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Spray Gun + Air Compressor Question

Tabor

volvoholic
Joined
Sep 11, 2005
Location
Portland, OR
I have a 30gal air compressor that puts out 4.6cfm@90psi and 8.6cfm@40psi.

I want to repaint my Porsche with an HVLP Sharpe spray gun. I want to know if I will have enough air compressor capacity with their finex gun. It is rated at 11.4 cfm@29psi. Now, I have never used one before, so maybe someone can help me out. I only turn the pressure up enough to get good atomization right? So I might actually be running at less than 29psi, right? What is a typical pressure?

Also, with 30gal charged up to 145psi and regulated to 29psi, with the compressor *trying* to keep up, do you think I can use this gun + compressor? TIA!

EDIT- Typo! I have a 30gal tank. *fixed*
 
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You will kill your stored compressed air very quickly. It can be done. It just will have to wait for the tank to will up alot. My dad did it this way for years. We just now got a 2 stage 80 gallon compressor.
 
As a professional refinisher, I run my guns at 40psi at the compresser, i have it regulated to between 7-10psi at the gun, with a HVLP gun its not how much pressure you can spray, itsyour working pressure thats important, as far as i see you wouldnt have any problems with your comresser size, but i would pick up a air regulator guage for the gun so you could run an optimum pressure, do a spray test ** ideal is about 6-9 inches of spray fan, spray it against paper you have taped on the wall, spray it horizontal and watch the way that it runs, try to adjust all your settings to where the paint runns as even as possible, TAKE YOUR TIME OR ESLE YOU WILL PAY FOR IT LATER** make sure you get a 50% overlap on every pass **just so you dont get any areas with less paint and it covers evenly all over, you'll see stripes in it if you dont do it.** If you have any questions PLEASE PM ME I WILL ANSWER ALL QUESTIONS, I have been doing body work since i was 16. I will ehlp out in the best way that i can. Good luck...Kaz
 
I have (among others) an early Sharpe HVLP gravity feed gun. I use a *edit: 80 gallon tank and a very old compressor. If I time it right, I run out of air just as I need to mix paint.

There's one way to find out if it will work, but if you want insurance, borrow/rent another compressor on a small tank, and T it with the other.
 
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77240dl said:
As a professional refinisher, I run my guns at 40psi at the compresser, i have it regulated to between 7-10psi at the gun

Do you mean 7-10 psi going into the gun?

Thanks for the help and the generous offer.
 
you can have full pressure coming through the lines, but with the regulator, you can fine tune the air flow coming though the gun allowing you to adjust the amount of air coming though, Too much ya get orange peel, tool little, you turn your paint gun into a squirt gun. Try it out, make your adjustments to where your comfortable with the gun, Just make sure that you clean the gun VERY WELL before you spray. with HVLP guns you dont need alot of pressure to get them to work right. **high Volume, Low pressure**
And to state the fact, Im 21, Yeah Im young, but i can turn out a car like ive been doing it for 40 years. ive worked at carstar, Comstock park autobody **michigan** and im currently enlisted in the air force doing paint and body work there, ASE certified in Mig, TIG and ARC welding, Frames, and panel repair And im getting Certified in engine rebuilding and Automatic transmissions/ Im in school finishing my degree in Automotive refinishing. Dont question my skill, Nos. I know what im talking about.
 
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The bottom line is that the problem with using a small compressor is that the compressor will run more (obviously), meaning more heat and more water as has been mentioned.

The water you deal with via dessicant drier. The extra heat means that you need to use the slowest hardener available for the product. Very important.

The comment about 7-10psi "at the gun" is either wrong or misleading.

An HVLP gun requires about that AT THE AIR CAP- which is different than at the gauge on the gun handle- which is what you'll be referencing.

The Sharp Finex is a serious POS IMO. Sorry. Don't get me wrong, people use it to good effect, but I hate them.

For a cheap, good quality gun that is less hungry for air, check out the Astro Pneumatic LVLP guns, or if you have the dough you should look at Iwata.

Astro is hands down the best for the money though, 90% of an Iwata or Sata at a fraction the cost. Plus it's worth having a cheao gun or two until you really get a lock on how to clean them.

Actually another thing to look for is a chinese copy of the "Binks 7" spray gun. They reccomend I thin 50psi at the gun but you can run them way lower than that. Also great for the money.

Hope that helps.
 
77240dl said:
Dont question my skill, Nos. I know what im talking about.

Never questioned your skills, I questioned your way of conveying you qualifications. You did however do a much better job above. I have no doubt you could lay better paint than I.
 
this is what im talking about, you adjust the working pressure at the gun with this little guy... http://search.cartserver.com/search...y=databaseDescript&maxhits=5&keywords=SHP2210

Find out what Fluid tip size you are running **unscrew the nozzle, its stamped on the fluid tip somewhere** also what type of paint are you spraying? Single stage or Base Coat Clear coat? THIS IS IMPORTANT INFORMATION!!! Also, What type of primer are you going to use? because there is the possibility that you may not need to even use primer at all, just scuff the original paint and spray over it. Is it the original paint on the car? For a smaller compresser, i would personally run a base coat, clear coat combo because you can do several light coats **less strain on air pressure** With it being a porshe i assume its one of 3 colors, red, black or white. What color are you painting it? black and red are not suggested for spraying light colors over, they have a tendency to bleed though the paint.
When you repaint a vehicle, there is one key rule. A PAINT JOB IS ONLY AS GOOD AS THE PREP WORK DONE BEFORE, IT SHOWS IN THE END. Its a porshe, i know you dont want a 20 foot car, ya know? looks good from 20 feet away... I can also tell you how to set up a make shift paint booth in your garage. Lemme know... Kaz
 
I don't want to derail too much as i'm in a very similar boat.. 30gal compressor, a few cars to paint and some cheap spray guns.. i want to experiment with the cheap guns on some smaller projects to get practice then buy a best bang for the buck paint gun, regulator, and look into inline filters/dryers(dessicant?) and all that so i have a reliable setup that i can get to perform well.. however i was wondering.. insead of using compressed air and worrying about the water and the pressure.. why not get a tank of nitrogen? A friend i have thats a sales guy for BOC was telling me about a buddy he had that would just come in a get a tank(size must matter here but i forget the number) and use it to spray his car(s) and i guess they turned out great.. I can see the benefits of using nitrogen but i can see problems with getting a nice spray as the pressure starts to drop.. what do you guys think about that idea?
 
I have no idea, but I suppose nitrogen would work for small projects.

Captain Bondo said:
The comment about 7-10psi "at the gun" is either wrong or misleading.

An HVLP gun requires about that AT THE AIR CAP- which is different than at the gauge on the gun handle- which is what you'll be referencing.
That is the norm now, as opposed to the first HVLP guns that needed a firehose to supply air.


77240dl said:
A PAINT JOB IS ONLY AS GOOD AS THE PREP WORK DONE BEFORE, IT SHOWS IN THE END.
Also good advice. If it has peel, you can usually salvage it. If it has craters and dings, you start all over.



The biggets problems I see are getting in a hurry, not practicing good habits (take your time, keep it clean, don't sand bare metal and filler/primer, cover it with more primer and let it sit a long time to shrink) etc.
After that it's the details that get you, like DIRT (including on you), using the wrong temp activator/reducer because the weather changes, falling on the car, dragging a hose in it, not knowing how to adjust the gun/viscosity, etc.
 
Thanks again for all of the help.

Captain Bondo said:
The Sharp Finex is a serious POS IMO. Sorry. Don't get me wrong, people use it to good effect, but I hate them.

For a cheap, good quality gun that is less hungry for air, check out the Astro Pneumatic LVLP guns, or if you have the dough you should look at Iwata.

Astro is hands down the best for the money though, 90% of an Iwata or Sata at a fraction the cost. Plus it's worth having a cheao gun or two until you really get a lock on how to clean them.

Awesome, I will go with the Astro Pneumatic if you have tried them both!

77240dl said:
Single stage or Base Coat Clear coat? THIS IS IMPORTANT INFORMATION!!! Also, What type of primer are you going to use? because there is the possibility that you may not need to even use primer at all, just scuff the original paint and spray over it. Is it the original paint on the car? ... With it being a porshe i assume its one of 3 colors, red, black or white. What color are you painting it?

I am going with a base+clear. I am not sure which system yet but probably an Acrylic Urethane from sherwin-williams or PPG. The car is maraschino red (almost a burgandy), and I am repainting it the same color. It has a maaco (or similar) paint job on it right now. I am going to do some body work so at least some of the car will be down to the metal.
 
mikep said:
That is the norm now, as opposed to the first HVLP guns that needed a firehose to supply air.

You mean 10psi as working or 10psi at the air cap?
The point of a low pressure gun is that is steps the pressure down internally- the low pressure part of the equivalent is at the air cap, not necessarily into the gun.

Here is that astro:

http://www.spraygunworld.com/products/Astro/Astro Pneumatic - EVO4014.htm

They have this one and a new one which is supposed to consume even less air, but I have only used the evo 14 and evo 18.

If you go through the other brands and such you'll see that 90% of even "modern" HVLP guns specify 29psi or 41psi inlet pressure- which is that that little gauge that screws onto the handle that Kaz posted will read.

Either way if you need 29 and not 10psi at the inlet it will be obvious because you won't be able to get any paint on the panel. :rofl:In which case try a little more pressure.

Here's the super low consumption one:
http://www.spraygunworld.com/products/Astro/Astro Pneumatic - AP40005.htm
I haven't heard anything about that gun yet though, so if you're considering that one I'd do some research first.

But the EVO's rule for the $$$.
 
Captain Bondo said:
Here's the super low consumption one:
http://www.spraygunworld.com/products/Astro/Astro Pneumatic - AP40005.htm
I haven't heard anything about that gun yet though, so if you're considering that one I'd do some research first.

SprayGunWorld suggest the Evo4014 for finish work on a car and the HVLPSL0007 for primer application. In fact, they even sell that combo (which I think I will get). Is it true that you shouldn't spray primer in your finish gun (even if you change the needles to larger sizes) to avoid contamination?
 
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