Spent about 8 hours so far deburring all the flap skin, spar, and rib holes. Takes forever. But, I cut my time nearly in half by picking up this deburring bit. It’s a Cogsdill Burraway bit. Kind of hard to see in this picture, but it has a spring loaded blade that deburrs the front side going in and the back side coming out. Instead of having to deburr both sides with two steps, both get done in one pass.