These ribs are now attached to the aft face of the main wing spar. Again, alignment is critical, since the aft ends of these ribs will be fixed to the rear wing spar, and that in turn will set the alignment of all the other intermediate ribs. Here's a shot inside the #1 ribs from the inside of the wheel well. The horizontal piece of plywood with the curved edge is the #5 fuselage frame, which is fixed to the inside of this rib. To hold the rib against this frame, I used two threaded rods running through the jig centerboard, thus clamping both left and right ribs to the frame. A lot of things had to line up. I wasn't satisfied with the first attempt, so had to pull everything apart, wipe & sand off the glue, and try again. It went better the second time.
The #14 ribs were easier to clamp in place. I just clamped the aft spar against the main spar with the rib in between. None of these ribs are attached to the rear spar yet. After these joints cure, I will remove the rear spar, check all the rib chord lines against the lower jig line, then replace the rear spar, and sand the aft end of the ribs to fit the angle of that spar. Then the rest of the ribs will be ready to attach to the main spar.