July 19, 2009

Fixed Air System, More Painting - 4.0 hrs.

Today, as I prepared for more riveting and assembly of the fuselage, I kept staring at my side skins. I'm not happy at all with the paint job of the top coat. With all the time and money I've spent on top quality materials and tools, I should have better results. The finish isn't even. You can see different textures in the finished job, from a nice satin sheen like I want to a spotty sort of splattered look. It all stems from the lack of good air flow, I believe. I've compensated for lack of air by narrowing down the spray pattern to a small circular spot, and I keep the gun moving. I'll spray a small area and wait for air pressure to come back up, then spray some more. When spraying smaller parts I can make it work okay, but this system just isn't working right. So I decided to troubleshoot the entire air system, from the compressor to the paint gun, and find out where the bottleneck is. I won't bore you with the details of the process and the steps I went through. Suffice it to say that I found the problem. It's this air filter that I'm using. When I plug my paint gun directly into a hose from the compressor, it puts out all the air I could ever ask for. But I need dry, filtered air for an HVLP sprayer. So I spent some time trying to figure out how to get a high-flow filter element of some kind into this filter, only to find out that's not the problem either.

You may recall that this is the filter I installed a while back. As big as it is, I couldn't see how it could be a bottleneck for good air flow. My suspicions were increased when I looked through the booklet that came with it and couldn't find any information or specs on air flow numbers. So I dismantled it to take out the air filter element inside. I just wanted to check and see how much air flow I would get with no filter element inside at all. To my surprise, the air still petered out a short moment after pulling the trigger on the gun. Whoa! So it's not the filter element at all. Next, I removed the chrome-plated regulator on the front of the thing and dismantled it. In the center of it is a tiny pinhole for air to go through. That's gotta be it! No need to worry about a filter element anymore. Just lose this stupid excuse for a regulator and I should be in business. I already have a regulator at the compressor, so this one went straight into the recycle bin.

After another couple of trips to the hardware store for parts, this is the assembly I ended up with. The crappy regulator is gone along with the cheap ball valve. In place are new 1/2" fittings connected directly to my high-flow quick-connector. I saved the pressure gauge. Why not? It's nice to have even though there's one at the compressor, too. I'll continue to use the regulator at the compressor as I always have.

When I put this together and hooked up my spray gun, wow! What a difference! Now I have all the air I need, the control I want, and I am confident I can paint from now on with much better results. I did end up reducing the paint with distilled water by 10%. It thinned it just enough to make a big difference in how well it sprays and flows together.

So I scuffed up the previous coat of paint on the side skins, along with a few other parts I decided to re-paint, and set everything up for another coat. The results this time are much, much better. I'm now finished with all the painting I'll be doing for a while. It's time to get this fuselage together and get this canoe flipped!

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