Building a Small and Quiet Air Compressor [4K]

[@DiffractionLimited]

Fusion360 Project (and .step file) is now available on Github: github.com/0x23/QuietAirCompressor

[@hullinstruments]

Dude. Seriously this is impressive. Usually photonics nerds aren't equally talented engineers 😂👍

[@oraziovescovi1922]

I absolutely admite how neatly organized your Fusion assembly looks, both the bodies' tree and the timeline down below! Bravo!

[@The123Smoke123]

Despite additive tech being available for decades now, one could rarely see something so useful being made on non-enterprise level. Brilliant work, every stage of it, really!

[@DUIofPhysics]

That seal is genius! Awesome design and assembly work!

[@TheHawkster16]

Very cool! It's impressive that so much of it can be 3D printed. Also, very fun to see creative engineering solutions.

[@MicroplaysMC]

This is actually so sick. Seriously would consider using something like this in a micro shop for delicate work or testing. It's basically got VFD standard so you can adjust duty cycle dynamically. 3D printers and just the overall democratization of manufacturing has seen some amazing things come from it.

[@SpringHaIo]

Very well put together, and great explanation on material choice and design for the strengths of 3D printing. I like the use of flanged screws to hold in the bearings, since press fits into 3D prints have the tendency to creep and loosen up.

[@DiffractionLimited]

Yes that is my experience too, press fits in 3D prints hold for a day or so.

[@vex123]

Thanks for mentioning that. This was something useful to learn about which I didn't know about before

[@HaloWolf102]

Apart from the audio interference in the beginning. This video is phenomenal. Great work!

[@wilsonarno]

That's so cool! Looks very easy to repair and maintain. It would be cool if you hooked it up to a fire extinguisher cylinder as a storage tank. The working pressure of most fire extinguishers is 12 bar or so.

[@DiffractionLimited]

True, I am indeed looking for buffer tank and one of those small fire extinguishers or a small propane bottle might do the trick. Thanks for the idea.

[@ІгорАлієв]

​@@DiffractionLimited1.5 L sparkling mineral water bottles do decent job for pressures below 3- 4 bar. They can rip at about 5 bar. 0.5 l bottles rip at 11 bar. I pumped bottles 1.5 L by foot pump to 2-2.5 bar. It is a bit tiring job if smth is leaking.

[@PatFarrellKTM]

Very cool design. I love your crankshaft offset design. Very clever and easy to make, well done.

[@tshenTube]

This is a very well done project and solid design. Good work mate!

[@Theballonist]

Pretty neat. I purchased a "quiet" air compressor last year and have found it still quite loud and annoyingly low on power. I'm excited for new takes on how to construct such devices.

[@patrickd9551]

I wouldn't get your hopes up on this one. There are basically three variables you can tinker with: Power, price and noise. You can only choose two. Basically a quiet powerful compressor is going to cost you (rotary compressors). A cheap powerful compressor is going to be loud. And lastly, a quiet cheap compressor is going to find you lacking in power.

[@AaroKo]

​@@patrickd9551this is very well said good sir :)

[@TeslaAtoms]

@@patrickd9551 Years ago, i built a 40l/min 6 bar compressor for

[@patrickd9551]

@@TeslaAtomsWell it depends on your application, but 40L/min is basically nothing for most applications, perhaps except paintbrushing. But you've proven my point exactly, because my $500 compressor does 350L/min, makes a lot of noise, and I still can barely run my plasma cutter on it. (those require massive amounts of air)

[@TeslaAtoms]

@@patrickd9551It really depends on the usecase! I use my compressor exclusively to supply air for tool changes on my VMC, as well as mql (minimum quantity lubrication). 40L is the perfect match for this!

[@vikingsofvintageaudio7470]

Very nice! Really like it that you went for eccentrics just like steam engine piston valves 🥰

[@ІгорАлієв]

Awesome project! You're genius! I saw such rocking pistons in small chinese air pump. That should be nice car pump if plastics will survive heat from compression.

[@peacesun29]

This is a brilliant piece of work!

[@smh988]

interesting concept, excellent build, outstanding operation. well done.

[@harrylenon9594]

Nice! A compressor is one of the first projects i want to try when i get my lathe. For some reason the piston not travelling vertically triggers my ocdness, so would probably design mine with a seperate piston and wrist pin 😂

[@AnnaVannieuwenhuyse]

It may annoy you, but the tilting motion seems pretty crucial to getting the seal tilting along with it in a reliable fashion. 🤔

[@harrylenon9594]

@@AnnaVannieuwenhuyse sure... but you don't need a tilting seal for a compressor. This design maybe, but other designs exist

[@darrenconway8117]

If you want a really quiet compressor, look at Guided Rotor Compressors. Only rotating parts. No reciprocating parts.

[@musik12]

Do you have any channel or video where I can see this compressor?

[@darrenconway8117]

@@musik12 en.wikipedia.org/wiki/Guided-rotor_compressor

[@musik12]

@@darrenconway8117 Ok, I found it on Wikipedia, I thought someone might have already done it in small sizes. Even so, thanks for your answer, hugs

[@darrenconway8117]

@@musik12 The GRC is scalable. On full size compressors the rollers are often semi-hard, low friction, plastic for zero lubricant applications. The housing really needs to be machined with a CNC mill, but an easy job for a CNC mill. Development of the GRC is published in a University paper somewhere. If you have access to a CNC mill, this would be scalable to small sizes.

[@musik12]

@@darrenconway8117 Ohh, ok, yes I have a small CNC like that for a very low price lol, but it works very well if you don't need high precision. I'm going to look for this project and try to do it on a small scale. I have no knowledge of engineering or mechanics or anything lol. But I'm quite curious and maybe I can do it. Thanks. Cheers

[@micultimy91]

Next step is to make a 3D printed head with custom valves. I highly recommend EPDM rubber sheets as they are durable, but they are also expensive. Otherwise soft silicone cooking mat can do the trick. Can't wait to see other videos about this topic.

[@DiffractionLimited]

Though about that too. But the valve head might get quite warm so a resistant filament material needs to be used + It should be air tight, which can be done by submerging the print in a special sealing fluid as I learned recently. The rubber sheet is a good tip and in the valveheads shown here a similar flat rubbery material is used. The construction is actually quite simple.

[@revilolavinruf]

At the beginning I was convinced this was going to be a waste of time, however I'm extremely impressed! I'd love to see a durability test on it! I'd love to know what the duty cycle would be!

[@patrickd9551]

Yeah I've clicked on three random points and saw the demo. Which part impressed you specifically? I wasn't really impressed by pressuring a small piece of tubing. That is if you have a basic understanding of compressors.

[@Ayce47]

First video i ever saw from you. Subscribed! loved this video!

[@Ayce47]

One thing i didn't catch, what assures the timing of the pistons?

[@DiffractionLimited]

Thank you. And the only thing important is that they are 180° out of phase which is guaranteed by the holes and the steel pins in the crank shaft.

[@killer120070507]

Amazingly done

[@WillBelden]

As a full-time RVer who keeps his toyhauler fifth wheel triple axle tires at 95PSI, and doesn't want to pay for ViaAir, you might have a market. I had a Ryobi (meh, but I don't have Dewalt tools), that could do the tires, but I let it run too long one day and now it can't do that kind of pressure anymore. You could have a market, sir.

[@stillness0072]

Impressive

[@helmutzollner5496]

Very impressive. Love the slow speed and low noise aspect of it. It is a great unit, I would like to have. However, I am not a maker. Would it be ok to get the components printed at JLCPCB. I think I could handle the assembly if I had the kit. However, as important tools tend to fail when you need them most, I would prefer to see this unit made 24x7 capable to consider buying it. What would it take to harden it for 24x7 operation? I guess the rubber ring valves would be primary wear parts? What else, the excenter pieces inside the crankshaft bearings? The check valves?

[@DiffractionLimited]

Hard to tell, I also have to gain some experience with this thing because I havent done anything similar before.

[@JavierChiappa]

This would be great to build a Stillsuit from dune, you could have a butane cooling system in your backpack, that not only keeps you cool in the desert heat, but also condenses moisture from the air and make water.

[@TheMadManPlace]

I have to wonder if this basic concept can be modified to be a vacuum pump... Need one for a vacuum table for my CNC mill. It does not have to be a very high volume but needs to supply a decent level of vacuum for long periods so maybe using printed parts is a step too far? Also, lubricating the piston will need to be looked at... This unit will need manual lubrication at quite short intervals otherwise the rings are going to overheat and melt at some point.

[@IhabFahmy]

_Cool! The initial lubrication of the cylinglder wall is fine... but how are you going to keep it lubricated during operation ?_

[@stefanguiton]

Excellent work!

[@DiffractionLimited]

Thanks

[@DgtalBreakz]

I believe with a simple under piston oiling system driven by the same motor as the compressor the build would be quite reliable.

[@AnnaVannieuwenhuyse]

that would work for solid machined parts, yes.

[@DgtalBreakz]

@@AnnaVannieuwenhuyse considering the pistons are running inside a metal cylinder, and the o-rings dont really have any relative movement to the 3D printed pistons, then yeah, Id say it would work quite reliably with continuous oil supply. Maybe a gravity fed oiling system running the compressor upside down and a filter of some kind at the exit to prevent oil contamination of the supplied air.

[@laurentcnc6662]

Very great Job !

[@Nyson]

very nicely done

[@joshua43214]

Pretty cool. Some major concerns though. It needs lube, how do you plan to keep it lubed? How do you plan to keep it from melting? PV = nRT, so as Pressure goes up, Temperature must also go up since Volume will remain constant (V will equal displacement). And yes, 10Bar will mean 10x temp per stroke. You will have to run it at very low RPM to dissipate that much energy. There is a reason even the tiniest compressors have cooling fins...

[@DiffractionLimited]

I plan to use it on pretty low duty cycle. But yes long term lubrication is an open problem. Ideas for improvments are very welcome. As for the heat I hope that some of it is still in the gas as it leaves the compressor and eventually I might add a small fan or two if it becomes a problem.

[@dimtt2]

The concept that the piston and "piston arm" aka con-rod are only subjected to compression forces is fundamentally wrong. They are most likely subjected to significant elongation forces during almost half of the upstroke as the piston decelerates to a stop at tdc and half of the downstroke as it accelerates from tdc. Depending on the rpm,bore,stroke and the pressure that the air is being compressed to, these opposing forces are somewhat cancelled out. But in practice the inertial forces are usually a lot lot higher than the force generated by the pressure which begins at zero and builds up. To quantify things a little these elongating decelerations and accelerations can be of a magnitude of a few hundreds to thousands of g's even for a couple of 1000's of rpm of the crankshaft.

[@DiffractionLimited]

Thank your for the constructive feedback. I am not sure though, that the Problem you are describing applies to this construction, so lets quickly run the numbers (SI-Units) for an unpressurized cylinder (worst case) to see whats going on: * 1000rpm crankshaft speed is about 17s rev per seconds. * The vertical travel of the piston is 0.01m. * The vertical movement (y) of the piston can be approximated by a sinusoidal motion: y = sin(17*t*2*π)*0.01m * The accelleration is the second derivative of the position: y" = -114.093 sin(34 π x) m/s² => so we have a maximum acceleration of 11.6G * Assuming the piston weights about 100g (its probably way less) we get a maximum accelleration force of F = 0.1kg*114m/(s*s) F = 11.4N [calculation was corrected as pointed out by @giantisopod] Overall I see your point, however the resulting force of 11.4N is still way lower than the 400N compression force due to the compressed air, so I dont think it will be a problem overall nor that the concept is fundamentally wrong. Time will tell if anything fails due to elongation forces and I will keep you up to date... Thanks again for the comment thoug :)

[@giantisopod]

@@DiffractionLimited Did you mean 7.3G rather than 73G? Actually, upon closer inspection, I'm not sure about your value for the second derivative, either. But it was nonetheless interesting to see how you arrived at your conclusion. I'm not an expert at any of this, but it makes sense to me, I'm just not sure about the numbers.

[@DiffractionLimited]

@@giantisopodI was surprised about the high G number too, so I double checked and it actually seems right. Used Wolfram for calculations so I dont think there is an error in the second deriv.

[@giantisopod]

​@@DiffractionLimited The unit for y'' is m/s², and 1 G ≈ 10m/s², so I think you are missing a decimal point :) Wolfram Alpha gives me -114.093*sin(34*π*t) as the second derivative.

[@DiffractionLimited]

@@giantisopodOhh you are totally right. I must have messed up something very bad. I am correcting the comment. Thank you !

[@Zero76606]

Design lends itself to being a W-6 (three banks of two cylinders) pretty readily, should you ever need to dial the output up.

[@BeefIngot]

My good sir this is awesome. My onky thoughts are that youd benefit greatly from getting yourself an ES15, and heat set inerts. Also, what sort of airflow can this thing get at pressure?

[@saxplayingcompnerd]

Use a 3 phase brushless DC motor. Steppers are hella noisy without special driver chips made to be quiet.

[@DiffractionLimited]

It is a 3 phase brushless DC motor (BLDC Motor) !

[@DennisGentry]

@@DiffractionLimited It definitely looks just like a big ol' stepper motor, but I believe you.

[@vex123]

This is excellent work! What type of applications would this specific type of compressor be good for?

[@gangulyrox]

10 bars would burst things into pieces! Truck Tyre Pressure is around 8 bar. (120psi) I cannot trust this design can produce that much amount of pressure. If it produces, it is dangerous and requires regulatory compliance.

[@dustinsackett3419]

This is a great video! What did you use to annotate your 3D model for the video?

[@paronzoda]

I love it!

[@titisimamora4755]

Small and powerfull,

[@DanVogt]

You should make a submersible!

[@k1zmt]

This is the first non-industrial grade compressor that actually capable to reach more 100psi. I bought a few electric ones that supposed put air into bicycle and car tires and all of them stop pumping at around 50-60 psi. I had to return all of them. Also, one battery powered even caught on fire. I would recommend you to commercialize your product and sell.

[@DiffractionLimited]

Thank you, but I think its far from being a product and I'd rather see the community use and improve upon it for free...

[@strangestuff1213]

Ooh nice, nice !!!

[@Nathan0A]

Very cool project but I lost it when the AI voice said “Ta Loud, Ta Big”

[@nerddub]

yerah that threw me off too

[@chris_piss]

Oh is it an AI voice? I just thought the dude was really nerdy or something lol

[@hristopopov7468]

Another brilliant video/project. Thanks. Now as you have the air supply, can we have an in-depth video on the air bearing, please :) Jokes aside, did you considered a repurposed refrigerator compressor as an alternative?

[@DiffractionLimited]

I am currently working on some changes on the air bearing to make it easier to manufacture - hence the delay... but it will come. As for the fridge compressors: Yes they are quite low noise and relient, but all the ones I know are filled with oil. Quite a lot of it can make it to the air outlet. But with a filter they might be a good alternative.

[@JulianMakes]

Incredible! Don’t the piston parts get too hot? Very impressive

[@DiffractionLimited]

Eventualy I guess they would, when running at higher rpm and at high pressure. However I think a small fan at each cyclinder would help quite a lot in that case.

[@JulianMakes]

@@DiffractionLimited it’s a beautiful design. Well done!

[@KarlMiller]

What about duty cycle? What kind of applications are good for this compressor design?

[@SuperBadBoyscout]

How many LPM is it? Thanks for sharing...

[@Xsiondu]

Subscribed. Also any recommendations for resources written about designing devices to be silent?

[@Rollmops94]

How did you design the gasket? What thoughts went into that? 4:13 Here it looks as if the right rubber ring is not sealing. Is the plastic piston itself sealing? Do you use formulas to calculate the geometry of these bodies?

[@Rollmops94]

Also: Why is the rubber seal u-shaped? And why is the piston upside-down cone-shaped?

[@megajoey1923]

Hi, as the other person said I love the idea of using screws to hold the bearings in place. I know in your video you said that the check valve was not shown properly but I downloaded the fusion 360 file and was wondering how the check valves work, and if it would be possible to get the files for them?

[@DiffractionLimited]

Thanks. I plan to add the inner workings of the check valves to the CAD in near future and maybo make a supplemental video to this one too, where I show how htey work. Its essentially just a springloaded rubber pad on a hole.

[@megajoey1923]

@@DiffractionLimited Thats awesome thank you for the reply! I will subscribe and wait to see it!

[@Ulm26m]

The design of the compressor is outstanding. At the moment I am printing the parts. Has anyone found a source for the other parts? I am looking especially for the seals and the pistonheads.

[@DiffractionLimited]

Nice, let me know how it worked out or add an issue to the github if you find some problems. I actually migh do a video on the parts you mentioned. As for the Cylinderpipes a good source are gassprings. You hace to open them up (which can be dangourous without the proper technique due to very pressure and oil) and then slice off rings. By design the inside is made to be a very smooth and a durable surface for seals. As for the seals them self search for 'Piston U-Seals' make sure they do not have a steel core. Also be aware that they have to be slightly oversized for the cylinder bore to seal properly. Good luck with your build !

[@Ulm26m]

Hello, I googled around the last days, but until now I was not able to find the mentioned seals in the needed dimensions. Do you remember, where you bought your parts? Also the cylinder heads. The 3D-printed parts worked out so far, the tolerances are a bit snug. Maybe a version of the parts with some larger tolerances would be helpful for a lot of people.

[@DiffractionLimited]

@@Ulm26mAs mentioned in the video I got the cylinde heads and seals from a cheap air compressors for car tires and alike. But I also bought some U-Seals from ebay as replacement. The OD can be a bit larger so you have some tolerance and should be able to finde some appropiate seals.

[@DiffractionLimited]

Bit I think the best order would be to look for cylinder - then for the seals - then adapt the CAD accordingly and then print the parts.

[@Dr.420]

How much CFM or volume can it push at the 90-120psi mark?

[@TheTurpin1234]

I really wanna see the volumetric output of this hoooked up to a small air tank. I would do anything to have a quiet compressor without spending $1000

[@DiffractionLimited]

Well then this thing might be for you. How would you measure it? Would the pressure over time given the tank volume be sufficient?

[@joshua43214]

@@DiffractionLimited You would measure it with a... Flow Meter. One of those things that looks like a glass tube with a ball floating in it.

[@sjoroverpirat]

I wonder how it would be to scale, Inline 12 for example

[@DiffractionLimited]

It should scale well, but you may need a thicker crank shaft and one or more supporting shaft bearings in the middle at some point. But it would also run smoother with more cylinders.

[@sjoroverpirat]

@@DiffractionLimited do you have any idea of its output?

[@Boris161]

Having it using a BLDC motor + speed control makes it even more quiet! Could it work also as a vacuum pump (using an other piston design, mirrored from the one you have)?

[@DiffractionLimited]

Yes sure. Then it would only have to work against 1 bar not 10 so you could increase the volume or reduce the belt reduction ration. However you would reach a very deep vaccuum because ther will be a certain dead volume within each cylinder with this design.

[@tobeproduced]

Consider using a scotch yoke instead of allowing your cylinder tilt, otherwise you are going to get uneven wear on your cylinder

[@brydenquirk1176]

The stepper is an extremely odd choice for a vacuum pump... unless its to be driven by a 3d printer board as part of a cnc machine of some kind

[@DiffractionLimited]

You are right, the motor looks very similar to a stepper motor but actually is Brushless Direct Current Motor (BLDC) with the same formfactor (NEMA23). Such a motor is well suited for the application.

[@1marcelfilms]

Now operate it until failure

[@zggtf211]

Would it be possible to seal the case and have a second one supply air to it, kind of like a 2.stage system?

[@DiffractionLimited]

I think in that case you would want to use a classical seal at the piston and a dedicated intake check valve in the valve head. Seems much easier than sealing the entire compressor body.

[@swecreations]

You really need a better microphone, the rest of the video is so good so it's sad that the sound quality is so poor. Edit: It seems to have quite a bit of sound artifacts, and the audio from you building the compressor doesn't seem to be that bad, so maybe it's just something your settings though.

[@DiffractionLimited]

You mean the speach or the actual audio? Note that the speech is generated with the 'bark' text to speach model and not me talking.

[@swecreations]

@@DiffractionLimited I did realize later on that you were probably using text-to-speech, but yes the actual speech. Honestly very impressive how well those sound nowadays, the actual voice itself sounds like a proper voiceover except for those weird artifacts and spikes in the audio. Maybe it's possible to remove those in post?

[@do_not_want_to]

What is the cfm? Approximately?

[@DiffractionLimited]

This depends on many things, but lets say the motor runs at a max speed of 3000rpm. Then we have a 4:1 reduction ratio and get 14ml per rev - this would yield about 10l/min which is 0.35cfm

[@joshmcdonald9176]

Witchcraft!

[@michaelpreston2392]

Now build a screw compressor

[@nin1ten1do]

just rob mama fridge and ejoy 27dbi with 12ATM.. ez púz..

[@nosidenoside2458]

Heh. Negative internal combustion engine.

[@HDFoxra]

While I'm loving the content for this video.. I just can't keep watching it... The AI voice has sharp high frequency screeches going in.. Sounds like wine glasses clinking together or like a sharp knife is trying to "cut" through a wine glass... It seriously hurts the ears and gave me a huge head ache... Other than that, I wish I could continue the video.. I'm so curious and interested, but I just can't live with that screeching sound..

[@davidchavez81]

That will melt into a pile of useless plastic.

[@LabiaLicker]

Subbed! This is really cool. I'd be really interested in what the free air delivery (FAD) is? If its a good then we can scale the amount of compressors. Generally speaking for cheap non-commercial compressors you are stuck with the noisy big bore belt driven units. A Chinese compressor company called Eluan has a different approach, they use these counterfeit German dental compressors originally made by DÜRR. And scale them sometimes up to 6 individual units on a single tank. Its a good design because you just turn on the number of compressors you actually need in order to have tank pressure never decrease i.e it scales with your workload. If the FAD is good enough then these could be used as a small shop compressor. And thats very exciting for an open source compressor.

[@DiffractionLimited]

Interesting. Free air delivery is expected to be about 10l/min which is 0.35cfm (at 3000rpm of the motor). However the piston travel and cylinder bore could be changed for more volume/more pressure.

[@LabiaLicker]

@@DiffractionLimited Yeah the bore and stroke would need to be adjusted. I also wonder about the volumetric efficiency at the intake. Sizing the right diameter to certain rpm for peak efficiency. No different from a ICE.

[@LabiaLicker]

@@DiffractionLimited So typically as a general rule of thumb for piston compressor, FAD will be 2/3 of your theoretical CFM (bore * stroke @ rpm). So free air delivery would be around 0.23cfm or 6.51 l/min.

[@Sillybutts]

Cool