Spraying Question

[T Conway]

Hi. I have sprayed in the past using wonderful equipment that belonged to my employers. When I started looking for the right spray equipment for myself I knew that I wanted HVLP and I guess I didn't do enough research. I ended up with a 2.5 gallon spray pot system with a Wagner NP HVLP spray gun. This unit got great reviews but I am not so sure about it now that I have experimented with it myself. I really would like a better quality HVLP or RP gun. The problem is, I have a very small shop and when I bought the system I bought a 3.25 HP, 4.5 Gallon Twinstack Ridgid Air Compressor. This unit creates 6.2 SCFM@90PSI. The spray pot is only rated for 60 psi. My question is, what kind of HVLP or related gun will deliver properly when spraying lacquers using this compressor and pot setup? I also don't like gravity fed or cup guns. I prefer the pressure fed systems. That is why I didn't go with the turbines. Should I just call each manufacturer for specifics on guns? Hopefully there is someone out there with good news for me! Thanks for any advice.

[Brian Parker]

Have you tried to turn the regulator down on the compressor to 60psi and then hook that up to your pot?

I have the same compressor only I have a bottom feed cup gun, not a gravity or hvlp one. My gun only needs something like 5.2 scfm @ 40psi and the ridgid compressor does 7.4 scfm at 40 so its never a problem. I've filled the cup all the way up with some distilled water and set the compressor reg to ~50psi and then the regulator on the handle to 40psi and held the trigger wide open until the cup was empty. I always had enough air to spray and it never got sluggish. For its size that little compressor packs a punch, the only thing is that it needs to be on its on circuit since its 14.5 amps.

[jim chambers]

T,

I'm not sure I understand the problem correctly, but a few things came to mind after reading your post.

I don't like turbines for the same reason you don't, and spray with a Binks conversion gun and pressure pot.

Here's how mine is hooked up. The compressor hose goes to a regulator on the pressure pot. On the other side of the regulator is a T fitting. One side goes directly to the gun, which has the smallest regulator I could find (a teeny binks one) mounted to it. The other side goes to another regulator which controls the pressure to the pressure pot.

So I don't mess with the regulator on the compressor. The first regulator on the pot I usually run at 60-65 psi so I can jack up the gun air to that amount to blow dust off the work just prior to shooting it.

What I run to the pot depends on what material I'm spraying, but I imagine it's around 10 psi (ten) or less. The gauge has been broken for about 15 years. What I do to set the pressure is shut down the gun air and squirt out the material with the gun held as high above the pot as I will be spraying. I adjust the pressure to the pot so the material squirts out about as far as taking a comfortable piss after one beer (ie. not going for a record).

The reason for the first regulator on the pot (regulating to 65psi or so) is because the nature of regulators is such that they operate much more evenly if you are not trying to regulate an extremely high ( 120 psi compressor air) to an extremely low pressure (10 psi pot air). The gun air you will probably not be knocking down to any lower than 40 psi form 65, and will get extremely even flow.

So if you are already hooked up like this, then the problem could be the gun, the tip (nozzle)/air mixer ratio, the air cap size, the viscosity or all the above.

You might want to talk with a Wagner tech rep before going for another gun. Could just be something simple.

At any rate, let us know what happened.

Regards,

jimc

[Charlie Plesums]

...Should I just call each manufacturer for specifics on guns? Hopefully there is someone out there with good news for me! ...
Jerry Work (a pretty accomplished custom furniture maker) wrote a manual for Target Coatings (water based finishes) but in that manual he reviews a number of different guns. See www.targetcoatings.com/home/manual.html (http://www.targetcoatings.com/home/manual.html)

[jim chambers]

Charlie,

Thanks for the link. I read the whole thing. It was a really good article, but it didn't deal with remote pressure pots like T has.

I've noticed that fluid pressure seems fairly critical using a 2 1/2 gal pressure pot, and it varies depending on how high the gun held relative to the pot, if you are spraying tall cabinets that are already assembled. But it's not a big deal so long as you are aware of it. I don't think T is to that stage yet.

I know that asturo makes good spray equipment, including air assisted airless setups that are the cats meow, and if T doesn't have any luck with his - I would recommend an email to Jeff Jewitt (who also sells asturo).

Good luck T.

regards,

Jimc

[Brad Schmid]

T,

The SATA Minijet 4 HVLP is a good candidate for running off a low CFM compressor (i. <5 cfm @ <30psi). I've done alot of looking at this gun over the last several weeks, although for a different reason (small size for tight quarters finishing). I intend to plumb it to a dual regulator CA Technolgies 2.5 gal pressure pot when/if I get it. There is some competition in the high quality min-gun market as well, so you can come close to SATA Quality for a bit less cost. Depending on the size of the projects you are spraying, and the speed at which you want to do it, one of these may fit your situation well.

Brad

edit: BTW - I spray pre-cat lacquer. For the setup mentioned above (along with the viscosity data for the lacquer), SATA recommends a 1.2SR tip set. I was a bit concerned with fan width, and generally just the mini gun itself, but the SATA rep I've spoken with on the phone several times now indicated he recently sprayed a china cabinet with the same setup in his own home shop with outstanding results. The fan width is 12 inches max and keeping a wet edge wasn't a problem.