I've been looking around for a compressor recently as well. The one I currently have is 7gal, 1hp Craftsman which does ok around the house but can't keep up with my HVLP sprayer. It also cycles far too much for my liking when working the main spar -5 rivets. I'm not planning on buying one until Father's day when everything should go on sale since it's not an immediate need, but here's my thoughts on the process.
As mentioned before, if you don't plan to use the compressor to paint, you should stick to a small size and leave it at that. I'd just use the one I have if I wasn't planning on painting.
Then you'll want to decide on oiled, vs oil less types. The oiled will be a bit quieter and should last longer but requires a small amount of upkeep.
Next, if you decide to go with a larger size, you'll need look at power supply. The larger you want, the more likely it will be a 240V supply which you may not have in your workshop. It's not too difficult to install a 240V plug, but it's still a consideration. There are some mid range that you can wire to accept either 120/240V so those are options as well.
Lastly you should consider how much you plan on moving the compressor. If it's not a lot, a stationary model may be worthwhile.
All those factors go in to determining price. Looking at these two compressors
https://m.lowes.com/pd/Kobalt-60-Gallon-155-Electric-Vertical-Air-Compressor/3370356[/video]
https://m.lowes.com/pd/Kobalt-30-Gallon-Portable-155-Electric-Vertical-Air-Compressor/3824207[/video]
the 110/220V capability, plus portability drives up the 30 gal, 2hp compressor to 90% of the price of a 220V, stationary, 60 gal, 3.7hp compressor. So for $50 extra, you can double your scfm at 90psi but you lose a fair amount of versatility. It just depends on what you're requirements are whether it's worthwhile. Hope that helps when you're picking one out.
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