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What size air compressor?


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#1 MaygZ

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Posted 03 June 2010 - 08:41 PM

G'day all,  I know it's a little like measuring bits of string, which has been covered in another thread, but  ..

I'm looking at buying an air compressor. 

Rule 1 - I am stuck with 240V, so that limits things a bit.

Rule 2 - not super $$$$$

I want to be able to run a sand blast cabinet, a bit of spraying, a few air tools, air sander etc.  As it's just me, I don't imagine I'll ever be good enough to do all at once, so they will take turns.

It has been suggested by a wealthy friend that I need 15-17 cubic ft/min (425-280 litres).  I suspect that they are huge and prob all 3 phase (see rule 1) and rule 2!!

What size compressors, and for that matter brands, are you blokes running for your sheds and Zed building?

Right Lurch, now you can make your 'girly' comments.

#2 Lurch ™

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Posted 03 June 2010 - 09:16 PM

Whats you budget?
Get a 3cyl one - much more efficient.

Paging Rev. Dave...

#3 MaygZ

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Posted 03 June 2010 - 09:22 PM

I don't have a concrete budget.  Expecting in the $500-800 range.  The more I spend on tools, the less there is for the Zed.

#4 reverendzed

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Posted 03 June 2010 - 09:56 PM

Maygz, I have a brand new one for sale, bought it and ended up fixing my old one, give me a pm or call zero 4 zero 9 62 zero 443
Rev.

#5 dalee

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Posted 04 June 2010 - 12:31 PM

As a gernal rule its recomended that minimum of 12cfm (free air) for spray painting. 
Basically buy big and do it once. 

I bought a 2.5hp, 4.8cfm (free air) unit, which struggles to keep up on basic tasks, but I only pd $50 brand new.


#6 Bigfella

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Posted 04 June 2010 - 01:18 PM

As a gernal rule its recomended that minimum of 12cfm (free air) for spray painting. 


Can I just ask what is Free Air is that oil free?



#7 gilltech

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Posted 04 June 2010 - 01:24 PM

A paint industry expert friend of mine recommends 12 to 15 cfm for high quality spray painting work, no less. Get a decent one, you can always on-sell it once you've finished with it.

#8 FuzzyDropbear

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Posted 04 June 2010 - 04:14 PM

I ended up with the same, or similar to what Rev posted up in the panel work thread, 3 cyl, 3hp, I think it has 16cfm at the piston and 10-ish cfm free air. Got it for $450 at the local engineering shop in Ballarat.

#9 MaygZ

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Posted 04 June 2010 - 04:46 PM

I just bought a compressor.  I don't know anything about it, other than a person with unquestionable integrity tells me it's just what I need.  And that's good enough for me!!

thanks guys.

#10 dalee

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Posted 04 June 2010 - 05:58 PM

Can I just ask what is Free Air is that oil free?

Basically free air delivery at the tap, often compressors are rated at the pump displacement.

Much like cars engine kw at the flywheel (manufacturer) vs ATW. (At the wheels- truer result)


#11 Zeddophile

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Posted 04 June 2010 - 07:22 PM

I know MaygZ has already been sorted, but thought I might make a few comments here in case anyone else is looking to buy one...

Basically free air delivery at the tap, often compressors are rated at the pump displacement.

Much like cars engine kw at the flywheel (manufacturer) vs ATW. (At the wheels- truer result)


What he said - FAD is basically what you actually get out of the air line.  If the sticker doesn't specifically say FAD or free air delivery, assume the quoted figure is what the compressor head is theoretically capable of moving.  To give you an idea of the difference, my compressor pump is rated at 16cfm (453l/min), but its FAD is 11.6CFM (328l/min).  You can see why manufacturers often use the pump displacement, as its not industry regulated to use FAD ratings. Ratio seems to hold pretty true in general, so if it doesn't say FAD on it, take 3/4 of the figure and thats probably a reasonable estimate of the FAD.  Some compressors are worse though, and some don't even give any figures - keep on walking...

A paint industry expert friend of mine recommends 12 to 15 cfm for high quality spray painting work, no less. Get a decent one, you can always on-sell it once you've finished with it.


Excellent piece of advice here, just look at what secondhand compressors of a good size go for on Ebay (and how many bids they have).

It has been suggested by a wealthy friend that I need 15-17 cubic ft/min (425-280 litres).  I suspect that they are huge and prob all 3 phase (see rule 1) and rule 2!!

What size compressors, and for that matter brands, are you blokes running for your sheds and Zed building?


Mines 16cfm (11.6cfm FAD), and its 240v, but 15amp (3hp motor).  There are quite a few brands around this size, and I think from memory one or two a touch bigger.  A 15amp outlet shouldn't cost much to have an electrician run in the shed if you want to do it the right way, or you could always do what mine has had done (as well as my cold saw, both before I took posession of them), and get out the file.  Highly illegal, and can potentially void insurance if you had a problem - I'll probably return to 15amp plugs once I finally get round to extending the garage.  That said, my cold saw had 10amp fuses in the power supply box on the motor, despite having a 15amp plug  ::)



Two other comments - bigger compressors with decent solid heads on them actually tend to be quieter than the little cheapies, and a big tank is useful.  Mines 120L, and I can do a fair bit on a full tank before I need to switch the bugger on.  For the smaller compressors, grabbing another tank may allow you to get a bit more usefullness out of it.  See guys flogging off various air tanks for $20 or $30 on Ebay, or you can make one if you have the required items... I have a keg in the back yard I'm thinking about using for race meetings.

#12 V8Datto

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Posted 04 June 2010 - 07:56 PM

I want to be able to run a sand blast cabinet,


Depending on what and how much your sandblasting, I'd say this will use the most air,

I have a sandblaster and used it on my 240z parts, I have TWO $700 compressors running together and they can't keep up.

I spent hours standing in that booth, If I had a better compressor I could have done it in half the time or less.

Find out how much air you need for the sandblaster and work to that
It will save you time and time is money

#13 MaygZ

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Posted 05 June 2010 - 12:16 PM

Thanks guys.  This is all really good info.




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