What's a good way to select an impact wrench and air compressor that are compatible?  Is CFM the best way?  When I find a compressor and wrench in my price range the two usually have CFM's or SCFM's that don't match.   I have a hot dog Craftsman but its CFM is so low, 2.4 @90 psi, that I don't think it has the power for most 1/2" impacts worth considering.  Did find an Eagle(Iron Horse) compressor at a local hardware store that fit the bill(enough CFM's, size and price, etc)...until I was taking it off the the shelf and saw the "Made in China" printed on the box.  Saw Ingersol/Rands on line with the same notation, or a nice Air Cat impact but it was just "assembled in the US."   So besides the first question I guess I'd have to add, are they both made in the USA?  Thanks Ed

CFM stands for cubic feet per minute, SCFM stands for standard cubic feet per minute. SCFM is more reliable for gauging the amount of air a tool uses. I always look for a compressor that makes ~30% more air than what I use. This will keep the compressor from pumping all the time. Companys that assemble their compressors in the USA get parts from all over the world. At least the final assembly is done by American workers.

I bought a craftsman at xmas. It is 1/2 impact rated at 400 ft lbs average air consumption is 5.2 scfm. manual only states using a 26 gallon comp for light duty, meaning you would probably have to wait for comp to refill to use it continually. A 33gal comp for typical use impact will run a little longer in between refilling comp. using a 60 gal pro for hvy use. however sears does have a pro unit that is somewhat portable it is a 27 gall on wheels with an oil motor that runs either 120/240 vots and is quiter than the oilless types. depending on how much you will use it is what you have to determine for yourself. however the oilless type use teflon linings and can go out on you anytime in this type of use. already burnined one out in less then 2 hrs!

In addition to what LFW said, most compressors list 2 scfm ratings - one at 40 psi and the second at 90 psi. It is the 90 psi rating that is of concern to you since you want to run an impact. The 40 psi rating is more for doing stuff like using a paint sprayer that requires a lot of air at low pressure.

I run a 3/4" impact with a 2 HP craftsman oilless compressor with a 20 gallon tank. When I got my compressor, small oil lubricated ones were almost impossible to find. I have been using it for several years now. I also have a 1 1/2 hp tankless, oilless aircompressor that I have been using for over 20 years.

If you find that you need more air storage capacity, with a few quick connectors, some airlines and a few plumbing parts a second tank can be added. I have 2 propane tanks (a 20 lb and a 100 lb) set up to provide extra storage capacity when required. The 20 lb tank I use with my tankless compressor for airnailing on small projects (such as when I build picture frames). I fill it up and shut the compressor off as the tank lasts for several picture frames. The big tank I use when I want to do something requiring a lot of air. I put a Tee on the tank and one airline from the compressor and a second line from the tank to tool.

My suggestion for an air compressor is to buy the biggest (scfm and physical tank size) that you can afford and have room for. If it is oversized for occasional use of an impactr or other tool, no problem. eaglz suggests a 60 gallon tank, which typically has a larger compressor, for heavy duty use. Be warned that even a compressor like this can't keep up to high volume uses such as continuous use of an impact, so don't expect to get one that will keep up to every thing you might want to do without pausing now and then to let the compressor catch up. These larger compressors usually have a 50% duty cycle. A duty cycle is 10 minutes long, so compressor should not run for more than 5 minutes without a 5 minute rest. That said, we often run the one at work for much longer than that at a time. The biggest problem is heat, they generate a lot of it.

When purchasing air tools, get the one's that are at least 25% or more below the rating (scfm) of your compressor.

You want the tool to do most of the work and not the air compressor do as much trying to keep up with the tool

I stopped about 2 or 3 years ago looking at "MADE IN..." labels. If I wanted to buy an American made tool, I'd be looking for a real long time.

I'm with Craig, I look for tools from a reliable source with a good warranty.

JDeere, I'd be careful about those extra tanks the condensate from the compressor can rust out the bottoms since they don't have drains, even if you have a drier on the compressor. My Dad had one take off and smash the side of his truck(he used an old well tank).

To keep water out of the tank there is a small pep cock in the bottom of the tank that drains the tank. I keep the valve cracked just a little to keep the water from forming in the tank.

I purchased a 30 gallion oiless compressor from sears . it has a star rating of the equipment it can safely operate printed right the unit .it is a 3 hp unit i don't remember the scfm. It  runs a 1/2 inch comerical inger sol-rand impact with no problem . It will also run a comercial random or-bit sander with short breaks.the sander requires more air tha the impact. Hope this helps in your decission   Good Luck      speedwrench

Posted By SWILEY on 03-05-2012 07:55 AM
I'm with Craig, I look for tools from a reliable source with a good warranty.

JDeere, I'd be careful about those extra tanks the condensate from the compressor can rust out the bottoms since they don't have drains, even if you have a drier on the compressor. My Dad had one take off and smash the side of his truck(he used an old well tank).

No more dangerous than an air tank that is never drained.  To drain, turn upside down and open valve, preferably with some pressure in the tank (not to much pressure).

Posted By Speedwrench on 03-05-2012 09:39 AM
I purchased a 30 gallion oiless compressor from sears . it has a star rating of the equipment it can safely operate printed right the unit .it is a 3 hp unit i don't remember the scfm. It  runs a 1/2 inch comerical inger sol-rand impact with no problem . It will also run a comercial random or-bit sander with short breaks.the sander requires more air tha the impact. Hope this helps in your decission   Good Luck      speedwrench

Bold by me.

Speedwrench's comment is right on.  As far as consumption goes, a 1/2" impact wrench isn't a very demanding load.  It is not because they don't gobble air in a hurry.  It is because you normally only use them in short bursts.

Four years ago I put together a little guidance document for myself on what pneumatic tools demand in the way of compressor capacity.  (I think most of it was borrowed from a table that used to appear in Sears Tool Catalogs.  They no longer have that table.)  I intended to insert the whole  document but it exceeded the 500kb limit.  So below is only the table as a JPG file.  Note how far down on the table you'll find the 1/2" impact wrench.  

                 

That third column which says it will handle the 1/2" impact wrench is for a compressor with the following typical characteristics:  2.6 SCFM at 90psi, 3.7 SCFM at 40psi, 150psi max, 4 to 6 gallon tank, 120 volts, 1.5 horsepower.  That sounds like the typical air nailer compressor seen on lots of home construction sites.  If I were buying a portable compressor, I'd go a little bigger than that.  

EDIT  ---  If anyone wants the entire MS Word document or the JPG file, drop me a PM with your e-mail address included.   

Thanks to all for the insightful and useful information! Ed

Hi ed - from the sound of your post, you already have a pretty fair idea of how to size the compressor. Your issue seems to be the manufacturing location. The Eagle compressor you looked at seems to be from
http://www.eaglecompressor.com/index.php
which, according to the website' is mfg in MS. Looks like they are also set up to handle internet sales if you're interested in going that route.

As some of the other posters mentioned foreign made parts may be assembled in the US. The boxed Eagle Iron Horse compressor I spoke of was clearly labelled, "Made In China." Perhaps other models are actually Made In The USA. I'll have to check out the website. Thanks for the information. Ed

thank you

air compressor

vacuum pump

????????.....

My thoughts exactly Ron. I did try the first of the 2 links and the site loaded so slowly I had to question if it was legit.