This is a compilation of several sessions over the last week. I worked each of the last 5 evenings back riveting the rows of rivets connecting the side and bottom skins, and the bottom most rivets between the side skins and forward two bulkheads.
I decided to back-rivet in part because it gives a better finish, but also because these rivets are impossible to do solo any other way. In theory, back-riveting is easy; lay the part flat on a slab of steel with a rivet inserted in the hole, then put the rivet gun on the shop head and set it. These rivets were tricky because of the curvature of the skin. By using cushions and pillows, and small lengths of timber, I was able to roll the fuselage on it’s side to get the correct angle.
I started with the forward right side and worked aft. I was fairly successful just guessing the angle by closely inspecting where the rivet head appeared to be contacting the plate. Once I had it set up, I could quickly set around 10 rivets before needing to move the plate and re-calibrate.
Everything went well, until I got to the aft most section. I was most concerned about the aft-most rivet, which passes through three parts; the side skin, the aft bottom skin, and a bulkhead flange. By putting a little weight on the fuse, and keeping the angle shallow, I ended up with a great result. But as I worked forward, I didn’t roll the fuse enough and ended up setting 8 rivets with too shallow of an angle. Part of the rivet head on these rivets protruded from the skin, and needed to be replaced.
I spent an evening removing these 8 rivets, most came out easy but two of them gave me trouble.
I didn’t enlarge any holes, so I redid these eight the next night with the same size 3-3.5 rivets. This time, I went slowly and used my iPhone’s digital level to record the angles. 10 degrees of roll for the bottom/side skins worked great, and about 26 degrees for the next holes up on the bulkheads seemed about right.
Eventually the right hand side came out looking great. Then it was on to the left hand side.
After some experimenting, I found that the angle at which the gun contacts the rivet head is critical for getting a good looking head. Any slight angle, and the heads don’t set straight. A had a few rivets that weren’t quite level on the shop head, but I left them in and moved on. For the most part though, the heads looked great.
I had no trouble with the left hand side, I just used the digital level to ensure I was getting as close to 10 degrees as possible, and 26 on the couple of bulkhead rivets. I worked from the aft end forward, and was done in about 45 minutes. Most of the time was spent adjusting the angle of the fuselage, and checking that the hull was flat against the back riveting plate.
