Large Compressor, Small Spray Gun Ok?

[Cagey]

I have the chance to get an air compressor w/ accessories that include a nice DeVilbiss gun at a fire sale price. Stuff's been sitting around doing nothing for several years, and the guy just wants to get it out of his garage. The compressor is a 2 cylinder 3hp unit with a 20 gallon tank. I want to be able to do burst finishes, which means using an airbrush or a smaller gun (any advice here is welcome, too) but I'm curious if there's any reason you wouldn't want to use a big supply with a little gun. I can't imagine it would matter if you've got a proper regulator, but not having done it I'd like a sanity check.

 

[pabloman]

No problems at all if you have the proper equipment. I have a 5 horse 30 gallon because I enjoy destroying cars. I mean restoring cars. I have lines plumbed all over the place. The biggest problem you will have is moisture. But that is what filters and dryers are for.  With a large air supply your compressor will be cycling less so that will help as well.

 

[MedianMusic1]

I prefer Preval Sprayers over compressor units or even rattle cans. I'm using the Preval's on my current project for paint. Ended up saving money too (especially when using automotive urethane paints).

 

[pabloman]

The problem I have with the preval is can't control flow and atomization. Those are pretty important for bursting jobs. The preval is good though and I still use it often.

 

[Cagey]

No problems at all if you have the proper equipment. I have a 5 horse 30 gallon because I enjoy destroying cars. I mean restoring cars. I have lines plumbed all over the place. The biggest problem you will have is moisture. But that is what filters and dryers are for.  With a large air supply your compressor will be cycling less so that will help as well.

Ok, good. I was going to buy into something smaller, if for no other reason than portability, but this is a deal and a half where I know the history of the unit. It's been kept clean/dry/oiled and barely used at all other than the occasional tire fill, which is a bit of overkill considering its size. Actually, it'll be a bit of overkill for me, too. All I intend to do with it is shoot guitars and other small items. At least at this price, if there's ever a future ex-Mrs. Wagner, I won't lose as much as I did on the last couple. Actually, to quote Rod Stewart: "Instead of getting married again, I'm going to find a woman I don't like and just give her a house." <grin>

 

[Cagey]

I tried the Preval units a year or so ago and didn't have a whole lot of luck with them. But, I suspect they want something very thin to blow, as I couldn't get the things to siphon worth a tinker's damn. I was trying to shoot sanding sealer, and I think that's a bit thicker than what they're designed for.

I also tried one of those rechargeable spray units like this one...

But even at 120psi there just isn't enough air in there to do much of anything. You end up constantly recharging it, and the the output is highly inconsistent. It's Ok if you're painting deck chairs or something you don't care much about, but anything else? Fuhgeddaboudit. It's more work than a brush and the results are iffy. Plus, you still need a compressor.

 

[swarfrat]

spray painting cars is a pathological case for air compressor needs. Most everything else, including spraying smaller stuff isn't that demanding on compressor capacity

 

[MedianMusic1]

I only use the Preval units for paint (i.e., automotive urethane). For primer and clear (I also use the clear as a sealer) I just buy the SprayMax rattle cans at about $20 each. Automotive urethane rattle cans cost about $30 - $40 each so using the Preval unit for paint saves me some money.

 

[Cagey]

I may have to change my mind. Been checking online, and compressors aren't as expensive as I remember. You can get a lot of machine for not too much money if all you're going to do is paint guitars and such. When it comes to mechanical stuff like this, new is always better. Plus, I don't see me painting any cars or running high-volume air-suckers like impact wrenches.

 

[anorakDan]

Just make sure you use a regulator and a water trap for the line. You don't want to run something like 100psi though an airbrush or touch-up gun. Dial that down to 15-20 psi or you'll ruin your gun.

 

[Cagey]

Not only that, it'll be a helluva injection hazard <grin>

 

[Tonar8352]

Size does not matter:  laughing7: :laughing7: and air pressure does not matter either.

It is CFM that matters. (Cubic Feet per Minute)  If your gun requires 12 CFM and you only have 5 CFM the compressor will be running the whole time you are spraying and your gun will no longer be breaking up the material correctly so it starts spitting.  This is really critical when you are doing shading because you really have to turn up the air pressure and back off the fluid pressure.

Check the CFM requirements of the gun that you are using.

 

[Cagey]

That's good information; thanks much.

I've not had that problem in the past, but I've always had pretty good-sized compressors that didn't starve the gun. So, maybe I shouldn't be looking at these little pancake rascals. Or, I should consider a smaller gun?

 

[Tonar8352]

Again size does not matter. The smallest gun I own is a DeVilbiss Jamb gun and it requires the most air to drive it.  I would look at HVLP guns and check what they require as far as CFM then get a compressor that meets or exceeds the requirement. 

Another important thing is to match the Fluid Cap, Needle, and Air Cap to the kind of materials you will be spraying.  If you use a set up that is for heavy urethanes to shoot lacquers or dyes you will not get proper atomization and you will wind up with runs or orange peel. Generally the information on the correct Fluid, Air, Needle set up for a particular type of material will be included in the manufactures information book in the box with the gun.

 

[leo12.]

Hi all
spent a lot of time on here educating myself (thank you all very much).
Cagey thats a big compressor it will need to be close to a power socket (no extension leads).
I use & like Devillbiss guns if you want to do bursts a gravity feed gun (pot on top of the gun)  i think is the way to go
it has more control the lacquer is falling into the airstream as opposed to siphon feed (pot under the gun).
if your in the  states you will get parts no problem (fluid tips, needles, air caps.)
Don't think an airbrush is going to work for bursts.
if you go with the deal get a filter & regulator if it is not fitted already.
Drain the tank, valve  under bottom of tank & practice away.
REMEMBER  LACQUER  THINNERS ETC ARE FLAMABLE, LOOK AFTER YOUR LUNGS MASKS ETC.
If you get numbers of the gun body, aircap, fluid tip, (unscrew aircap)  i will help you identify what you have.
good luck, now get that guitar of the month  in progress. 

 

[Cagey]

Thanks! I haven't done anything yet, I'm still doing research and trying to make up my mind.

 

[Watershed]

I acquired a great deal on an 80 gallon compressor with a dryer/filter in the last year, and have had some time to bond with it.
In all it's great, and it has even rationalized the purchase of some pneumatic tools.

The only problem with too much size is when you need to drain it.  The larger ones can take quite a while to empty and fill again.
The 220 volt hard line is a factor too.  And it's huge and heavy...

It's overkill for a guitar, but if you ever get into spraying any larger things (doors, tables, etc.) with a HVLP gun, you'll really appreciate the size.

 

[Cagey]

I don't see me needing that kind of capacity ever again. My car restoration/repairing days are over, and I don't see anything else on that scale coming along. Although, as Tonar has said, large flows can be important sometimes. Still...

 

[Watershed]

The flow is critical, and the HVLP guns are very convenient.
Nothing beats them for building up clear coat.

 

[Cagey]

Just as a follow up... I ended up passing on the great compressor deal and buying into an HVLP system. The latest from Earlex, the model 5500. 650 watt motor, 42CFM @ 2.2PSI

I also got the cleaning kit, an additional 1.0mm needle valve (it comes with a 2.0mm), and a viscosity cup. Seems to be a nice piece of gear; noisy little bugger, though. It uses a turbine compressor rather than the traditional piston compressor w/ buffer tank, so it sounds like a big Shop Vac with something caught in its throat. I'm hoping to hose something down with it this weekend if I can get some time to myself.