In article ,
"Charley" wrote:

[snipperized for brevity]

That is good advice and is similar to my experiences. Can't have too
much air.
The OP mentioned TWO sanders at the same time. Even the most efficient
sanders are air hogs. Two of them will break a genuine 5HP (not those
horsepower ratings from the Borgs, btw) into a sweat.
In a recent ad from Home Despot, I noticed a RHP rating of 1.7 HP for
the same compressor they rated 5HP just a few weeks prior. Maybe
somebody in the advertising/legal department finally figured out that
selling a 5 HP compressor which only draws 15 amps (about 2 R(eal?)HP)
is fraudulent.
When choosing a compressor, take the rated amperage and multiply by the
operating voltage and divide by 750. Deduct 15% for belt slippage,
bearing friction, and you'll have a better idea how much actual
horsepower you're buying. (All figures approximate as I am in no mood to
start arguing that 1 HP is 'really' 756 watts at 20.002 degrees Celsius
at sea level, assuming the wind is from the NE.)

Two stage with intercooler, 1" or bigger distribution lines, 50+ gallon
tank (not as important if your pump can keep up).
Automotive painting supply people know a thing or two about these things
as well.

FWIW, YMMV, HAND, DSFOHAYE.