What Volume Compressor For A Small Garage Workshop?

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Matabele

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Hi all,

I'm getting to the point where I can outfit a small workshop for myself (12'x31'). I'm going to have a CNC mill with flood coolant eventually, and would like a couple of air hoses at benches, plus a sand blaster as well as the usual small shop machinery. Just wondering what tank size I should be looking at and what CFM's? I might build a dedicated enclosure for it outside the main workshop to limit noise and free up some space.

Any thoughts appreciated, thanks.
 
sand blaster needs lots of cfm...100 gallon tank or better..8 cfm
 
Really, I find scfm to be the biggest factor. Shoot for as much as you can afford. If I were staring over, I would try to find a pump capable of delivering around 15 scfm @ 90 psi. Tank size will probably be 80 gallon for that size pump unless you put it together yourself.


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Even a small bench top blast cabinet is going to need a minimum of 12-14 CFM to function half way decent. A 2 stage 175 psi compressor with an 80 gallon tank would work. CFM is what you should be most concerned with, not so much the size of the receiver.
 
Thanks for the replies guys, you've pointed me in the right direction.
 
If you can find an old heavy slow speed cast iron head they run amazingly quiet. I have a 4 cylinder two stage that puts up some where around 20 cfm at 125 psi and it bearly keeps up with the sand blast cabinet. Tanks size means nothing with a sand blaster, the big portable commercial units have virtually no tank. But the 80 gallon tank will run the shop for quite a few days with the compressor off.
On a side note, how do they control the output of large rotary compressors? I know a chap that has an air hammer for boring up to 32 inch holes to set power poles in rock. The compressor is 1200 cfm at I think 300 psi. Driven with a V12 Cat engine. Again virtually no tank capacity. When the compressor reaches pressure, theres a simple butterfly valve that shuts off the intake air. The valve only has to handle atmospheric pressure, 14.7 psi to control the 300 psi output.

Greg
 
I have a v twin single stage that does 18 cfm at 90 psi on a 60 gallon tang. I can sand blast all day and the compressor cycles on and off.
 
To run a blast cabinet you are going to need at least a 5hp compressor. I recommend a 2 stage, 175 PSI rated unit (I run mine at 150), this will give you around 18 CFM @100PSI. Preferably a cast iron pump. Most tank sizes on those compressors are 60-80 gal. Be careful when buying compressors, the marketing department tends to inflate the HP on many of the big box store units. Many ''5hp'' units are more like 2 hp. A true 5 HP, single phase motor draws around 25 amps on 230 volts, and most do not even have an option for 115 volts. Look at the amp draw on the motor data tag. Stay away from the direct drive units, get a belt drive. The exception to this is the California Compressor line. Harbor Freight 5 HP units are not too bad either, they are not made in China.
 
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Your consumption while blasting, with all other variables being the same, will vary with on the nozzle size you use.

@f350ca: For rotary screw compressors my only experience is with VMAC brand and their models throttled the inlet like your friend's unit but it was a poppet rather than a butterfly valve.

The tanks on those units are air-oil separators and oil resovoirs; not accumulators/buffers like for reciprocating machines.
 
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