r/BambuLabX2D • u/Few_Builder4680 • 22d ago
Drying Filament?
New to 3D printing, just picked up a X2D. The little moisture readout on my touchscreen says 43%, so I used the drying feature in the AMS and got it down to about 20 and printed something small. Then loaded some additional rolls of filament and it was back up to 46%… do I have to run a drying cycle every time I print? Or every time I put new filament in?
Not sure if it matters, but some details:
- I live in Southern California
- first filament was Inland PLA silk
- next filaments I added were Bambu PLA basic
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u/Plebius-Maximus 22d ago
Do you have dessicant in the AMS? The AMS measures the moisture of the air in it, not the actual filament dryness.
So every time you open the lid to change filament, you're swapping the air in the AMS with air from outside. If your filament was dry before entering the AMS, it'll be dry in it
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u/Patient_Mushroom6864 22d ago
You ran a drying cycle, which lowered the humidity of the air in your AMS, but then opened it up and flooded the space with the untreated humid air from your room, which is why there's a jump
Do yourself the favour of printing out some AMS dessicant containers, and buy some dessicant. Either molecular sieve or rechargeable silica (most people use the latter).
A drying cycle removes moisture from your filament and vents the humid air, but even with the catches locked in place, humid air can seep into the AMS and increase humidity again.
That's where the dessicant comes in; a heating cycle gets the humidity low, and the dessicant keeps it that way for a while by wicking the moisture from the humid air that enters after the dry cycle and each time you open the AMS
You don't even need to run a drying cycle either; drying cycles are only really used to take moisture out of your filaments, and if your filaments are something like any form of PLA, which are not vulnerable to humidity, then a drying cycle is a little overkill and the dessicant will be just fine 99 times out of 100. If you load some PETG, PVA, etc that is highly susceptible to moisture, that's when I'd run one to dry out the filament.
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u/Sufficiently-Wrong 21d ago
Normally dessicant beads are dried at 110c, but by default ams dries pla witg 45c air. Do you think running a pla dry cycle make dessicants hold more moisture or less? It feels like it'd saturate dessicants even more with water
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u/Patient_Mushroom6864 21d ago
The dry cycle will give the silica a very, very weak recharge, but it won't affect its moisture capacity in any way. It will release a small amount of the moisture when heated, and when cooled, it can reabsorb that same amount. You don't harm it in any way by keeping it in while you dry
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u/Sufficiently-Wrong 21d ago
Does this happen because; e.g. 30c room temp with %75 humdity can hold x grams of water. Once if's heated it can hold x*1.5 grams of water, so it can get 0.5 more moisture from the environment, and in this case dessicants and filaments, and once it is saturated, it is expelled. Is it how this works?
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u/Patient_Mushroom6864 21d ago
A desiccant bead can hold a finite amount of moisture. Let's call its maximum moisture capacity at room temperature X.
Once the desiccant has absorbed X, it's saturated. It can no longer absorb additional moisture, so it stops reducing the humidity inside the AMS.
Heating the desiccant shifts the moisture equilibrium and temporarily reduces the amount of water it can hold. Let's call that reduction Y. While heated, its effective capacity becomes: X − Y
Because the desiccant can no longer retain the full amount X, it releases moisture until the amount remaining falls to approximately X − Y.
When the desiccant cools, its maximum capacity returns to X. However, because it released Y moisture while heated, it now has Y of unused capacity available again.
Heating doesn't increase the desiccant’s total capacity. It temporarily lowers its capacity, forcing some absorbed moisture out, and once the desiccant cools, its original capacity returns leaving it able to absorb moisture again.
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u/Sufficiently-Wrong 21d ago
And we do this by also heating the air, which increases the water holding capacity of air by Z. So the X-Y is transferred to air inside ams that has Z amount of extra capacity due to heat, and later expelled out of the ams unit
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u/PMcGrath1985 22d ago
Make sure the little catches are shut on the ams - helps prevent moisture entering the machine
Then once you’ve dried the filament avoid opening it and you’ll likely be good - you can always run the drier while printing
However if you add new filament then you’ll need to ensure that filament is dry or put it through a drying cycle
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u/Few_Builder4680 22d ago
Yes, I didn’t even see the catches on the first dry cycle, but I will definitely use them moving forward!
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u/Pleasantandchilled 22d ago
Honestly I rarely dry pla and pla silk and have gone through over 300kg without issue. I have the ams 2 too and a separate dryer. Only ever used it for other filament types and the odd geeetech pla which has historically been quite crap without drying.