In article ,
brian whatcott wrote:

Orval Fairbairn wrote:

NEVER countersink .032 aluminum in hopes of a good structure. ALWAYS
dimple anything up to .040 for AN-3 rivets.


:-)

I could almost see the dollar bills floating by, as I read that!

Brian W

Yes. Although the depth of AN3-426 rivet heads is exactly 0.032 in., it
leaves zero errors in countersinking. Also, it will not take the shear
stresses that a dimpled skin will take.

A friend of mine bought an RV-4 a number of years ago. As he liked to
put it, "There were only four things wrong with it: Structure, Controls,
Systems and Electrical."

One of the problems was that the original builder had countersunk,
rather than dimpled, all of the rivets in the fuel tanks.

Result: lots of leaks. I ended up shepherding him through building a
pair of brand-new wet cell tanks.

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