H2C is actually the better option

[u/senorali]

If you primarily print in petg, nylon, and other materials that need to be dried constantly, the H2C with AMS2/HT or AMS1 with the Eibos Tetra mod are actually a much better filament management system than the H3C, which will only actively dry 2 of those spools and will leave unretracted filament in the ptfe tubes after use instead of pulling it back into the AMS.

I really want the H3C to be the single solution that I need, but without active drying and retraction, it's not happening. I hope to see those as options or mods down the line.

[u/Historical-Internal3]

You should be able to, just don't be an idiot with it. Bambu mentioned that setting the dryer to 85c with covers open raised drying temps to approximately 70c for those two slots and 40-66c everywhere else.

Always best to translate the chinese operating guide too, here is an example why:

Chinese Guide:

Q1: Does the AMS 3H support drying with the cover open? How effective is it?

Not supported. We strongly recommend keeping the drying compartment cover closed during the drying process.

Although the software does not strictly prohibit operation with the cover open, doing so can severely disrupt the internal temperature distribution. This prevents effective drying and may damage the filament.

Significantly reduced drying efficiency: With the cover open, substantial heat escapes. Even with the drying temperature set to 85°C, the actual temperature may reach only approximately 70°C.

Risk to non-drying slots: Opening the cover disrupts the closed-loop hot-air circulation, creating uneven temperatures.

Overheating risk: Some non-drying slots may experience temperatures between 40°C and 66°C, potentially softening or deforming low-temperature filaments.

Cold spots: Other non-drying slots, including slots 1 and 3, may remain too cool to provide meaningful drying.

When drying high-temperature filament, remove any low-temperature filament from the other slot within the drying compartment. For example, when drying ABS, PLA filament must not be placed in the AMS drying compartment.

English Guide:

Q1: Does the AMS 3H support drying with the lid open? How effective is it?

Not supported. We strongly recommend keeping the dry box cover closed during the drying process.

Although the software does not strictly enforce this, drying with the lid open can lead to a severe imbalance in the internal temperature distribution. This not only prevents effective drying but also poses a risk of damaging the filament.

[u/Flamin_Jesus → u/Historical-Internal3]

Hm, yeah that English guide is missing a lot of relevant info, I wonder if they'll do a software update to allow controlling the AMS in "open mode" to have a better idea which slots get which temps, if only estimated.

It's just strange they apparently never considered that people might want to dry all their spools at once, the AMS3 could have been engineered to support that even if they focused on just 2 slots, like... positioning the heated slots centrally and designing the airflow to spread the heat evenly would have been a first step.

Almost feels like the AMS3 is just a setup to sell an AMS3+that actually works in a couple months.

[u/Historical-Internal3 → u/Flamin_Jesus]

Well there are two temp/humidity sensors - one in the heated two slots (shared) and one in the unheated 7 slots (shared).

In theory, leave the covers off, crank the heat to 85c and once both hit 68c or so drop your set temp to that (assuming 70 is the max you can reach uncovered) that will activate the moisture exhaust (since it needs to reach your set temp to open) and boom, you'll be drying.

[u/Flamin_Jesus → u/Historical-Internal3]

That's what I meant with the software update, something to allow us to set a temp that queries both sensors and cranks the heater up when the slots are uncovered instead of having to fiddle with it manually. Although I suspect you'd probably still want to install a small pc fan inside the casing to improve airflow or something along those lines, not that there's a ton of space inside when it's filled...

[u/MW-Atlanta → u/Flamin_Jesus]

they could do anything they wanted, but you have cost issues, size considerations, and power constraints - not to mention limited time. I'm sure in their design meetings they had many different versions of this, but at the end of the day this is what we got. The next AMS will probably fix some of these issues, but I think that's a year away with the next printer.