Hey Meghan, I don’t know yet how well my modification will work but am printing parts now to test fit. The stock Sunlu S2 seems to need some way to exchange air so if you go that route, might at least look at the doo-dads that prop the lid open.
I’m hoping this mod is what it needs to be much better though. I’m going to try it with and without pulling dry(er) air through desiccant and see how it goes. Hoping this approach pulls a little air but not too much. I’m going to use a hose barb to attach tubing from a desiccant container. Might still change things but this is what I have so far… The curved piece replaces the current base and mounts the fan. The other part becomes a new base with the hose barb.
I really like the dryer. The only problems I have with it is the PTFE tube location for dryer printing and the lack of ventilation.
Since no one makes a dryer that is fit for the filaments that need them most (Nylon, PCs, and PETs) I considered making one. But in all honesty, I’ve never had to dry for more than 8 hours so I guess making something high temp is overkill.
As for the design you made or found, I’m having a hard time understanding how that’s going to work with the S2. I get you mentioned it replaces the base, but that appears to need other significant mods to make the lid fit. Are we talking about the same Sunlu S2 dryer?
Ah - it’s for the Sunlu S2. What’s confusing maybe is there is a door/plate on the bottom of the unit that has the four legs at the corners. Here’s a photo of the bottom of the S2 where the new plate will fit - if it fits. That’s the current blower fan tucked out of the way so I can test fit. It’s normally attached to the bottom plate I’m replacing.
The new base replaces the plate and legs to create an air tight void below the dryer housing. The fan will draw from the void to blow air up into the chamber. It will pull air down through the port next to the fan in the replacement plate and also in through a side port which is where the makeup/maybe drier air comes in. The stock setup also uses that port. The stock fan rides in that opening but there is a slightly narrower section to the right which is the stock port.
Still waiting on the 24V Noctua fan, some silicone tubing, and some other bits but I think this could work. It’s all hypothetical at this point, though.
I recommend this spool holder for the S2, it works great. You pull out the rollers and it fits right in.
I never ended up printing the PTFE Holder in the other link, I just run the Bambu PTFE from the Bambu 4-in-1 PTFE Adapter to one of the holes at the top. I feed it through the plastic tube already in the hole. I position the spool so the filament goes from underneath the spool than up into the top hole rather than feeding it over the top of the spool. The path seems less restrictive.
I’ve used it with TPU-HF a few times, I keep the heater on while using it.
That is one impressive mod, my friend. It fixes almost everything wrong with the S2’s base and fan. This is already a great improvement over the tippy design using those subpar nubs they call feet in the OEM package. However, just a thought for added stability: have you considered giving it wings on the sides so that it’s not as tippy? They could be optional, or if you’re really going all out, make a 3mm plate that is the exact size of the base and mount it using a Nyloc nut so that the wings can optionally pivot out 90 degrees.
I left off the innerds until I got the fan but there’s a separate plate that mounts the fan that also has a throttle to set the differential pressure between the drying chamber (higher) and the bottom chamber (lower). The fan blows up from the bottom chamber into the drying chamber. There’s an outside air throttle but the hole is sized to squeeze fit silicone tube that can draw from a container of desiccant for lower starting RH if that behaves how I hope it might. That will need a bit more draw than just pulling outside air but flows should be low anyway.
I think your idea about the bigger base is a good one. I could just add it to the existing base as all a single piece if that would be easier than outriggers - or maybe they need big outriggers? How big were you thinking? I have no experience with printing from the S2 but I bet they do get tugged on pretty hard especially with a full roll. Only thing is that will more or less block off one of the vents/filament holes but that may not matter.
Was also thinking how to test. Trying to test how well each configuration works with any repeatability would be tough with filament rolls. Testing would change them. So I’ve got some silica gel packets in a jar so they can all equilibrate. I won’t know how much water they start with but if two lose water the same way I can hopefully trust the others are at the same water content and the humidity curves in different configurations should be directly comparable and show if there is any benefit to this.
Anyway, here’s the fan plate with the throttle on it. The throttle has the four holes but I also have a blank one that would restrict more. Don’t know what will work best yet. I’ll also print clips for the tubing to be able to throttle and close the desiccant off entirely. Have a clear Nalgene water bottle and fresh/sealed indicating desiccant for the dry air test and to run with if it works. Way overengineered.
For the short time I had the S2, one of the things I noticed as a design defect was that with a full 1Kg spool, the entire device was very unstable. This was particularly true when I sat the device on the table next to the printer. The table I have my P1 set up on is deliberately light weight. My thinking is that if you jus assume that the center of mass is at the center of the spool and then imagine an triangle jutting out from the base - use construction lines in CAD - where those triangle tips meet the base would be how far the canards would go. So then the question is, would that imaginary triangle have a 30 angle or could you get away with a 45 or even steeper 60 angle. I would imagine that 30 degrees should be enough.
Sorry for the crude drawing but this is what I come up with in five minutes.
For those adding a fan to your dryers, use as little a fan as you can find. The air renovation needed for the humidity to be expulsed is minimum. A bigger fan will move more air and will lower the temp or raise the power consumption.
For the fan, I highly recommend a 40mm PAPS one. PAPS is a very god fan maker and a 50mm one will be VERY silent in comparison with other fan makers.
Good points. I’m not familiar with PAPS fans, though. For this I’m using a 40mm x 40mm x 10mm Noctua fan which is also very quiet - much quieter than the OEM squirrel cage blower but any fan of the same size should fit. I made the mounting holes m3 and m4 so as long as other fans use the same mounting hole locations you should be covered.
(Edit - This design and the port already molded into the Sunlu S2 base will not accommodate a 50mm or larger fan. You can probably add a mount or duct to adapt it but I’m not going to do that. There isn’t a need and the Nuctua 40mm fan is probably overkill anyway.)
And agree on the overall fan/flow situation. Mostly what this will do is circulate air inside the chamber. It’s that circulation that will set up a small low pressure in the base which is what will draw in ambient outside air or “dry” air from a desiccant container. The small port cover swivel thing on the outside is intended to be used as a valve to limit the amount of outside air. If using dry air from a desiccant container, I’m making printable tubing clamps to limit that air flow.
In use the pressure differentials should be small. I only added the throttle on the fan plate to be able to make the pressure differential larger if needed. I think in practice it won’t be needed and the relative sizes of the fan hole and return air duct will create all the low pressure needed to bring in outside air. I’m stuck with that fan and return air port size since Sunlu built that ratio in their original design.
I’m trying to do this with the minimum modifications. No plastic cutting or drilling. Unfortunately the old fan has to be replaced (in part to end the high-pitched noise it makes) so a wire splice is needed, but that’s it. Everything else uses stock holes and ports in the Sunlu dryer.
I think the desiccant container will really help by supplying drier air than ambient outside air and help speed drying, but letting too much air flow through the system will just deplete the desiccant. Finding the proper flow rate will be important but that’s why I’m going to run some tests to validate performance and see how it works in different configurations.
The stock system would have brought in outside air with a draft if they would have added a port to the bottom feet plate under the stock fan. I almost went that way but wanted to have the desiccant option and more control over flows. There’s an interesting footprint under the stock fan that indicates they might have planned something else for the S2 but the final configuration only circulates air inside with no forced air replacement. They seem to rely on diffusion through small gaps and the filament holes but that’s slow.
Parts to finish finally arrived. The tubing, Nalgene bottle, and metal straws will be the preconditioner for air entering the dryer proper. The fan is a 24V 40x40x10mm Noctua. Time to get busy.
Hey @Olias - a stable base version. Who needs brim when you have a big puddle of plastic? . 3mf now has 4 bases in it - with and without a port for a temperature/RH meter and with and without the stable base. Was trivial to add but definitely see the utility! Just finished printing an updated fan mount so can do the assembly and set it on a stable base with RH port when that finishes. I’ll be testing this evening…
I can already tell this is going to work - at least with ambient room air and just the fan and holy throttle plate I get a good (but probably too good) stream of air out the vent holes with the lid closed. Printing the stable base now so have to wait to really test until that is done but with a base I should be able to regulate the flow out of the filament holes by using the swivel flap to regulate air into the base.
I used silicone seal to secure the fan mount. It has two locating pegs that can be expanded with m3 screws to tighten it up even more but I don’t think they are necessary. Just a little dollop of silicone in the holes should lock the fan mount in. I ran silicone around the port to seal the sides as well. The base area of the S2 is curved across the base from front to back, but it’s not as pronounced as the side to side curve. So the silicone around the port may be necessary. Not a big gap at the sides but a gap. In the last image the roller is just being used to hold the heater. But so far so good.
@MZip I’m following your progress with great interest. After you get it working to your satisfaction it would be very interesting if you could somehow quantify how much extra moisture your modified S2 is able to extract from a spool of filament as compared to a stock S2.
It may be hard to quantify that since each roll has its own history and starting water content. Best I could do would be to run some rolls bought at the same time from the same lot and color but that might be close enough. I do think comparing how desiccant loses its water should be a fair analog, though.
In doing all this I think the Sunlu is actually a little leaky around its base plate but mine is now sealed. Worse, the fan has turned the base into a sort of pump so it’s hard to say how close I can get now to a stock Sunlu. I should have run tests before I started modding but this was a slippery slope. Before I knew it the feet were off and wires were cut. But also, I’d need to do a big filament buy to try to take starting water content out of the mix as much as possible. It’s sounding like a bridge too far, to be honest.
Hopefully these desiccant runs give data that can be compared easily. I’ve run out of time today and silicone is curing. Tomorrow we ride!
No worries. I especially don’t want to burden you with any requests that don’t align with your own interests. Nonetheless, if you ever did get curious about it, I’d wager you could get a pretty good answer by
Note the initial weight of a filament spool before attempting to dry it, then
drying it to asymptote without connecting your desiccant apparatus, then
weigh it again and record the new weight
Connect your desiccant apparatus and dry it further until it asymptotes again, then
record final weight measurement.
Or, maybe there’s a better way. I’m sure you get the gist of it.
I did a variation on this measurement just recently, and the results surprised me. First I dried a spool of ASA at 80C for almost 3 days, measuring its weight beforehand as well as at several points in time along the way, until the weight loss finally did asymptote.
Then I quickly transferred it along with 500g of absolutely brand-new and fresh-from-a-sealed-package dry-and-dry silica gel desiccant into one of those sealed, gasketed cereal storage containers that a lot of people use for storing their filament. If anything, I thought that maybe the filament spool might lose a little more moisture to the desiccant. Well, two weeks later I opened the container to finally use it, and so I weighed it again. It had gained 0.5g of weight. How? From where? Maybe from the desiccant itself? That would be ironic. From the container? Seems unlikely, but I can’t rule it out. Maybe from ambient moisture penetrating through the container? I’m starting to wonder. Fortunately, I was at least able to rule out a measurement error because I have a 1kg calibration weight for calibrating the scale, and when I weighed that on the same scale it showed absolutely no measurable change in weight, and the scale’s resolution goes to 0.01g.
Now it has me wondering if whether I had stored the filament spool like that even longer whether it would have gained even more weight. So, just sayin’ when you start carefully weighing stuff–which takes barely any time at all–you may be surprised at what it turns up.
I am curious about cardboard spools.
Since my S2’s don’t have a fan, I don’t have a problem with cardboard spools…
But my Creality Space Pi, looks like it went mudding after 2-3 days of running cardboard spools. Cardboard dust all over the inside clear lid.
All good points and I’ll look into scales. It would just tie everything up nicely and people do use weight as a gauge for moisture.
About the ASA gaining weight in desiccant, I can see it. The ASA is known for being hygroscopic but obviously so is fresh desiccant. It could be that the ASA is a stronger desiccant than the desiccant and took water from it. It’s just a competition for who wants the water more.
What happens is the sites where water sticks have a range of affinities. It’s like those weights that get harder to pull at a tractor pull. The first water is easy to remove and the last water is really hard. It ends up just being a competition for which material has sites left that bind water stronger.
Or maybe the seal wasn’t tight or water diffused through the poly? Weighing the desiccant too would have told if it was gross water infiltration where both absorbed water or if the desiccant gave up water to the ASA in a closed system.
Hard to say for sure but water is really hard to get rid of. I used to work with vacuum systems and we had to pump things down and then heat the heck out of the vacuum chamber to get the water to unstick from very clean and dry looking metal and glass surfaces. To hit low pressures we’d have to pump and bake for hours to days.
That’s the current blower fan tucked out of the way so I can test fit. It’s normally attached to the bottom plate I’m replacing.
I get a good (but probably too good) stream of air out the vent holes with the lid closed. Printing the stable base now so have to wait to really test until that is done but with a base I should be able to regulate the flow out of the filament holes by using the swivel flap to regulate air into the base.
After you get it working to your satisfaction it would be very interesting if you could somehow quantify how much extra moisture your modified S2 is able to extract from a spool of filament as compared to a stock S2.
But also, I’d need to do a big filament buy to try to take starting water content out of the mix as much as possible. It’s sounding like a bridge too far, to be honest.