Cut lightening holes in VS rear spar stiffener IAW drawing. In the process, discovered I had misplaced two of the holes for the upper VS410 bracket. Re-drilled appropriate locations, deburred, dimpled/CS. Cutting the lightening holes required a bit of effort, even using the drill press. The hole saw bits worked ok, but all I had for lubricant was air-tool oil. Cut the larger holes at 1-7/8" vice the 2" called for, which turned out good, because there were a lot of tooling marks to get out. Deburred the holes and then spent a couple of hours filing and scotchbriting them as well as finishing the edges of the stiffener, spars, and skin.
