what is the minimum size requirement for an air compressor to use a impact wrench and paint spray gun etc...

 

I'm dealing with that issue right now. I have a 3hp 25gal Sansborn. It's about the same as any other 20~25 gal 3 hp <$350 compressor you can buy anywhere. I was having trouble with sand blasting, had to wait too long between fills, but running an impact wrench is not hard at all. Painting is a bit of a strain, you have to wait for the compressor to catch up from time to time else the pressure is too low and the finish will suffer.

Look for a cap run cap start type, it'll have two capisitors rather than one. Mine came with a 2.5" pullie on the motor and I tried several larger sizes from 3.0,3.5, 3.75 The 3.75 nearly burned the motor and the 3.0 is livable, the 3.5" works real nice but I switched back to the 3.0

The price to go from the $300 3HP 20 gal to a 5~6HP 30~60 gal is steep and the HP ratings on some of the 5's are peak hp only so it's tough to compare. Mine is rated at 8.6cfm @ 40psi, this is pretty standard for a $300 compressor. Size of the tank is not too important, re-fill time and running pressure is. Something like this will work, you just have to rest a bit every so often to let the compressor catch when painting. Sandblasting is tough, because I like to blast constant with very little rest and it barely keeps up with the overdrive pully.

Make sure it has dual caps (1 run, 1 start) and has a reset switch if you want to overdrive it. Use a cast iron pully from Grainger, diecast alum will break, don't overdrive more that 30% or so, mine nearly died at 50% overdrive. 20~25% overdrive makes it real usable.

 

Here's another low-buck approach. Hook two 110 V air compressors in parallel. You can easilly make a Tee from parts at the hardware store, and then use air compressor hose. In my case, I have an old air compressor that is on it's last leg, but still runs occasionally. I hooked that one up to the newer one, and I have twice the cfm (in theory). Still, it's hard to beat the 80 gal vertical 220V units. One of these compressors really bogs down when I use rotary air tools (die grinders, ect.), but two will keep up prety well.

 

Aaron, I have run my air guns off my 3/4 hp Emglo carry around compressor. It is used to run small nail guns. I have an old 1hp 12 gal. Sears air compressor that will run a paint gun fine. All single stage compressors will knock out at around 125psi. The two stage $700.00 & up units top out at about 180 psi. Goldblatt makes a high vol. low pressure unit for spraying texture on drywall ceilings.

The thing you need to look at is the CFMs at ?psi. rating. Sears still sells some good units.

John
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thanks guys