This information might explain a little.
Caution… There is some science involved…
Hello @jimandyen ,
Thank you for that.
It seems that my curiosity in drier design is being taken incorrectly.
So that I may clarify, I worked as a technician with a company that designed/made/calibrated environmental sensors accurate to better than .02% in some cases. For a number of years.
As such, I do understand atmosphere.
What I do not understand, is why the makers of filament driers have no escape for hot moist air.
Just to witness the effect, put a filament that has been exposed to the air for some time, in the drier turn it on and leave it for 2 hours.
Then lift the lid up and put your face close to it.
You will feel warm moist air.
That warm moist air is just sitting there with no where to go.
As I have stated before, “The Sunlu driers have a fan in them”, what is the point of simply moving hot humid air around ?
Cheers.
I’m not sure why they don’t either. I kind of know what you are talking about and I noticed that the article I mentioned didn’t talk about an air vent either.
Well, that is an interesting find !
It would be very interesting if Sunlu happened upon this and bought out a “Revolutionary new filament drier with a vented fan”.
Maybe Creality drops by and sees your post, then, voila, a new “you beaut” Space drier with venting fan.
So, it looks like we are on the right track anyway 
Cheers.
Hello every …
The subject about humidity and the associated filament driers doesn’t seem to leave me alone.
It is just one of those things I know various things about, but, not everything and it is bothering me and I need answers before I go spare.
I would VERY MUCH like to chat with someone in the research/design department that were responsible for the making of Sunlu/Creality/or other brand filament driers .
Why … … because, things don’t add up !
I have some reasonably accurate sensors for temperature and humidity. (they don’t need to be as accurate in reality … a couple of % is good enough to see what is happening).
OK, first question (which I have confirmed), does the filament drier need to vent the humidity ?
If the answer is yes. how is it best to do it and why are driers not made to do so.
Next question, when you are satisfied that your filament is dry enough and you put it in a vacuum sealed bag, why put a silica gel bag in with it ?
Where is the humidity coming from when the bag is so air tight nothing can get in? (you have sucked all the air out)…
Please don’t tell me the answer is 42 .
Cheers.
R_D,
While I’m new to this subject, my mechanical engineer’s instinct is to vent while drying, though not necessarily while printing.
After a bit of googling, I found a dryer with exactly that written beside its closable vent!
To answer your second question, sadly, ordinary plastic bags are moisture-permeable. (This can be a problem for medicines and foodstuffs as well - especially when the bag lets necessary moisture escape.)
If we don’t want to use silica etc, we need to use an alternative container, such as an aluminium-coated vacuum bag, or an impermeable sealed box. David
Hello Tuppenced and Welcome,
Thank you for your reply, in particular, regards the plastic bags as it makes sense.
I have gone the route of not venting the drier and instesd inserting Silica gel bags to catch the hot moisture.
Cheers.
Thanks to R_D and everyone on this thread, I’ve just ordered one of these:
whose instructions warn to keep hands away from the hot air outlet:
It’s a very simple ‘open-loop’ machine - no timer and no thermostat - but it’s very compact, very low power consumption, does well in review trials, and has filament outlets in refreshingly sensible places.
And it cost less than the spool I’m going to put in it !
David
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Hello Tuppenced,
That looks like a good solution.
Also good that it has places for Silica gel bags.
The humidity display is also a very good feature (note that the accuracy is likely to be around 1~ 2%, that is plenty close enough. Greater accuracy would involve a sensor that would make the price of the drier double).
I would be interested to hear feedback from you after using it for a while.
Cheers.
Yes, accurate AIR humidity is a red herring when it’s filament moisture that counts 
I’ve noticed that some reviewers are disturbed by the clicking of a drier thermostat - which won’t happen on this machine because there’s neither thermostat nor temperature display. However a cheap thermocouple probe can be poked through one of the outlet ports to calibrate the dial. For the adventurous, there’s apparently a ‘potentiometer’ inside to adjust for ambient temperature: the factory setting is for a 25C working environment, while my house is generally at 19C.
I hope I can position the box to feed my A1 Mini without cooking it. D
My EIBOS Easdry cost £32 including delivery from China to the UK.
It arrived in exactly a week, and I could track each step of its progess online.
It is barely bigger than a spool box:
Comparing it with my Creality dryer:
-
Both take up the same space on a storage shelf, with the Eibos able to fit many a spool rack.
-
Both have the same type of detachable mains lead, which makes them easy to swop around.
(And if you want to back them up to a wall, you can add a cheap right-angle cable adaptor.) -
On both, the on/off mains switch is annoyingly inaccessible, low at the back, beside the mains socket.
-
The top-loading Creality needs far less bench space, because the Eibos needs a lot of space on one side, to get the lid off and change spools, and on the other side, to allow air in and out of the side ports.
( Whether this matters depends entirely on what else is competing for space, and whether the hot air could cause harm.
To take an obvious example, a block of four Crealities could make a neat AMS for my Bambu A1 mini, while four Eiboses would need each need space to breathe.) -
The Eibos is very significantly quieter than the Creality, both in volume and in harshness.
At 1 metre distance, the Eibos raised the average sound level in a quiet room from 20dB to 24dB while the Creality raised it from 20dB to 29dB.
(Whether this matters depends on what else is going on in the room - your printer may drown both.) -
The non-thermostat Eibos will need calibrating before first use, because my mains is 245V.
-
The Creality doesn’t have the desiccant compartments that the Eibos has.
-
The Creality may need extra filament holes - and the starting point of this thread is that it may benefit from a closable air vent.
-
Eibos operation is necessarily simple (once calibrated):
- Turn it on,
- Set Filament Type,
- Remember to turn it off (or add an external time-switch).
- Creality operation is surprisingly fiddly, and I find the multi-function control knob temperamental:
- Turn it on,
- Stoop down level with the faint display screen,
- Twist the knob until Time appears,
- Set Time,
- Twist the knob again until Temperature appears,
- Set Temperature.
Finally, the simpler Eibos was two thirds of the price of the Creality - your Tariffs may vary.
Because I already have a separate drying oven (vented, by the way), I shall only use them during printing, and not for pre-drying.
I’m pleased to have one of each.
- I can imagine them suiting different types of print,
- I can imagine the pair forming a “Mini-AMS”, with one of them holding Support material at a different temperature from the Structural material. We shall see.
It will be a while before I can give you a comparison in operation, because my 3D time is limited and, as I’m new to home filament printing, it will take me a while before I become confident with filaments that need drying.
David
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I think, to a great degree, everyone’s missing the boat.
It’s Relative Humidity. That means it’s “relative” and relative is in relation to temperature.
For the sake of argument, let’s say that at 40F, a cubic foot of air has 1 gram of water in it (ALL of these numbers are made up, for illustrative purposes). At that point it may be at 90%RH. Heating that air to 120F may drop the humidity to 50% (even though it is still the same amount of water and air) and heating to 190F may drop it to 10%.
If air at 90F is at 100% RH, that means that it can’t hold any more water, it is 100% saturated. If the temperature drops below 90F, then that water must condense on something and no longer is in the air. In real life, this is what we call Dew.
Now, if I take that initial air and heat it to 190F and then let it cool back to 40F, guess what the RH is? It is back at it’s 90% initial RH.
Now, take some air and heat it up, it will drop in RH as the temperature increases. If there is filament in the box, the air will probably attempt to suck up some of that water.
Now to venting. If you let the hot air out, what’s going to replace it? It’s a relatively dry day for me and the RH is 37% at 77F. Whatever leaves the box, maybe at 150F and 10% is going to be replaced by the ambient air.