Dimpling and Countersinking

 
 
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The Sonex uses mostly protruding head (dome head) pulled rivets, but certain areas in the plane use flush rivets. The first time I dealt with this was on the spar carry through box. I purchased a pop rivet dimple die from ATS (Wicks has them also, PN: 5102D-3/32). It is a 100 degree 3/32" die set. They also sell 1/8" dies, but the hole comes out a little oversized when the metal stretches.
A word of caution here. The nail that acts as a stem will break if you use too much pressure (I know!). 25 psi to my rivet gun is about right to make nice crisp dimples, and still be easy on the nail. Even so, the cheap nails I am using break after 10-20 pulls.
You can see the grooves in the nail from the puller jaws.
Next, a #30 countersink cutter is threaded into my hex extension from my debur tool and set in the drill press. After experimenting with the stop nut on the press, I finally decided it was easier to just do it my hand. It didn't take long the be able to quickly tell if the countersink was the right depth or not.
Some areas the rivet hole is very close to a flange, and the dimple die could not reach it properly. To solve this, I bought another dimple die and ground down one side.
This was quick and easy using my angle grinder.
Less than a minute on the grinder produced the needed effect.

 

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Updated: 21 Apr 05