Rear wing spar and doubler plates prep - all parts deburred. For the 11 foot long rear spar, I sanded the edge with a belt sander, then the scotchbrite wheel on a die grinder. The smaller doubler plates were done on the bench grinder. On one spar, the aileron bracket doubler plates were attached, then drilled out. On the inner plate, the aileron pushrod hole needed cutting out (pic 2). I drilled the doubler plate with a 1/4" bit, then used the unibit seen in pic 2 to enlarge the two holes. I then used a Dremel with a couple stones and sanding drums to grind to shape.
Deburring spar and plates
Unibit cuts quickly
Final grinding to match shape of overlying spar hole
