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Right Rear Spar Work Continues

May 16th, 2012

Match Drilled Right Rear Doubler

Tonight I continued the rear spar work by match drilling the doublers. I read on several builder sites about the furthest outboard holes on these doublers and the need to countersink them for flush rivets. The reason flush rivets are needed here is because an aileron bracket goes over the top. I felt the doubler was too thin to safely countersink. Other builders felt the same. I prefer the stronger joint that is made by dimpling the holes. This is an acceptable modification per Van’s as well. I simply have to remember to dimple the end rib holes as well. This will leave all the material thickness behind the aileron bracket that will be attached later. It may be overkill, but it is my plane.

Holes done for Right Aileron in Spar and Doubler

Another thing that has to be done is matching the aileron push rod exit in the center spar doubler. I clamped the doubler tight against the spar, match drilled and clecoed it on, then traced the hole dimensions onto the doubler. I then removed the doubler and used my step drill bit to remove a majority of the hole material. Then I clamped the doubler into my bench vise and filed the hole just shy of the trace line. Once close, I clecoed the doubler back onto the spar and finished the hole with my Dremel and sanding drum until they were an exact match.

Once the holes were matched, I then put a Scotch Bright wheel in the Dremel and polished the holes together. They turned out great and took about 15 minutes for this spar.

Right Rear Fork Match Drilled

Next up was match drilling the doubler fork on the inboard end. Nothing special here, just hit every hole with a bit.

It was late so I called it a night.


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