Choosing an Air Compressor

[John Buzzurro]

Hi all - I know nothing about air compressors, so I need some assistance on what specs are important and which brands are good. I have limited space, so I'd like something pretty compact.

I mainly need something to blow out sawdust from power tools. It would be nice to also use it for tire inflation, but not a necessity.

I'm willing to spend enough for quality - I just don't want anything that's overkill for the application.

Thanks in advance.

John

[Mike Stanton]

It all depends on what you are going to use it for.If you don't want a big one you can get a pancake one or a small up right. But get a good one not junk. Mike :D

[Ken Fitzgerald]

John....

as stated by Mike, it really depends on how you plan on using the air compressor. If you don't think you'll ever need to run power tools with it or spray with it....you could be by with a small pancake or other small horizontal or vertical tank.

Big things to look for if you think you might use it for tools or spraying.....CFM at a given psi.......size of tank.........oil verus oil-less.....Tools that use air require a certain cubic feet per minute at a minimum pressure (psi)..........oil versus oil-less......some compressors require oil others don't......the compressors that use oil are generally...quieter and last longer........oil-less compressors are louder and supposedly don't have as long a life as their oil requiring couterparts......tank size......the bigger the tank...the bigger the air storage capability. A larger storage capacity would not require the compressor to run as often to maintain the output at a given psi and cfm. Good luck with your decision!

[Dick Heifner]

Hi John,
I just got the Porter Cable 6 gallon pancake compresser and It came with a brad and finish nailer, awesome unit. It' s about $300.00
Good luck, Dick

[CPeter James]

This is my tale on air compressors. I am on my 4th or 5th one, each bigger than the last. This is a 5hp (a real 5 hp Baldor motor) 80 gal IR that does over 16 CFM at 180 psi. Overkill, no way. Once you get an air compressor, you find new ways to do thing and a whole new world of tools. I picked up a Dynabrade sander this spring. Lighter, faster and does a better job than an electric. Also hose build in dust extraction, not just collection. Get the biggest you can afford, it will be cheaper in the long run. Get something heavy and get a two stage if you can, they are much more efficient. Air nailers are coming down in price and do a rel nice job and no hammer marks. Finish spraying uses a lot of air and for sanders, look to the body shop supply stores.

CPeter

[Randy Meijer]

......the compressors that use oil are generally...quieter and last longer........

While the above may be generally true, the oil lubed compressor I have now is as loud as, if not louder than, the oil-less unit I had previously. If you can, run the unit in the store to be sure it meets your sound requirements. If you are buying from a "box" store, you will probably just have to take one home and try it or maybe ask here for specific recommendations. One thing to consider is that a compressor that has a perfectly acceptable noise level when run outdoors as a sprayer or nailer may be a "KILLER" when running inside a small shop. I'm probably going to have to build a little sound reducing housing around mine*......I generally lift about 6" off my shop stool when the d### thing cycles on!!!


*or put it in another room and run a long air line to the garage.
Note: I bought a relatively inexpensive, 2HP, 5 gallon, store brand from PEP BOYS.

[Walt Pater]

I have used and abused for several years now a PC pancake compressor, and the thing refuses to die. It is the loudest, most annoying piece of machinery I own. Belt-driven models are quieter: if my PC ever checks out, I will investigate a belt-driven model.

[Allen Bookout]

Air compressor are like refrigeraters, they just seem to last forever if you get a decent brand so here is what I have to say.

1. Do not underbuy as you will have it for a long time - no use loseing money selling used and rebuying so get the largest unit that you can afford and have space for. You will need a lot of air since you will use it to clean things off with.

2. As far as I am concerned, any decent brand is good. No need going for brand name here unless you are going to run it eight hours a day - every day.

3. Two stage is great but probably not worth the extra expense for your use. If you can afford it without a blink go for it though as you will like it when you start using it for more demanding things as I know that you will.

4. I normally do not like to buy used tools but this is one case where you may be able to get a good unit at a really good price. Not too much to go wrong with it as long as it is less than six or seven years old. I would drain it though and see if any really rusty water comes out before I buy. Some water is ok as long as it appears somewhat clean.

4. As well as the normal places like Home Depot, Lowes, Sears, etc. take a look at Northern Tool. I have bough some of their pneumatic products and have been very happy with them for the money.

5. Basically, buy the largest unit that you have room for at the most economical price you can find and you will be a happy guy. While you are at it go ahead and purchase an inline water seperator. They are well worth the money and can save you some major headaches. Keeps moisture off of your tools that you clean and keeps water out of your paint guns and pneumatic tools and that saves you dollars every month.

6. Personally, I would not buy a pancake compressor unless I had to take it to job sites to use with non demanding tools such as nail guns. You just get more for your money with the other units.

[John Buzzurro]

Thanks for the replies. So, assuming that I still just want to use the compressor for blowing out sawdust, what CFM @ what PSI, and what tank size would be the appropriate choice?

thx
John

[Allen Bookout]

I would not want any smaller than this for your application. Anyone else jump in if you disagree.

5.8 SCFM at 90psi
125 psi minimum
20 gal or greater tank (25 gal would be much better)

You will use up a lot of air using it for a cleaning tool.

[JayStPeter]

Personally, I'd just get a shopvac with an exhaust nozzle for blowing off tools. Although I have found it useful to blow out tools (and other stuff), I wouldn't spend the money on a compressor just for that reason.
If I did framing at different sites, I'd get a pancake compressor for mobility. Otherwise, I'd get at least a 20+ gal model that will happily drive an impact wrench, air ratchet, air chisel, etc. Once you use these tools, you'll quickly see how great they are and never want to live without them.
If you truly think you need a small compressor just to blow out tools, buy something cheap. That way, you won't be out as much money when you upgrade to a larger model once you start to see the other uses.

Jay

[Randy Meijer]

Some people get a little over enthusiastic and will buy a four wheel drive truck because it snows in their area once or twice a year.........I'm sure you know the type!!

A 20 gal 5 HP unit would be wonderful if you need it and have the funds. On the other hand, if you really do want a compressor ONLY for blowing off tools and airing up an occasional tire why spend a thousand dollars when you can get a perfectly good portable unit for less than $200. I am in exactly your situation and that's what I did. I agree that air tools are great and would be nice if I had unlimited funds. About all I do to my car is change the oil so why would I ever need impact wrenches, etc....to change a tire, once a year?? Nailers are nice too; but I don't frame houses or do other major carpentry or woodworking jobs....so what's the point?? Sure, they would be nice to have on the shelf so I could use them once every 3 years when the "NEED" arises; but I will hardly suffer for lack of them.....my trusty Craftsman hammer still works just fine. I have a brick home so a spraying rig would sit mostly idle.....I don't refinish furniture either.

Bottom line........if you are reasonably "SURE" of your current needs buy what your really need now and not what you might have a 3% chance of needing 5 years down the road. On the other hand, if you can reasonably see yourself expanding your needs in the future, go ahead and buy a larger unit and give yourself some room to grow!!

The unit I have is one of those little horizontal two-tank, oil-lubed jobs. 2 HP(draws 13.5 amps), 4.6 gal. 115 PSI(max) 4.2 cfm @ 90 PSI. Weighs 53 lbs...cast iron compressor head. That air rate will run a lot of the smaller air guns and staplers; but probably not sprayers or sanders. BTW, the 110 V-15 amp circuit in the garage(typical in many homes) would not handle my compressor. I had to upgrade to a 20 amp circuit and the bigger compressors will require 30 amp circuits or maybe even 220 V so that is another expense that must be considered.

Good luck!! It is not an easy choice to make.

[Dev Emch]

John...

This is a very hard question to answer. If you use compressed air often or just once in a while makes a big difference. Another issue is that most companies lie to you about horse power and capability. This issue has already been covered. In general, the cheaper compressors use the less than honest way of stating horse power. If you find one with a motor by say baldor or leeson which is a standard industrial motor, your better off. Baldor will use their own motor tags and these dont lie. You will also notice that a 5 HP baldor is twice as large as say a 7.5 or 10 HP husky or craftsman compressor motor. Hmmmmm, whats up with that????

Tanks used on compressors these days are welded steel tanks with ASME certification. Many are identical and effectivly standardized. So there is not much of a difference in tanks.

The pumps are all over the board. Some are single stage and some are double stage. Some have intercoolers and others not. Some intercoolers are water cooled and most are air cooled. Some are aluminium and some are cast iron. This is the area where the makers really differentiate themselves and separate the boys from the men.

First of all, pumps get hot. They can get hot enough to burn the atomized oil myst in the compressed oil so getting the heat off that pump is important. Cast iron and large cooling fins really helps here. Also, large temperature fluctuations can cause issues with oil and compression seals. Aluminum makes a quick and cheap pump body but it warps and does not hold up to the long term. A cast iron sleave helps but the best pumps are all cast iron.

Motor life on a compressor is really extended if the compressor is built with unloaders. An unloader relieves the compression during the motor startup and only closes after the motor has come up to speed. Starting motors under a fully loaded condition is hard on the motors. So its nice to have unloaders on the pumps.

Most pumps today use splash lubrication. Here, a dipper on the connecting rod scoops up a bit of oil and allows it to drain under ambient pressure into the oilers on the connecting rods and crankshaft. The best pumps were built with pressure lubrication. In pressure lubrication, an oil pump pumps oil into these areas under pressure just like it does in your automobile engine. A pressure lube compressor pump will last almost forever!

There were a number of companies that really made excellent pumps in the old days. So there is no single answer to this issue. But Quincy is the most famous of these pressure lube pumps and they made them from a 5 HP model all the way up to a 25 or so HP model. I have one myself which is actually much larger than I need. Several of my freinds also have these. We bought all of ours at industrial auctions and mine is actually from the 1970s. Quincy still makes these today and you can order a new one if you like but the price is a bit hard to swallow. The 5 hp pump model will cost you some where around $2750 or so dollars. This includes a baldor motor and 80 gallon tank. Mine is in great working condition but has a lot of oil stains and dirt on the outside. I paid $400 dollars at auction for it and it is a 15 HP quincy 370 or 390 pump. IT can put out 54 CFM at 175 PSI continous so as you can see, its over kill for my operation. I would really like to get a 5 HP version with an 80 gallon vertical tank. That would be ideal.

I also noticed that some of the DeVilbliss compressors made during the 60s and 70s (give or take a bit) used greenish colored quincy pressure lube pumps. These are the same pumps as the highly touted blue quincy pressure lube pumps. Quincy sold these to DeVilbliss under an OEM contract.

So if I had to buy a new shop compressor today, without a doubt, I would buy a quincy pressure lube compressor. If you snoop around a bit, you may be able to snag one from auction at a deal.

[Gary Breckenridge]

:mad: I bought an air compressor from Sears. To make a long painful story short, the THIRD one has worked well. If I were buying another one I would shop locally for a different brand and then check Amazon.com;)

[Steve Clardy]

I have two 60 gallon compressors in my shop, tied together.
I also have two Porter Cable 6 gallon compressors for job site use.
I would recommend a small one, good brand, for what you are doing. Airing up tires, blowing off stuff.

[Vaughn McMillan]

John, I've got a 3.5 HP 11 gal horizontal tank compressor that I got at the local Auto Zone a few years back, for about $150 if I recall correctly. I use it for pretty much exactly the way you mentioned...blowing things off - both woodworking and other stuff - and filling the occasional tire. I went through two $100 compressors from HF that quit working within days of getting them home, then "moved up" to the cheapie one from the auto store that's done what I need it to do for a few years. I'm not running any air tools, but if I needed to I could run a small nailer or stapler. For me, it's been a good compromise between size, capacity and price. And it's lasted more than a week. Bonus. ;)

- Vaughn

[Ed Blough]

When looking for advice keep a few things in mind. Most of it is based on old data and most of it is mixed with personal preferrences.

I had an old oil lubed Sears compressor that was stolen. It was quiet, and it was big. I replaced it with a new cambell hausfield oil lubed that looked just like it. The new one was LOUD and big and took forever to fill. I took it back. I then started asking questions, testing machines. I found the biggest repair factor was improperly maintained oil lubed units. I talked to painters and they all told me to forget conversion guns and go straight HVLP. I plugged machines in and listened to them run, I measured them.

I finally settled on a PC3151 6 gallon tank 6 scfm at 90psi. It is small enough to slip under a shelf, is light enough to carry but has wheels and pull out handle to also be wheeled around. It takes 14 seconds of run time to replenish the tank and with an open hose at 40psi it takes 19 seconds for it to kick in. Therefore the run time is less than 50% in most applications. It is far quieter to me than many oil lubed units and I love all the space I got back. I now park an 3 horse gas edger, three gas cans, two buckets, floor jack, tool case and a stack of wood where the old compressor sat.

I use it for most air tools, (impact wrench, air chisel, die grinder and ratch wrench) I use to inflate tires, blow dust and drive nail guns. I think I could probably do touch up painting with it. I have wheeled it all through my house to nail up molding, chisle up a ceramic tile floor I was replacing, drive multiply nail guns during a bathroom remodel. I have also used to drive impact wrench when I rotate my tires, do a front brake job. Plus it fills the tires in my cars and mowers.

[John Buzzurro]

Just wanted to thank you all for the advice. I finally decided on a Porter Cable oil-less pancake model - 6gal, 2.6scfm @ 90psi. Tried it out yesterday, and looks like exactly what I need.