air compressors

Get the biggest air compressor you can afford. Look for a large tank, and the highest CFM rating at 90PSI you can find. I have a compressor with a 60gal tank and it pumps at around 10cfm @ 90PSI and it is almost not enough for a die grinder cause it runs constant. For my purposes that HF compressor would be too small.
 
What he said
I have a direct drive compressor (like that) in one shop, and an old style 2 stage belt driven compressor in my basement. The direct drives are LOUD! do not plan to be in the same room as a direct drive compressor without earplugs. the darn compressor is louder than my Harley. I will never again buy a direct drive, I will spend the extra money for a belt drive

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i dont understand the part where you say it runs at 10 cfm@90psi. whats the correlation? on the hf above it says 7 scfm @ 40psi and 4.0 scfm @90psi. how does that correlate into power? say i needed something to run a minumum of 60psi would that hf be able to handle it. or should i be looking for something that say runs 10 cfm at 60 psi.i have a vauum pump thats rated at 5.5cfm but what exactly does tha mean--thanks -mark
 
Each air tool or application requires a specific pressure, and a specific volume to function.....that what "10cfm@90psi" means....... the tool will take 10 cubic feet of air per minute, at 90 pounds per square inch to function correctly.

Most air tools require apprx. 80 psi @ 6 to 9 cfm. This would mean that you would want a compressor with a 60 gallon tank, and a 5 hp motor to sustain operation.

I personally would discourage buying a direct drive air compressor, in my experience, they are junk. I had TWO of them, both went bad within a month....... Sears/craftsman brand seems to be the worst!
 
Pardon my ignorance if I break this down too much for you. What I was talking about is that my compressor will pump 10 cubic feet per min into the tank with 90 PSI already in the tank. The "Power" you are looking for is the compressor's ability to keep up with the tools you are using. You always want a compressor that has a higher output than the highest air consuming tool you could ever conceive using. ever. The bigger the tank, the longer period the motor stays turned off.

The venturi pump that you use will use 5.5 cubic feet per min. If your storage tank is big enough you should be able to pull your vacuum and the pump will not come on at all cause it should happen that fast. I use a paint pot, venturi vacuum like what you have, and I can get to 25" in a min or so.

Heh, save your money and get this. Seems like a lot but you never know what you will be using it for.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=55995
 
Like with most tools, buy the best you can afford.
I've worked around compressors in the auto trade for prit near 40 yrs and can tell ya that you can't have too much. figure out how much you'll need then double that amount .
Also , go cast iron if possible.
There are lots of thoughts on tank size, I run a 5hpEmglo on a 30 gal tank and can paint HVLP all day. It keeps up.Running some of the larger grinders is another story.
 
It really depends on what you want to use it for. For me, the usage is nail guns, smaller grinders, impact wrenches, painting - all occasional, short-burst activities. A $90 HF 8 gallon compressor has served me well for something like 4-5 years, still running on original oil change, tucked under me work bench, out of the way in a corner. It is loud, but not THAT loud.

Now, tank capacity matters, but not a whole lot. Let's assume you're deciding between 2HP "rated" 115PSI comps - one @ 8 gallon, another one @ 30 gallon capacity.

The 2nd one will take 4 times longer to fill up to capacity - running for something like 4-5 minutes after initial turning on, till pressure switch shuts it off. It will also last 4 times longer, before the motor kicks in.

But, if you need to a piece of equipment that requires 6-9CFMs @ 90 PSI for 30 minutes, neither unit will get it done, as most of these direct drives can only do may be 4-5 CFM @ 90 PSI. They will be running non-stop, still unable to deliver the required volume.

The only alternative, as others have mentioned, would be upgrading WAY UP, to true 4-5 HP comps. If your usage requires this type of capacity, that's the way you need to go. Craiglist would be your best friend in this endeavor.

But, if you're not sure, I'd start with one of the HF's 8-gallon units, pay around $90 for it. When and if u do outgrow it, then you spring for a 60 gallon 5 HP monster :)
 
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