3 The feeder unit of the slot one is defective
I do use this printer for multi-color printing and multi-material printing a lot, but the above issues seem to be unusual for a 3-month-old printer.
Then the case leads me to new thoughts:
1 I replace the AMS related PTFE tube every 3 months (1 month on Bambu wiki)
2 The PTFE tubes never break in this way on my other 5 A series 3D printers, even though they print in multi-color most of the time.
3 Broken PTFE tubes cause filament loading issues and may damage the AMS mainboard, and of course your prints
4 The AMS 2 Pro and AMS HT are much more difficult to fix and maintain because of the heating function.
5 The gear may become easier to break after heating during printing feature is enabled on H2D and more models in the future. (Bambu Lab technical teams say no, but we still need to exam it.)
Before this case, I thought the poop chute was the biggest design flaw that slow Bambu Lab down on multi-color printing and multi-material printing, but now I must re-examine my ideas about this.
So, I have 21 colors on H2C, 2 colors on H2D, all the rest are Bambu Lab printers that are combo versions, and I use the Snapmaker U1 a lot. Plusing I open the AMS for regular maintenance, I’m very familiar with the AMS series.
Now I’m pretty sure that the AMS may hold Bambu Lab back now.
1 Cost
Bambu Lab released 250g combo (12 colors) for its PLA Basic in China due to many customers asking for. It means the community has realized that lowering the cost of multi-color printing is important while printers like Bambu Lab H2C and Snapmaker U1 has now been daily used. But clearly, filament is not the highest cost among the whole stories. The AMS and AMS-related products are the bigger part.
([V1] AMS Stacking System By Jaxel)
1.1 The AMS units are expensive themselves. We can get a whole brand new Snapmaker U1 for the cost of 2 AMS 2 Pro.
1.2 To use the drying feature during printing, extra power adapters are required, 32.99USD/pc.
1.3 The AMS Stack system is required to settle down the AMS Units, and it is expensive.
1.4 Requires more room when colors been added and the effecting reduces
1.5 Requires a better power supply System
1.6 Requires maintenance more often than single AMS or no AMS.
1.7 Requires extra PEFE Tubes and Bambu 4-in-1 PTFE Adapter(4.99USD/pc) to add AMSs
2 Efficiency
After the release of Snapmaker U1, the multi-head 3D printer has become affordable and accelerate the multi-color printing and multi-material printing significantly, making filament now become instant. Then we realized that the same thing takes 10 seconds on H2C is a little bit slow.
The AMS slow down the speed in two ways: process and structure.
Process: The former material must be retraced to its own area before the new material loads, the process takes time, and the time accumulates. And this process becomes slower when new AMSs are added, because that means longer PEFE tubes and more distance to pass. The process is already very long without the next flushing and extruding steps.
Structure: The 4-in-1 structure adds up the distance that the filaments pass. Compared to AMS Lite, Snapmaker U1, and Anycubic Kobra X, the filament must be retracted all the way to its own area inside the AMS, and then the only pass can be free for a new filament to load. It also happens Among AMSs, because there is only one PTFE tube to the extruder. It is also the reason that PTFE tubes break so easily in AMS.
3 Soft Materials
According to Bambu Wiki, the AMS feeding system contains one part called “Buffer”, it helps to deliver the filament. If you go check it, you will find spring, which makes it become the first thing that is not friendly to soft materials.
If you have printed TPU on H2D or H2C, you will find that the TPU port is bypassing the buffer.
After that, you will realize that the AMS also becomes paralyzed to load soft materials. If you have seen what is inside them you might know why: tubes, sensors, gears, it is just too complicated to load soft materials.
So, no general TPU can go trough AMS units. It has too much resistance to load TPU through the “TPU port” on AMS HT.
Some people may have questions about the TPU for AMS, well, it is not very soft.
TPU 85a also jams in filament feeders on Snapmaker U1. I have tried it. So, if you have seen sharp gears inside a system, you should know it is not friendly for soft materials.
In a ward, the AMS holds Bambu Lab down on soft material printing. But that’s very important for shoe printing, Bambu Lab must fix this to take full use of the new system.
After all, as a heavy user of AMS, I hope Bambu Lab can figure out the TPU printing with AMS soon.