Before I can attach any skins, I have to make sure the wing is square and free of any twist.
Getting the twist out is pretty easy, you just have to lay the wing flat on a table and make the whole thing level. However, I found squaring the wing a little trickier.
The way to ensure the wing is square according to the plans is to set the lateral location of the single hole at the end of the rear spar attach plate at wing station 19.0. That is, the hole needs to be 19" outboard of wing station 0.0, which is the center of the three 1/4" alignment holes in the main spar. You can kind of see this in picture #2 of Sonex's instruction sheet here:
http://www.sonexaircraft.com/documents/instruction_sheets/SNX-W07-02.pdf
I don't have a square that long, and I have the root rib attach angle and the outboard wing attach block in the way anyhow, so I had to figure out a different way to set the 19" dimension.
I started by marking the center of a 1/4" bolt and putting it in the hole at W.S. 0. Then I laid a ruler over that and carefully marked 19" outboard on the main spar.
Next I took a 48" piece of bar stock from Home Depot, cut it in half, bent each end a bit, and drilled a 1/4" hole at the end of one and a #40 hole and the end of the other. Then I bolted one to the W.S. 0 hole, and clecoed the other one to the rear spar hole. Now I can slide them relative to each other and clamp them to set the lateral position of the rear spar.
Finally, I leveled the main spar the long way, and dropped a plumb bob from the rear spar hole down to the main spar. Then all I had to do was adjust the length of my little jig until the plumb bob sat on my W.S. 19 line. That should do it!!
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