Today I pulled the my first rivets! The Sonex is built from 6061 alloy which doesn’t need to be primed for corrosion protection, however the blind rivets used are made from stainless steel which raises the question of galvanic corrosion. Sonex say they have never seen a problem with galvanic corrosion but because I live by the coast I decided to add extra protection and use Duralac, a jointing compound that is designed to prevent galvanic corrosion, on each rivet. This product contains Barium Chromate (so wear gloves) and is popular for riveting stainless fittings to aluminium boat masts. Its also been recommended by a number of other Sonex builders.
This builder has posted some tests that show it is effective: http://onex-svingenb.blogspot.com/2014/07/corrosion-tests.html
I just put a thin coat on each rivet before inserting. These rivets heads are going to the polished so I tired to avoid getting too much around the head but in the end it was easier to just wipe off the excess with some mineral spirits than try to be too precise applying it.
Some rivets on this part are very close to the edge, too close to get the pneumatic rivet gun in there. I’ve seen that people bent the stem so you can get the gun in at an angle and then used a wedge of material to help the rivet set properly. One half of my simple dimple die seemed like it would do a good job as a wedge but about one in three rivets would set with the head not flush with the part. Next steps are to improve my tools for riveting close to the edge, drill out the bad rivets and finsh riveting the spar.
Time: 2 hours