Monday, March 7, 2016

Cut the access holes in the inboard tank ribs - 1.5 hours

The next step is to cut the access holes in the inboard wing tank ribs. In order to do this, i needed to find the exact center of the hole. Not an easy feat. I decided to use the stiffener ring as a template to find the center. I transferred the screw holes onto the rib, and then using a ruler I drew a line from one hole to the opposite hole. This allowed me to find center

Next I used a punch, marked center, and then drilled a pilot hole to #40. Then opened that to #30. Now I was ready to use the fly cutter. I set it up on the drill press with a piece of scrap wood. Slowly i began to cut the hole. This really was a pain in the bottom as the fly cutter is not easy to use. Very nerve wracking as it is not stable and it seems very dangerous. After a while the holes did finally get cut and it ended up ok. The holes are nice and round, not the smoothest edge so a bunch of time was spent with files to take down the rough edges, then the 3M wheel came out, then scotchbrite.