Brief Description: Final drilling procedure chosen
Two principles need to be regarded when drilling assemblies such as the spars. (1) match drill everything, and (2) back drill anything that can't be match drilled the first time. Getting everything to line up precisely while drilling through multiple layers with different thicknesses is a bit of a challenge. Add to that the spar cap angles which stick out on the back side (the bottom when drilling) and things have to follow a precise order. Here is the order I have decided on. STEP ONE: With everything in place except the spar cap angles, cleco every 6th to 8th hole and match drill all layers from the top (front). STEP TWO: Move the stack to the edge of the table, and add the bottom spar cap angle, clecoing it to the set. Carefully back drill the bottom spar cap angle by hand. STEP THREE: Remove the bottom spar cap angle, insert solid rivets in the existing holes, remove the clecoes and match drill the remaining holes that were formerly clecoed. STEP FOUR: Add the bottom spar cap angle, aligning it using solid rivets and back drill the remaining holes. Repeat steps two through four for the top spar cap angles and you're done.