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Location:
Perth, Western Australia
Registered:
October 2004
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Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 10:37
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I have read a few threads on Air Compressors and for spraying cars in Acryllic paint and they have suggested that 12-14 cfm in about a 50 litre tank will do the trick.
I have been having a look around at compressors and have found that GMC has a 24L 2HP 7.3 cfm @ 80-115 psi compressor for $97 and a 40L 2.5HP 7.3 cfm compressor for $199 at bunnings. Ive read that compressors can be connected together to increase the flow rate.
So could 2 $99 compressors be connected to effectively make a 48L 14.6cfm 4HP compressor for $200? What fittings/piping would i need to use to connect the 2 together, and where abouts would i go to get them, as i didn't see any at bunnings. Would this go well compared to 1 bigger and more expensive compressor?
For spray painting panels, and maybe the whole car, what type of gun and nozzle would people suggest? When spraying a car in the same color, is it nessescary to strip back to bare metal or would it go just as well to sand back the paint and then primer over the top or just paint straight over the top?
If you get this far, thanks for reading and any help you can give.
- Matt
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 10:45
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when i did mine i ran off one shitty 2.5 hp with around the 7 cfm flow, hence why it didnt come out perfect and is requiring a lot of rbbing back to lose the orange peel, but it can be done, the panels that ive sanded and polished properly are awesome.
duno how to link them, cant helpwith that one
use a gravity fed gun (ones with paint tank on the top of the gun), i picked a top range up for hundred and 50 ish i think, was a few months back now, and it was worth every cent,
just strip off the clear coat, which tends to take most of the colour aswell, coz they mix into each other, if u go back to the undercoat, u will get pockets of colour which are dents that u couldnt see any other way and will show up with the new paint coat so its a great time to fill them. ive got a few docs written on how to paint a car i can send u if u want just send us ur email. they were a great help to me
~andrew~
[Updated on: Sun, 25 September 2005 10:46]
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Location:
Forster NSW
Registered:
September 2004
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 10:54
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Yeah, you can run two compressors in parallel, an idea I've heard is too hook them up to a bigger tank, like an LPG tank, that way you have more air on tap when you start spraying.
The only thing with the compressors, are they belt-drive compressors? They're definitely much better for spraying with!
A gravity feed gun as said above, there's no need to pay a fortune for one either, anything under $150 should be more than good enough. Use about a 2mm tip (if memory serves me correct there). The gun should come with two setups, a 2mm, and a 0.8mm for 2pac.
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 11:36
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yeah 2 mm sounds rite
mine was direct drive, but u spend alot of time waiting for them to pump back, belt driven give alot more air, are much better as said by dale
1 other thing which is worthy of a mention. many ppl say just put the water trap on next to your tank...wrong!!! when gas is compressed it is heated up, compressor goes to 120 psi, ver very hot air, whats gonna happen to the water in the air, it becomes gas, water trap wont stop this. put the water trap as far away from the compressor as u can to let the air cool as much as possible, the difference is rather notable in the amount of water u collect.
~andrew~
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Location:
Melbourne
Registered:
July 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 11:44
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Well I made do with one of the $97 GMC compressors, Not to bad for the price. And I use to work for Southern Cross Compressors!!! 
(Why, Why, did I not get a big compressor when I was working there!!)
I have used my little 2 hp compressor with a Gravity spraygun, the type with the paint pot on top. This uses less air, near 1/3 less than a suction type, just set it for 55 psi. Have sprayed the tub of my hilux and my motorbike, works great!
Rich
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Location:
Perth, Western Australia
Registered:
October 2004
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 11:57
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if you could email me those articles that'd be awesome.
moswald@iinet.net.au
thanks man.
What would be the most economical way to spray something tho. Dont really want to blow the bank on these things. But theres no point doing it half assed, as theres no point as it will turn out poor quality.
So money should be spent on a decent gravity feed gun, and what sorta compressor(s) would you suggest. The downside of a lower flowrate pump and smaller tank would be that id have to take my time in spraying i suppose?
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 12:25
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"This uses less air, near 1/3 less than a suction type, just set it for 55 psi, works great!" tru that
i spent resprayin my entire ke70, not including cost of gun and sander or compressor, just paint, thinners, sandpaper, bodyfiller, and spray putty, but i was having a few issues of the paint hitting the car already dry (gotta make sure ur close enough)
most economical way, get a pro to do it free id say get en0ough to do ur whole car, and do it, so it all looks the same.
i say yes spend on the gun, its quite important, u dont have to take too much time with a small compressor if ur using a gravity fed gun, less pressure=much less air needed.
ill send u the documents now
~andrew~
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On Probation
Location:
launceston tas
Registered:
March 2005
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Location:
QLD
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 14:40
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me too please 
Pat_ae86@hotmail.com
thanks
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Registered:
October 2004
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Location:
Victoria
Registered:
August 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 16:33
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maybe just post it.
Alot of people desperate for low cost spray jobs.
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Location:
Victoria
Registered:
August 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 17:00
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Heres something that might help:
| MS-75 wrote on Sat, 23 April 2005 01:38 |
BEWARE-ESSAY APPROACHING........
Yeah-as someone mentioned before in the thread (and I was also told many moons ago) that a 12-14 CFM (Cubic Foot per Minute) compressor was the go. A min flow ability of 12-14 CFM seems to be the accepted rate required to keep most air tools/spray guns running contiuously without needing the air compressor running 100% of the time. Once you have the comressor running 100% of the time it means that the comressor unit itself cannot supply enough air at the required pressure to run the tool/gun at the pressure for which it is designed.
Examples-
1. If you are running a die grinder almost constantly whilst doing a port job, or a spray gun for a re-spray, and the compressor unit is turning on only occasionally for just a short time, it means this:
The compressor you are using is of a good size and only has to run for a short time every few minutes to replenish the compressed air (potential energy) that you have used up to drive the tool/spray gun.
2. If you are running a die grinder almost constantly whilst doing a port job, or a spray gun for a re-spray, and the compressor unit is turning on shortly after you start and stays on the whole time you are using the tool-whilst the speed of the tool/paint delivery rate and spray pattern of the gun slowly decreases/degrades, it means this:
The air flowrate at the required (tool) pressure of the compressor you are using is too low.
However, The shaft speed , (ie. diegrinder-airdrill-airgrinder-rattlegun etc RPM), or the flowrate(paint gun, blovac, air bower etc), of the tool you are using will not drop to zero if the driving air compressor is running 100% of the time. (providing of course the compressor is capable of flowing a least a bit of air-ie a fish tank compressor is no good-derr )
However, as the (small and shitty Chinese/Gook Machinery Company-GMC) compressor, when running flat-out (100% of the time), is only capable of delivering say 2/3 the volume of air at the required pressure, or say the required volume at only 2/3 pressure, needed by the tool, then if the tool is run 100% of the time, and the compressor is on 100% of the time, then the tool speed/flow will fall to probably only 2/3 of what it would have been running with a compressor either of required minimum or larger size.
Having said all this-of course there are realistic ways around having to buy a $$$ 12+ CFM compressor.
1. Buy two (90-110 bucks each) 6-6.5 CFM GMC ones and hook them up in parallell (pressure is the same-but flow is 2X) - that will give you 12-13 CFM for 1/4-1/5 the price of a Clisby and 1/10th the $$ for an Atlas Copco brand one, etc.
2. Learn to live with a smaller CFM compressor unit by-
2A Fitting a supplementary reservoir (old LPG tanks are good)
so that once it has filled the bigger reservoir it
takes longer for it to empty and trigger the comp again.
(you are also waiting longer for it to fill back up though)
2B Being careful with your spray nozzles when painting so that
when you are blowing on the coat, you are blowing on with a
pretty small paint orifice/nozzle. This means you are not
using big flow rates, but rather small rates at the normal
pressure so the small compressor can keep up. It does mean
that you take longer to spray a given area, but that you
get proper atomisation and a smooth finish. (albeit with
more coats)
Case in point for patience, common sense and being stingy-
I have a story on a 290HP L28 240Z Datsun in an old Street machine with an AWESOME midnight blue paintjob that was applied using a tiny Beaver spray gun............
It took him longer than with a big 14 CFM compressor, but as a pretty inexperienced painter, had he used a (high flowing) professional spray gun he would have ended up with runs galore.
Anyway dude-thats my essay on the subject (prettymuch everything I know the subject really).
In closing though, as for acryllic and 2-pak, my advice (generally taken from a few sprayer friends I have) is Acryllic all the way.
Reasons-
1. 2Pak has cyanide compounds (as mentioned before-isocyanates(sp?))VERY VERY BAD when airbourne, and looks the best the day it's done-awesome for show cars that are garaged all the time-but degrades over time.
2. Acryllic is easier to spray on, is not a 2-part system, requires a buff once done to shine it right up, but once you get the clearcoat (also accryllic will do there) and buff it up only a pro can really tell-and the more you polish the acryllic the shinier it gets-even 10 years later.
Sorry for the essay-but thats it from me-I know nothing else about paint!
Sean
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BTW does anyone have a comprohensive writeup or FAQ on DIY Spray Painting?
Peace
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 22:15
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check this website
http://www.neilslade.com/Papers/Painting.html
i found it priceless, im pretty sure it contains everything the others contain in a shorter version. have a google around on 'how to paint your car at home' or variations on that and see what u come up with. its all i did if my memory serves me
goodluck to you all 
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Location:
Perth, Western Australia
Registered:
October 2004
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Re: Spray Painting / Air Compressor Advice
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Sun, 25 September 2005 22:53
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Thanks for all that great advice. Does anyone know how you would go about connecting 2 smaller GMC type compressors in parrellel?
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Location:
Brisbane
Registered:
July 2005
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 04:45
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Parrellel means you just hook them up through a 'T' piece onto the one air line going to your gun. Should be able to get the nessecary pipes and connectors from bunnings/tradelink. Just make sure you use decent connectors and some of that thread locking tape. 
I dont know much about this topic but I think the best way to use the 2 smaller pumps would be to have them both running into one big tank and then just have a single air line running off to your gun.
Maybe put a couple taps/valves on the outlet of the pump so you dont neccessarily have to have both pumps on at once.
Just make sure if your drilling into a pressure chamber you release ALL pressure first and leave the release valve open! You dont want to blow the thing up with you standing over the top of it now do you?
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Location:
MELBOURNE
Registered:
December 2004
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 05:53
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On that site he says to put up plastic sheet to stop wind etc. did you guys set up an exhaust fan to get rid of over spray? I keep hearing things about overspray settling down on the paint. and did anyone try grounding the chassis rail like he says to do? I'm interested in that!
Thanks
Troy
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 06:30
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well i did mine in the shed, usually on still nights after school/work, sometimes with the back door open, other times with it open, i did ground the chassis, but kept standing on the nail driven into the concrete with my barefeet  so i ripped it out towards the end, i figured that most the static would be gone by then
i had a few issues with settling over spray, no exhaust fan, from a distance the entire shed would disappear into oblivion, particulalrly with the spray putty, but had less problems when using a better quality one, and making sure i was close enough, i had more issues on the roof of the car with overspray coz of the angle that u apply the paint at, more across then on, so u get alot of build up on the other side, but i never found it an issue coz u wash and sand back between coats, so yeah no biggy imho.
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Location:
MELBOURNE
Registered:
December 2004
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 06:42
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When you say coats, you mean between cc and bc yeah? And what grit did you use? and did you wetsand the coats? Too many questions! Need more experience loL!
Thanks
Troy
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 06:55
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1200 grit wet and dry, wet, because i was having issues with the overspray residue esp. with the undercoat i did sand each coat, made it a much longer process, but i think it payed off.
cant quite remember but im pretty sure i did sand each spray putty/undercoat layer because it was coming up very rough coz it was hittin the car already dry. but i dont think i did sand the colour coat coz of scratchin the metallic particles, and if i did i used super fine wire wool very lightly, but 1200 wet would be good if u used it lightly, and yes i did sand and wash with thinners between each different layer, washed b4 and after sanding
lol experience is definately a crash course in painting, very steep learning curve, but do some research and read some b4, get the principles rite first.
im happy to try and help
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I supported Toymods
Location:
Melbourne Australia
Registered:
November 2003
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Location:
MELBOURNE
Registered:
December 2004
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 07:18
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thankyou! I read that thread but didn't follow it so I missed that huge post. Very helpful!
Thanks
Troy
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Location:
brisbane
Registered:
September 2005
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 07:26
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THAT HUGE POST IS THE SHIT!!
somehow i feel he paints for a living
but i found that cut and polish was better by hand, but i was using a gmc buffer,m so yeah, what pedro said is rite, im fairly tired but i didnt notice anything he missd, go pedro
!
can someone tidy it up abit and make it a tech doc?
~andrew~
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Location:
Victoria
Registered:
August 2005
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Re: Spray Painting / Air Compressor Advice
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Mon, 26 September 2005 17:09
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| da_horse wrote on Mon, 26 September 2005 17:01 |
have a read of this
orange peel and spray tips
| pedro2 wrote on Sun, 28 August 2005 02:52 |
YOUR PAST PROBLEM WITH ORANGE PEEL
In spraying all paints there is a rule of thumb as follows..
Firstly the preparation must be done right as to the rub down and any repair it pays to get good advice at all stages and next is to decide what type of paint and color you are going to do the car etc with like enamel/acrylic etc ok now the rule of thumb...
(a)
look at the job and find out the code on the manufactures plate, if the car has change of original paint code find out if enamel or acrylic, this will help you for some paints if within 3 to 5 yrs can cause certain reactions to other paints being applied over if not sealed or isolated etc.
(b)
Clean down area wash the area and start the first repair, only with water no detergents and let dry completely, always take repair area's back to clean metal and ruffian in this area to help adhesion of filler and only apply fillers lightly, coat each layer over after rub down to reform body shape, before you fill the damaged repair area you should if needed apply a rust inhibitor on the bare metal area, as to fillers you can start with a metal mend type and finish if with liter bogs etc but it pay;s to panel beet out the area as much as possible so not to have to much filler in the repair area etc, other wise future possible cracking.
(c)
Sanding down first stage, depending on paint condition good paint surface 600/800 wet/dry paper with ever water or dry rub but wipe as you go and watch all edges and rub out all possible chips bad scratches and take shine away right to edge unless doing spot repair, always use round motion/ not straight
(d)
Wipe down well, now mask of all area's not to be sprayed
always use clean cloths lint free and now wipe surface down with wax and grease remover and make sure you wipe all areas and not much on filled area's as this can soak up the solution and problems later on, turn cloth regally and change cloth and do not touch it with other hand best done in cool area to save solution drying out to fast leaving streaks etc.
(e)
Now have a good look at the surface and have car in a good lighted area inside a shed etc and make sure that you have read the manufactures full instructions as to the first stage as to Priming the job and now look at the spray unit.
(f)
Spray unit the most important thing in this job as with the painting etc, see that the tank is big enough to provide as much air as you will need to spray in large direct spraying or you will have to wait for it to catch up when you are spraying and make sure it has a water regulator trap and bleed on line, firstly clean out the regulator trap for any water within and filter or replace filter, check compressor for oil in motor is at mark, have the unit is a safe place and any air flow from the unit away from the spraying area, as particle's from the compressor will mix with your paint,
(e)
The gun make sure it is high pressure gun with fine nozzle and the finer the better, you can change the settings and the air volume and flow to suite the type of paint etc.
(f)
Make sure that the area is fully free of dust and anything in you way that you have a full face mask as to the regulations only the best mask will do, and make sure there is nothing in this spraying area that can cause and spark or flame etc keep it safe always and there is a saying there is only one of you and you can not be replaced and as with your lungs they keep you going and don't be a fool like so many others etc.
get a test piece and now read the thinning instructions as to the paint for first application, have mixing containers not plastic one's, a measuring pot marked so you can mix your primer and top coats,
NOW LETS GO BACK to the GUN and the compressor, turn it on and let the unit run to full pressure that it shuts down and then undo the drain until it restarts again, do this 2 times lets condensation out of tank now turn regulator valve air bleed open to release water in trap, now connect line to trap, now put a little thinners in pot and spray away from any area of job and away from all sparking and flame,
CONNECT GUN to hose and turn the air adjusting pressure to the manufactures setting as to the paint you are going to spray and to set the right pressure it pays to hold trigger open while adjusting so you have no line air change to the gun for the length of the hose can change the pressure to the gun,
Now you have the gun set and sprayed a little thinners, empty out the rest and fill the pot, make sure you have mixed your paint well and thinned it correctly, Go back to the trap and release any water etc,
NOW YOU ARE READY to test your spraying technique and adjust the air flow and the flow of the paint and set the right fan type you need,
IMPORTANT NOTE when spraying any paint it is very necessary that the air temperature is right and this has a serious outcome on final application and look of the job/ NOW when you test your spraying style hold your gun far enough away so that you do not get the job to wet or to dry start out off the edge of the job hold gun always straight at the job as you pass in a smooth even flow action and this will take practice to get it right, finish outside the job area and at all times fully depress the trigger of the gun, you have make some adjustment's a get the feel of the gun and your actions never be in a hurry to rush yourself and do not keep applying coats and allow to dry between coats,
NOW YOU are ready to start your job so let recheck all things and now start outside of the job area and at the set distance you are happy with smooth passes place a light coat over you job and work around your area let air flush off and reply second coat over lapping between your actions, you can apply 3 coats depending on the surface etc and let it dry fully,
After it has fully dried you now can recheck job and now wet or dry sand with 600 / 800 clean down with wax/grease remover and now you can apply spray putty coats with putty gun if needed to hide scratches, apply light coats allow to dry fully between coats and do not apply to thick, let fully dry and sand with worn out 600/800 wet/dry paper/ only dry sand and again wipe down now respray primer until it is fully covered to job leave to full dry depending on air temp.
NOW rub down the job with now 800 with a little water not to hard just work it easy and wipe down and check surface if need re-coat only area's needed and lightly rub the same, leave to dry fully.
BEST method for top coat, FULLY CLEAN THE GUN DRAIN AIR TANK and REGULATOR of any water and check the air temp VERY IMPORTANT, to cold no good to hot the same AROUND 19C to 26C is reasonably good, make sure job is fully clean and dry and now mix your top coad adjust the air flow pressure and fill the pot of the gun test your piece as a test spray as above, set the FAN AND FLOW AND AIR RATE UNTIL YOU ARE HAPPY WITH IT,
MAKE SURE THAT THE FAN RATE AND FLOW IS CLEAN AND OVERS IN A CROSS STROKE ON YOU TEST PIECE , now you are ready to apply first tack coat,
START OUTSIDE OF YOUR JOB and depress the trigger fully and on large area's such as hood it pays to start from center edge overlapping each stroke and finishing outside of the edge of job, FIRST COAT IS TACK COAT AND IS A LIGHT COAT, NOW APPLY SECOND COAT and cross at opposite direction overlapping and apply at a slower action NOT TO SLOW this will be a wet coat LET TACK OFF AND recheck job NOW APPLY IF NEEDED ANOTHER WET COAT BUT NOT TO WET, let tack off ,
NOW THIN THE PAINT TO A GREATER AMOUNT AS TO THE DIRECTIONS AND ADJUST AIR FLOW TO A NEW SETTING OF RECOMMENDATION AS TO INSTRUCTION now moving the gun at a faster rate and smooth action apply the final coats being careful at this final stage and not over doing it, YOU WILL ALL SO HOLD YOU GUN AWAY LITTLE FURTHER AS WHEN YOU FIRST STARTED,
YOU WILL ALL SO SEE THAT THE TOP COAT IS SHINNING MORE NOW AND YOU CAN LET IT DRY FULL FOR A FEW DAY'S OR YOU CAN APPLY A CLEAR COAT OVER MOST PAINTS THESE DAY'S, BUT THIS SHOULD BE DONE A LEAST 20 minutes or so after you have the top coat on so that the 2 applications form together,
FINALLY, some spray painters rub between each and every coat if there is MODAL OR ORANGE PEEL AND THIS CAN COME FROM MANY FACTORS, it is a leaning curve and technique, so be patient and practice remember safety all the time.
AFTER IT HAS FULL DRIED YOU CAN RUB DOWN IF YOU HAVE PROBLEMS LIKE ORANGE PEEL OR SLIGHT RUNS ONLY WITH ACRYLIC PAINTS AS WITH RUNS ETC ENAMELS ARE ABIT DIFFERENT AND YOU WILL NEED MORE ADVICE ETC,
THE FINAL RUB DOWN WOULD BE WITH 1000 TO 1200 0R HIGHER WITH PLENTY OF WATER BUT NOT TO WET, AFTER THAT YOU CAN BUFF OFF WITH A GOOD CUTTING COMPOUND WITH BUFFING MACHINE AND LAMBS WOOL PAD CHANGING IT REGULAR AND YOU MUST WATCH THE EDGES OF YOU JOB AFTER THIS YOU MAY WASH YOUR CAR BUT NOT WITH A HARSH DETERGENT AND WIPE IT DOWN CAREFULLY, AFTER SOMETIME WHEN THE PAINT HAS FULLY HARDEN YOU CAN APPLY TEFLON CLEAR OVER IT WITH UV PROTECTION IN IT ONLY USE THE BEST BRANDS NOT THE CHEAP ONES
BEST OF LUCK
Pedro the Painter
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THANK YOU
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Location:
Gold Coast
Registered:
July 2003
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Re: Spray Painting / Air Compressor Advice
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Tue, 27 September 2005 09:13
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| Hachi2Muchi wrote on Mon, 26 September 2005 02:33 |
maybe just post it.
Alot of people desperate for low cost spray jobs.
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I have a Car Body Repairs manual in JPG format, which covers a fair deal of spraypainting.
But it's 21mb (98 pages/pictures) so if anyone knows where I can host it I will.
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