Finally, the main spars are done. I installed the last rivet for the hole that I accidentally drilled out to 3/16. I drilled the three alignment holes in the spars to 1/4" as called out in the plans. After bolting the spars together through the alignment holes, I drilled the attach block holes up to a #12 drill, instead of all the way to 1/4". I don't have any drill bits that are long enough that are bigger than a #12. Anyway, after unbolting the spars, I noticed that the drill bits had wandered a bit as they were passing through the attach blocks. This may be due to the pilot holes in the attach blocks not being perfectly colinear. Other builders have had this problem, but were able to fix it as the holes were drilled up to full size.
