I have a Craftsman 33 gal 125 compressor; works great for everything I've used it for so far (10 years). I have found that cheap tools use a lot of air; it is often worth spending a little more to get a better quality tools that are more efficient.

 

I have one like this in the shop. It does well for most of my pneumatic tools like impact gun, hand grinders, shears, air ratchets,...ect......http://www.northerntool.com/webapp/w...5170_200365170

 

It is impossible to buy too much compressor. Avoid the oil-less versions (NOISY diaphram pumps) and look for volume. I bought a 60 gal Ingersol Rand twin cylinder single stage that moves about 15 cfm at 90 psi. I have yet to wait for air after the initial fill - my cheap air-hungry tools only run the compressor about 30% of the time. Max psi on a single stage is ~130, but it moves more air volume. A two-stage gives 150+ psi, but less volume. Expect to pay ~ $750 for a quality unit that your grandson will still be using.

 

I used a Sears 5hp, 25 gallon compressor for my impact wrench with no problem. Impacts don't run continuous like a grinder or sander. Last summer I purchased an Ingersoll-Rand, 240v, 5hp, single stage compressor with a 60 gallon tank rated at 18gpm @ 90psi. It was just under $900, out-the-door at Tractor Supply. Runs everything I need very well, very quite and can run continuous job cycle using synthetic lubricant in the pump. Many guys will say to go with the two stage units when you shop for a compressor of that size but there is usually a considerable difference in cost. Unless you'll be using sanders and grinders or doing a lot of spraying, the one you have should do fine.

My $0.02

 

man go to harbor freight!

 

Same one I got at the same place - and they don't sell it anymore.....

 

I have a 27 yr old sears that I have used on even the big semi trucks. 5 gal. still use it in the mc shop- takes up a lot less room and is easy to roll outside and wherever it is needed.
If ya need an impact - don't be cheap there, get a top dollar one.

 

I have the sears compressor you mention, it will run my pneumatic impact wrench but other air tools require more constant volume or CFM.

 

This is close to what I have in my shop and I can run every air tool I have. You can look around that site and check out other compressors to help you decide.
http://www.northerntool.com/webapp/w...6620_200396620

 

You need capacity, get at least a 60 gal capacity, twin cyclnder compressor. see pic of compressor in my shop.