After using my band saw to cut out my frame blanks I used my disk sander to round off the corners to a 1 1/2 inch radius. Then I got out my 12 inch scale and a blue fine-tipped Sharpie and marked the centerline of the blank followed by the locations of the 2-inch diameter holes to be drilled in the frame. I wanted to go with a 1 inch radius for the holes in the leading edge skin and the frame to reduce the stress concentration factor caused by the hole, Image 1 shows the marked up frame blank. Image 2 shows my protable drill press being used wth a 2-inch hole saw to drill the frame blank. Note the use of clamps to hold the frame blank in place while the hole saw does it's thing. Image 3 shows the frame with 4 holes drilled in it.
0.050 Frame Shim Blank with Hole Marked in Blue Sharpie
Using a 2-inch Diameter Hole Saw to Drill the 0.050 Frame Shim
