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OT-homemade air compressors

Goatwhiskers

Aluminum
Joined
Dec 30, 2004
Location
Batchelor, La. 70715
Probably trying to reinvent the wheel here. Got a Campbell that absolutely screams when it kicks on and I'd like to utilize the tank to make something very quiet to use inside my workshop. I have read of folks using refrigerator or freezer compressors, in fact at least one company produces such, but in making one how would you know the CFM? I need about 2cfm. Also heard of using a rotary automotive A/C compressor but I have concerns about the lubrication. Any of you guys have any knowledge on the subject?
 
My dad built a compressor using a refridgerator compressor. We used it for years. It would pump up to 120psi but it took a little while but not realy too bad. The tank was about thirty gallons. It was mainly used for tires and blowing stuff off in the shop. It was as quite as fridge!! The round compressor thing was about 10 or 12 inches in diameter.
 
The early AC compressors could be made into air compressors because they were self lubricating. New AC compressors rely on a closed loop system whereby the lubrication circulates. Therefore kinda tough to make air comp. out of new type AC compressor. Always seems to be a used air compressor pump at the flea market.
 
Goatwhiskers,

This does not answer your question but I'd like to comment about this portion of your post:

"...Got a Campbell that absolutely screams when it kicks on..."

One thing that compressor manufacturers do to "inexpensively" increase CFM is to use the same pump but increase the speed. This results in substantial noise! I don’t know what CFM your present compressor delivers, but if it's more than the 2 CFM you want, you might consider decreasing the speed. Try a larger pulley on the pump or, if possible, reduce the size of the pulley on the motor.
 
Mike, oh how I wish I could. The thing is a direct drive, high speed motor, with a squirrel cage type fan inside the housing. You can't stay in the garage when it kicks on.
 
Do not know how to build one, but have an incredibly quiet one. It is a little thing, Swiss I think, used by professional airbrushers and the like. It looks a lot like a fridge unit, and sounds even less.

No idea of cubes per min, but I took a giant-ass* extra tank and hooked it up. Takes forever to fill, but that is okay since I only use it sporadically to blow chips. Full tank lasts a while.

Suppose I could look closer at it later. Is that a viable alternative?

*around 1.5 ft diam x 2.5 ft tall.
 
Goatwhiskers,

It sounds like you have an "oilless" compressor. Those things have a kind of reciprocating bladder that makes horrible noise. They are inexpensive, loud, and don't last very long.

The next step up is something like an Emglo portable compressor which is commonly used on construction sites. They are compact, use oil lubrication, and are not as noisy. I think typical output is around 4cfm at 90psi.

The ideal stationary shop compressor will have a motor separate from the compressor unit, with a pulley and vee belt drive. With that, you can cahge the speed to suit your needs. You can buy separate compressor units at places like Surplus Center:
http://surpluscenter.com/item.asp?UID=2006030913120502&item=4-1470&catname=

Maybe you can salvage parts from your Campbell unit to make a complete system. Aside from the regulator, you will need an automatic pressure sensitive switch:
http://surpluscenter.com/item.asp?UID=2006030913120502&item=11-3042-A&catname=air

Also (very important for safety), you will need a "popoff valve" to release air if the pressure gets too high. There should be one of these on your tank already.

I think thread is on topic. There was a previous discussion abut this last year, when I found such a homemade system which I now use:
http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=1;t=014537
 
My current compressor is a homemade unit. '70s Craftsman 20-gallon tank, stock plumbing, Square-D pressure switch, Home Despot wheels. The pump is a small one-lunger I my father found somewhere years ago.

I originally had a 1/2HP 1750RPM motor driving the pump for a few years. It was very quiet, but I needed more oomph so I put a 1HP, 3540 motor.

Building a new one has been on the Round-Tuit list for a while. I have a couple of '50s stationary 20 gallon tanks (with neat cast iron legs) plus some nice pumps like a Kellogg and Champion.
 
Goat......if you were located in California, I could set you up with a suitably quiet compressor easily enough....oh, well....

Except for some really expensive compressors intended for dental operatories and suchlike, there's no such thing as a noiseless compressor pump of course.....but its not at all difficult to set up a low-noise compressor if your air needs are relatively modest.

Look on your local 'Craig's list', your local advertising papers, etc., and find yourself one of the smaller of the old real industrial grade of compressor pumps. There were several good makes of those, such as Quincy, DeVilbiss, Kellogg-American, Curtis, and some others.

Be sure that the tank you intend to use is an 'ASME' tagged tank, marked for 200psi working perssure, and in good condition....its rare that old rusty tanks actually 'blow up', but you really don't want to take any chances.....there are some real 'horror stories' about tank failures.

Make up a mounting plate from two or three laminations of 1" plywood, and set up your compressor pump with a 3/4 or 1hp (old rating) 1750 motor, using the smallest v-belt pulley you can get for your motor, so that the pump will run relatively slowly.

Use thick resilent rubber cushions between the motor/pump mounting board, and the floor, putting the compressor under a bench (if you can't have it outside in a little doghouse)

On the intake side of the compressor pump, fit a length of rubber hose of suitable size, going to an ordinary small car muffler...the intake pulsations of a compressor are the primary source of compressor noise.... put the air cleaner on the other side of the muffler (use a clean new muffler, obviously)

Run a suitable length of copper tubing to the air tank, with a coil or two formed in the tubing to allow some flexibility, so that the tubing won't break at the fittings from vibration....

I've set up a few compressors like this, for various friends, one time and another....a setup like this will work for inflating tires, using a blow-nozzle for cleaning, or running a light detail gun, spraying lacquer or well-thinned primer.....it won't provide enough cfm to use air drills, DA sanders, nut-runners, etc., for more than a very few minutes at a time.

Wire the motor to the pressure switch on the tank, verify for a certainty that the switch opens and stops the motor at *no more than* 120psi for a single-stage pump, or 175psi for a two-stage unit..... and, as the old saying goes...'Bob's your uncle'.... : )

cheers

Carla
 
For about 15 years I have used a homemade air compressor built from a Copeland 1 hp refrigeration compressor from a junked ice machine, mounted on a salvaged 100 pound propane tank. Copeland units have a motor directly coupled to the 2-cylinder compressor, will easily go to over 100 p.s.i. and are fairly quiet. I have another air compressor that I put together using an older style crankcase-type York air conditioner compressor from an auto junkyard, they were common on Ford cars during the 60's-70's. This one is belt driven at about 575 rpm by a 1 hp motor and works fine, but is noiser than the Copeland. Also an automotive compressor has an electric clutch built into the drive pulley, so you would need to either have a 12 volt DC power supply to activate it, or remove the solenoid and bolt the 2 halves of the clutch assembly together.

Mike
 
ALternative #1 is a sealed unit refrig compressor with a verticle rise of a few feet where the line exits to let oil drain back into the compressor between blows. I don't know if this works on all of them, but I used the compressor out of a large window unit for years that way, ading a bit of plain ol' oil direct to the line from time to time. It was still running when I sold the shop some years later. ALternative #2 if you don't use much air is either a bottle of industrial air or co2.with a proper regulator. I just finished building the complete shell of a 1000 square house with a framing nail gun and only swithched 50 pound tanks once, and that was after we forgot to shut off the main valve one nigh and the quick coupler hissed all night.....Joe
 
While we are on the subject of building your own air compressor system I have a question. I aquired from work a very large 2 cylinder Ingersol Rand Vacuume pump. It looks like converting this to a Air Compressor is just a matter of switching the inlet with the outlet. Will this work? If it will work I was thinking about driving it with a couple of import 5hp single phase motors.
 
Jon Spear, I bought a junk Campbell oilless and I don't think it has any kind of bladder. It has a rod and piston that runs dry. There is no crankcase bottom under the cylinder, just a little plastic cooling fan. Are there 2 different types of oilless? James
 
There are two kinds of oilless compressors. Smaller ones (like medical and airbrush) use a dished metal diaphraghm that's popped back and forth. They're not bad, really, but they don't make much air.

The other type uses a dry cylinder, a wobbling piston with a teflon ring, and prayers. I can't stand the things. I have a portable CH contractor unit that a guy threw out I'm going to repair one of these days, but it's probably deafening when running.
 
J. Randall, I don't remember exactly what I saw when I dissected the oilless compressor. I thought there was a bladder, but I might be wrong. If there was a piston, I think it was short and fat. What John in MA wrote sounds correct to me. Sorry for not being more knowledgeable. My first compressor was oilless, high pitched, and loud---probably very similar to yours.
 
Jon, I think that describes mine pretty well, short wobbly piston, runs dry. John I may fix mine one of the days to, but will probably pass it on to someone else. James
 
I have a small air compressor that I use for pumping up tires and such. It's made from a used 3.5HP B&S vertical shaft lawnmower engine with a modified cylinder head to increase the compression ratio enough to get about 60PSI max. It's driven with a 1/3HP motor from a washing machine. The hose serves as the "tank" It's not much to look at:
000_1269.jpg

But, it's served faithfully since 1970 with no maintenance whatsoever. It's even got the original used oil in it.

I did install a longer tank a while back, though. Got tired of lugging it around the truck.


Roger
 
Winchman, on the B&S compressor - how did you deal with the valve timing - or are you using a 1-way valve in the sparkplug hole and ignoring the exhaust valve?

Just maudlin curiouslity - I have 3 compressors here already but do appreciate macGyver engineering...8*)

alan
 
I built one 22 years ago from a scrap freezer from the local store. It had a perfect compressor in it, the kind with the motor on the end and it has oil lube that i can fill. I got an air tank from the wrecking yard off of a semi truck. I only have 15 bucks in a switch...Bob
 








 
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