minimum specs for a compressor

[Bren G]

I have been looking for a compressor or a while - obviously bigger is better, however I hav'nt the funds or room for a 150L item.

I would like something that I can use a spray gun with - the main reason for buying it is that my resto project needs paint and I was hoping to have a go myself. I take it an oil less item is preferred for this work, what is the minimum CFM I would need for this?

I was hoping to get something that may run a saw or cut off tool as well, I appreciate that a small tank will get exhausted very quickly - TBH some of them look so small I actually wondered what they could be used for apart from inflating tyres.

Any advice appreciated - I have looked on ebay at new vs secondhand, a lot of them being sold secondhand with little or no information.

 

[shenion]

Select the gun you want to use. They will specify the CFM needed.

My gun uses 7CFM and I seem to run ot above that sometimes. You will need a compressor that has at least the needed CFM spec'ed as FAD.

If a compressor has no FAD specs, just displacement, you will want about 1.5 times the needed CFM as displacement.

In general, get as big as you are willing to spend. It will never b big enough

3HP seems best for running on a regular socket. Mine is about 3HP running and will run a die grinder or my gun all day. It is about 11CFM FAD (probably 14 CFM displacement.)

 

[langy]

In my opinion you want a 14cfm minimum

 

[merckx]

Yes, 14cfm minimum with the 3hp motor which is the number the manufacturers like to quote but in reality you get a lot less.

I've used mine with a full size spray gun successfully.

A little shabby but the specs are ok.

http://www.ebay.co.uk/itm/240v-3hp-...Air_Tools_and_Compressors&hash=item35c767695c

 

[Daz1968]

I bought a 3hp 14cfm displacement with 100 litre receiver from machine mart on a vat free voucher, works well and runs a da sander although duty is a little high when constantly using sander. It does however hold above 90psi however long I use it. Have had no issues with a full size spraygun with 2.0 tip. I also use a spot blaster which my old 1.5hp compressor wouldn't run, so I agree and state that a good 3hp compressor belt driven with min 100 litre receiver is minimum I would use.

 

[Julian_P]

the main reason for buying it is that my resto project needs paint and I was hoping to have a go myself. I take it an oil less item is preferred for this work, .

Well you don't tell us what your project is so none of the previous advice is necessarily valid.

If it's something like a BSA Bantam and you're doing the panels one at a time then a 1.5 hp will keep up with a gun with a smaller nozzle that's well able to do the job for you. On the other hand, trying to paint vast areas of panels on a 1930's Rolls will make a 3hp work for a living. One potential way around this is to add some extra storage capacity with some (say) large propane bottles off the tip is you have the ability required to sort it out.

Forget oil-less comps if you can - cheap and nasty things that start getting too hot if used for lengthy periods.

Julian.

 

[merckx]

I sprayed a large caravan with my 14cfm, 3hp, 50 litre compressor.

 

[Chipper]

As Julian P asks - what's your project? Don't need a monster to paint bike bits. But generally the more pump you can get the better, and the bigger tank. You can get ones with vertical receivers to save space. Or if you're handy you could relocate the tank up high or in loft space. Mine live in a separate building to the spray room.

 

[langy]

Well you don't tell us what your project is so none of the previous advice is necessarily valid.

If it's something like a BSA Bantam and you're doing the panels one at a time then a 1.5 hp will keep up with a gun with a smaller nozzle that's well able to do the job for you. On the other hand, trying to paint vast areas of panels on a 1930's Rolls will make a 3hp work for a living. One potential way around this is to add some extra storage capacity with some (say) large propane bottles off the tip is you have the ability required to sort it out.

Forget oil-less comps if you can - cheap and nasty things that start getting too hot if used for lengthy periods.

Julian.

He said he wants to run a cut off saw/tool so the advice given is relavent I would say.

 

[the snooper]

He said he wants to run a cut off saw/tool so the advice given is relavent I would say.

I would agree with steve, running air tools requires a good bit of air and if painting a full car then 14 cfm is needed if you don't want to run out of pressure, also what paint will he use if its 2k he also wants an air fed mask and a bigger cfm still or a secondary compressor to run the mask

 

[Julian_P]

He said he wants to run a cut off saw/tool so the advice given is relavent I would say.

Well, not really. He also wants to spray - that's the decider for compressor size.

A cut off saw/tool will run quite hapily, for short periods, off a smaller compressor.....

Julian.

 

[waldershelf]

Can I suggest one of these is ideal for the home hobby workshop. An Atlas Copco ER9, 3200 cfm, 600 horsepower 3.3KV motor 2 stage reciprocating compressor with integral intercooler. You will need to add an aftercooler, air receiver, air dryer, cooling tower and a suitable soundproof building some way from your/neighbours houses as they produce a bit of noise and vibration. They are not available new anymore but you can pick them up second hand and those nice people at Atlas Copco still do most of the spares. (picture from the web)

 

[Julian_P]

They are not available new anymore but you can pick them up second hand and those nice people at Atlas Copco still do most of the spares. (picture from the web)

Atlas Copco do spares, as you say. They wanted about £60/litre for screw compressor oil for my diesel engined machine that I use on the sandblaster. I gave the spec to Rock Oil in Warrington and they blended me about 20 litres for a similar price!

Julian.

 

[Bren G]

My project is a rover SD1 - it will more than likely need both sides painting.

I am going to get a couple of bodyshop estimates first before committing to a compressor - I wont be happy if I spend time and money then end up having to have it re-done professionally.

 

[Julian_P]

I'd think that painting the sides of an SD1 would be a bit ambitious for a first paint job unless you're prepared to do some practising first.

That said, you'll never regret having a decent compressor around the place.

Julian

 

[Bren G]

I have been let down by a local bodyshop regarding a quote, so I will probably take the plunge with a compressor in the near future.

I have sprayed panels before using a compressor and a pot gun.

My rationale is that a suitably sized compressor is a handy thing to have, if I cock it up I can do it again, and as a last resort I could always sell the thing if I hardly used it.

 

[pedrobedro]

I sprayed a large caravan with my 14cfm, 3hp, 50 litre compressor.

I have an old SIP direct drive 3hp 50 litre which has painted anything from a Transit to bike bits but I wouldn't try to run any air tools other than my sprig nailer and a rattle gun off it. FAD is about 8cfm and I have a cut off tool and die grinder both of which run the compressor out of air in minutes so they are now replaced with electric versions. One foundry I worked in had a compressor salvaged from a WWII submarine.

 

[Daz1968]

My 3hp clarke industrial allows me to use a da sander but it works hard so wouldn't like to use it all day. It does however keep it above 90psi all the time. It's supposed to be 4cfm useage but it uses far more than that as my compressor should be about 9cfm fad although listed as 14cfm displacement