[Rivethead]

I'm about to drill a new hole in my spar carry through. I don't much like doing it but I'm left with no other options that I'm willing to consider any further. Since I really don't want to screw this up I'm considering the best location to place the new hole and find that I'm confused at this point by the term "Hole edge distance". Does 2X hole diameter refer to center to center or is it center to edge of the adjacent hole? This is going to be a 3/4" hole and of course at that size wont be for a rivet. I think Vans construction manual covers this but I haven't been able to find it.

 

[apkp777]

Edge distance is from the center of the hole to the edge. In the olden days of McDonnell Douglas they used the term Edge Margin which was from the edge of the hole to the edge. Now everyone is using E.D. which ideally is no less than 2x the rivet diameter. 2.5-4D is preferred.

 

[JonJay]

what model and what are you doing this for?

Edge distance as mentioned is for holes for fasteners. As you can imagine, a lightening hole would never meet this requirement. If your drilling through the spar web material to pass wires or cables through, that is a different story. Honestly, I dont know what the "rules" are for this but I bet someone here does.