Brief Description: Roll Bar - Drill roll bar to fuselage. Part 4.
Next we need to enlarge and dimple the forward roll bar skin holes. Open the skin holes to #19 and then dimple with a #8 dimple die. As you can see the squeezer does not make a very crisp dimple. Later when I take the skin off I’ll use the DRDT-2 to make a better crisper dimple.
Now that the dimple is made you can use the dimple as a guide to how deep the counter sink should be. At this point the forward holes in the 631C/D are only drilled to a #30. So I used a #30 counter sink bit. After the counter sink you open the hole to #21 and tap it to 8-32.
Why tap it instead of just drilling it out to #19 and putting a nut on the inside? Well, its because this hole perpendicular to the side skin, not the roll bar. A nut on the inside would not fit flush against the roll bar. Small point however.
