Introduction: Homemade AirCompressor

Picture of Homemade AirCompressor

This is how to make a cheap aircompressor from parts from the junk yard, for running airtools, filling tires and pneumatic spudguns.

Step 1: Safety

This isn't quite a set of instructions but more like a guide line. Because I made this from scrap, none of the parts are standard. Also take safety into account when working with compressed air, old tanks and rust out and explode with terrible results unless you know what your doing dont make one by one. So if you make one and it bursts and blows off you leg dont come crying to me.

Step 2: The Compressor

Picture of The Compressor
An air compressor has three main parts, a pump, a motor, and a tank. To get these you can go to you local scrap yard, they usually have a few scrapped compressors that can give you a pump and sometime a usable tank, if not with a bit of work you can use a AC compressor from a car, if either of these is unavailable harbor freight tools sells compressor pumps. For a motor you can get one from you local motor repair shop or from a scrapped washing machine, electric lawnmotor, or even a gasoline engine(this one would require a pneumatic clutch). And as for a tank you can use one from a old compressor, but I like propane tanks, you can get from walmart or ameri-gas(amerigas usually have old tanks that have the valves removed I bought my tank for $3)


Markfothebeast (author)2017-10-02

I don't believe I heard anything about a check valve. A compressor pump should have a dedicated line with a check valve. This stops air pressure in the tank from flowing back in to the pump cylinder(s). Without it, the electric motor can draw an immense amount of starting current to fight the compression in the pump cylinder (when the tank is pressurized). It can either set off a breaker and/or potentially damage the motor.

I read several mentions of oil/water separators in the comments. Having a separator on both the pump line and tank output is ideal. However, removing moisture doesn't work as easily as simply installing a separator or two. The hot, compressed air will wizz right through a separator and leave very little, if any moisture. You may find some oil residue inside, though. The air requires a means of cooling before hitting the separator to allow the moisture to be removed. The most effective way of cooling is with a parallel cooler such as an automotive AC condensor (or any AC condensor in general). The separator is just a neat compressor decoration and slowing air flow if it is not serving its purpose.

compressorguy (author)2015-05-28

This thing scares me. It looks like something out of "Mad Max"! Hopefully, this post doesn't encourage careless amateurs to put together their own air brushing machine/accidental IED.

If you're really in need of an air compressor, you can purchase a used or refurbished one from a shop or even online. Look on Craigslist, buy or trade someone for a decent looking set-up, bring it home, and follow these steps to freshen up your air compressor: How to Maintain Your Air Compressor. Change or replace a couple things and it'll be good as new! (And not to mention, far safer than attempting to build your own!)

cdhair (author)2010-01-23

 I think a propane tank is a good choice probably a better choice than a water heater.  Propane tanks are designed with a 5 to 1 safety margin.  If the working pressure is 200 lbs than it is designed to withstand a 1,000 lbs of pressure.   At the low pressures required for air compressor storage I doubt the exploding tank scenario.  Metal is malleable.  I think the metal would tear before it shattered, at these pressures. If the tank does rust over a long period of time a weak spot , probably the bottom of tank, due to condensation would occur.  I think  the worst case scenario is the tank would rupture not explode.  Maybe it would take off like  a rocket for a couple of feet any way. 

sparhawk7 (author)cdhair2014-03-05

i've heard people talking about using CO2 tanks for air compressors and such, and thee only thing i've ever heard anybody day about the water and condensation is to take some good paint and swirl it around in there to cover it all up. otherwise... just be careful guys!

tinker234 (author)2011-06-23

hey could i airbrush with this

sparhawk7 (author)tinker2342014-03-05

i'm assuming you could, as long as you could airbrush with an ordinary air compressor. i got a kit for it at harbor freight for 12 bucks, and it works ok.

sl0j0n (author)2012-09-17

Hello, all.
I know everybody wants to do this as cheaply as possible, BUT.
You *need* to spend a little, to save a lot.
Commercial water traps and oilers are available, used or refurbished.
Pressure relief, and 'pop-off', valves are cheap,
compared to the damage that can occur.
Not to mention the possible injuries.
Cheaper to just oil the intake, regularly.
A water trap, or what "metal_flowboard" said,
will prevent water build-up in the tank.
When I was an industrial maintenance mechanic,
most pneumatic systems used a drain petcock on the tank,
and a watertrap, or two, in the compressor's output line.
One before the tank really helps it last,
and another one before air tools, with proper lubrication keeps them running.
Most of the valves, fittings, etc., can be scrounged or salvaged,
but you *REALLY* need to buy a relief or pop-off valve.

Have a GREAT day, neighbors!

LoneStarWD (author)2011-12-08

Awesome! This is probably the most useful thing that I've found on the internet today.

thesecret-96 (author)2011-08-15

If moisture in the tank is a problem,I've seen some air compressor pumps who's intakes have 1/4 inch threads, why don't you put an air desiccant?

beijing2013 (author)2010-03-25

 nice. would it be possible to use a gokart engine, remove all the gasoline parts and use that as a pump? because down here a gas motor is cheap and i can't find a pump anywhere. and anyone can buy a new compressor. any ideas?

berekleonard (author)beijing20132011-03-15

It's been a year since you posted this question, but I hope it helps someone.

Yes. It is possible to convert an engine into a compressor pump. They are both piston machines working off of the same principles. It is about the same relationship that DC motors and PM generators have. For instance, there are people who convert antique pumps into hit and miss engines.

On the other hand, people have also converted 4-cylinder engines into a pump/motor, "monoblock" combination by making 2 cylinders air pumps and the other 2 cylinders are left to run normally (with ignition mods, etc...)

Pizzapie500 (author)2010-12-26

I was just about to make this but then I got an air compressor for xmas! So happy =)

NATIVEBOY (author)2009-10-13

 could you modify this so you can pressurize wood-gas?

wak166 (author)NATIVEBOY2009-11-11

yes, there is an intake on all air compressord . you need to find it and pipe your synth gas into that . you could use a smaller propane tank and a propane converson kit for you car/truck and fill propane bottles with synth gas. let me know if you do this please .

NATIVEBOY (author)wak1662010-04-13


Rahdzhillaxxx (author)2009-07-12

Adding more tanks in line should increase your capacity VS finding a larger tank

stephenniall (author)2009-05-26

I got two old air compressors Like this one but not as powerful And i did something like this but with my little stationary engine

And i mounted it to a little butane can n made a compressor Not very good thouigh will try to post some pics if ican get some Its hidden away somewhere in the shed as i use my dads new Electronic one Lol its louder But safer

Bender is great (author)2008-10-09

can the motor come from an old air conditioner and how much horse power do you need.

Derin (author)Bender is great2009-02-07

Just for your information:

Esmagamus (author)2008-08-31

Not a bad idea. There's a kit for volkswagen flat four engines that makes one side work as a two cylinder engine and the other as a air compressor.

Derin (author)Esmagamus2008-12-25

Ah-engines are a good idea for the compressor.

dvdhrry (author)2007-12-19

Propane turns into a liquid at a pretty low pressure.. not sure I would use a propane tank at all. However.. I used a hot water tank to expand my air storage capability before I bought a bigger compressor. Hot water tanks are pressure tested to 300 psi at the factory and the pressure relief valves in them are set for 150 psi. As for refrigeration compressors.. they will work for a while as either a compressor or a vacuum pump.. but the lubrication for the compressor flows with the refrigerant thru a closed loop... since you no longer have a closed loop, the compressor will eventually seize do to lack of lubrication. This is an excellant way to recycle tho!

Derin (author)dvdhrry2008-12-25

You could drip some oil in through the intake to oil it...

Derin (author)dvdhrry2008-10-25

that is a great idea...a demirdöküm aden heater would give the tank and a gauge,and you would be able to make your own compressor with pvc

Derin (author)2008-06-26

for the pump,we have a vacuum milking machine AND THE AIR OUTLET IS STANDARD THREADED!!!the problem:the outlet makes a loud sound like a low note on a brass instrument

when we upgrade im using it

Derin (author)Derin2008-10-25

and its 3 phase

Mitten (author)2007-03-07

I saw something like this before with one of those little air dusters used for keyboards. Is it possible that the moisture in the air could rust the inside of the tank, create a weak spot over time and then one day just explode sending shrapnel all over your garadge/workshop

Estwald (author)Mitten2008-08-29

This is why commercially made air compressors have a drain valve on the bottom of the tank. Also the tanks for air brakes have them.

ehmbee (author)Mitten2008-04-30

It could-that's why propane tanks are only used for so many years and replaced-they can rupture, so at minimum i'd place it where it can't hurt anyone, unless you want to work in a Kevlar jumpsuit.

srilyk (author)Mitten2007-07-02

I wouldn't think that 120~ psi would ever be able to explode one of those tanks. As long as you have a pressure relief valve...

NachoMahma (author)Mitten2007-06-12

> Is it possible that the moisture ... weak spot ... explode ... shrapnel
. Very possible! Tanks should be inspected periodicly.

fegundez1 (author)Mitten2007-03-08

you can get a dryer from any refrigeration supply they are used for coolers in stores

treekids (author)2008-04-29

Very interesting. Thanks! Would be cool to use something like this on a bike-like vehicle to store up energy at a stoplight so you can get up to cruising speed quickly. It's inefficient, I know, to store up energy pneumatically, but it's not like I would have done anything else with the potential while I'm just standing there, and I might as well get a little more fit. And besides, the quick cooling from the takeoff would give one a nice source of air conditioning as a reward when the light does go green (assuming the tank is mounted ahead of the rider or you have a fan)

Derin (author)2008-04-24

aka deathblades comment

microman171 (author)2008-04-23

This is definatly a long term plan that I wish to do :D Great instructable. If you put the silica gell (the desicant) would that be good for the moisture? Or would it just go throug the nozzle at high speed?

thermoelectric (author)2008-04-13

I must say, It must be a fun way to get your leg blown off. As i say "Quick and simple"

SWV1787 (author)2008-03-14

now you just need to find an old shopping cart or similar to give it a handle and wheels to lug it around

eastie617 (author)2008-03-08

That's really a good idea, glad to see recycling of parts that would probably never been used again. Keep it up

pandaboy292 (author)2008-02-29

how much did it all cost?

kraken1988 (author)2007-12-21

Excelent. This seems pretty dangerous at first, but hell, I'd try it if I had the parts. I want to make a smaller one for an air cannon, like a spud gun on crack. I won't sleep until I put a hole through 3/4 in plywood with an avocado.

DeathBlade (author)2007-12-20

Propane tanks are rated to 200psi so 120 from the compressor is just fine, as for the switch there are two adjustment nuts inside you adjust the larger one till you get the pressure you want, but first you have to pick a switch with the right amount between start and stop pressures like a 30psi-50psi switch(the 20 psi between the two pressures is preset so it could be 60-80 100-120 etc) As for refrigerator compressors seizing you can add a inline oiler on the intake to get it oil while its running or once you done using it a few squirts of oil down the output and intake.

jolshefsky (author)2007-12-20

How did you hack the well pump switch to hit 90psi?

killerjackalope (author)2007-12-19

This setup seems pretty decent, though it's all a bit puny for my liking, we built 'the daddy' version of this for a few special applications, capable of running 250psi+ (we limited the pressure relief valve to 250psi) But it was simply a twin cylinder pump version of this with an engine that had been ripped out of an old go kart (that was fun till I bent it) and using a belt drive with a significant step up in the drive made 200psi... Engine and pump tweaked it kinda sang, and scared the hell out of all of us due to the massive flywheel used (if it came off you would liken to when helicopters crash in films) Yes we used rated tanks as a reservoir. But there's no reason for you compressor to be no more use than the rubbbish you get from most places now. A good source of engine and drive is a petrol 3/4 or 1 inch shaft drive torque wrench, you can basically make a plug and play engine by using a socket on the end of the drive (eg centre and weld a socket on to the end of the pumps drive axle or cut a spare hole to fit, and then use the same tool to power a go cart or your bicycle... (~500ft/lbs of torque)

iffee (author)2007-12-19

Here in Pakistan people are using compressors from the old refrigerators for the same purpose. Seems cheaper and easy. Have you tried compressor from a refrigerator??

metal_flowboard (author)2007-09-02

if you used the tank upside down, put in a T in the pipe on the inlet/outlet so the air could leave horizontally, then a pipe underneath for the water to drop vertically down into into, with a tap on to drain it ok you would need a small frame to hold the tank up slightly but at least the water wouldn't collect in there, and your tank would stay happy

Steamdnt (author)2007-05-19

yay pricess auto

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