Default desiccant melted and my AMS is sticky

So I was getting underextrusion all of a sudden after I moved my AMS from on top of my P1S to beside, and I couldn’t figure out why (checked extruder/replaced hotend, PTFEs, etcetcetcetc) and so I decided to take apart my AMS and when I lifted in the inner body out there was literal liquid dripping out onto my desk.

Apparently the silica had melted or something??

So my question is, is the first stage feeders supposed to be drenched in grease originally, or is it covered in molten silica and causing slipping and I’m totally fked? Btw I’ve only had my P1S/AMS for less than 2 months…

Maybe for the future you may be interested in some models I have made :



I heard the liquid from a used-up desiccant of this type (apparently calcium chloride) is corrosive, very bad for parts or circuit boards. But I can’t see how it would end up in your gears - the desiccant tray drains to the bottom plate. You should open up your AMS and clean that out though. And I figure that draining is poor design… would be better having it contained in that tray.

It did end up at the bottom of the tray, but the components were dry.

The problem was, I was only checking for a broken filament without realizing the silica was molten, so I lifted/tilted the inner body of the AMS to unhook the back PTFE/pins… so yeah, it basically dripped everywhere through the top grate cover… -.- Both silica packs were melted. The amount captured in the photo is after I realized there was liquid coming out of my AMS and I opened up the desiccant cover to look… :frowning:

I would try and rinse the mechanical stuff (obviously not the motors) thoroughly with plain water and then dry with compressed air. Then maybe re-lubricate with something sensible.

Spare parts are cheap, so however it ends up it’s not the end of the world.

Don’t talk about silica, it is not silica. It’s calcium chloride, an alternative desiccant, actually salt where the sodium was replaced by calcium. It works completely different, as you found out, it liquefies. Probably not what you want in your AMS, I guess it was chosen as the trays are too small for silica gel to work sufficiently (calcium chloride is more efficient).
If you want to replace it by silica make sure to add additional containers. Best desiccant would be molecular sieve, it can dry down to almost 0% but it’s more expensive and hard to regenerate at home (temp around 300°C).

IMHO, it seems that the calcium chloride should go into containers that won’t leak all over everything. That way if you get distracted and your vigilance goes down, you won’t be faced with cleaning up a mess inside your AMS latter on.

Is there already such a container somewhere on printables or thingiverse or makersworld or github or…?

Here is one. I haven’t tried it.

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Yeah mine did exact same thing. it’s in the gear. and the AMS is not working.

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Thank you for the post. Mine did exact same thing. and AMS is not working. All four gear are wet. I try to clean one of them but how. I open it and wiped and closed back it. There was really nothing I could do. I mean if I wash it does it work? plus it behaves like the circuit is wrong. like it’s not reading. or reads but not pulling back properly. is yours working after cleaning?

Hey, mine worked after cleaning but I did take each extruder apart for a full wipe down. I also noticed there was hair (human and cat lol. I think the wetness attracts it) tangled in one or two of the cogs and I cleaned all of that too. I also checked for clogs in the AMS hub, checked all the PTFE tubes inside, checked that the electronic components were all dry and connected well (it did drip all the way down to the underside).

Another thing you might want to check is the filament buffer (the grey thingy at the back with the spring). That sh*t gets stuck sometimes and makes you think it’s the AMS failing when it’s not. I had to take it apart to oil too.

I now put my AMS somewhere else. I’m pretty sure the heat rising from the printer is also warming the insides of the AMS (I live in a hot country), which causes condensation inside the AMS and also softens the filaments in the worst case. Hope this somehow helps you.

Thank you so much for your kind explanation and help.

Thanks for the original post and follow up comments from everyone.

I have found myself in the same situation.

Synmptons from my end.

  1. Leaked desiccant packets on in both compartments.

  2. All of my first stage feeders have visible splatter internnaly (I thought it was excess lubrication). The residue is spread horizontal and seems to have originated from the vertical worm gear from the motor assembly.

  3. When you try to feed filament there is a high pitch noise that almost sounds like it was being generated from a piezo speaker.

Currently I am trying to clean one of the first stage feeders.

  • Full dissassembly of yellow gears
  • Clean with degreaser, wash/rinse in water then put it in my homebrew dehydrator to dry

i’ll follow up with results

It is again Bambu going cheap :frowning:
Silica gel won’t leak, especially not if supply in leak proof and RE-USABLE bags.
What Bambu uses is the same stuff you find in those contraptions to dry your room - the stuff is highly hygroscopic…
Once full it keeps collecting moisture to the point of turning into slime, getting thinner but not less sticky and not less CORROSIVE.

I removed all the Sh!t provided and replaced it with silica gel.
Simple kitchen paper bags, closed with wood glue…
One between every motor and then some between the spools where it fits…
Once the AMS indicates a humidity level above 3 I replace the lot with fresh ones, rip the old ones open and put the beads into the recycling jar.
When the jar get full I use the oven to dry them and am ready for the next round…

Looks like the root cause is the 2nd stage feeder. The motor runs abnormally fast and cannot grab the filament. Since the motor spins so fast it is unable to grab the filament and all you can hear is a high pitch sound as the filament rubs against the rotor.

Upon further investigation I noticed evidence of electrical over stress on main motherboard header “J13” and the mating connector which is where the leaked desiccant made contact. This happens to be the same connector that feeds the motor so it aligns with the symptoms.

I live in Singapore and I have seen dessicant “melt” before in the humidity.

You may wish to use a silica-based one instead.