CHAPTER 15 - Riveting the Spar
To begin the riveting process, I assembled the spars with clecoes and cheap bolts wherever a bolt would be in the finished spar. I placed a board from the wing kit box across two saw horses and placed the spar to be riveted on its side on the board. The photos show me in the process of riveting the #4 rivets, which went without any problems.
Then came the #6 rivets. I had bought the modification for the c-frame tool from Avery, and set up a riveting area in my living room (concrete floor surfaced with carpet). When I began riveting, I found that the spar would tend to bounce, sometimes allowing the rivet to have a gap under the manufactured head. I also found that the spar strips tended to spread. After drilling out a few bad rivets, I came up with a procedure that worked for me.
Each rivet had to have the holes on either side of it secured with either a bolt or a rivet. This prevented the spar strips from spreading. I minimized the bounce by weighting the spar and using my free hand to hold it while using the hammer with the other hand. I still found it advisable to set the rivet with two medium blows, and check the manufactured head. If it was gapped, it could be set flush by using a large nut to drive the spar back to the rivet. After this, three heavy blows would finish the shop head, and the rivet would show no more tendency to gap.
It was tedious work, and my arm got very tired. If I had to do it again, I would arrange for a pneumatic squeezer. I would also advise beginners to start with the long rivets - the spar is heavier at that end and moves around less, making it actually easier to set the rivets.