Changing out Air Caps, Needles, and Nozzles on HVLP Sprayers

Usually all three parts are swapped out at once, but sometimes it makes sense to mix and match. August 8, 2008

Question
I'm new to HVLP and just purchased a Finex that came with a setup already in it and I purchased two more. When changing out, do I swap all three pieces - cap, nozzle and needle?

Forum Responses
(Finishing Forum)
From contributor A:
The needle and the nozzle need to be swapped out together. The cap that comes with the set should be pretty good for what it was designed for. But if you are using different paints of thicker viscosities you may need to swap out the cap. With my HVLP I usually use the next cap up. If I am using a 1.7 needle/nozzle setup I will use the 1.9 cap. My clears run thicker than what was designed for the gun, so I need to have a bit more air for better atomization.

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From the original questioner:
I will keep the 3 piece sets together and swap them out as needed. I appreciate the help.

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From contributor B:
Your air cap will affect the spray pattern and flow levels. It allows you to get some in between spray/flows that you might not get when switching out a whole set. For most users those are pretty finely differentiated though and not overly useful. The air cap crossovers do become useful when you need a bit more flow for a large panel when you are in the midst of spraying a cabinet set. By switching to a larger air cap and increasing your material flow setting you can spray faster on the panel and switch back quite quickly.

For some specialty purposes I also use different air caps. For example, when I do spattering I will use a very large air cap with very low pressures and thicker paint with a medium sized needle. I actually ordered a special air cap for this purpose, one that is at the large end of my gunmaker's line.