Air compressors - which one?

No matter which entry level compressor you buy, you'll probably want more down the road as your shop time increases. For impact wrenches and air tools a 5 hp, single stage, 230V, 60-80 gal. tank, 100 PSI, 50% duty cycle is a good start. It'll have enough air to paint parts and maybe smaller cars but nothing larger. They can sandblast and run air sanders but at 50 on/ 50 off it takes all day to do a job... which ain't bad if you like beer breaks.

I started w/ a Sanborn (now Coleman) 5hp like said above. It's over 15 y/o and was a real workhorse. It ran 230V off of 12/2 wire and 30 amp fuses but the 50% duty cycle was killin' me for productivity. I recently upgraded to an 230V Ingersol-Rand, two-stage, 5hp, 100% duty cycle, 100 gal tank, cast iron pump w/ air intercooler. Now I can paint, sandblast or run air tools all day long, I couldn't be happier.

I found this compressor listed in-store at Tractor Supply for over $1200 but they honored the on-line price I found for $1K. It's a beast for a home shop at over 600 lbs and needs 8 ga. wire ( no 12/2 or 10/2 here) and 40-45 amp fuses. I run it off the welder receptacle till I rewire the shop entrance. This might be the last compressor I need... until the next time.

After looking at the prices, etc. I think wiring in a 220 and getting a larger unit is the way to go in the long run. I'll probably won't use it at capacity very often, but for the times I do, it'll be worth the saved aggravation.

A little different perspective (a grassroots solution to needing a big compressor)...

Everything previously posted is very nice and accurate.

However, there are work arounds to the big motors and 220V.

Larger air volume capacity can make up for a smaller compressor.

I have a 60 gal vertical 220V in my shop.

But my mobile units (which I used primarily for construction) are 110V and small enough to be easily portable. We also have a couple of air tanks (just a tank, no compressor). If we are on a jobsite where we are trying to use a lot of air powered tools and the compressor can't keep up, we add an inline air tank with air hoses and quick connects. The larger volume makes up for a lot. Plus, for smaller applications, the air tanks can be charged off the compressor then carried around to multiple points of use (they are much lighter than a compressor).

I have used a portable 110V with a couple of air tanks and an inline water filter to successfully paint a fairly large job. Just as good as my big one.

So, you could buy a cheapo 110V, and add an inline tank (a non-working compressor or other).

Caveat: Never, NEVER, NEVER use a tank for an inline application that is not rated for pressure SIGNIFICANTLY in excess of your maximum.

WilberM3 wrote: yea mine's wired from sears at 110v but it's RIGHT at the limit of older 15amp circuits and usually beyond when it kicks on at higher pressures. i actually have a 35 foot extension cord running to a newer 20a circuit and it's never been a problem there.

That's not a good idea. It's better to keep the compressor as close to the outlet as possible and run more hose. A long cord can create voltage drop and make the compressor not run at it's correct rpm - especially if you're house is 110V.

I'd like to echo those questioning the need... I've wanted one for years, finally got an oiless craftsman professional oilless 33 gallon (14 cfm @ 40 psi, 9.9 @ 90 psi) for a really good deal. I really don't use it that much. I used it for the nail guns that helped me build my kickass garage, but other than that.... a space taker upper. I have the HF electric impact and it works fine if that's what you think you need. I'd take a good look at what you plan to use it for first, and then decide if you really want to invest in the machine, the tools, the wiring for 220 and the maintenance.

Take it for what it's worth. If you do get one, my research showed that 10 cfm at 90 psi will run almost anything you need in a shop, so I'd get the smallest one that would fit that requirement. And I totally lucked out.

Thanks for all the input. I'm convinced with everyone's opinion of getting the biggest I can afford...when I'm ready for it. At the prices for a really good one, it's something I can probably put off until later.

I'm a complete novice mechanic. Before a few weeks ago, I'd never done anything besides oil changes. I'm just starting to tinker with the pair of '76 Fiat Spiders I bought recently. So while I'd love to have a big fancy compressor, for the money, maybe I'll make do with an electric impact wrench from HF. I don't plan to do any major paint jobs or grinding, etc...in the near future. Just learning basic mechanics. I'm probably going to need to pull the crank nut off one of the Spiders soon, and right now all I have is basic hand tools.

SVreX wrote: Caveat: Never, NEVER, NEVER use a tank for an inline application that is not rated for pressure SIGNIFICANTLY in excess of your maximum.

Why does it need to be rated for more than your max pressure?

I have a craftsman "commercial" 2 stage compressor I got of craigslist 4-5 years back after my 30gal single stage unit was stolen from the shop I use to work at. This unit has a 175 psi tank pressure. I think it is a 30 gal tank (it stands as tall as me) It has been a great unit for what it is.

What I found is that by going to a 175 psi unit you have increased that volume of air as compared to a 120 or 150 PSI unit (what my old unit had). This increase seems to really help. My unit is also supposedly a two stage unit (so says the label on the cover) It is MUCH quieter than my old oil less unit. You can actually have a conversation standing next to it when it is running. I keep it in my basement and even in the confined space the noise level is fine.

The other side of the equation is to be careful when selecting air tools. Get air tools with the lowest working CFM rating that still provide the power and size you need. These are usually more expensive as they are better made and are more efficient.

Photo of my unit.

This unit fills the middle ground between the really cheep noisy ones and the much more expensive $1,000+ commercial units.

It has been the ideal unit for my needs. So far I have not had an issue with capacity but again I have been careful with the tools I purchased. a 6-8CFM DA would probably not work well. A 4-5 CFM tool at 90 psi has no issues. It can keep up with that all day long.

Ian F wrote:

WilberM3 wrote: yea mine's wired from sears at 110v but it's RIGHT at the limit of older 15amp circuits and usually beyond when it kicks on at higher pressures. i actually have a 35 foot extension cord running to a newer 20a circuit and it's never been a problem there.

That's not a good idea. It's better to keep the compressor as close to the outlet as possible and run more hose. A long cord can create voltage drop and make the compressor not run at it's correct rpm - especially if you're house is 110V.

yea its not ideal, but there's no other solution without rewiring the old garage, and its not my garage. i made the extension cord out of the largest gauge cord i could find. its never been my primary work space either though.

Zomby woof wrote:

SVreX wrote: Caveat: Never, NEVER, NEVER use a tank for an inline application that is not rated for pressure SIGNIFICANTLY in excess of your maximum.

Why does it need to be rated for more than your max pressure?

Actually, I incorrectly used the word "rated".

Osha typically utilizes a 4x safety margin. That means, if it is rated for 200 psi, it's been tested to withstand 800 psi. So, you are correct, it needs to be rated for your maximum pressure.

However, I was assuming (in typical GRM fashion) that someone was going to take my advice and install a couple of air quick connects in a beer keg to fashion their own "pressure tank". What I meant to be implying was that the 4x safety margin is important (in case of a faulty pressure valve, gauge, interior deterioration, etc.). If an alternate tank should be used (without an official rating),
it is important that it can handle significantly more than you maximum working pressure (although if it has a "rating", then the rating needs to match the working pressure, because the safety margin is already built in).

Is that better?

WilberM3 wrote:

Ian F wrote:

WilberM3 wrote: yea mine's wired from sears at 110v but it's RIGHT at the limit of older 15amp circuits and usually beyond when it kicks on at higher pressures. i actually have a 35 foot extension cord running to a newer 20a circuit and it's never been a problem there.

That's not a good idea. It's better to keep the compressor as close to the outlet as possible and run more hose. A long cord can create voltage drop and make the compressor not run at it's correct rpm - especially if you're house is 110V.

yea its not ideal, but there's no other solution without rewiring the old garage, and its not my garage. i made the extension cord out of the largest gauge cord i could find. its never been my primary work space either though.

As long as the wire gauge and length matches your amperage draw, you are fine.

If "the largest cord I could find" is a 16 gauge extension, it's not OK.

I got my compressor from an unconventional source. It had gone out of warranty, and the owner chose to replace it rather that replace a gasket and the cylinders. He had the repairman haul it away. Said repairman gave it to me, with advice on how to fix it. For the price of a couple of parts, I have a compressor.

I'm so cheap, I used one of the cylinders as part of my CAI setup.

Sometimes, it's not what you know, but who you know.