Finishing Kit

July 1, 2012

The Canopy Fairing - 3.0 hrs.

Today I'm ready to start sanding! The layups are as hard as a rock, and I can get on with it. My first sanding efforts revealed low spots in the middle of the fairing. This will be filled in soon.

You need a sanding block that has the desired curvature for the smooth transition you want in your fairing. I borrowed an idea from my friend Mike Bullock, and used a standard hard rubber sanding block, with the sandpaper stretched across the curved top rather than the usual flat bottom. This turns out to be just right! For this initial sanding, there's a lot of work to do, and I started with 40-grit sandpaper. As you can see, it produces tons of dust, and your sandpaper looks like this in just a few minutes.

I keep my shop vac close at hand for this work. I flipped it on every few minutes and sucked off all this dust from the work, and also cleaned up my sanding block. My technique is to hold the hose in between my legs, and using a small wire brush, brush the sandpaper vigorously while it's over the hose and let the vacuum suck away the dust. This greatly extends the life of your sandpaper and makes less work exchanging for new pieces of sandpaper. Plus, your shop stays clean as a whistle. Below, sandpaper looks like new! I sanded the whole fairing down with just one piece.

Here's another shot of that technique, with the vacuum hose handy clamped between my legs and the brush attachment on the end. This really works great. Just don't let anybody see you with the vacuum hose coming out between your legs, while you're brushing away. They'll wonder what you're doing, and it looks pretty funny!

After a couple hours, this is pretty much the result I was hoping for. My objective was to sand the glass down to the same level as the PVC tape, and get a smooth curve transition below down to the canopy skin. Low spots that need filling have been revealed. By the way, I'm happy to report that this PVC tape holds up very well to vigorous sanding, even with rough paper like 40-grit. This was a good choice for this stage of the work.

Now it's time for another layer of resin. This time, I'm mixing in some microballoons. It should result in easier sanding, now that the structural part of the job is in place. No need for any more pigment at this point. Below, I applied it all over the front and down the sides. Now, to find something suitable to smooth it out.

I'm not sure how well this will work, but I found this plastic thing that's flexible. It's designed to go on a gallon bucket of paint, to allow you to pour the paint and avoid paint running down the side of the can. You can get these at Home Depot or any paint store. Let's see how well it works for smoothing out epoxy resin.

It turned out to be a bit more flexible than I would have preferred, but I was still able to get a pretty smooth coat, bending it down into the curve as I pulled it along.

Here's what I ended up with, at the end of this session. Not bad! All the low spots are filled in. I don't think I'll even bother applying peel ply. I feel like I've come a long way today.

The wax paper across the front is to avoid dribbling epoxy into the fuselage. I find that leaving the canopy in place on the plane is the best place to work on it. At least for me. Keeping my shop vac handy has allowed me to clean up as I go along, and not create a big mess from all the sanding. It's clean as a whistle in here.

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