HVLP help

[sirron1957]

I would like to start spraying finishes with HVLP but can't justify the cost to buy a unit.  Can I buy just the spray gun, dial my compressor down to 10 psi and spray like that?

Thank you for any and all help,

    J.R.

[fredhargis]

You can, easy-peasy. But don't dial the compressor down to 10. The concersion gun I have works best for the finishes i use by setting the compressor to 40 PSI, then the regulator on the gun (most of them have that, I think) is set to 15 with the trigger pulled. Each gun, and each finish may vary so it's not a blanket rule. A lot of guys here swear by (as opposed to swear at) the HF purple gun.

[sirron1957]

Is this the HF Purple Gun you are talking about??  http://www.harborfreight.com/20-oz-8-cfm...67181.html

[jteneyck]

What finishes do you want to spray?  That HF gun has a 1.4 mm N/N.  It's great for spraying shellac, dyes, and low viscosity finishes like NC lacquer up to about 25 seconds #4 Ford cup, but it's not a good choice for the higher viscosity waterborne finishes I typically spray, and worthless for paint.  What you buy depends on what you want to spray.  

John

[fredhargis]

It is. But my comments are not based on any personal experience, just what I've seen posted here (and other forums). John makes a good point, that gun does have any other needle sets available (AFAIK) so the 1.4mm is the only one you have available (didn't even know that was the size). For most guns a new needle set alone would be 3 times the cost of the HF gun.

[Snipe Hunter]

You can, easy-peasy. But don't dial the compressor down to 10. The concersion gun I have works best for the finishes i use by setting the compressor to 40 PSI, then the regulator on the gun (most of them have that, I think) is set to 15 with the trigger pulled. Each gun, and each finish may vary so it's not a blanket rule. A lot of guys here swear by (as opposed to swear at) the HF purple gun.

Not to pick knits but anything over 10psi at the tip isn't HVLP. The only thing that makes those "conversion" EPA/HVLP compliant is by "converting" them to HVLP by using a regulator at the gun, dialed down to 10ps or below..

I'm not giving you a hard time, I do it too. It's the only way I can get them to work well.

Honestly, I set it at 40psi or take it off completely and just set the regulator at the compressor at 40 or 45.

[jteneyck]

With my  gun, 29 psi inlet pressure at the gun = 10 psi at the nozzle.  I only know that because that's what Qualspray says it is; I don't know how I'd actually measure it.  My point is there's a pressure drop through the gun and it takes more than 10 psi at the inlet to get 10 psi at the business end.  FWIW, I got great results with the purple HP gun with about 20 psi inlet pressure with shellac and 30 psi with WB at about 40 seconds #4 Ford cup.  I have no clue what the pressure at the nozzle was, though.  Fortunately, I don't need to worry about it. 

John