Source: 2025 Q4 Beartracks, George Huntington

HOLDING WING STRUT ENDS SQUARE WHILE DRILLING
Make a spacer block that fits into the flat inner area of the strut. Leave enough space for a support. I used a piece of 1/8, 2024 that sticks out to support the strut while drilling and keep it 90 degrees to the drill bit.
Draw a straight line down the center of the flat part of the strut, on the outside of the strut, for hole spacing layout. Use aluminum sheet as spacers to get the strut fitting to sit flat to the inner spacer and the inside of the strut flat surface. This will ensure the strut fitting is the same angle as the inner flat portion of the strut. Clamp it all together once fitted to the wing and fuselage. Look into the predrilled holes of the fitting (which are smaller than final size) and verify that you are in line with the center line mark. I drilled one side first, then installed the fitting into the strut using pins, and then finished drilling the other side from the existing holes. The last step was to final-drill all holes to the correct bolt size.