Paint Spraying

[ChrisH]

Hi,

This thread has only a loose relationship with our Reno 4, but there is a link and method in my madness!

I am thinking of getting an air compressor (+ receiver) for my workshop. I have only a limited amount of space to fit it and only a limited amount of cash to buy it! However,

I am thinking of buying a 1.5hp oil free air compressor with a 24 litre receiver, or tank. Stated output is 6.2 cfm. That will be enough for my workshop needs, but will it be sufficient to enable me to spray say a bonnet or door on our Reno 4 and achieve - given practice, fair winds and a favourable tide - a reasonable finish? If so, what spray gun should I go for? If not, what minimum size of air compressor/receiver should I aim for and what spray gun should I require? And what paint should I use?

I am a novice when it comes to paint spraying, hence the request for advice, and I would not be spraying the 2 pack stuff what with all the elf n' safety stuff I have read, I think more like spraying cellulose or the like, but would welcome the advice other who have been there, done it, could give.

Chris

 

[Cornish4]

Hi Chris, I'm not an expert at paint spraying, just a hobbyist, but I have done a bit, and the compressor I used was of the same size that you are thinking of buying. I had quite a bit of success with it, even complete cars. I used a suction type gun, but a gravity fed type will do also. One problem though, cellulose paint is being phased out, so you may need to talk to your local supplier for advice to see what they can offer you. Regards, Brian.

 

[Azazello]

I am in your same condition, looking for a small air compressor to do home painting... I had some research through the net and on diy forums, and I think it is better to go for a 50 litre tank, the price is almost the same but it will give you more chance to paint a sufficient area.... And I will go for an oil lubricated one, I was told they have longer life... Still remaining in a low price zone.
I was planning to make an external isolated box for the air compressor, to keep down noise level, and have only a switch and an air cable in my garage...
A friend of mine has a 380v 100 litre used compressor for sale, and I am thinking seriously about it, but i should see the air tank condition and how to transform it in a 230v one...

 

[malcolm]

Some advice on compressors and painting here: http://www.mig-welding.co.uk/spray-painting.htm

Don't forget the advertised CFM is at input to the compressor. For a 13cfm compressor the output might be 8cfm. It's the output that the spray gun needs, so don't get fooled by marketing.

I'm a fan of 1.4mm spray nozzles (most spray guns come with 1.7mm) which reduce the input cfm required. It's an important part of the process so best to pay more than £10 for the gun.

I'd not go any less than a 2.5hp compressor which would be about 6cfm output.

Don't forget to filter the water out else you'll end up with lots of bubbles under the paint.

 

[barnfind]

Hvlp?

You might like to consider one of the turbine unit HVLP units such as those by Earlex and Apollo.
They tend to get sneered at by some officianados, but they have a lot of advantages for the occasional sprayer. They don't put as much paint into the air as a conventional compressor and gun, so overspray is more contained and general pollution of the surrounding area is reduced. They don't usually have issues with entrapped water and oil and they are relatively inexpensive to buy. I have resprayed several smaller vehicles successfully with one of these units (using cellulose, don't be tempted to try spraying 2K at home) and generally leave my compressor for spraying waxoyl etc. through a schutz gun and probe.

 

[ChrisH]

Thanks for the replies.
The HVLP units look good but would not supply general workshop compressed air needs I suspect, as they seem more designed just for spraying. That said, they seem like good products which I hadn't come across, so thanks barnfind for the info.

I was going after the oil fee compressor as my workshop compressed air needs are not huge, therefore the compressor should last a while, and oil free is good for paint spraying. Azazello, your 3 phase unit would be OK on single phase if you got a suitable inverter to run the 3 ph motor, which is what I did to run my lathe motor.

The 1.5hp compressor supposedly does 7cfm, would not that be enough Malcolm? I ask this as this output is what the compressor puts out at piston displacement. The maker also quotes F.A.D (free air delivery? I don't know, just making a guess!) as 4cfm, so perhaps 4 cfm is what I can expect out of the end of the air line? I saw a spray gun advertised with a 1.2mm nozzle size requiring only 3 cfm to run it and claiming to be capable of achieving 'excellent results' with cellulose and gloss paints and wondered if that would do the odd R4 door or bonnet? Any thoughts guys? I admit to being confused by the outputs claimed by manufacturers, as some claim FAD and some piston displacement and I can never be sure I am comparing apples with apples.

 

[barnfind]

Hvlp

You are right. The HVLP is only for paint spraying.
If you are thinking of air tools as well as a spraygun, a 1.5 hp compressor, probably with a 25 litre receiver, will have to work very hard to keep up, and will probably not really be up to anything that runs for more than a couple of minutes at a time. So tools such as, say, an orbital sander, are probably not going to work properly.
I'd go with Malcolm's suggestion, which will probably come with a much bigger receiver.