Posted by Mike McClintock on June 23, 1999 at 05:32:09:
In Reply to: Re: someone here knows, right? posted by Nick on June 23, 1999 at 00:11:41:
Nick,
A 5hp compressor should be adequate, you're not shooting production. The size of your tank is equally important.
I use a binks mach1, which is a $500 gun, because it's what I have from when I used to lacquer furniture. Great gun (probably hte best production gun available) but pricey for a part timer. I cant speak about other makes, but the one Ray uses sounds like a good unit. I dont know about pressure reduction at the gun, but it would help air volume at the gun with a smaller hose. A larger diameter hose is desirable with HVLP, but a pain. I use as small a hose as I can get away with because I feel speed and mobility are important.
There's no real mystery behind cup guns, HVLP or LVHP. Like most things it's just time with the activity. The thing to remember about HVLP is actually obvious, it's putting out alot of paint (high volume) with barely adequate atomization (low pressure). The benifit is practically no overspray, therefore greater paint economy, and enviornmental protection. The drawback is that it's much more difficult to achieve good flow-out and film thickness. In a production situation this is no drawback, you mix in the morning, and paint all day. And since you're painting all day, your touch is light and sure, and your film thickness is consistent. If you're going to use HVLP spend some time experimenting. Flow out is the key, and everything affects it. Start with paint viscosity, and use a thinner that promotes flow-out, I like xylene. Next the prportion of gun pressure to cup pressure controls the size and density of the spray. My binks is nice because I have a seperate regulator on the cup, giving positive control of paint delivery to the gun, kind of idiot-proof. Lastly work on technique. It's very easy to paint unevenly, or go over a partially dry earlier pass. Too much paint will sag, because you've mixed for flow, and wet over dry will be rough. Great system, but takes some time to get used to.
All that said, I still use LVHP for alot of my work. For small set-ups it's ideal. Much less picky and more forgiving. Setup is simple, atomization is powerful at a wider range of viscosity. Beautiful flow and film thickness is a snap. You do wind up sweeping more than half of your paint up off the floor though. For onesies and twosies I use LVHP and for production or large things I use HVLP.
MM