Building a "silent" air compressor

[rc-eflyer]

I just started a project that I thought some might find helpful and thought why not make a thread documenting my success or failure.  The one thing that I hate when airbrushing is the noise when the compressor kicks on.  My setup is pretty simple with an old Coleman "oil less" (meaning annoyingly LOUD) compressor with a 2.5 Gallon tank feeding into a Freon bottle with a conversion kit for holding air, and this feeds a water trap and regulator for the airbrush.

After doing some research on Google (where else, right?) I found the quietest compressor is the type used in your good old refrigerator. Bad news is, that type on a commercially available air compressor is around $600 US.  Good news is, you can search "DIY silent air compressor" and find lots of helpful info and videos on making your own for MUCH less. In my case I'll be using everything on the old unit except the compressor and motor that drives it.

Anyway, that's what I'm attempting and I'll post updates with pictures when I have something to show.  As of now I have ordered a 1/3 hp refrigerator compressor for $150 US shipped to my house.  Still this will be MUCH cheaper and more fun (I hope :rolleyes: ) than buying one.

Anyone who has done this or has ideas, PLEASE chime in, Thanks

Steve

[rc-eflyer]

RE: Building a "silent" air compressor

The compressor arrived today and seems all is good (shipping wise). The top 2 copper tubes are the intake (suction) side and the smaller one
on the bottom right is the output (pressure) side.

.

Here's all the electrical connections. Spade at top center of picture is ground, the spade to the left of the copper coil (start relay) is line
and the one on the bottom left little component (overload protector) is neutral wire.

[WintrSol]

RE: Building a "silent" air compressor

Interesting; hope it works. How do you plan to keep the compressor lubricated? Also, these are high-pressure and low volume, so your regulation has to be good.

[rc-eflyer]

RE: Building a "silent" air compressor

Interesting; hope it works. How do you plan to keep the compressor lubricated? Also, these are high-pressure and low volume, so your regulation has to be good.

That shouldn't be a problem from what I've read. It will lose oil over time but with my useage I don't think it will be a problem, hopefully. If you buy a commercially available (very expensive) one, they have put a sight-glass on the side and provided a filler plug on the top. One DIY'er actually cut the whole top off right where the little edge is below the factory weld and then made a gasket out of a vacuum cleaner belt to seal it back up so he can add oil. As far as the regulator goes, I'm not using the existing one as I have a good one and a water/oil trap.

Steve
[hr]
A little more progress today, got the old compressor off and unwired.

Before......


After.......


Took some measurements and will make a mounting plate next.

Steve

[rc-eflyer]

RE: Building a "silent" air compressor

Todays progress, Cut an aluminum plate, drilled holes and got it all mounted



Tomorrow, hope to get a 3/8" piece of copper pipe sweated to the pressure outlet. This is a bit of a challenge as the OD of the outlet is .325 and not a standard tubing size.



Here's the "adaptor" I made.Kind of hard to tell, but I took a 5/16" (.3125)drill bit and swagged out the 3/8" copper tubing to fit over the outlet. That should give enough clearance for solder to flow between the 2 pieces. After it is in place I can use a standard compression fitting to attach to the tank.



Today after re-thinking the "adaptor" idea I decided to just go ahead and make the line from the compressor to the tank all one piece. I just swagged out the compressor end slightly and sweat soldered that, made a few bends and used a standard compression fitting at the tank. You can also see the little plastic air filter that was just drilled out to fit the intake line and pressed on, there another one on the other side also.



Here are the final electrical connections to the pressure switch. The top 2 are line common and line hot, the ones below that are motor common and motor hot, and finally at the bottom the grounds are tied together.

[rc-eflyer]

RE: Building a "silent" air compressor

Today was the first test run and everything seems to work. One small problem I'm working on is the unloader valve up on the shut-off switch. When starting with no pressure at all in the tank the valve is a little sticky and not quite closed allowing air to leak out. With as little cfm as these compressors put out this valve has to be very free and clean.  For now I just held it closed long enough to build up a little pressure and then it shut and worked fine.  I'll clean it up and see what happens. If it proves to be a problem I might just eliminate it altogether as these pumps start up under pressure in normal use anyway.

Next, I'm replacing the tank pressure gauge and regulator with better ones I already have.

[rc-eflyer]

RE: Building a "silent" air compressor

FINALLY FINISHED!! ;)
Got the moisture trap, better tank pressure gauge, and regulator mounted and cleaned up the unloader valve with some contact cleaner and everything works just fine.  I decided to leave the old regulator on and use it to limit the pressure in the moisture trap to 80psi. It has a working pressure of 100psi and the cut-off switch is not adjustable(120psi). This also lets me use old regulator as a shut-off valve also.  As you can see in the second picture below the tank has just shut off at 120psi, the moisture traps at 80psi and the airbrush is about 20psi.

All in all I'm very happy with the project. The tank fills from 0psi to 120psi in just a couple of minutes and at around 20-25psi with the airbrush valve fully open you have lots of time (not very scientific, I know :P ) before the compressor kicks back on at 90psi.  Great thing then is, it's so QUIET :cool: you don't care. The check valve in the tank does make a slight noise and that could be improved but really I don't think it's worth the trouble.  I thought about making a short video to show the noise level but that really doesn't mean much as my phone would probably boost the sound and make it meaningless.

Look forward to actually using this contraption in the near future to do some weathering on the FW "Iron Ass" P-51 you see on the bench.

[Grossman56]

RE: Building a "silent" air compressor

Pretty awesome RC!
I have one of those noisy beasts as well as the little stock compressor.  The trouble with those is they're always running,albeit quietly.  The bigger one runs less but rattles your teeth every time it comes on.  I'll have to try this.

Grossman56

[rc-eflyer]

RE: Building a "silent" air compressor

Pretty awesome RC!
I have one of those noisy beasts as well as the little stock compressor.  The trouble with those is they're always running,albeit quietly.  The bigger one runs less but rattles your teeth every time it comes on.  I'll have to try this.

Grossman56

Thanks, if you decide to do it I'd be glad to help.  I hope to actually use it in the near future doing some weathering on Iron Ass.

Steve

[Bill Wakeley Jr.]

Being a slacker on some days, I got tired of my compressor drowning out my new Jimmy Buffett CD. So I emptied the undersink cabinet in the bathroom next door, cut and fit 2" rigid insulation to line the cabinet, and punched a hole in the wall under my work bench. My new Blue Hawk compressor fits snugly under there and now I only get a slight hum and a little vibration when it kicks on. Yes, I am a redneck Parrothead and enjoy myself at every opportunity!

[F22trainer]

My compressor is only used when my tank runs empty...last tank lasted 10 years and it is totally silent.