Replies

1. 
   Andrew | Apr 22, 2003 10:52pm | #1

   The thing is that not all HVLP guns have the same air requirements. Some can run off of very little air pressure while others need a bit more. The difference is that a higher pressure gun can atomize thick fluids better than a lower pressure gun. However the tradeoff is that higher pressure causes more overspray. Also some designs use air more efficiently than others, so they don't need as much pressure to atomize the finish properly.

   I don't know if Asturo needles come in stainless, but any gun that can use different size nozzles also has different size needles to go with them. Have you asked Jeff @ homestead finishing about this? He knows a lot more about this stuff then I do.

   hope this helps

1. 
   MarkMortensen | Apr 24, 2003 07:12pm | #4

   Thanks Andrew.  I'll give Jeff a call and ask him too.  I'm sure his feedback will be similar to everyone elses input.  At least I'm getting a better understanding of how HVLP spray guns work!

   Thanks again!

   -Mark

2. 
   TomT226 | Apr 23, 2003 07:31pm | #2

   MM,

   I've got an Asturomec 9010 with the CA technologies 2 qt pressure pot that I bought about a year ago from Jeff Jewitt.

   The gun has a pressure adjustment from 0 to in excess of 50 lb.

   The gun also has a fan adjustment to permit adjustment of the spray footprint.

   The pressure pot can go from 0 to 50 lb, when the safety valve releases.

   I have a 3.5 HP 25 gal compressor which I set at 70 lb when using this gun. I usually spray heavier bodied acrylic paint (thinned) at 24 psi tip pressure, with 15-20 psi on the pot. This is with a 2.2MM tip.

   Water based lacquer is sprayed (unthinned)at the same tip pressure, with the pot cranked down to about 10 psi, with a 1.3MM tip.

   With these settings I get very little bounce and overspray.

   I'd reccomend a pot over a suction because it feeds the medium no matter what position the gun is in. It's also easier to manuver just the gun with no pot attached.

   You can get any length hoses for this setup. A dozen or more tip sizes starting at 1.0 MM to 2.5 MM.

   In my opinion, Jeff and his bunch offer exellent products and support.

1. 
   MarkMortensen | Apr 24, 2003 07:21pm | #6

   That does sound like a wonderful setup!  For me, due to budget constraints, I've decided to start small and grow as time goes on.  I realize a gravity gun may not be ideal in all situations, but I figure its a good place to start!

   I'll keep your setup in mind for hopefully not too far down the road!

   -Mark

1. 
   DonStephan | Apr 28, 2003 02:08am | #7

   I have a regular size HVLP spray gun from J Jewitt and a touchup gun for testing stains, hiding sapwood, etc.  While I didn't realize it at initial purchase, the regular size spray gun, which I purchased with a 2 qt remote pressure pot for ease of use, was able to also use a small pressure cup attached to the underside of the gun.  The latter is MUCH better for small spray jobs - significantly less cleanup time - but in essence I have convenient setup for both small and large spray jobs without having to purchase two complete spray guns.

1. 
   MarkMortensen | Apr 28, 2003 07:17am | #8

   Don,

   Your spray gun has a small pressure cup that attaches to the standard input nozzle for the remote pressure pot?  This small pressure cup isn't just a regular siphon cup?  If not, this sounds like something I'm not familiar with.  With the small pressure cup attached to the bottom of the gun, are you able to spray with the gun oriented in any direction (or is this really just a standard siphon cup where you need to have the gun fairly straight up?)  What type of gun do you have?  I'd like to check this out a bit more.

   Thanks for the info - this is the kind of information I just love to keep gathering!

   -Mark

1. 
   DonStephan | Apr 28, 2003 07:49pm | #9

   My primary spray gun is an Asturo ECO/SSP that I purchased from Homestead Finishing http://www.homesteadfinishing.com. The small cup I added from Homestead is a small pressure cup. When I have this one attached I do not turn the gun much off vertical. When using the remote pressure pot I have no hesitation to turn the gun upside down, sideways, or any other orientation that helps.

3. 
   Paul_Snyder | Apr 23, 2003 09:31pm | #3

   Mark - to be classified as HVLP, spray guns have a maximum of 10 PSI at the air cap. Different brands have different air conversion ratios, depending on the design. For example, some spray guns have a 3:1 ratio, and 30 PSI at the inlet translates to 10 PSI at the air cap. Some have a 2:1 ratio, and 20 PSI at the inlet provides 10 PSI at the air cap. If the material you're spraying will atomize well at lower pressure, you can turn the air down at the inlet which will reduce the air pressure at the air cap below 10 PSI. You can exceed the recommended air pressures on most spray guns, but you will get more overspray and will not comply with HVLP regulations.

   Air consumption, in CFM, is also a big consideration. Some spray guns need as much as 20 CFM to atomize the spray, and some need as little as 5 CFM. The more CFM, the larger the compressor you will need.

   I would not be at all concerned by the mild steel needle. As long as you flush the spray gun after use with water, then solvent, you will never see a problem. There may be an optional stainless steel needle for the spray gun that you can order, but don't try to use the needle from a different gun unless the supplier recommends it. Leaving WB finish in an aluminum cup is a lot more worrisome then having a mild steel needle.

   Paul

   F'burg, VA

1. 
   MarkMortensen | Apr 24, 2003 07:18pm | #5

   OK, that clarifies the pressure settings much better for me.  I just couldn't figure out why the spray guns from different manufacterers were so different in their pressure requirements! 

   Thanks for reassuring me about the mild steel needle.  I guess I read somewhere that if shooting WB finishes, it's much preferable to have all stainless steel parts.  From what I've read and received feedback on, that's not a concern.  Great!

   Thanks Paul,

   -Mark