Setting gun pressure with a conventional spray gun?

[turtle5353]

Hey guys I had a quick question on how I should set my pressure on my spray gun. I have read some conflicting info on the web about this and wanted some of you guys opinions. I have a Sharpe Finex FX2000 Conventional gravity fed spray gun. This is NOT a HVLP gun. So it runs some higher PSI than the hvlp. My question is do you set the recommended pressure at the regulator on the gun or when the trigger is pulled?? I set my pressure just slightly above what recommended at my wall mounted regulator. I lose a couple PSI when it gets to the regulator at the gun. But I set the regulator at the gun at 43PSI which is what is recommended by mfgr. When I pull the trigger it drops some but seems to spray well. Should I bump my PSI up so that when I pull the trigger I get 43psi at the regulator mounted on the gun? Here is a link to the manual for the gun. Thanks for any help Gentlemen

http://www.sharpe1.com/sharpe/sharpe.nsf/Files/RNDVRNDW/$file/312372J.pdf?OpenElement

Technical Data

Maximum Air Inlet Pressure 100 psi (0.7 MPa, 7 bar)

Maximum HVLP Inbound Air Pressure 29 psi (0.2 MPa, 2 bar)*

Air Consumption

FX1000

FX2000

FX3000

7.0 SCFM at 29 psi (0.2 MPa, 2.0 bar)

9.5 SCFM at 43 psi (0.3 MPa, 3.0 bar)

9.5 SCFM at 29 psi (0.2 MPa, 2.0 bar)

Fluid and Air Operating Temperature Range 32-109°F (0-43° C)

Spray Gun

Air Inlet Size

FX1000 Weight with cup

FX2000/3000 Weight with cup

1/4 npsm (R1/4-19)

0.9 lb (0.4 kg)

1.1 lb (0.5 kg)

Wetted Parts Aluminum, stainless steel, engineered

plastic

Noise Data**

FX1000 sound pressure at 29 psi (0.2 MPa, 2.0 bar)

sound power at 29 psi (0.2 MPa, 2.0 bar)

FX2000 sound pressure at 43 psi (0.3 MPa, 3.0 bar)

sound power at 43 psi (0.3 MPa, 3.0 bar)

FX3000 sound pressure at 29 psi (0.2 MPa, 2.0 bar)

sound power at 29 psi (0.2 MPa, 2.0 bar)

78.17 dB(A)

85.32 dB(A)

81.91 dB(A)

89.23 dB(A)

80.60 dB(A)

87.74 dB(A)

 

[jbojo]

I use a gauge at the gun and set it at the pressure I want when the trigger is pulled. I use a HVLP gun though.

 

[Mister 4x4]

I use a pancake nail gun compressor with my airbrushes, and have not only the output pressure regulator at the compressor itself, I also have an inline regulator with an input and output gauge at the airbrush hose fitting (I made it myself years ago - more often than not, the line pressure coming from the compressor is a little different than its output regulator pressure gauge reads). If the "In" side of the homemade regulator falls below about 30psi higher than the intended output pressure, then the line pressure at the airbrush suffers and I get inconsistent results. My airbrushes seem to work best in the 19-25 psi range (down to 6-9 psi for fine line work), so I set the compressor's output regulator to 60-65 psi (according to my homemade regulator "input" side gauge, and the "output" side to 19-25 (according to the "output" side gauge).

I'm sure there are commercially produced examples of the same thing I made, and I'm also pretty sure that just having a second [final] regulator with its own gauge will probably get you where you need to be.

 

[turtle5353]

I have a second regulator set on my gun to 43psi. But should that be 43 psi at the gun when not in use or 43psi at the gun with the trigger pulled?

John you set yours with trigger pulled? So I would have to bump my pressure up a touch because when the trigger is pulled I lose some PSI.

 

[Mister 4x4]

It should be set with the trigger pulled, because that is your working pressure. You're probably going to have a short initial 'burst' of slightly higher-pressure air when you first hit the trigger, but if you set the regulator to 43 psi with the gun not in use, you'll likely see less than 43 psi after the initial 'burst'... which could affect your outcome.

The only way to combat the 'burst' is to have absolutely rigid air lines going from the regulator to the gun itself. The main reason for the 'burst' is because the rubber hose expands slightly when the air is contained, increasing the line pressure.

The 'burst' is also part of the reason it's best to start the spray 'stroke' before passing the gun over the object intended to receive the paint.

Since you have the gauge at the gun, it should be fine... but I'd still set it with the trigger pulled - just to make sure.

 

[turtle5353]

Nice. Thanks. I have been running it at 43psi without trigger pulled. And it seems to work pretty good. Hell it will probably work even better with the proper pressure LOL!!! :shootself:

 

[jbojo]

If I remember correctly I was using 23psi with trigger pulled and the air pressure was about 25 with trigger off.

 

[Austin Vert]

Hi Kevin,

I have PM'd you with all the tech details you will need. ( A lot of tech detail)

As i recall, you're running a 1.4 setup on your gun you bought.

For the Forum's benefit - yes, you pull your gun trigger all the way back in, keep it in, and then adjust the mini gun regulator to 43 psi with the max air moving through the gun head.

The biggest problem that domestic compressors have is not being powerful enough to keep up that 43 psi pressure constant to the gun head over a period of time, such as a 3 to 4 minute constant run. That's when you get volume and pressure fade away or dy back when spraying, which leads to improper atomization of the paint you are spraying - not good.

If that happens, then stop or pause painting and let the compressor catch up and try to build up more air for you to make use of. That's a cheap, temp fix to help get you out of jail so to speak. You should try to match your gun's air draw or air consumption spec to the compressor output or air delivery spec which should be presented as an FAD spec. (that's a free air delivery spec in cubic feet per minute)

Greg.

 

[turtle5353]

Thanks for all the replies gentlemen!! Greg, I sent you a PM. Thank you again for all the help , as always your advice is spot on!!

So I feel like a pretty big ******* now! :whistling: I have used this gun many times and I have never had it set up properly once. I was still getting very good results but it was never set up just right. Last night I set the pressure at the gun to 43psi with the trigger pulled. I shot the bottom of a hood with single stage and it turned out really nice. It has some dust in it because I'm just shooting in my wide open dirty garage, but it worked. The paint covered and atomized better than it ever did. I put three coats on it and I think my compressor kicked on once for about 30 seconds.

My compressor is an Ingersoll Rand 80 gal. 2 stage compressor with a 5hp motor. So it doesn't have any problems keeping up.

Again thanks guys for all the replies and I should be able to lay down some paint now that my gun is set properly!! ::thumb::

Heres a couple pics of my set up and some of the parts I am going to be spraying this week.

 

[Austin Vert]

Thanks Kevin,

Glad to be of help. I noticed in you pics that you have quite a lot of gear attached to your spray gun. My advice would be , try your best to reduce or eliminate as much of that as possible, as it affects how you put the paint on your cars. It makes it much harder to spray your panels correctly with a good gun application technique.

Greg.