Shooting primer

[GSpreeman]

As I do some work on the car I would like to shoot it with primer. Maybe a quarter panel at a time, tops. I just purchased a Porter-Cable CPFAC2600P 2 HP, 6-Gallon Pancake Compressor. Some of the details include:

2-horsepower motor provides 3.7 scfm at 90 psi and 2.7 scfm at 45 psi
High-pressure design keeps tank pressure between 120 and 150 psi
Higher tank pressure provides more usable air per tank re-charge
Six-gallon tank provides excellent reserve capacity

Can I use it to shoot down a small part of the car at a time? I don't want to waste money getting a paint gun if it's going to be useless with my compressor.

[toolman]

A tank with only 6 gallon capacity will get you about one pass and run out of air volume. You need at LEAST 30 gallons, and a compressor that delivers 10 cfm at 90 lbs to spray anything. If you use what you have, your primer will go on very dry and not work properly ensuring a rotten paint job. To do any serious spray work get a 220 volt, at least 5 HP, 60 gallon tank, over 15 cmf at 90 lbs,and a good air drier with regulator.

[Rot 911]

Your compressor is definitely too small. Hose pancake compressors are great for airing up tires and using nail guns. On the other hand, while the 220 volt, 60 gallon compressor would be ideal, I have done a reasonably good job with my 6.5hp 30 gallon oilless compressor. On the other hand, my next big tool investment is going to be the bigger compressor.

[curlesw]

Having just gone through this, the compressor is too small for painting. I have the same one and am confident it was the cause of some of my painting problems. On the other hand, the primer went on "ok" but the base coat and clear was a disaster and I think the compressor/lack of air pressure was part of the reason. I’ll be getting another, larger compressor soon for my next my next painting project.

V/r
Wayne C.
83 SC

[targa911S]

Don't leave it in primer too long. Primer is designed to absorb, and it will. Re prepsol the area before you finish sand it for color coat or you will just push the oils from road use, your hands, and airborn pollutants into the primer.

[Early_S_Man]

Does anyone look at the published cfm requirements for the spray gun they intend to use before buying compressors these days???

While a 60 gallon rig would be overkill ... my 5 hp 30 gallon compressor exceeds the needs of my spraygun, from day one, for the past 20+ years. Both were made by Devilbis with Sears Craftsman labeling. Painting isn't done at 90 psi, BTW! More like 15 - 20 psi for touchup guns, and 45 - 50 psi for 1 qt suction guns.

[toolman]

If you are using the latest technology, HVLP, you need lots of volume, which is measured at either 90 or 100 lbs in cubic feet per minute. No one I know sprays paint at 90 lbs, but in order to have enough volume (capacity) you need a large reserve, ie: 60 or 80 gallon tank.

[curlesw]

Originally posted by Early_S_Man
Does anyone look at the published cfm requirements for the spray gun they intend to use before buying compressors these days???

Warren, I did, and even spoke to the paint shop beforehand. They said I was one the "edge" of the compressor being suitable. No doubt, "operator error" (i.e. me) may be the cause but I could not get a good setting (i.e. nice spray of material and correct preasure at the gun under load) for the base coat or clear. After spending last weekend with Kevin at Automotive Innovations and Restoration and seeing first hand the proper operation of a paint gun, I'm not convienced my compressor is adequate. However, operator error is always a possibility and I have all of 1 data point under my belt.

v/r
Wayne C.
83 SC

[72 four door]

Ive also had excellent results from using a 5hp 30 gallon unit. You will need the adapter to the gun that removes moisture. If i was doing cars all day i would nt go this route but it will yeild great results. The little pancake compressor might work if your patient.

[targa80]

I have been asked recently what I was using to prime and paint my car. These are the answers I gave

Q: What paint gun did you use?

A: I purchased two guns from Harbor Freight. One is the HVLP suction gun Model 7901-8VGA with the 2 quart cup. If I remember correctly I paid ~$100.00 for this gun. This is a gun with two hoses running from the paint cup to the gun . The cup has an input pressure regulator(40PSI MAX) to adjust the pressure at the nozzle.It requires 10CFM. I used this gun to shoot the POR-15 and the Primer. The second HVLP gun is the gravity feed Model 43430-8VGA for about $40.00. I used this gun to shoot the base coat and the clear coat. The gun requires between 9.5 ~14.8 CFM My gun is stamped 43PSI on the connector going to the handle. This means I need 43PSI at the handle to spray 10 PSI at the nozzle. The gun documentation does not mention this info. So if you want 8 PSI at the tip you would set the regulator at the gun to a little less like 35 ~ 40 PSI. There are other HVLP guns with lower CFM You will have to decide which one you want.

Q: What size air compressor did you use?

A: I have a Campbell-Hauesfeld 60 gallon vertical tank with 220 Volt 7 HP motor. Rated at 10.3 SCFM @ 90 PSI and 11.8 SCFM@40 PSI I set the tank regulator at 90 PSI so I get plenty of CFM at the spray gun regulator.

Note: I am no expert on painting. These guns and setting I have is based on what info I read or heard from other people. Setup of each gun was based on trial and error. Lastly I bought these sprayguns because they were cheap and I felt they could do the job. Naturally, If anyone would like to donate a top of the line Devilbiss HVLP gun to me I would be most greatful.

[RickM]

Quote Warren: "Does anyone look at the published cfm requirements for the spray gun they intend to use before buying compressors these days???"

Good point. I have "primer only" guns that are Craftsman/Devilbiss as well. They have relatively low consumption charecteristics. However, if you get into the higher end Binks and Sharpe (production type) guns you're looking at substantial volume requirements.

BTW, I've used a 1 hp / 13 gallon oil type Craftsman compressor for many years and did some decent paint work with it. As mentioned above, moisture is you're biggest enemy as the heat generated by the motor & overworked compressor struggle to keep up. Need to take your time.

[kenrinc]

Well at least you didn't buy the gun yet :-) Anyway, that compressor is far too small. I've done jobs with those units and they become nightmares really quick. That poor thing will work so hard to keep up it will be on constantly creating a ton of moisture and oil vapor in the lines. In a length of typical 3/8" 50' air hose so much of that hot air will condense into water vapor that it's worthless to even shoot. The pressure usually drops off within 15 seconds of pulling the trigger and that's using THE most air efficient gun you can buy -> a Sharpe Platinum LV (7.5cfm@50psi). You will literaly be shooting water vapor at the end of 30 seconds. There are ways to reduce the moisture but not the volume requirement. See if you can rent or borrow something else if this project is something that you really want to come out nice.

Kenrinc-

[PorschePilot]

My two cents. I just finished up a paint job that I would say was equal to a body shop, not as good as a custom shop. Looks great for the money.

Compressor: Ingersol-Rand 5 HP 20 gallon tank with inline dryer
Gun: Devilbliss HVLP "Finish Line II"

Prep for all stages is everything and take you time. The compressor and gun setup worked great.

[3.2 CAB]

Gee, who whould have thought, I tried leaving a post last night in this, but it would not work, toooooo small, it will be trying to catch up all the time. Can't go cheap, not n any paint finish!

[Zeke]

In a pinch, he can use the pancake to charge an auxillery tank and do a panel at a time. You guys are harsh, especially Warren. Sometimes you have to work around a problem and improvise and/or compromise. It's just primer he's asking about for chrissake.

We all can't have complete shops. I have thousands of dollars worth of tools, it never ends. I improvise when I have to.

[UTKarmann_Ghia]

Flame me, but I just bought a 4 gallon compressor from Checker Auto which delivers 6.4 cfm @ 90psi. So far my air tools dont require even that much cfm so I'm good for now. I paid $89 for it and while it's not "professional", it was able to rattle off/on my tranny nuts for me.

[kenrinc]

Harsh? I only gave my opinion based on past experience using the same equipment. It didn't work for me and I don't remember saying he had to purcahse a complete shop to do the job. Just get a reasonable compressor. The 4gallon 6.4cfm unit mentioned above, would be a leap forward compared to the original pancake mentioned in the original post.

I'm not EVEN going to get into the DIY attitude about "it's just primer"

Kenrinc-

[RickM]

I consider a compressor one of the vital organs of a shop, even a DIY shop. It's useful for so many things, therefore a very worthwhile investment. For a few hundred you can get a great unit.

The compressor I mentioned above is 24 years old and still works perfectly.

[Zeke]

Originally posted by kenrinc
Harsh? I only gave my opinion based on past experience using the same equipment. It didn't work for me and I don't remember saying he had to purcahse a complete shop to do the job. Just get a reasonable compressor. The 4gallon 6.4cfm unit mentioned above, would be a leap forward compared to the original pancake mentioned in the original post.

I'm not EVEN going to get into the DIY attitude about "it's just primer"

Kenrinc-

Sent you a PM with an apology (of sorts).