Filament Dryer - Sunlu S4 review.

Filament Dryer - Sunlu S4 review.
My Sunlu S4 filament dryer

Last year, I joined the hype train for the SunLu S4 filament dryer by backing the kickstarter. The dryer boasts being able to dry 4 rolls of 1kg filament at once, with an optional 3D print to convert the dryer to support 3kg rolls.

When I went through my issues with printing that stopped me printing, I had 2 rolls which I was having issues with. The first was a red roll, that had literally been on the printer for over a year. I live in the UK, and so I live with high humidity. It was a fair bet that some of this had been soaked up.

I chose to start the red filament off with a 4 hour test, trying to get the humidity down to 25%. After about 4 hours, I started to print with it. This was also the filament that was jamming in my hot end before I replaced that with the phaetus. Amazingly, the filament printed - and printed well. There were no hint of popping or cracking that I would have associated with the filament still having water within it.

For the next roll, I tried resurrecting the grey filament. This had at least been in my dry box for the last year to keep the filament relatively dry. The dry box I was using was designed by Ricky Impey on youtube.

I still keep this dry box around, as the S4 does get switched off, so I still need a longer term storage solution.

Again, the grey filament printed like a charm. It also printed like a charm on the my CR-10 Max as well, and I did use this filament for my initial benchy on the printer. So far, I don't seem to have found anything that could really be considered a downside to the dryer.

With my purchase of a second printer, the S4 was able to supply filament to both printers simultaneously, while having space to prepare the next 2 rolls to go on them.

So... What could be better?

Well, if you read the blog regularly (I do try to publish every week...), you'll know I am a home assistant user. I think that for the sake of a small cpu the dryer should have been able to connect to wifi and mqtt for stats and reporting, along with the possibility of remote control.

I do have the S4 on a smart socket (along with CR-10 Max) so I feel automation could have been pushed a little bit further here.


So, despite the lack of pushing the automation boundary here, the S4 is a great dryer. I've had no issues with it and I am very happy with my purchase from kickstarter. It works really well, and great for feeding multiple printers, or printers with an AMS system on it.

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