Air Compressor Buying Basics?

[Paschale]

Hi everyone,

I was in a thread about removing rust from a WM, and got some advice to use an air grinder from VA-Sawyer and Electic_AL.  It's definitely on my list of things I need/want to buy, and as I've been mulling this over, I'm wondering if I should buy one sooner rather than later.  I've had very little experience with compressors, though, so I'm not sure what the minimum requirements would be to do the things that I'd most likely want to use it for.  Any help would be greatly appreciated!

Here's what I'm thinking:

1.Using it from time to time to run tools, such as an air grinder.

2.Using it perhaps to do some blasting--VA-Sawyer mentioned glass bead blasting (which is new to me too), and in past posts, people have urged me to steer clear of sandblasting, since it could gum up the works of the bandsaw itself.

3.  Perhaps using it to repaint the WM.  I had thought about repainting once it's all rust free.  Maybe having Maaco or somebody do a cheapie $99 paint job.  Then, the thought crossed my mind with a compressor, if I buy the right one and a hand sprayer, I could do it myself.  

4.  Finish spraying for woodworking.

5.  Powering some air brad guns for woodworking.

6.  Uses yet to be determined!

I've been doing some looking in stores, and online, and I really can't make heads or tails yet of all the variables and differences one needs to consider.   : Any suggestions?  

Thanks!

Dano

[Buzz-sawyer]

Hey bud
I think a compressor is a must but there are several issues to consider..........first of all an inexpensive electric angle grinder works real well....I bought many, but the off brand china angle grinder has held up for a decade and cost 29.00 bucks.....they can cut really well with a disk and grind and polish , they are light and work great......
As far as compressors you need a high cfm capacity ( which mean cuic feet per minute....the amount or vollum of air you can push)... to run those little cheap grinders, which means a bigger motor 5 horse is min. but will work..........and big air res. bout 20 gal or bigger.
I would recomend air nailer and brad nailer , and impact  wrench ...I cant live w/o em...... :D :D
I would recomend paintin it yourself its fun and totally easy.....you can get a cambell-hausfeld kit with above mentioned tools combined for cheap or free with one of thier 5 horse compressors...like 250 at lowes for everything you need
except cheese cake to eat when your worn out from all that grindin ;)

[Norm]

Just to show you how much I appreciate having an air compressor I own three of em. Handiest tool on the farm, at the mill and in my shop. :D

Sears used to have some good deals on em too, I have a campbell hausfeld that broke after about one year of light use, not sure if this indicates anything but the old sears just keeps on plugging away. It's a five gallon size and 5 hp motor, I've banged it around for years. Plenty of other good brands out there too, after you get one you'll never know how you made do before.

[Gilman]

Paschale,

In your list of uses above, sand blasting will consume the most air, 2nd would be the grinder.  You'll need at least 22 CFM @ 90 psi for the sandblasting.  You won't be able to blast continuously but sandblasting is a miserable job and you won't mind a break. I have a 7.5 hp two stage air compressor with an 80 gallon tank and it can't keep up with a sand blaster.

Get a 2 stage pump, they are more efficient and you get more CFM/ hp that way.  60 Gal tank would be ideal.

If you don't get the bigger 5+ hp & 60 Gal tank, I'd recommend getting a smaller 2-3 hp portable air compressor and later move up to the larger air compressor.  You'll always have a use for the portable air compressor. And you can run the two compressors into one line when sandblasting.

Oddly enough, the paint sprayer is one tool that needs a large tank supporting it.  Not due to air consumption, but due to water condensating in your lines.  If you use a small tank the compressed air will not cool in time and will hold a lot of water in the air.  When the air expands in the line, this extra water will condensate and will come out your paint gun, ruining your paint job.  Doesn't matter that much on farm equipment, but on that woodworking project or a care, it is really frustrating.

Also, if you are going to use a paint gun, don't ever put lubricants in your hoses.  Oil at the tool only.

[GF]

Sand blasting takes a large amount of air, I have a two stage Industrial Air compressor made by Coleman  it keeps up with sandblasting pretty good.

I would also look to make sure it has a cast iron compressor and not an aluminum compressor.  I would prefer to pay a little more soomething that will last longer.

Here is the website for the industrial air compressor
http://www.colemanpowermate.com/compressors/industrial.shtml

I have the model IV5038023 it came with a 5hp balder motor, picked it up new for $999.  So far I have been pleased with it.

[jgoodhart]

A air compressor is a must in my book, got a 5hp 2 stage with 20 gallon tank that does most of the work painting, impact wrench, grinding and blowing the mess out the door. The 20 gallon tank allows it to be portable so I don't need to run long lenth of hose and have pressure and cfm drops. You just need electrical oulets here and there to handle the load 220 vac . I have used the 5hp for sand blasting and they will get the job done but I must wait for it to catch up. I also drug home 1 day a old 15hp 2 stage Ingersolrand compressor with about a 80 gallon tank and the compressor has a unloader for contiues running. I just run the compressor off the belt pully on my John Deere 70 diesel and I can sand blast all day at 150 psi. The important part of finding one of those old cheap compressor like that is it must have the unloading feture, that allows the compressor to stay running but it won't pump air till the pressure drops in the tank.

[Larry]

I have a 2 stage 7.5 HP compressor with 80 gallon tank.  The intention was to use it for a little sand blasting along with spray painting.  Got tired of sand blasting real quick.  Respirators, sand to buy, (and clean up) hot, and you can wear out a $1,000 compressor real quick.  We found a guy that will almost sand blast for the price I can buy sand.  It runs the rest of the tools like grinders very well.  It is amazing how much air a little die grinder can use.  My big complaint is the noise.  The 2 stage compressors in the $1,000 range run fast and generate a lot of noise.  They belong in there own little building way way out on the back 40.  I would like to sell it and get something with about a 20 gallon tank that is quiet.

Got a commercial Thomas 1-1/2 hp with maybe a 3 gallon tank for nail guns.  It has been abused and way over loaded for years but still keeps on ticking.  Only complaint is it is heavy and I think it pulls pretty close to 20 amps so it will trip a breaker now and then.

Next compressor is a cheap DeVilbiss import pancake oil less compressor.  I bought it about 5 years ago and figured with it would be dead by now.  I take it slow and easy on it and it runs good.  

I bet CK has a good advice on what makes a good compressor.

[karl]

Have worn out a half dozen or so 2 hp twin tank portables over the years- have a 3 hp 4 gallon porter cable that has the quick couplers and guages protected with a "roll cage" really like it as those were the areas most easily damaged on jobsites and in the truck- 'bout $260. Puts out 5.3 cfm@90 psi- pretty light for impact/die grinders but more than adequate for nail guns and staplers.
In the shop I have a 5 hp - 18.5cfm@100 psi with 140psi max.
Still not really big enough for serious sandblasting.
It is LOUD, It has caused a number of unsuspecting souls to call out to their Savior when it started ;) :D.
I'm satisfied with both compressors for what I use them for, course it would be nice to have a gas  one for the mill yard and those cabins off the grid.

[DanG]

I'm no expert, but I did some serious shopping when I bought mine. Ended up with a Husky from Home Depot. It is 5hp with a 26 gal tank, belt driven, cast iron cylinder, made in USA.  I think I paid a bit over $300 for it. It keeps up with all my air tools just fine, and isn't near as noisy as those "oiless" direct drive things.

Air tools to buy:
Impact wrench.. how could you exist without one?
Air ratchets...how could you exist without them?
Die grinder(whizz wheel)...how could you exist without one?
Air stapler...How could you exist without one?
Air chisel(great for digging nails out of logs)...how could you exist without one?
There's a lot more tools out there, and each time you buy one you'll be asking yourself that same question.

[Fla._Deadheader]

  I don't got none of them air thingys.  ;D ;D  All I got is a DA sander and a sand blaster (quart size). OH, and a tire chuck filler thingy. ;D ;D :D

[DanG]

How do you exist? ??? :D :D :D

[Fla._Deadheader]

  I'm just a figment of my wife's imagination : :

[Minnesota_boy]

Before you decide what air compressor to buy, find somebody with an oilless compressor in their shop.  Have them start it/use ait until it starts.  Bet you don't get one for your shop!  ;D

[J_T]

When painting I have put a large air tank in the line for more voloum and a good dryer is a must . Both are cheep .When I had a tire shop  I used Milton couplers they were the only ones that would take a lot of use and not leak.

[etat]

For a shop go ahead and spend the extra for a two stage.  In the future you'll be glad you did.  I used a 5 horse forty gallon tank for years, and grew to hate waiting for it to pump up.  Tools that take a lot of air include paint sprayers, grinders, chippers and air hammers.  Impact wrenches need a lot of volumn.  I've now got an 80 gallon two stage off brand, have had for five years, and still no complaints.  As JT said milton connectors are the best.

I too have a bone yard of them little double tank oiless compressors.  Used to wear one out about every 8 months to a year.  About a year and a half ago I bought a Dewalt, single tank portable 110 volt.  While still a oiless compressor it now contains a oil resivor that keeps a small amount of oil splashed ont he lower part of the cylinder.  As I said I've been using it a year and a half and still going strong.  They are lightweight and will pull up to three air nailers easily, though not effective for other types of air tools.

[CHARLIE]

Don't buy an oil less air cooled air compressor. They are extremely noisey.

Look for the highest CFM you can get for the money you want to pay. Be sure it is belt driven, oil lubricated with cast iron cylinders.  The oil lubricated with cast iron cylinders are a lot quieter.

I purchased a Campbell Hausfeld with a 20 gallon tank and 5HP motor. Mine is on wheels 'cause Tom told me to buy one on wheels.  I can take my air compressor to the work if I have to. If you buy a stationary compressor, you have to bring the work to the compressor.  I have had my compressor for about 8 years and have never regretted my choice.

Once you buy a compressor, be sure to keep the water drained from the tank so it won't rust. That's important!

[VA-Sawyer]

Dang,
Man, you sound about like me. All them years of working on planes got me in the habit of running an air line over to the job before moving the toolbox.  I have a regulator/separator/lubricator mounted on the side of my main box. It has 1 in and 3 outs. The first outlet is teed into the inlet so you can drop another hose off of it. The second outlet is between the separator and the lubricator, just in front of the check valve going into the lubricator. This give me clean regulated air for things that don't use oil. The third outlet is from the lubricator for feeding tools that need oil. I use different style couplings on my oiled hoses than I do my oil-less ones. Like somebody said earlier, you don't want any oil in air hoses you use for painting. This setup makes sure that the tools that need oil will be hooked up to a lubricated source. I have a 25 year old air drill that still has pretty good power after years of drilling out rivets.
Do you get the feeling that I depend on a lot of air tools too ?
VA-Sawyer

[Paschale]

Guys:

Thanks for all the replies!  I'm going to have to sit on this for a few days and process it all, and then I know I'll have a few more questions.  I did a lot of looking today at Menards, Home Depot and Sam's Club at various size compressors, so I'm gettin' a bit of an education on these things...

Need to absorb the info you guys gave me, and figure out how I ever existed without a compressor!   ;)  

Thanks!

[OneWithWood]

One thing I have done that has not been mentioned is to run a solid line around my shop with outlets where I work on different projects.  I used PVC pipe rated a 400psi.  Standard water supply line works fine and is cheap and easy to work with.  At each drop I extended the line below the coupling and incorporated a ball valve so it is easy to evacuate the line and blow out any condensation.  I mounted the compressor on wheels and use a flexible air hose to connect to the solid line.  This way I can disconnect and move the compressor if I need to.  I ran a line to the outside of the building for working on things like the crawler that I do not want to bring inside.

[Gilman]

VA,
Good idea about using different couplers for you clean hoses and oiled hoses.  I'll have to take some photos of some features I like and don't like about my air system here.

Gilman

[Rocky_J]

Paschale-
Take it to heart when you hear one after another advise against an oilless compressor. Virtually every compressor at HD is oilless except for one or maybe two models. I am also looking at that $300 deal at HD for the 26 gallon tank and 5hp belt driven compressor. The only reasaon I haven't bought it yet is because I don't have the concrete floor poured in my shop yet.

[ElectricAl]

We were given a 6 month old 5.5HP 30 Gal compressor by my Grandfather. It is oilless and really makes a racket.

It get's 4-5 minutes of run time 6 days a week.

About a year after we got it the compression ring broke.

I took the cylinder head off and looked inside..........SAWDUST

Wonder were the sawdust came from ???


Well, I ordered up the parts including a new cylinder : and reed valves and slapped it together.

To prevent that pesky sawdust from getting in the cylinder I added a K&N cleanable air cleaner.

We use to use K&N air filters on our race cars and motorcycles, so I guess its good enough for an AirCompressor

[Mark M]

Dan,

Keep in mind that the 5 hp and bigger compressors usually require 220 volts. I have a small Porter Cable oil-less that works well for my air nailers etc. It is noisy and I wish I had bought the one will oil. I also have a 5 hp Sears that works very well. Check out the farm stores as another source.

Don't forget safety glasses and a face shield (I use both) when using air tools, especially grinding.

Mark

[CHARLIE]

Mark M, my Campbell Hausfeld 5HP, belt driven, oil lubricated, cast iron cylinders on a 20 gallon tank with wheels (whew! :D ) runs on 110V.  If I had to make the choice again, I'd buy the same thing.  

My cousin bought an Ingersol Rand, which is the cadillac of air compressors, but very spendy.

[Quartlow]

ok for my 2 cents worth, 2 stage compressors do not always equate into more volume, more pressure is the goal with a 2 stage.

A friend of mine in washington purchased a single stage 5 HP quincey last year that is a low rpm 4 cylander unit. It's quiet and makes a gob of air volume wise. it only makes 135 psi but thats plenty. I checked the quincey website and can't seem to find it. I calledhim and he couldnt remember the model number off the top of his head. It's in storage right now but as son as he gets a chance he is going to get it for me.

He has ran as many as 3 lines of of it at once working on trucks and has yet to run it out of air. the best part was he bought it for less than $1000.

[rebocardo]

>  to use an air grinder from

When using an air grinder or cut off tool, you really need a lot of CFM. A someone mentioned, at least 22 CFM @ 90 PSI. That = $$$$

For light normal use, get something that puts out 6 CFM @ 90 PSI (not 40!). This would be about $300 from northerntools.com. This is enough to run most air tools for a few minutes including an impact wrench.

The nice thing about a small 120v 6CFM@90 compressor is it is light enough to put in your truck and take somewhere. Same deal with a a 120v MIG welder.

[isawlogs]

I also have (  Campbell Hausfeld 5HP, belt driven, oil lubricated, cast iron cylinders on a 20 gallon tank with wheels (whew!  ) runs on 110V  ) I can also wire the motor to run on 220  
  Thanks Charlie it was faster to copie and past , hope I didn't infringe on any copiewrite laws here ....  ;)
  If I had to buy another it would be a little bigger and standing,

[Larry]

Few more comments on air compressors.

I plumbed my shop with PVC the first time.  Pipe is plenty strong but fittings are rated a lot less.  I had trouble with them cracking and then leaking.  Running 175 psi from the big compressor.  Second thing if you have a little fire and it melts the PVC you will have an inferno in seconds and your insurance company may not cover the loss.  Running copper in the new shop.

The big compressor is an Ingersol Rand 7-1/2 hp with 80 gallon tank.  It may be the Cadillac of compressors but when it comes on you can hear it a mile away.  If in the shop you need ear muffs.  Wish I had the Quincy that Quartlow was talking about.  

I have never seen a compressor over a true 1-1/2 hp that could run on a standard 110V 15 or 20 amp circuit.

My little DeVilbiss oil less compressor really does not make very much noise.  Not promoting any brand but it is pretty quiet.  Nothing like some of the other models.

[Gilman]

Larry has a good point about the pvc, with its low melting point and potential to crack.

Here are some features that have worked out well for me.

The first is a paticle/water collector that is at the bottom off all the drops.  The main lines are in the attic coming from the compressor.


Here's the air compersor mounted on a mezanine. No point in wasting valuable floor space.  It's a 7 1/2 hp 2 stage compressor that came out of a navy ship.


Here's some of the air tools put away on a mount.  Most of the tools are held in place by their air fittings. The large tools like the impact wrenches slide into a large hole that is a little bigger than the tool body.


Here's a closeup of the compressor mounted to the plumbing system with a flexible hydraulic hose.


The is the best feature in the air system, an outdoor fitting.

[DanG]

Oh, you people make me sick with you fancy shops, and all! :D :D  You oughta see mine! :

Larry, I agree and disagree. You said, "true" 1 1/2hp, which is a figment in today's world. HP is strictly a sales tool any more, imho. I have a 1400lb horse that can go from 0-40 in about 3 seconds with my 200lb butt on her. Show me another 1hp motor that can do that!  It seems that HP ratings are just assigned by marketing groups to get max sales. My 16hp mower don't cut a bit faster than the 10hp model it replaced. ???

On the other hand, 120v @ 20a should produce about 3.2 mhp.(Marketing HorsePower). ;D

[iain]

what ever you get make sure the air going in is CLEAN  
i got a 7.5hp 80gal ingersol 1987 came from jims paint shop when he retired
 im also surrounded by workshops with compressors (six) there all loud cept the air screw one in the top yard that runs 75cfm its really quiet

[Paschale]

OK...I've finally had some time to process all this information!   :P

Thanks for all the info, guys--once again, the brain trust of the forum comes through.   8)

So, I've gleaned a few ideas from the thread, but it's raised a few more questions too.

Seems like a minimum is a 5HP, 20 gallon compressor.  Ideally with a cast iron cylinder, and ideally a 2-stage.  And I'm wondering if the two stage is a two cylinder compressor?  

For me, anything around $1000 is way too expensive right now.  But what confuses me is that Gilman says that for paint spraying, you need a large tank, though sounds like j_goodhart does this with a 20 gallon tank.  I'm thinking that a "large" tank is more into the 60-80 gallon tank.  Can you do painting with a 20 gallon tank OK then?  sounds like Buzz, that you're able to do some painting OK with that cambell-hausfeld.  Can you get a nice paint job with one of these?  I'm a little confused.  

It sounds like I should sorta give the idea of sandblasting the heave-ho.  Sounds like a dirty, messy, thankless job, and that in order to really do it well, you should use a big ole tank.  Though jgoodhart says he's able to do it with a smaller tank--he just gets "built in" breaks from time to time, which are greatly appreciated.    ;)  From what you all said, though, I'm thinking using a grinder is the better way to go.

Speaking of air grinders...I'm a little confused on this one too.  From what everyone said, it's surprising how much air an air grinder uses.  I guess I'm wondering if I go with a "Campbell Hausfeld 5HP, belt driven, oil lubricated, cast iron cylinders on a 20 gallon tank with wheels (whew! :D )," will I be able to successfully use an air grinder?  And do some painting?

The most important thing I learned:





DON'T BUY OILESS!!!





 :D

Thanks for all the help guys!   8)

[J_T]

I once quick hooked a hundred lb lp tank to a small compresor and ran a tire machine 8) I now have one them cambelhasfeild jobs an use a binks #7 paint gun most painting is at a low presure and you need to stop and fill ever now and then.  Mine was cheep and on sale it had a bunch of tools plus a good warrenty at walley world ;D

[etat]

Unless ya got lots and lots and lots of air, just go ahead and get an electric grinder.  For small jobs them smaller electric grinders are hard to beat.  An air grinder, or buffer even  suck the air outa a little outfit quick, and ya'll be taking more breaks than ya want to. And getting aggravated at the same time.

You can absolutely paint with a smaller compressor, but you can't do as good a job on something like a car or truck where once you get started you need to keep moving.  It CAN be done but it's harder to get as smooth a finish. For fine finisheses a bigger compressor, and HVLP paint gun is the ticket.

A two stage can be one cylinder.  It pumps both on the up, and the down stroke, I 'believe' I'm right.

I'd REALLY like to have me that ole 4 cylinder unit.

Sandblasting, along with painting a base coat, clear coat type automotive  paint is among   the most horrible jobs in the world. I personally will NEVER again paint base coat, clear coat.  Proper respiratory gear is an absolute necessity. If you want to keep breathing that is.  

A air paint gun does not paint latex or heavy equiptment type paints very well, if at all.. Especially a smaller outfit. For these type paints, especially latex,  a commercial, airless, electric paint sprayer is the best option.

I would not buy a larger type tank with wheels.  I'd get a longer hose.  If I wanted portable, and I use one EVERY single day to run nail guns, I'd go with a smaller oiless compressor.  Get something larger than the small pancake type compressor though.

One thing that may be of intrest.  Most semi portable belt driven, oil filled compressor, WILL NOT keep my nail guns running.  Some contractors use em, and many have invited me to plug into their compressor.  The bigger tanks on em will hold more air of course, but all I've run across pump down too low before kicking back on.  And then wait too long to pick back up enough pressure to keep the nails fully driven. A 'good' oiless compressor will kick back on when the pressure drops to 90 lbs, and take only a few seconds to pump back up. And all the time we're shooting them guns wide open. As I said with the belt driven we have to wait a minute for the pressure to come back up. More often than not I'll have them contractors just go ahead and hook their guns up to my 'little' compressor. They ain't ever shooting their frame guns as fast as we are nailing on shingles anyways.

My choices would be 'either, or'.

Shop type, 80 gallon tank two stage, stationary.

If I couldn't have that I'd go with a oiless portable, name brand, with an oil splash on the cylinder  that'd pump as much air as possible with a 110 motor.

I wouldn't get anything in between.

My recomendation for semi oiless, and I've used about ever type there is.  

http://woodworker.com/cgi-bin/FULLPRES.exe?PARTNUM=114-080&LARGEVIEW=ON


This is NOT a loud compressor.

I've got more commercial time on this compressor in the past year and a half than most average homeowners would get in ten years.

Either way the CFM, and recovery time compared to what tools you'll be using is what you want to go by when making your decision.

Some will lie about their horse power, cfm, and recover time.  

Sorry fer confusing you even more.

[J_T]

Ck get on that presure switch with your screwdriver  :D :D Once I set the off pressure with the relive valve you can set the on at what ever you want to. I know where thare is a screw compressor beleive it was used at a cly Co . One them things I hid a while back.

[Quartlow]

I'm firm believer in single stage for most use's.

A 2 stage compessor use's 2 cylanders or incraments of 2 cylanders. Cylander one is larger in diameter than cylander 2 in most cases. Air is sucked into 1, on the compression stroke it forces the air into cylander 2 which pumps it into the tank. The advantage of a 2 stage is higher operating pressure's. Since you are forcing the air into 2 you are creating basickly a supercharged compressor.

Most air tools operate in the 90 to 120 PSI range. While higher pressures  will make a 1/2 inch impact do more you shorten the life of the impact gun this way.

2 stage compressors generate more heat which also equates into shorter compressor life and more water in the system.

Now on the average most single stage compressors will generate more volume but at lower pressures. The one thing to keep in mind here is they sell them buy the HP range of the motor not the compressor. To truly compare a compressor you need to know the cubic inches of the compressor and the amount of air genorated of CFM ( cubic feet per minute)

I've seen 7 HP 2 stage compressors that only produce 13 CFM at 90 PSI and 5 hp single stages that produce 12 cfm at 90 PSI

Most single stage compressors shut off at 125 to 135 PSI So why would you need a 2 stage that goes to 175 PSI?

You not going to paint at 175 PSI or run a nail gun at the pressure. So why waste electric making pressure you don't need.

We have 3 compressors here on the farm a 7.5 HP single stage a 5 hp single stage and a 3 hp single. The 3 and the 7 are both Ingersoll rands. Both are over 10 years old. The 5 horse is an off brand chinese thing. Its 2 yearts old and its whipped allready.

IMHO you want a single stage that makes the greates amount of CFM for a given HP range

[VK540_1]

I just purchased an air compressor and now I would like to buy a nail gun to use with it. I would like a gun that would be good for nailing osb on floors walls and roofs. Is a brad nailer good for this or would I need a framing nail gun? Any brand recomendations ?

[jgoodhart]

Check out this site got some big compressors cheap if you have a power sorce or tractor to run them.  I dont know if the link works but www.hgrinc.com will get you there than search inventory. http://www.hgrindustrialsurplus.com/List.asp

[jgoodhart]

Wow the link works, just went to the wrong section :-/. 1st time I did that.

[Gilman]

Wow, great prices on the dust collectors.