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DYI Airbrush Compressor

DIY: Homemade Airbrush Compressor

I’ve been surfing the net the other day trying to find some airbrush compressors and found out theavailability is very good so anyone can buy airbrush compressor online with no hassle. Of coursefor a good one you will have to pay nice bunch of money. But at the same time I found reallyinteresting solution for those of you that prefer some DIY over shopping.

If you build it yourself it will help you to save some money. The whole “know-how” comes from aRussian website so I will become translator for a while. The main issue for all the airbrush artists isthe right air pressure at the input of the airbrush gun. One of my issues at the start was money so Iwas looking for a simple and at the same time cheap solution. As you probably already figured outairbrush won’t work without compressor. I knew that there is one kind of compressor that most of uscan get for free or for a very little money. All I needed was just to find the way how to use it. Whatkind of compressor am I talking about? …I’ll tell you later.

For now you can follow these steps:

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Surgery

Preparation

Utilization

Maintenance

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There is many places like basements, scrap yards, trash bins – places were people put the stuffthey are not going to use anymore. All you have to do is to look for a big, usually white box calledFRIDGE .

Yes, you’re right. Every fridge has a compressor, even the broken one. If you go to search fora big white box don’t forget to take some tools; usually couple of screw drivers with different heads,some combined pliers and spanner set as the size of dies in fridge can vary. If you’ve found yourpatient you can start the second step.

Surgery

You don’t have to be a doctor to do that but you have to be careful and avoid any problems causedby carelessness. First what you have to do is to cut off the copper pipes from fridge radiator.

DO NOT SAW IT!!! The sawdust would get into the pipes and your compressor will become “sick”and die after a very short time.

Use only pliers and try to keep the pipes as long as possible as after all every cm matters. Thepliers will squeeze up the pipes at their ends and this will also prevent oil leak during the transport.Some types of compressors used to have a metal plate with numbers sticked to pipes – do not takeit off.

At this point it is good to check the oil inside our trophy. Pour some oil on a piece of white paper. Ifyou see any silver particles in the oil you can stop the whole operation and memorialize the poor guywith a minute of silence. If the oil is clean you’re good to go.

Very important thing – the compressor is not the only one big piece of metal junk you’re going need.

We will need one more part – start relay. It’s small black or sometimes white caddy separatelymounted near compressor. It has some cables connected to it.

I would recommend to make a drawing of how it was mounted and connected before you take it off.

Some types of compressors have their relay directly on them, so you won’t need to unmount it. Butyou surely will have to cut of two input cables.

Once you have unmounted everything don’t forget to take all the pieces with you.

Preparation

At this point you have to arrive home. Tired, dirty from oil and perhaps with some scratches but itdoes not matter because you have the trophy .

Now first of all you have to check if your compressor is still alive. We have to do the launchcheck.

DO NOT turn it on now – READ FIRST!

Put the relay back on the compressor according to your drawing you’ve made before. Relay has tobe oriented exactly the same way as it was on the fridge as the relay depends on earth gravitation.Otherwise it may cost you the relay or even the engine inside the compressor might burnout.

Now connect the temporary cradle to the input of the relay and don’t forget to use electrical tape. Idon’t think you want to die. This is how the draft version looks like:

Next use the pliers and release the squeezed pipes andleave them opened. When everything is ready connect theplug into the mains socket. The launch itself could be veryloud depending on the power of the unit but itunderstandable so don’t get scared. If you hear the engineand it is pretty quiet then everything should be fine. Thepipes will suck and blow the air – you have to find out whichone deos what. You don’t have to leave it on for a very longtime as the main thing right now is to make sure that it isalive. If the engine didn’t start or if it started but than after

short time went off the things aren’t looking good. If youhave some experience and electric multimeter you cancheck what exactly is wrong and more skilled of you couldeven try to fix it. Otherwise forget about the whole thing andstart looking for another one. If it’s working skip thechecking process.

Checking: Take off the relay and check the coils of engine for short circuit. Theyshould have a small resistance between them even in different combinations. If atleast one of the coil doesn’t show anything it means that we hold a dead body ofthe compressor. If every coil has some resistance you have to check the relay andclean it. Carefully open the relay box and clean the contacts with fine sand paper.DO NOT BEND OR BREAK THEM!!! And do not grind them to much. Now closeit back and try the whole launch again. If it didn’t start or if it keeps going off byitself than I’m very sorry about that (if you are not using original relay from anotherfridge then switching off can be caused by engine being too powerful for the relayand you have to look for another relay – that’s why you ment to keep the metalplate on the pipes, it will help you to find the specific relay for your engine).

I hope that you didn’t get into any trouble and everything is working. Now we can start to build ourmachine. Everyone has his own equipment, facilities and resources but I’m going to point out whatyou’re going to need.

Visit your closest car parts shop and buy this:

1L of motor oil 10w40 or other semi-synthetic motor oil. If you can get a 500ml package it isgoing to be enough.

oil and fuel resistant durable armed rubber hose about 1m long and 4mm of inside diameter. Itwon’t hurt to take a small piece of copper pipe to try it on in the shop just to be sure.

6 metal hose clamps for the rubber hose with diameter just a little bit bigger than the hose.PVC hose for windshield screen washer. It’s half transparent hose (some are even armed butwe don’t need those). Choose your own length as your comfort will depend on it. I wouldrecommend at least 2m.

Two filters for fuel filtering – one for petrol (gasoline) and one for diesel fuel. Visually they aredifferent as petrol has a paper harmonica inside while the diesel one has a synthetic net.

thick silicon (oil and fuel resistant) sealant. Thin, black silicon sealant is not very good for thejob.

Than go to electrical shop and buy :

power cable with double isolation and at least 1.5m long.

on/off switch closed type

lag screws size 3.5×16 or 3×16

That’s all you will need at the moment:

Next we have to change the oil. Why?Read next article on this topic.

At this stage there is a technicalquestion: Which type of compressordo you have in your hands? By shapethere is two types – cylindrical andcasserole type. First one is practicallyextinct as production of this typestopped at the end of 70s, but if youmanage to find one and it’s alive youare very lucky. The pressure on itsoutput is higher than on casseroletype. So how do we change the oil?The cylindric one has a big screw-bolt. Unscrew it and drain out the oilinto some bowl so you can later measure the volume of the oil. Depending on the type of cylinder itmight be something between 300ml and 500ml. Then screw the bolt back and don’t forget to seal itusing silicon sealant.

With the casserole type it is a bit more complicated as there is 3 pipes sticking out of it. Two arepumping the air in and out, the third one is for oil. Again do not saw the pipe!!! And remember afteryou have drained the oil out do not turn the compressor on, you have to pour the new oil in first.

On the second picture isthe same compressorhowever a bit restored andwith new oil already in. Asyou can see I’ve usedrubber hose on the oil pipeoutlet.

For this type of compressoryou will need about 250 –350 ml of oil. After thatscrew the lag screw intorubber hose and put somerubber seal under thescrew.

I know that there are goingto be some people that aregoing to feed the oil tocompressor during the run. Ido not recommend to dothat.

Oil has to be changed before you turn on the compressor as running it without oil is the sameas to kill it right away.

Second of all if you pour to much oil (in pistons mechanics) you risk something called hydraulic hit.It happens when into space above the piston comes more fluid that it can compress (fluids arealmost not compressable). As result we destroy the whole piston system. I hope you get the point.

Lets continue. On the next image you can see how it is going to be set.

If you connect everything according to this drawing you’re going to get fully working airbrushcompressor. To make it more practical you have to fix everything on some kind of stand or table thatwill minimize the possibility of breaking it. I have used a piece of timber board. The size of the boarddepends on the size of the receiver you are going to use. Receiver is a big white bottle you haveseen on the photos. Why do we need it?

It smoothes the pulsation of air coming from compressor so at the output you will get a smoothfluent flow of air without pulsation.

It also catches the drops of oil and exhaust from compressor.

For this type of compressor we will need receiver with capacity of 1 – 2l. Practically you can use anyhermetically firmed reservoir. I would not recommend to use plastic or glass bottles as under thepressure they can blow off and cause injury. I’ve seen some people using an old empty fireextinguisher as the receiver but it requires more skills and tools to accomplish something like that. Inour case we use old water reservoir from a car. It is made of polyethylene that is more firm that theplastic bottle and it’s hard to destroy even with sharp knife. Even if it blows off it does not make amassive explosion as for example glass does.

How to make a receiver? When you have your bottle ready take the lid off and drill two holes into it. Ifyou can get 2 copper pipes something like 15cm each (if the pipes on the compressor are longenough you can cut those off but leave at least 10cm on the compressor). These pipes are supposeto fit into holes on the lid you’ve drilled before. After fitting put some epoxy resin on the inside of thelid but not too much so you can screw the lid back on the bottle. Do that only when the epoxy is dry.Don’t forget to use some silicon sealant between the bottle and the lid. When you will be fitting thepipes make sure they are very close and their ends are exactly as on the drawing (output pipe isshorter and the end is positioned higher).

After you have all the parts ready you can see what size of board will you need for the chassis. Don’tforget that compressor needs some cooling so leave some more space around it. I used timberboard with size of 30cmx40cm. The finish of the panel is up to your own taste. I’ve also used rubberpads to prevent the stand from moving during the work process and it absorbs the noise as well. Ihope you didn’t forget all the screws at the crime scene as now you’ll need them to mount yourcompressor to the timber board.

I would recommend to mount the receiver exactly as you see below:

of course as belt you can use anything,for example rubber, leather but it hasto be firm.

And here is an example of how to fitthe relay, switch and cable:

When you finish with the electrical part we’re going to fit the pneumatic system. At the inlet of thecompressor we connect petrol (gasoline) fuel filter using short rubber hose and 2 metal clamps.Someone might say this is useless but I say go for it anyway, it’s cheap and you won’t have to worryabout dust getting into your compressor. Very important thing is not to get any oil into that filter as itwon’t do any filtering anymore.

Next, with a piece of rubber hose and other two clamps connect output pipe of the compressor withinput of receiver. On the output of receiver put another piece of hose and fix it with a clamp andother end of it will hold diesel fuel filter fixed with last clamp we have left. Be very careful when fittingthe receiver and make sure you don’t break the lid.

Diesel filter is almost last element of our unit. Now fit the PVC hose. Usually the diameter of thathose is smaller then output of the filter so it is very difficult to put it on. If you have white spirit put theend of the hose into it but not deep (5mm is enough). After that it won’t be a problem to fit that hose.Fit the hose to timber board and it’s done. Congratulations if it works well, but I would recommend tostart using it only after couple of days after silicon sealant is completely dry.

Utilization

Nothing special about that.

The only thing to remember – do not let your compressor to overheat.

Usually the temperature rises to 40-45°C in 25-30 minutes of continuous work. After that time youshould let the compressor take a break. Otherwise you will have to regulate the air pressure.Some types of compressor can produce more air than we need for airbrushing. In that case we willhave over-pressure in the hoses, filters and receiver and the compressor itself will be overloaded

what can lead to fast overheating. If this is the case, you’ll have to get a reducer. The reducer has tobe placed on the input of the compressor not output, as that would also cause overloading. Byplacing the reducer on the input we reduce the capacity of the air coming in – that regulates thepressure. So what can we use as the reducer? Any calibration pipe placed on the input of petrolfilter will work as reducer. You can make one yourself or visit pet shop and buy an aquarium valvereducer. It’s cheap and very useful as you can regulate the pressure during the work.

Maintenance

This process is not complicated but to do so you will have to take off some parts. Of course youdon’t have to maintain at all but it will definitely extent your compressor life.

The steps you have to follow:

Changing the oil

Changing the filters

Cleaning of the receiver

Oil, even the best one, is loosing its properties and goes dirty with the time. So regardless ofworked hours I recommend to change oil once a year.

When you’re going to do that, take off the compressor all the hoses, unscrew the screw from thefilling pipe, drain the oil out and pour new one in as you did during the build. Remember not to turn iton when it’s empty. While you have all of the hoses off exchange also filters and drain the oil if anyfrom receiver. Do not pour that oil back into compressor.

Fit everything back and that’s it.

The End!