Clecoed VS-808 reinforcement plate to VS-803 rear spar channel. Clecoed hinge brackets in position. Back-drilled remaining holes through upper hinge bracket of VS-410. Clecoed skin to rear spar. Drilled all holes to full size. Disassembled all components; removed protective plastic from flanges. Dimpled holes in VS-803 flanges. Dimpled holes in VS-803 where VS-808 will attach with flush rivets. (Had to reverse dimple dies in hand squeezer to reach holes.) Machine-countersunk VS-808 to accept above dimples. Fabricated ��4” dimpled test strip to QC countersink depth. (Protective plastic got in the way when test-fitting the dimpled & countersunk holes together, so I removed it.) Deburred all holes, and sanded all surfaces and edges in channel and reinforcement. Cleaned and primed both. Sanded off gloss from rudder hinge brackets in preparation for future painting.