AMS Humidity not decreasing

Got my X1C on Monday and was done setting it up around 6pm. We’re closing in close to 48 hours and the AMS humidity is still too high per the display. I checked the rubber gasket and it seems fine, I have 7 packets of desiccant in there (calcium chloride) and none of them are yellow or caked. I also have 4 silica gel packets in there. Starting to think I might have a bad sensor?

Unless you you dried the filament, it can take a couple of days to sort itself out.

Keep in mind that the AMS is NOT heated.

If your ambient humidity is say 50% where the printer is located, the AMS isn’t magically going to be 10% just from the little bit of desiccant in the AMS.

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Thanks for the response!

I’m drying the filament as we speak with a food dehydrator overnight. The AMS has been empty for a while though so I’m thinking I can rule out wet filament

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Hi Paul, thanks for that perspective. The hygrometer I have reads my indoor ambient humidity at 34% (read for 30 minutes and peaked at 34%). Inside the AMS it drops to 20% (possibly the lowest range readable, inside unit for 45 minutes and stabilized at 20%). I live in a high altitude desert so it’s pretty dry here

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My AMS readings will generally fluctuate between around 13% on the low end to about 20% or so.

Does your AMS still show green as the humidity status when it gets up to 25%-ish?

Both of my AMS units have additional desiccant capacity added, and the cheap Amazon sourced hygrometers at least agree with each other.

Room is 36%. Both AMS units read 10%.


very strange mine is just sitting at 19% inside the AMS and hasn’t lowered to green status

This is the corresponding AMS humidity reading in BBS

I wonder what the threshold is for green versus red versus orange

I have similar issues. AMS is loaded with dryied spools of filament, I added many packs of desicant. Humidity in the room is around 50%. Humidity inside AMS does not drop below 35%.

The indication is from a cheap hygrometer. The sensor indication on the display sucks. There should be a bigger indication with actual values so you have at least the possibility to understand a bit better what is going on.

Any suggestions on how to reduce the humidity inside the AMS?

Supposedly older firmware for the AMS/Bambu Studio did have a way to retrieve an actual humidity value - but not any more.

For keeping the AMS dry, I found several prints for containers that fit inside spare space in the AMS and hold silica gel beads. I also found a print for spool center weights that also hold silica gel. They’re both from printable if I recall. Make sure to get the orange silica beads from Amazon as it’s safer than the cobalt blue

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Still possible via MQTT.

Still possible via MQTT.

How can you retrieve the value via MQTT?

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I think, the main problem is, that the typical desiccants like silica take up less water the lower the air humidity, so it is impossible to achieve close to 0% even if you fill the complete AMS up with desiccant.

If you want to further reduce humidity, you have to switch to molecular sieves, also known as Zeolithe. They are able to bring humidity down to 0%. They are a bit more expensive, need 300°C for regenerating and are more difficult to source, but I made a far better experience with them.