Air Compressor Size Question, How big is big enough? Options

[roblav1]

My old 110V portable Sears unit I bought in 1988 crapped out (piston slap) last summer. I needed 110V and portable given my current shop conditions (big extension cord running to the shop / garage). So I bought this:

IR Garage Mate Small Portable Reciprocating Air Compressor 2 hp

It has almost the same CFM as the old Sears unit, but the larger tank helps. It's also very quiet. Runs paint sprayers and the usual air tools just fine.

[enikolayev]

https://www.youtube.com/watch?v=cfjSm_ieRkE

Air compressor ratings explained. Essentially need a compressor with 4x the CFM rating for the tool you want to run.

[bbrock]

Great advice on size. I will add that I would avoid an "oil-free" air compressor. When I started my build, I bought a barely used 60 gallon, 6 HP Devilbiss Pro Air II with killer cfm specs. I didn't know anything about oil-free compressors. Right off the bat, the thing seemed to have slow recovery times so I rebuilt the pistons. That didn't change much. Nevertheless, that unit got me through all the cutting, grinding, spraying primer, and even sandblasting the entire car, but I spent a LOT of time waiting for the compressor to catch up. Despite trying to be careful to keep it to a 50% duty cycle, recovering times got worse and a second piston rebuild was completed (About $50 per cylinder for parts). Finally, the compressor literally blew up, sending a shattered piston top into the head. Huge waste of money.

I now run a 60 gal. 5HP 2-stage compressor and and am MUCH happier with it. As others have said, it is more than enough for lower consumption tools and paint sprayers. It is adequate for blasting, but requires waiting for it to catch up to keep the duty cycle reasonable.

I think for most DIY occasional use guys, the 60 gal. 5HP 2-stage is about the sweet spot. You can do a lot with a smaller compressor, but you can also nurse this size through occasional more demanding tasks that smaller units couldn't handle. For example, when I have a lot of cabinet blasting to do, I try to set up one or two other projects that don't require air to switch off to while the compressor is catching up and getting a rest.

[tvdinnerbythepool]

I think what you mention in the original post will work well.

One of my jobs is in guitar manufacturing and we run an Ingersoll compressor about 15hrs a day for Paint mostly. Some sanding and occasionally sandblasting car parts for me.

The name of the game is CFM. You can have a big ass tank and a high PSI rating, but if it can't continue to produce that PSI rating, you're toast. We learned that the hard way!

[rhodyguy]

Continuous duty cycle.

[jd74914]

(IMG:style_emoticons/default/agree.gif) With Mark, if you can find a screw compressor buy it if it is in your price range and performs to specification, you will also need a tank, but you can find 60-80 gal tanks on Craigslist that include none working compressors. Or just tie several 20 gallon units together. If you have loft space the screw units can be lifted up there, and then the tanks installed.

Of course if you have the coin, Eastwood Scroll Compressor.

Wonder how quite that scroll compressor is? All of the larger one's I've seen are pretty loud.

My lab has a nice screw compressor (similar to what Mark pictured-just older). Thing puts out ~350 cfm @ 100 psig (25hp motor) and has a refrigerating dryer and a 500 gallon tank.

That said...I wouldn't recommend anyone buying a used screw compressor unless you're really committed to maintenance and understanding it or have a large checkbook. There isn't much technical documentation online and as such troubleshooting the electro-mechanical controls is not for the faint of heart or really anyone not intimately familiar with industrial systems. Part prices are crazy too.

[IronHillRestorations]

The Eastwood scroll looks interesting to me, but the reviews are either good or bad. I'm going back and forth on whether to move mine or get a new one, whenever I can move.

I've got a 5hp two stage Champion with an 80 gallon tank that I got new in 1995, and it still works great, but it's noisy as a locomotive. I don't have any neighbors at the old shop, but the new one I will, so I'm exploring options, which is why I got excited about the Eastwood scroll, but it's pretty much 100% MIC which kind of scares me. My old Champion had a 5 year warranty

[mb911]

Perry,

Same here. Looking at a California compressor.. They seem well liked.

[maf914]

I am curious what sort of filter/separator is needed to provide clean air for painting, when the compressor is not oil-free.

I am familiar with small scale hobby type systems using an oil free compressor. Even with these, an oil/water filter/separator is important for clean air.

[mb911]

From a sound stand point I am going to look at sound absorption panels 1st..

[Mark Henry]

I am curious what sort of filter/separator is needed to provide clean air for painting, when the compressor is not oil-free.

I am familiar with small scale hobby type systems using an oil free compressor. Even with these, an oil/water filter/separator is important for clean air.

there are all kinds of DIY water trap vids on YT like this one.


https://www.youtube.com/watch?v=KzBNscMrQMs