I started the night by riveting those bearing brackets for the control support that required double-flush rivets. The pneumatic squeezer did an impressive job on those. The shop head is almost completely flush. Less than 1/32" is protruding, I hope that's good enough. This shows the shop side.
Then I riveted the doublers on and this is where I made my first mistake without even noticing until now. The manuals have a bold note saying that you should put the manufactured head of the rivet on the bulkhead whenever possible. Well, it was possible here but I chose not to do it because it looked prettier. Grmbl!
When I found out I immediately checked with Dave's blog and saw that he did the same. As he didn't say anything about it he might not even have seen the note. More importantly though, it appears that he didn't run into an issue with this either, so I am going to leave them in. The reason for this note is clear to me. The bulkhead is relatively thin and the forces to build the shop head are quite high. So if all of the shop heads are on the bulkhead then the bulkhead will bend slightly and this will later be a struggle to put the skins on which will very likely only be possible by applying a lot of static force. Not good. I'll keep an eye on the shape of the bulkhead. If it appears bent before putting it on the ribs, I'll drill those rivets out and put them in from the other side.
When finishing the bearing bracket I made another mistake. I quickly put the pull rivets in and pulled them all. Then I thought - Oops - those brackets are quite thick! I wonder if the LP4-3 are long enough... maybe I needed LP4-4... Sure enough!
I drilled them all out and replaced them with the longer version. Getting them out was unusually hard as the rivet had almost disappeared in the hole when the shop head was built. And so it wasn't enough to just drill the head off, I really had to drill the whole thing out. Fortunately, I did it straight and no hole was elongated or widened.
Fitting the stub spar receptacles was not necessary, a little bit of Scotchbrite polishing was enough. Then I riveted those on. No mistakes there. Yay!
When riveting the flanges of the doublers to connect them I followed the option Van's made in the manual and squeezed them with two flat head dies. The simple reason was that I don't have a cupped die for AD3 rivets. We haven't used this size with cupped heads in the whole build until now and I don't have dies for that in my toolkit. Dave was wondering why Van's was so generous and he didn't understand what that option would have given him. Well, obviously he had those dies that are not in the list of recommended tools, I suppose.
Finally, I riveted the bearing brackets to the bulkhead. Initially on the wrong side. Sure! Well, after drilling out another 12 rivets I fixed that and also squeezed the nutplates on, the ones with the screw hole on one side.
The manual suggests to first rivet the brackets to the bulkhead and then to rivet the nutplates on the sloped flange. I didn't follow that order as handling the bulkhead with one hand while squeezing the rivet with the other is awkward and the process is way easier when the part to handle is light and small. So I put the symmetric nutplates on first.
I'm on page 21-12 now and the next step was to rivet a two digit number of nutplates onto the bulkhead. That's when I seriously felt like I wanted to call it a day ...
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