Along with scarfing the one edge, there is also a procedure to "roll" the edges down. The process of riveting skin onto a spar or other surface that has an opposing skin butting up to it, can sometimes leave the skin a little stretched and some wavy-ness can occur in the skin. Rolling the edge of the skin puts a pre-bend in the skin so it tends to sit flush against the skin after riveting. But like all other aluminum work - it's a matter of how much to do, or not do.
I did a few of the edges on the bottom skins in case they turned out, "sub-par" and left them on the under-side of done while I hone the technique. I will see once I start riveting, how I am doing and adjust from there.
See the picture below - it's kind of hard to see, but the edge is bent "up" slightly. I used the edge rolling vice grip tool from Cleaveland after deciding that the roller tool was not an option. I also tried out the stick of wood method with a saw blade width cut in it. We will see.
