Roll Bar Riveting

The roll bar assembly has been labor intensive so far. It seems overly complicated but no doubt the engineers at Van's had their reasons for designing it the way they did. I'm sure it was a compromise between weight and strength and this was the best way to handle those opposing goals. More grunt work today deburring everything after disassembly after match drilling all the #30 holes. Then more grunt work machine countersinking all the holes along the forward outside perimeter and the two window straps. Machine countersinking is used throughout the kit but is a chore I dislike. It's used when flush riveting is required but the material being riveted is too thick to dimple. But usually the material being countersunk is still pretty thin so great care must be used when using the adjustable countersink cage or it will cut too deep and enlarge your rivet hole by cutting all the way through to the backside. It's take multiple attempts and adjustments to get the cage set up just right where it will consistently cut deep enough so the rivet will not sit proud but not so deep that you've gone all the way through. The margin can be just a few thousandths of an inch. And then there's just a lot of holes to countersink. I finally got to a point where I could rivet the 2 straps into the forward roll bar assembly. That all went smooth. The lower strap used AN470 rivets and the upper used AN426 flush rivets. My careful countersinking was rewarded with nice flush rivets around the entire upper perimeter. I'd hoped to finish the roll bar assembly today but its going to have to wait until next week. Gotta work the next 3 days. Additionally, my new corrosion free and correctly primed QB wings are arriving next week. They picked up the old defective ones Aug 30.