Air compressor - painting cars

Have been wanting to buy an air compressor for years. What's the
minimum capacity required for spray painting and operating air powered
tools?

Allan.

 

You can never have too big an air compressor, I have a "5HP" in
marketing speak which is really more like 2HP so read the fine print on
the labels and treat anything called "peak" as a completely bullshit
number. It's just barely adequate for sandblasting and works for general
purpose painting but I'm not sure I'd try painting a car with it. I
should add that it's a twin cylinder cast iron unit which is an absolute
necessity for anything more than occasional air tool use, run a cheap
oil less unit continuously and you'll burn it up in no time.

If you can afford it, I recommend a true 5HP (it'll be 240v, if it can
use 120 it's not 5HP) two stage cast iron with as big a tank as you have
room for. That should run just about anything, if you buy less you'll
certainly want more sooner or later. If you want to do painting you'll
need a very good filter and moisture remover.

 

Thanks... I looked at some today and there's high pressure and low
pressure types. Sandblasting was the other thing I'll be using it
for. So uses are spraypainting, sandblasting and air tools (air
sander, ratchet, drill, die grinder, wheel nut remover, etc.).

Anyone know the diff between low and high air pressure?

Allan.

 

For sandblasting you want all the volume you can get, about the highest
pressure I've ever used for anything is 90 psi so I suspect low pressure
is fine, just get the highest CFM you can, any true 5HP 240V twin stage
reciprocating compressor with cast iron cylinders should do the trick.

 

Hello Allan:

Choosing an air compressor if one wants to use it for automotive
painting can be difficult as one is presented with many choices and a
great deal of misinformation.

If all you wish to do is touchup on a few panels a small compressor,
inexpensive spray gun and an airbrush will be fine.

But painting an entire car is a different story.

Bottom line is that the CFM a compressor delivers at a certain PSI is
the most important thing if painting a car in one shot--and that both
manufacturers of compressors and sprayguns advertise the "maximum"
output and efficiency of the unit.

While some things have likely changed, to do a job right one usually
needed a two stage compressor with an output of > 11.5 CFM at 100 PSI
in the past to do a great job. Otherwise the compressor could not keep
up with the tak at hand...

in other words, that smaller compressor would be fine for painting a
door or doing touch up on a door or small body panel--but forget it on
something like a 240 Brick roof of hood.

That said...preparation is generally 95% of what makes a good paint
job on a other items like a home, but on a car it needs to be as close
to 100% as possible and then the painting process must be 100% as
well.

You don't mention where you live, but in my area (Upstate NY) the
local government-funded vocational schools offer classes for adults in
many areas--including body repair and painting, welding, etc.

Classes are reasonably priced but do take time. THe advantage is that
one need not buy tools and will have the benefit of using the sort of
equipment that professional shops use.

Downside is that unless one had a car they could "layup" for a while
it might not work out.

I worked in a body shop part-time when I was in high school and
learned a lot--and also learned how much time a good paint job
takes--most of which is the prep and masking.

A friend of my brother's has a small shop near me and does excellent
work--perhaps beyond excellent. He has a downdraft booth and does
meticulous prep work and painting. Not much of a businessman though.
Take your car to him and it will be ready for a show when he is
finished--but it might take a month and he will seldom answer the
phone if you call....but will call you when it's complete.

His prices range from $4000 to $6,000 depending on the car, but it's a
job that will last for years and look better than the OEM paint.

Unfortunately, like many one-man shop owners in that trade in this
area, he has a drinking problem. Sad but seems to be true in this
area.

Anyway, first place to start is at the library with a few books about
automotive painting..and with a few links I am providing. First link
is from a VW fan but is quite detailed and well done.

By the way..when I was at university in California I had a neighbor
who was retired and restored cars for a hobby. I watched one day as he
sprayed a 1930 Cadillac convertible in his back yard. All he did was
wait for a calm 60 degree day with clouds, sprayed down his back lawn
and then sprayed.

Results were nothing short of incredible!

One other option is to find a small one-man shop in your area and ask
him if you can work for him a few hours a week at no cost to him to
learn about the trade--and be honest about why you wish to do that.

If he agrees he'll start you out on grunt work sanding tasks and
things like that, and then gradually let you do a bit more.
Upside is that you can also watch and learn. Offer enough time in
trade and he may be willing to spray your car if you pay for the
materials.

Speaking of which..materials for automotive prep and painting can get
expensive--even before one. buys primer, paint and clear coat.

I'll be painting my wagon this Spring and expect it will likely cost
me over $200 for sandpaper and incidentals..and another $300 to $ 400
for paint etc.

Add the estimated 70 plus hours I'll spend on prep and it becomes
clear why a paint job costs so much these days.

Too bad there is not a Maaco paint shop in my area.

Maaco does quick and cheap paintwork for folks on a budget who want
the car back in a hurry.

Thing is..if you bring them a car that is properly prepped and pay for
the "premium" paintjob and then bring your own quality paint you can
end up with a job that looks about as good as an OEM job.

I did that on a 264 I was selling a few years back. Thing looked so
good after they were done I hated to sell it.

Some might think of them as the "Pep Boys" of paint shops and while
that's true they do have some skilled painters. Key is spreading a few
dollars around and a lot of donuts and finding out who that person
is--make friends with him and then let him know he will get something
extra for a nice job. Keep in mind all the guys who spray the paint do
is that task alone--5 days a week, and some get to be as good as it
gets skill wise.

I had them do the initial prep work on the 264 and then took it home
and did some some detailing and corrections (20 hrs)--and then back to
them for final primer and painting.

Total cost was about $500 but I ended up with what would have been a
$3,000 job anywhere else

Link to Maaco (operate in US and Canada only http://www.maaco.com/

Just noticed they have a shop about 120 miles from me so may go to
them in the Spring for a quickie job on a car I wish to sell.

Ahhh...as usual I have digressed....

Here are a few links for the DIY type:

http://www.thebugshop.org/bsfqpnt.htm

http://members.tripod.com/~bobstory/faq.html

http://www.stovebolt.com/techtips/hvlp_paintgun_basics.htm

http://www.scottgrundfor.com/ideas/paint3.html

http://www.lemmer.com/air-guns.htm

http://www.finishsystems.com/qanda.html

http://www.furnitureknowledge.com/spraying_equipment.htm


Sorry for the length of my reply...but there is a lot of info in the
links that many should find helpful.

Regards,

Doc