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Match Drilling the Rudder Skins

August 18th, 2011

The Sacrificial Table Tip

Once the kids were off to bed, I figured I could get at least one step in the build manual checked off. It calls for match drilling the skins and stiffeners together. Van’s has a tip in this step where if you have a table that you are willing to drill into, that match drilling can be made easier on these thin 0.016″ skins. I came up with a decent system that worked well.

  1. I laid the skin on the bench.
  2. I drilled the lower left hole in the skin only and clecoed it to the table.
  3. I smoothed the skin flat on the bench and then drilled the skin only in the upper right corner and clecoed it (thus anchoring the skin).
  4. I then would drill the skin only in the outer holes and another hole in the middle of that line of holes.
  5. I then clecoed on the stiffener using the 3 holes that we now in the bench.
  6. I drilled the holes through the stiffener and skin into the table adjacent to the holes used in step 5 and clecoed them down.
  7. I then removed the first 3 clecoes and completed match drilling the stiffeners to the skin and replaced the clecoes.
  8. I then match drilled each hole adjacent to a cleco and then clecoed them down to the table until all holes were drilled and clecoed.
  9. Repeat steps 4-8 in each stiffener until complete with all the stiffeners.

It sounds like a lot but it seemed to work like a charm and was fairly quick. I completed both skins within 30 minutes or so.

Using the Stiffeners as the Straight Edge

Once the skins/stiffeners were drilled, I thought about how I would remove the vinyl coating so I could then deburr and dimple the skins. I had an epiphany of sorts and thankfully it happened when I had not removed the stiffeners from the second skin. I was about to remove them when I remembered the EAA Video of Doug Kelly showing the hot soldering iron trick I have used in the past on the other skins.

It dawned on me that he used the stiffeners in the video to guide the iron. Well….duh! So I did the same on the skins. As for the outside of the skin, I simply flipped it over and clecoed the stiffeners to the outside using the holes from the prior skin so it would lay flat on the bench and it worked like a charm. Once complete, I simply repeated the process for the first skin I had left. My forgetting to do the first skin when it was on the bench actually turned out to be a good thing. Because I had drilled both skins prior to wanting to remove the coating I could use the holes drilled into the bench for both sides. I just lined up the respective set of holes and clecoed the stiffener on and melted away.

Ready for Next Session

Here is what the end of the day left me with. With both sides sans vinyl over the rivet lines I can deburr, dimple, scuff, and prime the rivet lines. I can now do the same on the stiffeners. If all works out, I can be back riveting the stiffeners on Saturday!


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