I have seen complaints about the difficulty of match drilling through the aluminum flaperon skins into the steel counter-balance tube. The bit tends to travel over the hard steel and elongate the hole in the aluminum nose skin. The following technique seemed to work pretty well for me:
1. Use a spring-loaded center punch to put a small crater in the middle of the hole in the nose skin (into the steel).
2. Then use a small bit (1/16") and drill through the steel. The small bit seems to find the crater and stay in it better than a #30 bit.
3. Then drill through the hole again with a #40 bit.
4. Then drill through the hole again with the final #30 bit.
The trick, I think, is using the very small bit to drill the first pilot hole through the steel tube because it stays in the crater made with the center punch.
1. Use a spring-loaded center punch to put a small crater in the middle of the hole in the nose skin (into the steel).
2. Then use a small bit (1/16") and drill through the steel. The small bit seems to find the crater and stay in it better than a #30 bit.
3. Then drill through the hole again with a #40 bit.
4. Then drill through the hole again with the final #30 bit.
The trick, I think, is using the very small bit to drill the first pilot hole through the steel tube because it stays in the crater made with the center punch.