Then I phoned my friend Martin (he’s building a -7) to hear his opinion on that issue. He said that he had a similar problem while building his tanks. He then suggested making sure the holes are thoroughly clean before inserting a rivet in the hole. That same evening, I’ve undertaken a quick search on VAF’s forum to realize that many others have had a similar issue. I then took the decision to try cleaning the hole using the deburring hand tool mounted with a #40 countersink bit. It worked. The end result is a rivet that sits nicely flat on the bottom of the hole.
In fact, I believe that the “interference” comes from residues of tank sealant being dragged out by the mandibles of the cleco that was resting in tank sealant. The rivet hole on the far right in Picture #2 is a very good example of this interference. Looking at Picture #3, it is obvious that if that rivet was to be set as it is, it would surely be defective.
It doesnMt show like that but these rivets are standing proud on one side
See the remains of partly cured sealant in the right hole
Not being set yet, the third rivet (on right) is showing evidence of misalingment
