I deviated somewhat from the builder's guide and followed what previous builders have recommended in order to get an extremely straight trailing edge. I fabricated a drilling guide from aluminum barstock and carefully drilled matching holes in it at 84 degrees. The guide's hole on the left did not line up perfectly with the rest so it was not used at all. Then working from the center of R-1006 and R-1001 outward, I drilled every 2nd hole not only through the parts but through the angle iron bucking bar also.
