Air compressor for small shed shop

Hi I'm in the market for an air compressor but have no idea about them. It will never be used in a professional capacity, and I'm low on storage space (just a small shed).

Somebody said in a post somewhere that I should get minimum two HP and 3 gallons. Is this enough? Can I get away with less? Is there anything I should be looking at besides HP and tank size? I'd like to keep this expense under $200 (CDN) if possible.

 

Decide first what you want to do with it.

Air tires? Blow air through carbs for cleaning?

Run Air tools? Which Air tools?

Shoot paint? What kind of gun?

Look at the tools you'll use or think you'll use. Find their CFM and then find a compressor to match. I think you'll find what you really want/need vastly differs from your budget. Mine does.

 

Sanders and grinders use a lot of air and a small comp will empty quickly. Spray guns aren't quite as bad since you dial the pressure down and if you are just doing cycle parts you should be ok. You can rig up a pony tank out of an old (larger) propane bottle to help with this. I would get a comp that is oil lubricated, not quite as noisy and they last longer. Not sure what stores you have there but in Denver small compressors are about 150-200 bucks.

 

And if you're going to spray paint, you better get a dryer/water trap for it, too.......and one that is not oil lubricated!

 

check out princess auto or keep an eye on canadian tire flyers for sales once you determine what size you need.

 

Sounds like I'm looking for a 2hp 3.0gallon 5.0scfm non-oil-lubricated compressor.

Thanks for the help!

 

I picked up a 21 gallon 5 HP from Harbor Freight for $110 on sale. I got a 20% coupon from the back of a Cycle Source magazine and they were on sale also, but I think the usual price is $199 US.

 

If only there was a magical store full of low price tools in Canada, too.

 

They have a website bud, I'm not sure if they ship to Canada or not though. Harbor Freight Compressors

 

I have a large 5hp 60gal tank for my shop (cabinets and woodwork) and a small 2hp 5gal, both are oil-lubed. Have never had a problem spraying lacquer. What's the problem with spraying paint???

skillet

 

You can get small amounts of the oil in the air line and it mixes with the paint.

 

And then you get the dreaded "fish eyes" in your painted surface.

Unless you use, believe it or not, "fish-eye eliminator additive"........and although it works, it tends to not produce as nice a finish for super high-end paint jobs.

 

Go for a tank of about 8 gallons or better. Smaller tanks do not hold enough air to do any real work with air tools not even for home garage use. I use 3 gallon for my air brush. Just not enough capacity for anything else. Check CT, Princess Auto and TSC for them on sale.

 

Go for a tank of about 8 gallons or better. Smaller tanks do not hold enough air to do any real work with air tools not even for home garage use. I use 3 gallon for my air brush. Just not enough capacity for anything else. Check CT, Princess Auto and TSC for them on sale.

 

Good advice.

I have a Craftsman 5hp with around a 25 or 30 gal (horizontal) tank; it's just big enough for about anything you might ever want to do as a home mechanic or for home improvement, but not huge at all.

I paid around $169.00USD for it, but that was about 25 years ago...

 

If you are gonna paint with it, you should get a GOOD filter/water eliminator.
A good one will cost more than the compressors you are talking about though.

My local paint shop has the little disposable canisters that go on the hose just before the gun since it doesn't help much to have a filter at the compressor if the hose is full of water.

Using both is even better.

 

There is and it's called Princess Auto. There is one in your neighborhood to:
http://www.princessauto.com/locations/kitchener
I think all their stuff is Chinese, but whos' isn't these days. Hydraulic bike lifts, wheel chocks, compressors and on and on and on!
For the weekend mechanic it's like a candy store, check them out.


Cheers, Graham

If you are looking for a reliable mechanic, I have a friend and fellow racer that has a shop in Ayr, great work and great prices.

 

Thanks for all the suggestions but I'm still a bit confused.

Let's say a compressor is rated to provide 5.0 SCFM. Is that 5.0 SCFM continuously with the motor running? Or is that 5.0 SCFM for some period of time if the tank is full?

Fitz and Ground-Hugger both say to get a bigger tank but nothing about the motor size or SCFM. If I get a big tank with a smaller motor, am I still able to get 5.0 SCFM for a while, but then do I need to wait for the motor to refill the tank? Is that how this works?

Is the SCFM output adjustable on air compressors?

Thanks again for the help.

 

Hopefully I understand this correctly. Here goes:

Think of the tank as a bathub. It holds a certain amount of water. If you fill it then pull the plug and turn the faucet on one of three things will happen.

1. Your tub will drain. Because the drain is faster than the faucet refilling. This happens with a small tank and a small motor with a big tool. making the motor run constantly and your tool function at less than ideal.

2. Your tubs water level will stay constant but the faucet stays on.
This happens when the motor and required air output match. The motor will run but you'll always have the air.

3. Your tub overflows or the faucet turns off. This is because your drain is slower than the refill. The tank stays full and the motor cycles on and off.

2 or 3 are best. 1 gets you mad when the tools stop working in the middle of something. Also an important note with air rachets, air hammers, etc they don't work at their peak without the correct CFM. Nothing worse than trying to use a "better" tool that doesn't work right.

Your SCFM output by the compressor is constant. You'd have a regulator on the outbound side and adjust there. Some tools are also adjustable.

 

That's a good way to look at it. If I go by your explanation, though, what's the point of ever having a big tank? If I'm always going to want the motor to be able to generate the SCFM my tool needs then why do manufacturers make 25 gallon tanks when 1 gallon would suffice.

Along these lines, when a compressor says it does 5.0 SCFM, is that 5.0 SCFM motor-to-tank or tank-to-tool?

 

Because most people are doing more than operating one tool, and you don't want your motor running all the time. They're not designed for continuous use, especially the cheap ones. I use mine for impact wrenches, air ratchet, air chisel, da sander, paint gun, and even an air powered table saw. A few of these tools don't use much air, and some use a lot. When you're switching back and forth, it's nice to have a big tank so that you can maintain constant air pressure rather then relying on the motor all the time.

 

CFM rating should be at the motor to tank. Also note that there is a pressure associated with the CFM rating (i.e. 5 CFM at 40 psi, 3.5 at 90 psi). This is important because you want to make sure you have enough CFM at the pressure the tool needs. The higher the pressure gradient (atmospheric to tank pressure) the more power it takes to flow the same amount of air. One site I read on compressors quipped that a box fan can flow 1000 CFM, but the pressure difference is minimal. So know the pressures you will be using your tools at.

Also know that compressor ratings (like small engine ratings) are/have been inflated. A 120 V compressor cannot produce more than 2 HP (power is current X voltage and your wiring/voltage limits your current), which at best will flow 8 @ 40 and 6 @ 90 (CFM @ psi). A big tank helps for small jobs - you can charge it up and get more work done before it runs out, but to really get the compressor output for big tools/paint guns etc, 240 V compressors can produce 4 X the power of a 120 V compressor (twice the voltage and twice the current typically), or you have to go with a gasoline powered one (HP ratings between electric and gasoline do not line up 1:1...I think it's 1:2 - 1 HP for electric compressor = 2 HP for a gas compressor).

You might be able to find one used for a good price, but you have to be careful because if the tank is rusted out it could fail catestrophically. I think I have a similar craftsman to bigfitz (I'm going to assume the HP numbers were inflated, since mine is 120 V 2 HP - but I could be wrong) for $35 on craigslist, that was only a couple of years old, and only needed a wheel.

 

Air powered table saw? I've heard of air operated clamping devices etc, is the blade actually run by air?

 

Wouldn't be too hard. It would operate like an air drill. The air spins the arbor the blades attached to. Can't say I've seen one though.

Back on topic:

Look at the duty cycles on those motors. very few are 100% and I doubt any in your price range. thus the need for the larger tank.

 

So I'm still confused. iwingameover says "Also an important note with air rachets, air hammers, etc they don't work at their peak without the correct CFM. " but I hear from others that advertised SCFM numbers are inflated and that unless I go with a 240V or gas powered one I'm going to have too low SCFM.

I'm beginning to feel that the actual answer is "unless you're going to spend a fortune, get a decent sized tank so you can get your small-ish jobs done before the engine gets too far behind the pressure in the tank."

 

Yup. A guy actually gave it to me because it was old and he couldn't figure out how it worked. I found that there was a cracked air hose from the connector to the on/off valve. One trip to Home Depot and a whole lot of oiling and cleaning later, it was working fine. I've never taken the whole thing apart, but I just plug in my hose and keep the pressure at 90psi and let 'er rip. Pun intended.

 

Here's an example:

Look at this rachet: 3/8 craftsman from sears http://www.sears.com/shc/s/p_10153_1260 ... hets#specs

It says it has 50ft/lbs and 170RPM run down speed. It also requires 3.4SCFM at 90PSI.

With less pressure and less SCFM it will not develop 50 ft/lbs or it's 170RPM run down speed. It may well still turn and get the job done though.

Which back to my orinigal point of pick the tools you want to use and then pick a compressor to run them.

If you go here: http://www.aircompressorsdirect.com/com ... essors.php it has a wizard you can pick through and it'll recommend compressors for you. Also has alot of good explainations.

 

Boy, you got that right! The research alone to figure out what is what, and then to determine who is telling what truthes in their advertising claims, is basically a full-time job.

I've found these guys to be pretty honest, they'll also talk your ear off about their products if you call them...........they now carry air compressors:

http://www.badboyblasters.com/index.html

 

Good score pacocase. I've been a contractor for over 20 years and have never seen or heard of such a thing.

 

Sorry to hijack the thread with the chatter about my saw. To be honest, when I bought my compressor about 10 years ago, I went with the biggest 110v I could afford. I hadn't accumulated as many tools yet, but for future expansion, I figured that was the best policy. I ended up buying a 30 gal Craftsman with a vertical tank, and it has never let me down. There have been some times when I've been doing something really intensive like media blasting that I've wished I had a slightly bigger one, but the 30 gal is adequate for almost all jobs and doesn't take up that much space.

If you're just messing around as a shadetree mechanic, a 110v with a good oil less compressor and a medium-sized tank will make you very happy.

If you're a pro, and you're going to use it industrially, go with 220v or gasoline. These tend to only come with huge tanks - 60-120 gallons.

 

Ok feeling better about what to get now. Thanks to all for the input.