Hi all,
I’m doing an experiment with a cabinet for filament with a small dehumidifier in it. I can get it to sit at 35%, but not much lower. I’ve sealed the cabinet with foam tape, and dried most of the filament first.
Are there any tricks to help improve performance of the mini dehumidifier? Maybe adding more heat to the cabinet?
The goal would be to use Home Assistant and the humidity sensor to turn things on and off as needed.
Thanks!
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Are you sure it’s 35% ? I’ve found those cheap digital hygrometers to be off by 10-15%.
I bought a box and some say 10 and some say 20. I ended up buying several different brands and price ranges of hygrometers to try and figure out which ones were correct.
I use cereal boxes with desiccant and without any active dehumidifier they stay at ~25% despite being frequently opened and closed. So like others suggested, put a large flow-through bin of desiccant in and forget about it.
Also is that a compressor dehumidifier? I suspect it’s a desiccant wheel because it’s so tiny.
It’s a compressor, which is probably the problem. I’m using a DH11 on ESPHome, so am pretty confident of the accuracy, it’s down in the bottom center of the cabinet. (I designed these https://nowsci.com/only-sensor)
Edit: Also, what do you mean by flow-through?
The DHT11 has been replaced twice with similarly-priced but more accurate models, first the DHT22 and then the AHT20. In my experience, the AHT20 is a lot better than the DHT22, mainly because its power consumption is far lower, so it doesn’t mess up its readings by getting hot.
Also, at that size, I’d be very surprised if the dehumidifier has a compressor. It’s much more likely that it’s got a Peltier plate, and they’re not very good. They use a lot of power to develop and maintain a fairly small temperature difference, so if they’re in a confined space, they heat up the air quite a bit, and then the water from their tank will more easily evaporate.
If you’re willing to spend some money, a solid state ion membrane dehumidifier might be better for a small cabinet than a compressor-based one, as it’ll be easy to ensure the water goes out of the cabinet instead of into a container that can’t be emptied without opening the cabinet and letting more humidity in. They’re definitely not cheap, though. I think they’re still under patent as there’s only one manufacturer that I can find, so maybe they’re the dehumidifier of the future even if they’re not suitable right now.
While I’d rather have 2% accuracy than 5% on paper, it’s been fine, and checking with higher quality sensor has always put me within 1%.
Also, I mentioned in another comment it was a peltier, and I’d love to do SS but just soooo expensive. :(
Re: flow through
A mesh like container so all sides are exposed to air. Many 3d printed designs have channels so air can get into the middle of the desiccant container.
Ahh thanks. Also, as a correction, this thing may be a crappy peltier dehumidifier.
Not sure what type of humidifier that is but you may need a rotary one to get lower. There’s a technology connections video on them. They essentially are silica that’s constantly dis/recharging. They’re very energy inefficient but don’t have the same performance limits as compressor based systems.
I got one earmarked for exactly this before I moved. They’re simple enough I was planning gutting it and adding smarts using ESPHome. But moisture hasn’t been an issue for me so the project is a low priority.
I suspect that’s what he already has. I can’t imagine a compressor based dehumidifier that’s so tiny.
Ahh nice. Thank you, I will take a look.
Yeah, I loved that video :)
I am no expert, but in my own research for a previous task I had to deal with for work, most everything I saw said that getting below 30-35% for even a small room like a closet was going to be difficult without moving to heavy duty and expensive equipment. I don’t know if there have been improvements in the technology since then (dehumidifiers have definitely gotten much smaller) but you start getting into issues were you are pulling moisture from the surrounding walls and items in the room.
I suspect in you situation you May be able to make some gains with heat, but I have to wonder if how hot you can go before you start seeing problems with the cabinet itself. I have seen cabinet delaminate just from being in hot garages, so I am not sure how hot you can get.Yea, I was curious about “limits”. I’d like to be stable at 30% vs 35%, then I can keep the petg and tpu in the dryers and everything else in the cabinet.
I have a couple of mini heaters I was going to build into chamber heaters for the SV08 Max, so I may stick one of them in there to see what happens.
I remember an article a few years ago about an experimental tube system that just rapidly dehydrated segments of filament in line on the way to the printer. Was hoping to see a commercial version of something like that by now as it just sounds so efficient. This setup looks extraordinarily unefficient on the other hand. I understand your efforts for better work flow, but to heat and dehumidify this properly will be a significant energy sink.
what would be needed? an addon that that replace the pipe from the spool/ams to the extruder to have a small heater/fan to pass warm air to the filament?
doesn’t sound overly complicated or hard to make and prototype.
Assuming I can get it working, not really. Your described method would be good for occasional prints, but terrible for higher volumes. Keeping an area at a target humidity (especially a small one) is much more efficient than a constantly running device.
Wood breathes. You will need something watertight lining the inside. Paint is not enough. 8mm plastic is my first thought - but many plastics also allow moisture through and I’m not sure what is safe. An epoxy finish on the inside might work. But getting a continious layer could be a pain.
That is hardly wood. And the coating itself is airtight by itself. Focus on the cracks at the back wall and it shouldn’t be an issue anymore.
Aluminum foil maybe?
Hmm had not considered this, but I doubt that’s having an impact on minimum humidity (currently), as that feels like it would impact when the system isn’t running?
Get some silica gel in there too
I’ll do that eventually to help “maintain”, but trying to figure out the active dehumidification without any other variables first.
I’ve done a similar thing using IKEA Samla Box (fits 6 rolls). With a few boxes of silica gel (dried periodically in my filament dryer) I can get it to stay relatively dry for a few weeks (goes from ~15 to ~25% in a few weeks).
Yea I was hoping to avoid manual maintenance but I may be stuck with it.
35% sounds amazing. I don’t know if you can get much lower
If only I had a big solid state dehumidifier…
How well are those glass panes sealed to the wood? Could silicone the panes in. Doubt it would help you go lower, but I’m curious how much the dehumidifier runs after it gets to 35% to keep it there? I didnt realize they even made dehumidifiers that small, might have to look at them. 🙂
I might give this a shot, but since the humidifier isn’t producing any water, I think I’m at it’s limit wothout changing something in the air.
