Yesterday I finally came up with a (relatively) inexpensive way to jack up the wing center per the plans. I used some spare threaded rod, Al angle and 2x4s to make these little adjustable supports.

Wing center support

The only feature that isn’t apparent in that picture is the flat surface on top. It’s just a piece of plywood left over from a wing crate, with a nut attached to the bottom with JB Weld. I didn’t want to clamp anything to the spar center lest it be damaged if the support was disturbed or kicked out of place.

With the support in place, all that was left was to use it to remove any sag from the wing box. I didn’t have a plumb-bob or fishing line, but I did have a spiffy new laser level I found on sale at Sears. So in an awesome display of obsessive over-engineering, I used the laser level to get the wing box adjusted and sag-free.

Left wing laser-leveled

The picture is a little dark, but you can see the laser line illuminating a row of rivet holes on the spar. I’ll definitely use the approved solution (fishing line and plumb-bob) to check twist before the skins go on, but the laser works well. And that threaded-rod support made it wicked easy to adjust the spar.