Centrifugal Compressor 120mm Case Fan Conversion

by Kiolia Jun 8, 2018
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Do you have (or know of) any functional model designed for the power output of an RC brushless motor? I don't have any application for one yet, but I'm curious how much pressure I can generate using a spare 100 Watt outrunner I have lying around.

have a look at this https://www.thingiverse.com/thing:2757570 it is for an RC brushless motor?
I use a a FLY-A35-10XL RC brushless motor AND I HAVE TO HOLD ON TO IT WITH TWO HANDS


by Theidd

Looks interesting! I would've liked one with just a single output though. Maybe something based on a turbocharger's geometry but tuned to work at 12,000 rpm instead of the usual 50-100k rpm.

its cool just dont know what id use it for

Thanks! I'm glad you checked it out, anyway. It can theoretically handle anything you'd use a plain centrifugal blower (of similar power) for, except it's quieter and not whiny. And, well, much bigger. This was the tradeoff I was looking for in my use case, but I'll admit it's pretty niche.

Could this be (one of the versions) used to pipe air to cool the hot end as well as on parts? Move the direct fans (and their weight, minor vibrations etc) off the print carriage and use one or two of these remotely. Add a hose or two to the 'umbilical' that serves the hot end and make adapters for the part blower and extruder cooler. Yay/Nay?

That's exactly what I use them for, actually. 19mm cPAP tubing does the trick. Check my other posted things for the effector I designed for the purpose :)

what is the hub in the neighborhood???

Sorry, I wasn't thinking about translation issues when I wrote this! "in the neighborhood" is idiomatic for "around" or "close to" (and "hub" means the round center of the fan, not including the blades, in case that wasn't clear). Basically, this design is meant to fit a 120mm case fan with a hub 39-40mm in diameter, and there's also an option for larger hubs (around 42-46mm). Let me know if there's anything else unclear and I'll do my best to help!

really thanks. now I understand. I'm going to buy a fan to do this awesome project!!!

If I had the cad talent to pull it off I'd redesign the compressor wheel so that it doesn't stand so proud, otherwise the angled first parts of the blades aren't doing anything. I might print this anyway, looks like a great tool to have and I have a spare 120mm (3A!) delta fan that recently got broken, this will be ideal! thank you :)

I'll admit I didn't do any testing with variations on the upper end of the blades -- I only focused on what happened when I changed the tip orientation. I did make some "dome" variants with no inducers, just tips, and one of those is posted, but they were all much too loud and obnoxious for my taste (since my goal with this was to replace some cheap 40mm blowers that performed fine but sounded like dentist equipment). You could always trim back the inducer portion of the blades with a utility knife after printing and see if it makes a difference!

Hi, realy nice design. Could you adjust the hub for a 43mm hub? I only have some fans with 43mm hub. Would be nice if you could do this.

I think that should be doable. Watch this space!

Nice! I can't wait for the part!

Okay, posted! There wasn't a ton of room to work with inside, so hopefully the thinner walls won't pose an issue. If you're going to print this, start with the new base to make sure it's going to work, and let me know if you hit any snags with the part.

The new adapter fits perfectly! Only, how do you print the volute? I've tried it with support, but then I can't get the support out of the volute.
Do you have some tips?

Glad to hear it! I was able to print the volute without internal supports (Touching buildplate only) at both .1 and .2 layer height in PLA, although I ended up pointing a fan at the part during printing to help ensure the overhangs didn't warp; if you're having overhang trouble at .2, try .1 (it takes a long time, but oh well). If you're using Cura, you can bump up the minimum X/Y support clearance settings to something like 2mm (default is like .25) so that no support will be generated in the open slot leading up into the volute, and that should make life easier (if you're using some other slicer, there's probably some equivalent setting). Good luck!

Do you have a remix of the impeller for a 47mm hub? I have a nice 120v comair fan I want to use

At 47+mm inner diameter there wouldn't be enough room for the adjustable "grippers" in the current design, so it would be tough for me to design something properly universal. However, I think you might be able to get the adjustable impeller base onto a 47mm hub if you just start trimming away the grippers inside -- there's probably enough clearance without them, and if you want to pump a lot of power into this you'd probably want to be gluing the impeller to the hub anyway (after getting the balance very, very fine-tuned!). The one-piece impellers might be trim-out-able to fit 47mm as well. Depending on how willing you are to sacrifice plastic, you could always print one (or half of one) and see before you commit to printing the whole thing. Let me know how it goes if you get it running with some super-powerful motor!

I'll give it a shot, I have a bunch of these from an old industrial machine and was trying to see how I could use them with my eleklaser a3 for air assist so I could get better cuts without buying an actual air compressor lol. I'll keep you posted for sure though

So I did end up making an experimental impeller base variant to fit bigger hubs. 47mm is still going to be a squooze, but I think a little judicious sandpapering might let you sausage the hub in there, if you want to try it!

Sounds cool! No promises this'll do what you want, though, if the "real thing" would be a legit air compressor. Centrifugal compressors can build pressure head, sure (and to be fair I don't have any idea what kind of head this design could develop at whatever maximum power it can handle without the impeller exploding, since I don't have the motors around to explore inputs over about 1.5A), but you might need something more like a positive displacement pump. I've seen at least one decent-looking rotary lobe pump floating around Thingiverse (I forget the link, sorry) -- that might be worth checking out.

This is pretty awesome!

Will this move more air compared to the unmodified fan?

Thanks, glad you like it! In terms of moving air, it depends on your application. If you just want to move air around a room -- like to cool your face off on a hot day -- the unmodified fan is better. If you want to move air into a balloon or mattress or down a restricted tube, though -- anywhere there's back-pressure to overcome -- the modified fan should be quite a bit better. Google axial vs centrifugal fan applications if you're curious to learn more!

Really cool! Neat way to repurpose a fan.

Thanks! I always build my own PCs, so I had plenty of used 120s lying around in boxes waiting for a second life. I just wish I could come up with a similar use for all my unused stock Intel CPU coolers :)

That's simple! Make a huge LED flashlight with them :D
Don't really know of any other DIY things you can make with 'em. Maybe evaporative cooling would be a neat project aswell ;)