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?
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.
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.