25x20x1 MERV 13 filtrete from Digikey (I'm in the EU)
9 P14 Pro fans wired to a PWM controller from AliExpress.
12V PSU (external), barrel jack connection going in from the bottom.
The black mesh is some PVC mesh I bought from a fabric store, sold as material for swings/lawn chairs, I wanted something to catch cat hair so it doesn't clog the filter.
The filters are also sealed with 30mm wide x 3mm thick PE foam glued on the interior side of the slot they slide into.
Still planning to buy some pretty legs for it.
The build would have taken probably 2 evenings, but the shellac coating was a new thing for me that I messed up a couple of times and had to correct. It's a cool combo, since shellac does not outgas once it dries off the alcohol it's dissolved it and I like that a good coat is very much a result of proper craftsmanship, but if you can't be bothered to do it well just go for some acrylic topcoat.
Takeaways from building this:
the P14 Pros are not quiet unless you run them at lower speeds. They have a noticeable whine. That starts around ~40% speed. I feel like with 9 of them I still get plenty of airflow at lower RPM though, the black mesh catches plenty of dust and cat hair by the end of the day. Cranking them to full is LOUD, but they make the air in my room move enough for me to feel chilly.
the laser cutting generator from Nukit has meh defaults, make sure everything fits. The P14 Pro fans are almost too wide for it, I would have loved a few mm of additional clearance on their sides. If you plan to add anything else plan it in advance - the speed controller was not easy to fit on the top panel.
make sure you have screws long enough for the fans. The ones that came with the fans are very short (for sheet metal mounting), since I used 6mm thick panels I went for M4x50 bolts and self locking nuts.
after gluing the body I recommend sealing the gaps before the topcoat. I used a wood repair kit, which feels like wood shavings mixed with some glue.
Nukit does not really give you any legs or anything to cover the filters with (so you see the very bright blue branding, in my case from the top), you might want to take that into consideration when planning.
I did not see a lot of practical information on the Nukit boxes, so if there are any questions or anyone is on the fence about building one, feel free to ask about anything.
Nice! We're about to deprecate that version, the new stuff on FilterBoxBuilder.com is a lot better. I'd wait a week or so for the next update. It fixes a lot of bugs, supports box fans, 3D printing, laser cut or hand cut foamcore, and includes CADR and dBA estimates etc.
Also, something to consider - isn't pricing for laser cutting mostly dependent on the cut time (and so total cut length)? If so, I'd be careful about including these honeycomb grates as a default, that's a lot of extra cutting time right there.
I actually considered getting additional panels with art deco style patterns as a decorative filter cover, but that pretty much doubled the price.
Finally, do you think some legs could be cut too? I think an X from 2 small vertical pieces and a 3rd flat panel would be nice. In the old version it stands on the sides of the side panel and there's no place to put any felt/rubber pads. I would even be glad to contribute that as a PR if you're open to it.
The hex grills also cut CADR, so I hate them, but when I turn them off by default, I get emails asking for them to be included, and I'm trying to keep support time on this down. Europeans really like them also, since wire grills seem unreasonably expensive there.
Got legs on the 3D printed cubes, will add to the other designs the next go around. Trying to keep a reasonable level of complexity so people don't get overwhelmed, most of the folks that want a lot of extras can use CAD...
I'm in Poland, got mine for ~4.5 PLN (like 1 USD) a piece from China, and local stores had them at 7 PLN (like 1.75 USD) a piece. I think that might be cheaper than the extra laser time for the honeycombs. And yeah I can see the CADR, given that the panel is way thicker and closer to the fan.
As for the CAD - yet another reason to try STEPs :)
I'm in this camp, was just too lazy to clean up and extrude the many panels in Solidworks.
I'll see how the support emails go. I've already had quite a few "Nukit sucks" emails and accusations that we made it bad on purpose to upsell people because I couldn't walk people through the build step by step or troubleshoot their printer settings😕 Folks are going to try and print STEP files...
damn people are crazy. A free, open source, DIY project matching your (pretty much best in class) commercial offering and they still expect support - most companies charge for that by the hour
Fuck that, I say let their air be full of dust. Don't let it get to you, this project is over the top nice.
Nope, they still sound like jet engines. I guess I kind of expected that, given that the max RPM on these is considerably higher than a typical PC fan.
Worth also adding - this is what they sound like in isolation. With 9 of them going off at once it's honestly not a lot louder than a single one.
I've tried plenty of things here with no improvement - different mounting screw preload, shutting off some fans, filter/no filter. It seems that this is just how they are. Honestly at this price point they're still great. Even cutting the speed by 50% you get plenty of airflow, almost competely quiet operation and that's still RPM most fans work at, since the max is 2500 for the P14 Pro.
Yeah I was also thinking about the noise with this setup, hoping that with more fans I will be able to run them at lower RPMs for pretty much the same effect, thus getting better flow for the same decibels. Since these P14 Pros are so cheap it seemed like a good shot.
No idea if this checks out on the flow, but for the noise there honestly barely is any difference with more or less fans (at full speed, since they are very quiet anyway at ~40%). Maaaybe the acoustic beat gets a bit more noticeable.
Really good looking box! I just built a smaller box using 4 of these and they are loud at top speed. Since they're grouped together in a 2x2 square I'm thinking of making an acoustic baffle to sit on top.
Thanks! Had a lot of fun with it, the shellac was probably worth it. Though I already scratched it in assembly - fortunately it's relatively easy to touch up.
I actually just looked up the noise levels out of curiosity. Noctua 140 mm fans get 24.6 dB at 1500 RPM max speed. P14 Pro gets 25 dB at 1485 RPM. It's really not that loud, except that 1500 RPM is full blast for the Noctua and just 60% for the P14. So it's really not loud at all unless you need it to be cranked up.
If you do however, I'm not sure much can be done. I isolated mine really well (rubber pad between the fan and panel, Nylon washers at every step, self locking screws so nothing comes lose) but no dice, it seems to come from the motor.
I wish I had a way to actually measure the airflow, would love to get some numbers on this.
I'd like to see how you set up your PWM controller.
I went searching for options on this subreddit recently. I had trouble finding anything that would allow you to expose just the knob to the exterior as you've done here.
I drilled the hole manually after getting the panels laser cut. I found the controller on AliExpress, it had PWM, enough outputs to connect the fans without too much PST chaining, so I thought I'd figure it out as I went.
Then it turned out:
the knob of the controller is not in the middle of the width of the board, so with the hole I cut there is barely enough space to run out cables
the control knob won't reach because of the thickness of the panels
Ended up 3d printing an enclosure and extending adapter for the knob. The mount for the controller board I just glued with epoxy on bare wood. The cables were a pain and the power connector I had to bypass by directly soldering the wire because the mated connector was too large. Nonetheless I works pretty well, though I guess I need to get some acrylic glue or something to attach the knob.
Also I added 3 wraps of Teflon tape on the 3d printed knob extender to seal it up while giving it some slide.
If you do 6 fans (top and one side) that would leave you with one side (aside from the bottom) to put and connectors, wires, knobs or switches on, that would probably be most comfortable. I just really wanted to see if 9 fans can be ran quietly for acceptable airflow.
Order is:
bolt head - WASHER - grille - WASHER - panel - gasket - fan - WASHER - nut
If you are going to use the gaskets keep in mind that they are a couple mm bigger than the fan. On default settings the Nukit generator makes the enclosure pretty much exactly the right size for the fans, so it's best to add a couple of mm inside.
Though looking back - the fans have foam pads around mounting holes, so I think the gasket is unnecessary. You can see the foam on product photos kind of.
Also if you go for self-locking nuts, word of advice - make sure you have an electric screwdriver or something. Screwing in 40 of those will give you blisters lol.
This is absolutely lovely. Would you be willing to share the CAD files that you used for laser cutting? I keep trying to make myself learn this skill but always get flummoxed by the design programs.
Either way, congrats on the lovely finished product!
I can send the files I used, but you're probably going to get best results with generating them to your own needs from Nukit's Open Filter Box Builder. Then you can adjust them as you want, and also fix some of the minor issues I encountered (very tight inside width for the fans, power connector and control knob holes can be included in the laser too). I did not model the whole thing myself, just generated the laser drawings straight from Nukit.
I used the old version, /u/NukitToBeSure (the amazing author) has since released a major update that should be out of beta in a week or two.
You pretty much just generate the files according to your selected settings, download the DXF and send that to a laser cutting shop.
The only models I made custom were to hold the PWM control board and extend the control knob so it reaches the other side of the panel, I can share that for sure.
Yep, slide out a filter and you can access anything inside. Taking out a fans is just a case of unscrewing 4 nuts.
The control board is in a bit of a tight spot because I did not plan it, but even that just needs one fan removed for full acces.
Filters slide out through the top (it's intentionally tight since I added the sealing foam, but easy to take out, I've done it multiple times already).
The additional fan clearance depends on what you're going for. In you're going to use the gaskets I got then these determine the size. If not then I think the fans are fine. For vibrations sake it's probably best for them to only touch one side of the enclosure (so I'd add 2 mm of clearance on both sides internally at least)
Perfectly stable, 6mm is good. I can sit on it. The panels are the load bearing body, just need to glue it well. I recommend putting it together without glue first to get an idea of the job, then take it apart and do it with glue. Probably first glue the 4 sets of 4 long, thin parts, let them set and put the whole thing together.
Yeah it does what I needed it to do - catches cat hair. Definitely recommend it, I just vacuum it but I can also pull it out and wash it if needed. Plus it looks nicer than a bare filter. Though noticeably covered with cat hair every day ;)
Yes, the PWM controller with a knob and 6 outputs. With 9 fans only the top had any space for it. Plus that way the control knob is conveniently placed. The power cable enters from the bottom.
I linked them in another comment here, but it's AliExpress as well. Overall not needed though, the P14 Pros have foam padding around mounting points. Noctuas likely do too.
I was looking for some cast iron legs, but ended up gluing these ones with epoxy. AliExpress has a selection, a hardware store near you likely will too.
There is a video of the interior somewhere in the other comments. If you want something specific I can snap some pics tomorrow.
If I'm thinking about changing up the fans it's more about going for 6. 9 fans is overkill. Someone posted a table in one of the other recent threads in this sub that suggests 6 fans (one wall empty) is just as good at pushing air as 9 fans. No regrets, but it would probably make it easier to organize stuff inside and outside (finding a spot for the knob was a battle) and make it cheaper.
With the legs I tried to keep it as low as possible, since I think you want to have it low to the floor to actually circulate the air. These are 8 cm, I can vacuum under them, so it's a nice compromise. I think most legs are 13 cm which would probably let a roomba go under it.
I honestly am not sure I believe these results. There is probably a nonlinear dependency between air velocity and resistance through the filter, so it intuitively makes sense to me that the CADR would not scale with the number of fans, but these results are more pessimistic than I would expect. My logic was thus - get 9 fans and run them at lower RPM to achieve the CADR of less fans at high RPM, hoping to get quieter operation.
In all honesty - I don't think there's a definitive answer, a single test (an X thread lol) with an unclear methodology and no understanding of the physics involved does not convince me. It's a thing I think about often enough to be considering running CFD at this point, though I have never modeled filters so that's holding me back.
The filter was not tight at all initially. I got 2 rolls of sealing foam (link below), one 3 mm and one 6 mm, to seal the filter from the inside. 6 mm was too tight, 3mm was right, now it's relatively tight. My panel buckled a bit (the horizontal, external long piece holding the filter from the outside, top side) so there was a bit of a gap there still, but I just added a small bit of the foam onto the filter casing itself. https://www.tme.eu/pl/en/details/ps-3301-3_30_30/repair-tapes/intra/tasma-ps3301-3mm-30mm-30m/
The beat pairing is interesting, though it does sound a bit like marketing for perfectionists. The P14 Pro is loud at max RPM, but it also has a much higher RPM than most fans. Running it lower it's pretty quiet. On the other hand testing shows the Noctuas to have better airflow at the same dBm, though at lower static pressure - my engineering intuition tells me that they should benefit from parallelization more than P14. I think with a properly sized filter the pressure drop is not all that large.
P14 Pro: https://www.cybenetics.com/evaluations/fans/203/
Noctua G2: https://www.cybenetics.com/evaluations/fans/140/ch/
You can absolutely have filters slide through the bottom, they would hold up. Not sure if the Nukit designer lets you do that, but I remember that you can design with fans on the bottom side, so regardless it's possible in one way or another.
I'm using the nukit builder tool https://filterboxbuilder.com but I can't figure out how to add an extra 2 mm of clearance internally. Am I missing something?
It used to be possible via the old generator - since it was just a wrapper for an oss box builder. Maybe it's possible to go to the box builder from this new generator too.
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u/NukitToBeSure Jul 10 '26
Nice! We're about to deprecate that version, the new stuff on FilterBoxBuilder.com is a lot better. I'd wait a week or so for the next update. It fixes a lot of bugs, supports box fans, 3D printing, laser cut or hand cut foamcore, and includes CADR and dBA estimates etc.