More work on wing folding area: Continued working on the ribs and backer plates for the folding area. Had trouble determining the proper counter sink bit to use with the CCC-42 / 44 rivets. I initially used a standard 100 degree 1/8" CS at my home shop to CS the backer ribs. I had forgot to bring home some CCC-42 rivets to test the CS fit so I used some 1/8" blind flush rivets I had left over from my RV9 build. I CS'ed all 4 backer ribs so the RV blind rivets fit well but when I got to the hangar this AM and tried the fit with a CCC-42 rivet I discoved they did not fit at all. Apparently the RV rivets are 100 degree heads where the CCC rivets are 120 degrees. Also the CCC rivets have a thick edge rather than a sharp edge as did the RV rivets.
So, I ran over to Cleaveland tool company (about 1/4 mile away) and bought a 120 degree CS bit. I spent quite a bit of time finding the correct depth to set the microstop CS tool. To get the depth correct, the diameter of the CS ends up wider than the head of the CCC rivet. This is because the edge of the CCC rivet head is not a sharp edge so you end up with a small valley around the edge of the rivet. Anyway, all the backer ribs are now CS'ed and ready to be riveted.
Cleaveland tool is working on a new dimple die for us Sonex builders that is supposed to improve the fit. Currently if you use a regular 120 degree 1/8" dimple die, the rivet appears to fit somewhat below the surface of the skin. Apparently some builders have been drilling the rivet hole to #40 and using a #40 dimple die, then reaming the #40 hole out to #30. This creates a very good fit but requires an extra step. The new dimple die should basically be a #40 dimple with a #30 pilot, at least I think that is what they said. Anyway, I hope to test the new dimple die next week.
