Another off-topic question: Air Compressors...

[Jumpem]

I want a cheap $100-150 one. It's primary use will simply be inflating car tires. Perhaps some casual air-tool use in the future.

So what do I need to look for? Is there a certain gallon capacity that I would want as a minimum? What about the motor's hp, or psi?

Thanks.

 

[quakefiend420]

portable?

 

[Jumpem]

Originally posted by: quakefiend420
portable?

No, I'd leave it in the garage.

 

[iamwiz82]

What kind of air tools? A nailer requires much less air than an impact wrench.

 

[Juice Box]

just go to sears...theyll hook you up!

 

[NogginBoink]

The metric to use is cubic feet per minute (CFM). Look at the tools you might use in the future and determin how many CFM they need. Buy a compressor that can provide that.

Nearly all CFM ratings are at 90PSI.

 

[Jumpem]

Originally posted by: iamwiz82
What kind of air tools? A nailer requires much less air than an impact wrench.

It would be stuff for automotive work. The only things I use would be an air ratchet for basic stuff, and an air hammer for wheels.

 

[Jumpem]

Originally posted by: NogginBoink
The metric to use is cubic feet per minute (CFM). Look at the tools you might use in the future and determin how many CFM they need. Buy a compressor that can provide that.

Nearly all CFM ratings are at 90PSI.

Ok, given the couple air tools I listed, what sort of base CFM should I be looking for?

 

[iamwiz82]

I got a cheapie 5.5CFM with a 25 gallon tank for $200. While it's not a whole lot of power, the large tank makes up for it. The compressor runs a lot when I am using it, though.

 

[FoBoT]

thanks for reminding me on this, i am going to get one of those little portable jobs

 

[Jumpem]

Originally posted by: iamwiz82
I got a cheapie 5.5CFM with a 25 gallon tank for $200. While it's not a whole lot of power, the large tank makes up for it. The compressor runs a lot when I am using it, though.

Hmm, ok. I guess I'll need something more than I was thinking if I want to do more than fill tires.

 

[iamwiz82]

Originally posted by: Jumpem

Originally posted by: iamwiz82
I got a cheapie 5.5CFM with a 25 gallon tank for $200. While it's not a whole lot of power, the large tank makes up for it. The compressor runs a lot when I am using it, though.

Hmm, ok. I guess I'll need something more than I was thinking if I want to do more than fill tires.

Yeah, an air hammer will go through a lot.

 

[dullard]

Typical values for home use (heavy use industrial equipment could significantly increase these numbers):
Impact wrench: 4-12 CFM
Air rachet: 4-5 CFM
Air screwdriver: 4 CFM
Air grinder: 3-4 CFM
Air drill: 4-6 CFM
Air nailer: 4-5 CFM
Air saw: 3-4 CFM
Air polisher: 6 CFM
Air shear: 6 CFM
Air sander: 4-6 CFM

So if you just want to use one tool at a time, 6 CFM will handly just about anything you throw at it. Note: a continuous use item really needs that CFM requirement to maintain power. Conversely, a nailer which is only used in pulses (one pulse per nail) can function with a lower CFM (but you might have to wait an unbearable amount of time to pressurize the tank or between nails if the CFM is below the requirement).

Also note: most CFM listed on compressors is exaggerated by ~30%. So if you buy an air compressor that lists 4 CFM, it probably is just 3 CFM. This exaggeration is pretty much industry wide and is quite unfortunate.

 

[Jumpem]

Originally posted by: dullard
Typical values for home use (heavy use industrial equipment could significantly increase these numbers):
Impact wrench: 4-12 CFM
Air rachet: 4-5 CFM
Air screwdriver: 4 CFM
Air grinder: 3-4 CFM
Air drill: 4-6 CFM
Air nailer: 4-5 CFM
Air saw: 3-4 CFM
Air polisher: 6 CFM
Air shear: 6 CFM
Air sander: 4-6 CFM

So if you just want to use one tool at a time, 6 CFM will handly just about anything you throw at it. Note: a continuous use item really needs that CFM requirement to maintain power. Conversely, a nailer which is only used in pulses (one pulse per nail) can function with a lower CFM (but you might have to wait an unbearable amount of time to pressurize the tank or between nails if the CFM is below the requirement).

Also note: most CFM listed on compressors is exaggerated by ~30%. So if you buy an air compressor that lists 4 CFM, it probably is just 3 CFM. This exaggeration is pretty much industry wide and is quite unfortunate.

Awesome! Thanks for listing that.

 

[franksta]

You might want to get one that stands vertically just for the space savings. I got my father-in-law's hand me down "hot dog" style that is a tight fit in my garage.

 

[dullard]

Originally posted by: Jumpem
Awesome! Thanks for listing that.

No problem. I just opened up a catalog and looked at the home products and the CFM from various products from various companies. I'm sure there are some tools that are slightly outside that range, but probably not many that you'll run into. The reason is that most tools are designed around the air compressor. Tool designers know that most people have a 4-6 CFM compressor since that is what the local hardware stores carry. Thus it is stupid of them to design a home tool for more than that flow rate.

I don't have a lot of experience with air tools myself, although my work is entirely based around designing an air powered machine. In my searches, I've found great tools/machines/workshop stuff from Grizzly. Grizzly sells Chineese made knock-offs which are often higher quality than the real thing for about half the price. So if you are willing to put up with possibly hard to read manuals (poor translations at times), you can save yourself a bundle with Grizzly.

Anybody have other recommendations on how to save money?

 

[PawNtheSandman]

Go to Depot or Lowes or Sears. All of their compressors usually have the same package deal where you get the compressor, hose and some tools for around $229-$299.

 

[Vanman]

Not your big name brands, but I've had decent luck with the stuff from Harbor Freight. I would think one of these would be good for light home use. We have one at our warehouse that is used mainly for filling tires and the occasional impact wrench or air nailer and no issues so far. If it's going to get a lot of use might want to go with something a bit more expensive though.

Cheers,

Dirk