Since I had a reject front center spar web, I decided to prep it (and scrap spar caps) to simulate the actual riveting job I will be doing. I quickly measured and drilled the top cap for AN-470-AD-5-9 rivets and the bottom cap for AN-470-AD-6-8. This is because I have drilled out my actual bottom front cap and web to rivet size 6 because of some slightly elongated holes. Problem solved, but it does introduce another size of rivet with different riveting characteristics. You may know that there is not a 6-8 rivet (to my knowledge), so I purchased 6-14 rivets and a rivet cutter. 6-8 is the length that I found compresses to form the correct size and shape of shop head. After drilling and deburring, I put in about 10 rivets of each type and experienced no buckling of the web whatsoever. I also got a better feel for starting the rivets and believe I can do the job now, if I will take my time with each rivet to start it with all the parts fully compressed and flat.
