First (real) air compressor reccomendations?

[ckadams00]

There are probably tons of threads about this but I didn't see anything when searching.m Looking to get a "bigger" compressor. I currently have a small Husky "silent" which I love for small jobs (brad nails, etc) which is replacing my Bostich pancake 6 gal (which I want to get rid of). Got some money and I'd like something bigger - I am not a heavy user but I'd like to be able to: run small metal reciprocating saw, a die grinder, an air drill, air hammer/chisel. I don't really do any painting but I'd buy a cheap paint gun if it worked - better than the rattle cans I currently use. That's about it and not heavy use. But the guys at Menards were no use at all about what I need. I don't want to spend any more than I need to but I'd certainly like to be able to use the tools listed . . . suggestions?

 

[md21722]

Die grinders, air drills, and paint sprayers use enormous amounts of air. Your typical die grinder or air drill uses 17-22 CFM. The more powerful 0.5 HP - 1 HP ones use 25-37 CFM. At that point it depends on how long you need the tool to work. Someone buzzing off gasket material with a cookie wheel for a few seconds is a bit different that someone trying to clean up a bunch of metal with a wire wheel on their die grinder.... for the latter you'll need at least a 5 HP air compressor and it will probably cost over $2,000 unless you buy used. Remember, air is not energy efficient. Its efficiency comes in other ways, such as the tools being smaller & lighter, less operator fatigue, fit into tighter spots, no danger in water, no electrical hazards from cut cords...

 

[WhiffySpark]

You'll be fine with a box 60 gallon. I have a kobalt it works fine

 

[seanh303]

First, look at the consumption of the tools you currently have. Research the consumption for the tools you plan to use in the future. Estimate the cycle you will use the tools to determine the total CFM your compressor needs to handle.

A drill for example might be 5cfm at 25% factor, which is 15 seconds of use for each minute, 10cfm at 50% factor and 20cfm at 100% factor.

A die grinder and paint sprayer are similar. If you will use them continuously (100% factor) you'll need a compressor capable of 20+ cfm. If you'll use them intermittently you can get by with less capacity. Here's a chart that will help:

http://www.industrialairpower.com/wp-content/uploads/Air-Compressor-Consumption-Charts.pdf

Look at cfm ratings not horsepower. Be sure to check the duty cycle of your compressor aswell. It may be rated at 20cfm, but a 50% duty cycle, which means in a 1 hour period, it can run for 30 minutes and rest for 30 minutes. Buy one with as high of a duty cycle rating as possible, with 100% being ideal (i.e. it can run continuously at the rated output without overheating etc.)

Once you know how much air you need, save up for the best unit you can afford, ideally from a reputable brand, with a solid warranty, from a retailer that can offer you local service.

 

[theoldwizard1]

Sand blaster consume HUGE amounts of air !

 

[bdelmar2]

Without getting too picky, it comes down to the consumption of the tool you are using, and how much you plan on using it.

In order to realistically run higher consumption tools, like sprayers/sanders/blast cabinets you want to at least match their rated air consumption.

You can cheat a bit if you plan around waiting for the compressor, but this will of course have the compressor running a lot, which leads to how much you plan on using it, or what is called a 'duty cycle'.

Duty cycle is what really separates a 'home' compressor from a 'pro' compressor. (Not whatever sticker they happen to slap on it.)


On the other hand I work in a shop where they got by with a 60 gallon husky single stage compressor for some years. Yeah, it said 'pro' on the sticker, but it definitely was not.

It was fine until we got more than a couple people working constantly, then it would get hot and melt the plastic line to the regulator, I would fix it and tell the owners it should have blown up. (yet again) It also melted out the back flow valve, and blew a couple capacitors and what have you, but I always kept it going.

Mechanic/Transmission shop, not a body shop.

The local napa finally ran out of the little air fittings I was using and I ended up getting a little better designed one.

So instead of melting the line, it blew up the last time it went.


They of course wanted to go buy another cheap one like they had, but I talked them into buying an older used 'real' compressor from craigslist. We got an old Kellog 4 cylinder 80 gallon with magnetic starter on 4x4 skids for $750.

Its pretty old, but way quieter than the husky was, and from what I could find online its something like 22cfm. I wasn't able to find the duty rating, but generally anything with a mag starter has a much higher duty rating.

Although I did see some compressors labeled as 'pro' and having a mag starter, but were in fact the exact same compressor as the next lower model they had, just with the starter, I guess to make you think it was more heavy duty - napa website was where I saw it.


In any case it has been an excellent compressor, quiet, and keeps up with no issues even though we run it harder than the old one. If we ever do have an issue, its likely possible to rebuild it, well for sure is - if the parts are available.

Plus having the sound of a 'real' compressor running is unique and comforting. More of a bass rumble as opposed to a high pitched squeal.


At home I have a porter cable 80 gallon 2 stage, supposed to put out 17.2 cfm at 90 psi I think, though I have it set to 175 psi where it says 9 cfm or so.

I bought it off craigslist for $300. Its in decent shape, came on wheels, with a good cord/plug, and regulator/ball valve.

Its good enough to run a spray gun or what have you, but still not a 'pro' level compressor. No mag starter, and home duty cycle - even though it also says 'pro' on it.

Also worth noting, I believe all these lower end compressors are actually made by the same company, or most of them, whether they are labeled 'husky' or 'porter cable' or 'dewalt' or whatever. I think the actual manufacturer is Campbell Hausfeld.

From what I can tell the pumps aren't really rebuildable. I did find kits for them, but they cost as much as buying a replacement pump. A new pump cost about what I paid for my whole compressor, or a bit more.

When mine dies I'll probably just go buy another similar one for about the same price. Unless I'm actually using it more, like depending on it for a living, or if I happen to have the extra money then I might buy a good 2 stage unit.

A decent new compressor in the actual 'pro' (2 stage/175 psi 17+cfm, mag start/high duty cycle, 60/80 gallon) range is around $1500 to $1700 at the low end, and up to the sky basically. I did see one somewhere for around $1300 or so, but I was concerned about its factual specs.

Side note: single stage compressors top out at about 135 psi.


Harbor freight. I'm sure someone will suggest their compressors. I don't really have any experience with them. I've read a lot of good reviews and some bad ones, but you know how that goes.

I do know a shop owner who is a bit on the cheap side, and when his pump went out he went and bought a hf pump. Took his mechanic a bit to get the fittings and mounting to work and then it blew up in about 2 days, took it back and got another one, it lasted a week, took it back and got a third one, which as far as I know is still working.

I have seen a couple of the mid range units around and working, but I don't know for how long or how well.

Their prices don't seem to be very far off the box store compressors in any case.


There you go, compressors in a nutshell more or less.


For what you want to do, the single stage 60 gallon unit would probably be fine, just keep an eye on how hard you run it. (duty cycle)

I don't think I'd want to try painting a whole car with one (given the price of paint these days), but ok for smaller painting jobs.

New they are like $500 or so give or take a bit, used I wouldn't pay more than $200 or so at most.

A 2 stage 60 or 80 gallon would be better, the kind labeled 'pro' but really isn't. Good enough to paint a whole car, still want to keep an eye on duty cycle.

Should be able to get one used for $300-$400 give or take, and around $1200 ish new.

A true "pro' compressor with a high duty cycle, high output, is really overkill for what you appear to need to do. On the other hand it would last forever, and you wouldn't have to keep an eye on it, just make sure to keep it drained, change the oil and filters now and then.


These are all 220v btw, you won't be happy with anything 110 anymore.

If you go the used route, you want to have a look at the compressors general condition.

Outside being a little dinged up is fine, but look at the belt adjustment bolts, if they look untouched its better than if they look rounded off and have squashed washers and lots of marks where the bolts have been moved.

If its covered in a fine oil mist around the pump, not good. If its been wiped down recently, but you can see where it used to be oily, not good, especially if it has suspiciously clean oil in the pump.

If it looks like its been worked on a lot, be concerned. Might be just like the husky that finally blew up on us.

It its been freshly painted, I'd also be concerned.

Only buy one you can hear run.

Drain it if it isn't already. Expect some rusty water, but gallons of it is not a good thing.

Close the drain and fire it up. It should turn right on and run without any alarming noises, knocking of any kind is bad obviously.

Keep track of how long it takes to fill up and shut off. A good indicator of pump condition is how long it takes to fill the unit. I don't know the times right off the top of my head, but for each kind of compressor you are considering you can find the time frame with google. If it takes a fair amount more time than it should, the pump is most likely worn.

Run enough air out it starts again and refills and shuts off. If it has a hard time restarting it has issues, probably the unloader valve, but possibly other problems.

One way to do this is to pull the ring on the safety blow off, then when the compressor starts again let go, should reset itself.

Tanks are also dated, I've never had, or heard of anyone in real life having one blow out, but I gather it does happen.

I'm not sure how good an indicator of safety the date really gives as the older tanks are way thicker/heavier than the newer ones are, plus how well the tank was maintained I imagine is a large factor.

In any case it will give you a date of manufacture, so if they tell you its 3 years old, but has a date from 15 years ago on the tank, I'd believe the tank over the seller.

 

[sberry]

I painted about 25 cars with a 3 hp. Some big trucks too. But somewhere someone has picked out a couple 2 stage import box store models that look pretty good. Mechanics type, I think about 800 or so. If you can really wear it out buy a new one.

 

[American Locomotive]

Unless you absolutely have to buy new, I'd go used and search Craigslist.

There are tons of old Campbell Hausfeld, Ingersoll Rand, Quincy, etc... heavy cast-iron compressors out there. Most of the 5HP and under ones are actually pretty quiet, and they're built tough enough to last two lifetimes.

bdelmar2 gave a pretty good summary of what to look for on a used compressor. The only thing I slightly disagree on is that to me, personally, it's not a big deal if the compressor head is a little oily. Old seals are going to weep some oil. As long as the compressor has oil in it, and it's not visibly dripping or pouring out of the front seal or from any gaskets, I wouldn't worry about a little oil residue.

 

[Citation]

The "$400" 60 gallon big box compressor is probably the best bet in this case. To put some of this in perspective, a guy I know is doing fabrication work (tube frames, sheet metal, grinders, rivet guns, air drills etc) with a 2hp (230V, honest 2 HP) compressor with a 30-40 gallon tank. He hasn't really liked it but also hasn't felt it was quite worth spending real money to upgrade. His previous compressor was a 5hp Champion 80 gallon with something like 4x the flow rate. His biggest motives for wanting more is the current compressor can't run a sandblasting cabinet and the compressor is just old and no longer starting up as well as it used to.

Anyway, I think you will find that a $400, 60 gallon would be the sweet spot for a new compressor. If used is on the table then what ever you can find. I just picked up low end 80 gallon compressors for free (will have to put parts in to get them running) but I doubt I could replicate that luck again! One of the three is going to the guy I just mentioned. Sadly I really don't have room for something that big and given my garage situation I doubt I will ever get that opportunity. Also, such a compressor would require running new power to my garage and putting in a sub panel. The 3hp models typically can work off a 15A 240V breaker and 14-12 gauge AC wire. Bigger compressors will often require a 30 A breaker.

Just to throw out one more idea, and this is what I'm likely to do for my self, consider pairing two 120V compressors. If you have two circuits in your garage so you can run two compressors at once, you can get ~10 CFM out of a pair of compressors. Alternatively, you could add a 120V compressor to what you already have.

I have two compressors, one like this Speedaire, and a 4 CFM contractor twin tank type. So with the pair I have almost 10 CFM @ 90 psi of pump and about 25 gallons of air capacity. Not as much tank as I might want but I already own all of it. All I have to do is pay for the stuff to connect them together. Such a setup will take up less space in my garage vs a stationary 60-80 gallon and offers some flexibility. I can tuck these smaller compressors away, still use the smaller one as a portable unit etc.

You have a compressor that is probably around 3 CFM. If you get something as cheap as the HF 21 gallon, 4 CFM for not much over $100 you will have a big increase in air flow and tank capacity. You can use just the quiet compressor when you don't need big power and the price is really low. Not as nice as a big 60 or 80 gallon compressor but perhaps enough to do what you want and without spending even $200.

 

[md21722]

The 3hp models typically can work off a 15A 240V breaker and 14-12 gauge AC wire. Bigger compressors will often require a 30 A breaker.

3 HP compressors nameplate is often 230V 15A. By code they must be wired with #12 THHN (in conduit) or #10 NM-b (Romex). Breaker can be up to 50A to prevent nuisance trips but are more commonly run on 20-30A breakers...

I am of the opinion that 3HP 60 gallon single stage compressors from big box stores do little more than look nice in the garage. Even running a little IR301 die grinder, if you're doing any more than buzzing off gasket material with a cookie wheel you're going to come up short...

In my opinion if you can do what you want with a 2HP 26-30 gallon unit, that's great. But if you need more air, you generally need a bunch more air and are best served by going straight to a 5-7.5HP dual stage with 80-120 gallon tank w/ after cooler or equivalent. Most people stop upgrading and asking once they have 7.5HP with after cooler, even when sandblasting.