Tips to help Ease Project Car Work - Pressure and Fans

Tips Help Ease Project Car Work Gravity Feed Spray Gun

Pressures And Fans
There are a lot of knobs and dials on a paint gun to mess with, and it's easy to get carried away fiddling with them too much. Here's how to dial in your gun. As the infomercial goes, you can set it and forget it.

There are only a few things you can control on a spray gun: how much air goes into it, the pressure of the air as it enters, what the shape of the air looks like as it exits the gun, and how much paint flows out of the gun. To explain this further, we'll identify the parts of a High Volume Low Pressure (HVLP) spray gun.

Tips Help Ease Project Car Work Spray Gun

(A) Paint cup
(B) Pressure cap
(C) Trigger
(D) Fan adjustment knob
(E) Needle adjustment and jam nut
(F) Air volume adjustment knob
(G) Air hose fitting
(H) Air pressure regulator
(I) Air filter

Inside the pressure cap are the following components:
(A) Pressure cap
(B) Fluid tip
(C) Needle
(D) Return spring
(E) Needle adjustment and jam nut

This is a gravity feed spray gun. The paint cup screws to the top and paint drops down into the nozzle area. Because the paint is not mechanically pushed through the gun, it remains a liquid at atmospheric pressure until it exits the gun at the fluid tip. In fact, if you pull the trigger of a paint gun with no air line hooked to it, the paint will just trickle out in a light, steady stream.
This is a gravity feed spray gun. The paint cup screws to the top and paint drops down int
You can control how much paint flows out of the gun by changing the size of the needle and fluid tip. This 1.4 tip size is good for topcoats, but larger tips, 2.0 or 2.5, flow more paint and are good for thicker materials, such as primer intended to go on in heavier coats. Smaller tips, like 1.3 and 1.0, are also available and are good for spraying clear, which can run or sag (or both) if sprayed on too heavily. Needles act like a drain stopper, blocking the flow of the paint and air. They are available in different sizes, too, and must match the fluid tip size you're using.
You can control how much paint flows out of the gun by changing the size of the needle and
With the fluid tip installed, install the needle, spring, and needle adjustment knob. Hold the trigger fully open and tighten the knob just until you feel the trigger being pushed forward. Back off the knob until the trigger is fully open again and tighten the jam nut. Be sure to hold the trigger fully open while you're painting.
With the fluid tip installed, install the needle, spring, and needle adjustment knob. Hold

The needle blocks the air and paint passages at different places inside the gun, so you can pull the trigger about 1/4 of its travel and no paint will flow out, just air. This allows you to adjust the air pressure before you start painting. Most HVLP guns work best with 27 psi entering the gun. By the time it reaches the tip, air pressure will have dropped to just 10 psi, thus the low pressure in HVLP.
The needle blocks the air and paint passages at different places inside the gun, so you ca