Air Compressor Question

**zipseattle** · 10-03-2008, 10:06 PM

I have a few questions for those of you that use air tools. I am interested in an air compressor that can handle a cutoff tool and a die grinder. The tools I've looked at are rated at about 4 to 5 CFM at 90 psi.

I've been considering a few compressor models that are between 10 to 20 gallons and about 5.5 CFM. Is that enough to run those tools effectively? Oiled vs. Oil free? I am trying to balance portability, cost, and lack of garage space...

Thanks

jeep2003 · 10-03-2008, 11:06 PM

The genral rule of thumb is to get the biggest best one you can. Id definaly go with an oiled unit preferably 2 stage. Actually im not sure they even make an oiled single stage. You can get an upright model which wont take up much space. I have a 25 gallon and it works everything well. i even have a da sander and it doesnt work all that hard to keep up. I wouldnt go less than a 20 gallon.

**steven Durham** · 10-03-2008, 11:13 PM

Well I know tools LOL A few years ago I bought my Son-in-law a Coleman oil-less air compressor for Christmas that is the biggest piece of crap, because of the noise it makes I used it once a few years later and was shocked at how loud it was. buying a small compressor will fit the size and space part but expect it to be running almost non stop while using the die grinder. And a oil splash lube will be quieter by far.
One thought is to buy a broken used compressor for the tank and if you have an attic above your garage you can pipe in the extra volume by making a manifold and then plug in your compressor to the manifold to refill the larger tank and have a small piping system to hook the air tools to.
Make sure you have a way to drain the water out of the storage tank.
Steve

**steven Durham** · 10-03-2008, 11:33 PM

Quote:

Originally Posted by jeep2003

The genral rule of thumb is to get the biggest best one you can. Id definaly go with an oiled unit preferably 2 stage. Actually im not sure they even make an oiled single stage. You can get an upright model which wont take up much space. I have a 25 gallon and it works everything well. i even have a da sander and it doesnt work all that hard to keep up. I wouldnt go less than a 20 gallon.

As for needing a two stage air compressor I question why? The higher pressure would be great if you are using a big impact wrench for truck tires . The CFM is what is required for most tools, the second stage cuts the volume of air that is produced. Most shop tools don't need the high pressure they need volume I knew I was buying a blast cabinet so I bought a big compressor that has 3 cylinders and is only single stage but still puts out 18.5 CFM and 135 pounds of pressure.
Steve

**zipseattle** · 10-04-2008, 02:33 AM

Thanks for the feedback. Looks like its going to be Oiled - less noise is good. I guess I'll be looking for something like this (hopefully I can find something for less $$) -

Pneumatics & Hydraulics > Air Compressors and Vacuum Pumps > Portable Electric Air Compressors > Compressor,Air,2.0 HP : Grainger Industrial Supply

Any recommendations? Home Depot, Sears, Harbor Freight, Craigslist? Brands? My concern with going used is not being able to spot potential problems...

jeep2003 · 10-04-2008, 09:00 PM

Quote:

Originally Posted by steven Durham

As for needing a two stage air compressor I question why? The higher pressure would be great if you are using a big impact wrench for truck tires . The CFM is what is required for most tools, the second stage cuts the volume of air that is produced. Most shop tools don't need the high pressure they need volume I knew I was buying a blast cabinet so I bought a big compressor that has 3 cylinders and is only single stage but still puts out 18.5 CFM and 135 pounds of pressure.
Steve

Oh. I assumed that "stage" meant # of cylinders for some reason. Thats what i meant. Now i dont know whats meant by "stage"

**GTO** · 10-04-2008, 09:29 PM

Hey Zip, Get an oil type,,,,try craigslist for a real clean one and from someone who doesn't have a "shop". I picked one up for $90 and it's been doing good.

**steven Durham** · 10-04-2008, 09:57 PM

Quote:

Originally Posted by jeep2003

Oh. I assumed that "stage" meant # of cylinders for some reason. Thats what i meant. Now i dont know whats meant by "stage"

Well that's easy to explain the two stage has two pistons the first piston is larger and pumps the air pressure up to about 100 PSI and then the air is piped to the intake of the second piston where the air pressure is compressed with a smaller piston the pushes the pressure up higher and they usually go up to 175 pounds of maximum pressure. The delivery of the air to the tank usually has cooling fins on the line and is passed next to the big pulley that acts as a fan to cool the delivered air and the body of the compressor.
Lots of heat is generated during the compression cycle.
Steve

jeep2003 · 10-04-2008, 10:22 PM

Good to know steve. I think mine is a single stage 2 cylender. Ill have to look at it. In anycase Zip's choice look like a good one. Never heard of that brand though. Mine is a porter cable

**Oldsalt** · 10-05-2008, 02:06 AM

Quote:

Originally Posted by GTO

Hey Zip, Get an oil type,,,,try craigslist for a real clean one and from someone who doesn't have a "shop". I picked one up for $90 and it's been doing good.

Couldn't agree more. Eldest son gave me a relatively new 6 HP noise maker when he bought a bigger one. I quickly found out why he gave it to me and got a piston type with oil. But it was too late because I had already given away my old 5 HP two stage to a good friend. When that things starts up the dog leaves the building. That damned thing is the only tool in my shop that I hope blows up so it can be replaced without any questions.