Compressor selection help

[QC]

I am thinking I want to buy a small compressor. Light to medium-duty home use. Would like to use an impact to remove wheels, maybe some painting. What's the smallest size that I should consider? There are some 5 - 6 gallon units at Walmart and Sams for $130 - $150. I'll probably go the ebay route, but need some pointers. Do's, don'ts etc.

Thanks

 

[Chief101]

Re: Compressor selection help

Look at the needs of the tools you will want to use and find a air machine to match. What you are looking at may not even turn an impact. Chief Chief zzz

 

[ZmOz]

Re: Compressor selection help

For an impact wrench or painting, you need a BIG compressor. Those little things are for filling your tires and scaring the cat. For an impact wrench you want a big tank...20 - 30 gallons at least, although the compressor size doesn't matter a whole lot. For painting you want a good compressor, and the tank size doesn't matter so much.

I'm guessing you want to stay with 110v compressors, which means you're limited to a max of about 2.5hp, which is what you should probably get.

Something like this from harbor freight would be perfect:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93351
They sell the same compressor attached to many different tanks for many different prices, so look around. I have the same compressor attached to a different tank and it works great for the $125 I paid for it.

The two most important factors for long life and low noise are to make sure it's oil lubed and has an iron cylinder.

 

[Boomyal]

Re: Compressor selection help

QC, I just bought a compressor at Costco. It was $149.00. It is a little heavy but visually of very good quality compared to what you see at Harbor Freight. It is an oiled cast iron unit. It has very good pressure and cfm. This will run your Binks style paint sprayer and impact wrench. Here are the specs;

Master Power Air Compressor (by Cooper Tools)
2HP
5.6CFM @ 90PSI
6.8CFM @ 40PSI
[colour=red]150PSI[/colour] MAX
Cast Iron Pump
5 Gallon Twin Tank
Oil Lube

 

[dolluper]

Re: Compressor selection help

Cfm at 90 lbs is what you want to look at,since a half decent impact will run at 5,.0 cfm at 90lbs,small tanks are not the best when using impacts,rule of thumb min of 20 gallon tank or you will be waiting for it to recover.
So 7.0 cfm at 90lbs and 20gallon tank would be great if you could find one with the 120 hookup.
Canada has Princess Auto they have one
7,6cfm at 90lbs ,20 gallon tank 110-120 hookup

 

[Bondo]

Re: Compressor selection help

You could get by with a smaller compresser by having alittle Extra Volume.......
It helps cut down on Wait Time between Pulls of the Trigger.......
This is my temporary cure to living with Too Small of a Compresser.......

 

[puddle jumper]

Re: Compressor selection help

Get the biggest one you can afford and or have room for.When using air tools you can never have enough air
reserve. Cheap air tools are air hogs and you get what you pay for when it comes to them.
You need to match the cfm"s of your air tools to the maximum continuous cfm out put of the aircompressor.It blows when you always have to wait for the compressor to catch up to what you are trying to do.
hope this helps

 

[ZmOz]

Re: Compressor selection help

So 7.0 cfm at 90lbs and 20gallon tank would be great if you could find one with the 120 hookup.

No such thing exists. You just can't get that many CFM out of 120 volts.

You also have to keep in mind when a cheap compressor says 5-8 CFM, what they really mean is 2-5 CFM. And when a cheap impact wrench calls for 5 CFM, what they really mean is 10 CFM. Tool companies are all a bunch of dirty liars.

 

[QC]

Re: Compressor selection help

Thanks all. I am coming to similar conclusions, but nothing beats your experiences. I sorta understand this stuff for much larger applications, namely compressed natural gas, and I managed a truck shop for a few years. so I definitely know how much techs scream when air is holding them up

Thanks for the reminder.

With the 120 volt limitation it does seem like reasonably large storage is a requirement. The one Boomer got is similar to what I saw at Sams Club. I am curious how that will do when removing/installing auto wheels as that is probably the heaviest duty thing I'll be doing. I have bought 2 complete sets of wheels/tires off of ebay recently and I do my own brakes too. The worst part of the job is the lugs if you ask me. Does anybody make an air jack?

 

[Boomyal]

Re: Compressor selection help

You not only need cfm to run an impact wrench but psi as well. A lot of small compressors will not achieve the 150 psi. The above ratings are for the compressor itself, not what the storage tank can deliver for short bursts. Mine operates an impact wrench just fine. It's not like I am trying to do production work.

 

[Solittle]

Re: Compressor selection help

Forget using these small compressors for any impact application. My 25 year old Sears 20 gallon, 220 volt, 125 psi unit won't take the nut off of a tricycle wheel. Neither will it power a decent air sander. These require lots of high pressure air which these small units can't deliver. Mine is great for blowing up tires, cleaning, spray painting and the like. They require little maintenance.

I do have a real neat attachment that has saved me lots of hours cleaning my boat & trailer (salt water use). It is a tree sprayer and intended to be used in blowing chemicals up into trees. It acts like a pressure washer. You connect it to the compressor and a hose. Got it from Sears.

 

[bjcsc]

Re: Compressor selection help

IMO, it's the type of painting you are going to do that is your limiting factor. If you plan on running an HVLP gun, and you spray properly (air moving through the gun at all times - 2-stage trigger) you need at least a 30 gal. tank or you will be waiting for it and working the compressor to death leading to moisture in your lines. Bond-o's setup is a great solution. Any compressor will run an impact gun. Big tanks will just run them more. Like Boomyal said, you're breaking lug bolts loose not going into production or opening a tire rotation company. I have a 30 gal. 120V that I bought at Lowes. Paints great, impacts, die grinders, orbital sander, straight line sander, air wrenches, nibblers, shears, all work great. High CFM tools, like cut-off wheels, jig sanders, drills, etc. are out, but it's great for home use. Does it compare to our 240V 2-stage at the shop? - no, but it does anything you need at home.

 

[ndemge]

Re: Compressor selection help

I painted my basement ceiling (subfloor/flor joists) with a cheapo air sprayer from walmart... With 20gal Camball hausfield compressor, had regulator set at 40 and it kept up... ran constantly, but it kept up.


One problem though, the smaller the tank, the hotter the air inside is, and doesn't cool off until it's in your hose and now you have a LOT of moisture going through your tools or paint.

The tank is where you want the moisture to condense so you can drain it.


If you go the super huge tank route like Bond-o... This is great to get you going if you are going to be using a lot of bursts with breaks inbetween, because it's going to take a lot longer to get that big system back up to pressure, and your compressor will be running non stop.
I did this exact same thing in the shop a while back, our air usage was high, I had a 30gal compressor pretty good compressor, pulled a full 20 amps, that was tied to my CH compressor, and then another 20 gallon empty tank. Both compressors pretty much ran non stop, but that kept up with our surges of air that neither could keep up with by themselves.

Now we have a bigger setup and have more air than we can use, so I have less moisture and not killing the things with 100% duty cycle.

 

[Drowned Rat]

Re: Compressor selection help

I'd go with ZM's advice on this one. I bought a 3 gallon compressor not too long ago and it was a complete waste of money. It's not enough to fill even one car tire, it just barely fills a bike tire. I can't imagine a 5 gallon would be a whole lot better.

 

[tommays]

Re: Compressor selection help

In the real word its 3 CFM per HP on a piston type

Generaly a 110 volt motor needs 11+ amps per HP

And thats if its a GOOD one


Tommays

 

[ZmOz]

Re: Compressor selection help

I've found that Bondo's favorite, propane tanks, make perfect extra air tanks. 20# tanks are about 5 gallons and $25 brand new, and rated for something like 250 PSI instead of 125 like most air tanks. I have three 20# tanks hooked up in my garage and two more in my back yard...that way I only had to run cheap 1/4" tubing and it isn't a bottle neck for tools.

Now I'm eyein' the 400 gallon propane tank on sale at home depot. 8)

 

[rogerwa]

Re: Compressor selection help

I bought a reconditioned Campbell Hausfeld 26 gal 120v unit off of e-bay. It claims 4.6 or something like that at 90PSI. I have run my impact wrench with it just fine. It removes the lug nuts without a problem. It will also run 30-45 minutes on an air nailer without having to power on.

It is not exactly portable but I can tote it around the house when I need it and can take it to the cabin if necessary.

When I removed the tile in the bathroomlast year I went to HF and bought a $9 impact hammer. That was an awesome combo..

I don't use it everyday, but it suits my purpose..

 

[Bondo]

Re: Compressor selection help

I've found that Bondo's favorite, propane tanks, make perfect extra air tanks. 20# tanks are about 5 gallons and $25 brand new, and rated for something like 250 PSI instead of 125 like most air tanks. I have three 20# tanks hooked up in my garage and two more in my back yard...that way I only had to run cheap 1/4" tubing and it isn't a bottle neck for tools.

Now I'm eyein' the 400 gallon propane tank on sale at home depot. 8)

I'll just add that,....

Used Propane Tanks are usually Free.............

If you go,+ visit a Propane Supplier,+ Ask,....
They're always Up-dating their customer's tanks at different times,+ the tanks that are rotated out of use are Usually dumped into a Scrap Dumpster......

Btw,.... By removing any Valves, or Plugs from the Tanks,+ turning them Up-side, Down for a couple of days,......
Any residual Gas is Purged,+ they're Totally Safe to use.......
Remember,.... This is Propane,+ Not Gasoline.......

 

[ZmOz]

Re: Compressor selection help

HF has this one on sale now:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90385

Like I said above, I have the same compressor on a 23 gallon tank. Much to my surprise, I calculated exactly 5CFM at 100 PSI, which is about what the sticker claims. If the tank turns out to be too small for you, go nuts with the propane tanks. d

As cheap as HF stuff is, I've never had one of their tools break. I have broken about every other name brand...

 

[dolluper]

Re: Compressor selection help

Exact same one on e-bay right now,same price but in Canadian bucks,hummm