Rib locations

Hi Everyone

Sorry for so many questions, but this one has us stumped.

We have cut the 0.063 3/4 x 3/4 angles that are used to attach many of the ribs to the spar. We have then marked the rib stations onto the spar. This as we do not have the premade spars.

When we then put the angles at theses stations, the holes that will have to be drilled through the angle to pic up the 3/16 pre drilled holes in the spar are either on one extreme side of the angle or the other, which either gives us no edge distance or no space to put a bolt through.

Our plan was to just drill the holes through the middle of the angle but how do we then know that this will place the ribs in the right place to pick up the predrilled holes in the wing skin? Should we rather measure the predrilled skin holes now and use those measurements to place the angles and ribs?

How did you guys make sure that once your ribs were placed that they would align with the holes in the predrilled wing skin?

I hope this makes sense and would really as always appreciate any help

Thank you so much

I clamped the predrilled skin on the spar caps so I could put a mark with a sharpie through the first holer on the spar cap. Then used a square to draw a line on the spar cap to indicate where the center of the rib should be. THen clampd the angle peice to the ribs and checked the location so that I could a) get the skin rivit line as close to center as possible while b) getting proper edge distance for the bolt holes on the angles. IIRC I had riveted the angles to the ribs before I did this.

By shifting things one way or the oehr I was able to get enough edge distance on both the angles and the rib flanges. But frankly the angle to spar holes don't line up in the center anywhere near exactly.

In the old old days before predrilled skins you just put the skin holes where they needed to be.

Thank you

Thank you so much for the great reply Richard, that sounds like the best way to get things all accurate and lined up