Worked on installing the aft root rib. I first laid the wing down, clamped down the spar, and hiked up the rear spar until it was level with the front spar (per Sonex's recommendation).
In the pictures below I used a long drywall T-square against the spar web, and aligned with the 0.0 station point (you can just see the hole in the 1st picture).
In the second picture you can see another metal ruler clamped to the T-square. Since I'm measuring 19" off the 0.0 station point you can just see that I have 19" aligned with the right edge of the T-square. I used a carpenter's square to make sure the T-square and the ruler were perpendicular.
Then (in photo 3) I used that carpenter's square on the table top at the end of the ruler (the end is at 19" remember). Then I shifted the rear spar until the hole (in photo 3) was centered on the vertical square.
It's actually not all that important to have the 19" point right now. That's important when I get to skinning. But it was good practice. It WAS important to have the wing level, to get the root rib aligned with its support angles on the spar. See the photos on the following pages.
T-square against the spar web, and clamped in place.
Metal ruler clamped at the 19" mark.
Carpenter's square to aligne the hole in the rear spar.
