The first pieces for the main spars are extensions to hold the angled tip rib. The material this connects to was the rolled up main spar web and the upper and lower spar caps. I had to cut these from sheet stock and then make the clips from angle stock.
Next up are the wing attach blocks. I cut these to length from a 1"x1 1/2" bar and chamfered the edges.
Essentially, the main spar is attached to the fuselage with two bolts. Each spar gets two of these and when they cross these blocks are backed up to each other. The bolt will go through the fuselage spar box structure, then one of these blocks and its 3/16” mount, next through the 3/8” spar, the other spar, the other block and out the fuselage wing box. That is over three inches of material just in the two spars. The rear spars each attach with one bolt.
