Sunlu filament drier

[BazyleParticipant @bazyle]

After reading the review of the Sunlu drier in May ’26 issue I decided to upgrade my er ‘homemade thing’ for the purpose designed one and it arrived today.
Yes it does have a fan inside (reviewer not certain) which blows air up the front edge of the reel so the filament is fed out through a hot wind as a final drying action.  I too got a little package of 4 mystery bits of clear plastic tube about 4mm internal dia, 3mm long, and maybe .75mm wall. My thought was they might fit on the roller bars to sort of control the position of the reel or, just now thinking they might be replacement bearings. Can’t see the ends of the roller bars without taking it apart. Might look later for spare parts on mfr website as if they wear fast enough that you need replacements then you are gong to need them every year.
It is currently sitting at 40c with an old roll of PLA in it and timer for 4 hrs.

Now it started at about 17C and humidity 52% and when hot got to about 25% humidity. But if you heat a closed volume of air its RH will go down – that’s just how humidity works. So as it is sealed apart from the filament exit hole has the water got anywhere to go?
In theory if I put it outside tonight to cool (or even in the fridge?) the water if it came out of the plastic into the air might then condense on the inside of the casing. Also maybe a lump of cold metal on the case would encourage that. As it cools it will suck in some air which I guess is about 50% RH hence the initial reading.
Should I remove the hot reel and seal in a bag, not leave in the machine? Probably but that would replace all the internal air so negating the condensation experiment above.

I might also experiment with sachets of desiccant but should I put them in there when it is heating, or when it is cooling?

Some of the online adverts show two sort of tubes which I didn’t get – but no list of contents to indicate what these might be. I thought they might be the rollers but those are just plain 3mm steel rods.

[Neil WyattModerator @neilwyatt]

Hi Bazyle,

I had the same ‘where does the water go’ thoughts. Apparently Nylon 66 can hold 8% water but under normal conditions (50% RH at 23C) it holds 2.5-3%. That’s around 27 grams or an ounce of water in a kilo of filament! For printing below 0.5%, ideally below 0.1%, is what is required, apparently. I store my filament in warm dry places OR in a box with a chemical dehumidifier, so my filament probably isn’t as bad as 2.5%.

From the improvements I saw the water clearly does get sucked into the hotter (and therefore) drier air, I assume the case is leaky enough for the air to slowly change while still allowing the heater to keep up the temperature.

What I can say is I get much more reliable results with it than my previous ‘on top of a radiator’ approach.

I’ve also tried leaving desiccant in with the filament (overnight) to ‘refresh it’ – after this they work really well for keeping my jarful of biscuits crunchy.

So I’m sure it works, not sure that my filament was really wet, just wet enough to cause issues.

 

Neil.

[renardiere7Participant @renardiere7]

Bazyle, there are several different Sunlu driers as I understand it so it depends on which model you have I suppose.  I can only comment to say that I recently bought an E2 filadrier which came with a good set of directions, several longer lengths of PTFE tube for filament transfer to printer but none of the short lengths you mention.

The directions clearly state that in use the top silicon vents/ports must be opened to spill moist air and closed after use.

I’ve just looked on the Sunlu UK website and it looks as if their support page is unavailable at the moment.

Would also add that I’ve found it a well made and effective bit of kit.

[BazyleParticipant @bazyle]

I have the S1 version as per the article. This morning the cooled down unit showed RH of 47% at 17C so a bit less than starting point. I have put some of my dry desiccant bags in it and set it for 2 hours at 40C, no filament. I will see if later it registers a low RH from the desiccant drying the contents – or maybe they will have been further dried from being in it.

[HuubParticipant @huub]

My PolyDryer works by circulating hot/warm air that is dried using silica-gel. I don’t expect the inner filament to be dried at all. That vapor has “no way” to go.
Since I store all filament air tight with silica-gel, my print quality has improved a lot, even for PLA.

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