What air compressor would you go with?

[skipnay]

I would like an air compressor that I can use in my garage. I have been using a 30 gallon Craftsman with a CFM of 7.2 at 40 and 5.8 at 90. Max pressure is 150 psi. I don't use a lot of air tools but what I do use is a die grinder, 1/2 impact, 3/8 ratchet, and an air hammer. I prefer something 60-80 gallon. I was looking at the ones at Tractor supply but since I have a code for Zoro I will probably just order from them. I would prefer to get something made by INGERSOLL-RAND. I need it to be 1 phase and don't mind it being 220/230. We have 400 amp service coming in. It gets divided into the house and garage. 200 amp goes to house and the other 200 amp service goes to the garage.

Do I want a 2 stage?
Do I need to spend $2400 (prefer $1100-$1500)?
How much is a motor starter? Are they easy to get? Which one will I need?

 

[md21722]

Any compressor that needs a magnetic starter will come with it as part of the compressor, unless you are buying used where they sometimes sell them without. The size recommends depends on how long you plan to use the die grinder. If you plan to use it for minutes straight, you need enough CFM to keep up with it. Typical 0.33 HP rotary air tools use 17-19 CFM, 0.50 HP use 23-28, and 1HP use 35-43 CFM. Some people think this advise is crazy and have said nobody uses a die grinder 24 hours a day. No, they don't. But if you need it for 10-20 minutes, then you need enough air otherwise you wait on the compressor. If you only need it for 30 seconds, then a smaller compressor with a larger tank will suffice. The least expensive IR dual stage is about 15.8 CFM which is marginal for prolonged use of a die grinder at full load. The impact wrench is used in bursts, so even though it may be rated for 37 CFM you don't hold it continuously for long enough to matter. It probably work fine with your current compressor. The air ratchets typically use more air because they run for longer periods. This may be marginal with your current compressor. Air hammers typically use the least, only about 10-12 CFM and is probably fine with your current compressor unless you are running the air hammer for a long time.

Two stage is not strictly necessary, but the higher pressure sure is nice. Typically air tools run at 90 psi. This is often the 'cut-in' for a single stage compressor. But the regulator and hose usually take 10-15 psi off that, so you're at 75 psi at the tool before the compressor kicks on. You can fix that by adjusting the regulator, or replacing it with an adjustable one. Dual stages typically cut in around 145 and shut off at 175. This gives you about 40% more air reserve, and will avoid low pressure situations unless you are using an air tool that uses more than your compressor makes and you run it down that far. There isn't much special about IR compressors. I would get a 5HP 17-19 CFM dual stage compressor with a 60-80 gallon tank if I was in your situation. That's probably not the cheapest IR dual stage, but one level up.

 

[redmondjp]

Have you read any other compressor threads? All of your questions have been asked and answered.

It sounds like you can get away with the typical box-store 60-gallon single stage 240V 3.5HP unit just fine. But if you use the die grinder a lot, that compressor is still too small and will run out of steam after 5 minutes of operation, then it will get really ticked off and start spitting water out the line at 70-80psi as it runs continuously (personal experience speaking here).

You're going to need an 80 gallon unit capable of at least 15cfm at 90psi to run a die grinder (or other high-volume air tool) continuously. There are plenty of other threads to read on single-stage vs. two stage as well as on motor starters. You don't need a motor starter (although it is a good idea) unless you are using a true 5HP motor or larger that doesn't have built-in thermal overload protection.

It all comes down to how much you want to spend. It is great to hear that you have sufficient power in your shop to run a 7.5hp compressor, and you will never regret getting too large of a compressor IMO.

 

[skipnay]

Any compressor that needs a magnetic starter will come with it as part of the compressor, unless you are buying used where they sometimes sell them without. The size recommends depends on how long you plan to use the die grinder. If you plan to use it for minutes straight, you need enough CFM to keep up with it. Typical 0.33 HP rotary air tools use 17-19 CFM, 0.50 HP use 23-28, and 1HP use 35-43 CFM. Some people think this advise is crazy and have said nobody uses a die grinder 24 hours a day. No, they don't. But if you need it for 10-20 minutes, then you need enough air otherwise you wait on the compressor. If you only need it for 30 seconds, then a smaller compressor with a larger tank will suffice. The least expensive IR dual stage is about 15.8 CFM which is marginal for prolonged use of a die grinder at full load. The impact wrench is used in bursts, so even though it may be rated for 37 CFM you don't hold it continuously for long enough to matter. It probably work fine with your current compressor. The air ratchets typically use more air because they run for longer periods. This may be marginal with your current compressor. Air hammers typically use the least, only about 10-12 CFM and is probably fine with your current compressor unless you are running the air hammer for a long time.

Two stage is not strictly necessary, but the higher pressure sure is nice. Typically air tools run at 90 psi. This is often the 'cut-in' for a single stage compressor. But the regulator and hose usually take 10-15 psi off that, so you're at 75 psi at the tool before the compressor kicks on. You can fix that by adjusting the regulator, or replacing it with an adjustable one. Dual stages typically cut in around 145 and shut off at 175. This gives you about 40% more air reserve, and will avoid low pressure situations unless you are using an air tool that uses more than your compressor makes and you run it down that far. There isn't much special about IR compressors. I would get a 5HP 17-19 CFM dual stage compressor with a 60-80 gallon tank if I was in your situation. That's probably not the cheapest IR dual stage, but one level up.

Do you recommend something else Zoro has? I was actually looking at this one.... http://www.zoro.com/ingersoll-rand-electric-air-compressor-2-stage-14-cfm-2340l5a/i/G4485853/

 

[redmondjp]

Do you recommend something else Zoro has? I was actually looking at this one.... http://www.zoro.com/ingersoll-rand-electric-air-compressor-2-stage-14-cfm-2340l5a/i/G4485853/

Don't order that exact one, as it has a 3-phase motor on it!

 

[skipnay]

Don't order that exact one, as it has a 3-phase motor on it!

I realized that after I posted it and F it. Yeah I know I need 1 phase. Do I really need something that is $2400?

 

[mg283680]

Why cheap out?
As already mentioned w/ slight changes: I would get a 5HP 17-19 CFM dual stage compressor with a 80 gallon tank and a 1725 RPM motor.

What you need is defined by you. The fact is, no matter how much air you have, you'll want more.

 

[94_C/1500]

I suggest looking at used stuff too. I've seen some great deals. The best I've found is a 30 gallon 2 phase 3hp for $150. I've found found an unused 60 gallon Kobalt for $300 as well.

 

[ovrrdrive]

By tomorrow people will be recommending you take out a mortgage on the house and get the biggest rotary compressor you can find... lol

You don't need all of that. I have one of these from HD and it is working great for me. The worst tool you mentioned is the die grinder but even that is within the specs for this unit.

http://www.homedepot.com/p/Husky-60-Gal-Stationary-Electric-Air-Compressor-C602H/205389936

I'm sure IR has something comparable for just a little more money. It is true to always buy the most air you can afford but it gets to be overkill at a certain point.

 

[CNGsaves]

Here's a good "learning project" for $200 on 60 gallon compressor . .
. . . bargain down to $100 or $150 and see what you have . . . what is it ??
http://pittsburgh.craigslist.org/tls/5456963744.html

Here's IR 60 gal with 3 HP motor for $350 . . . this would get you by on a budget and I'm sure there's bargaining room in that price.
https://philadelphia.craigslist.org/tls/5393238766.html

Seriously, no need to spend $2,400 when what you need is a decent 60 gallon compressor. Start shopping CL like a hound dog in surrounding area.

 

[redmondjp]

Seriously, no need to spend $2,400 when what you need is a decent 60 gallon compressor. Start shopping CL like a hound dog in surrounding area.

Yes, you can get a good deal on a compressor on CL if you are in a major area, but you have to really jump fast to get a good deal - the ones I see that are priced really well disappear within 4-6 hours after posting. Not to brag, but I scored a Quincy 325 on CL awhile back for $400, but it does have a 3-phase motor on it (I'm going to do a Steelman conversion on the motor so it can operate on single phase power - will post a new thread on this when I have got it done).

Another idea - you can parallel two smaller compressors when you are using a high-flow tool like a die grinder.

 

[md21722]

3HP compressor will not run a die grinder for long. Any rotary tool that says less than 10CFM is talking about average air consumption which is typically 15 seconds out of 60 seconds... So it if says 4CFM it means 16CFM continuous.. That's why the 5HP 17-19 CFM compressors come up so often. The way I look at it, if a 2HP 30 gallon won't work for you, you probably need a 5HP 17-19... I'm not sure what market the 3HP really fills except for the folks that want a big red 60 gallon tank that needs 230V. I've had the 3HP models and they didn't run my $60 IR die grinder for as long as I needed.

 

[WhiffySpark]

I will be buying the 449 husky with a 10% lowes coupon

I'm sure I need an 80 gallon 24 cfm compressor as well. But this is my personal garage and I've gotten by with a 25 gallon 5-6cfm for 8 years. No way in hell am I spending $2400 on an air compressor that doesn't make me money lol

And there's nothing used in my area even if I wanted to