Rivet shop head lesson

[bestbearhawk1231]

Hi guys, I went to a fly in today and the A&P college students were putting on the breakfast. Having heard that the instructors were EAA friendly, I shoe-horned my mostly completed flap in to my car and headed down there. After clean up I had the instructor and students look it over to make sure I was on the right track..I had asked him to treat it as if I was a student and he was grading it. Long story short, he was impressed by most of it and stated that I was very consistant. He also pointed out that every shop head was too low and indicated that the rivet was about 1/2 size too short and needed to be drilled out and riveted again. He asked me if I had gauges and how I used them. I had been using them correctly so I really looked like a shmuck. Well, after a 2 hour drive back to the shop I realized what I had done. When I checked the rivet length, I placed the guage flat on the part and didn't account for the dimple. The dimple was about 1/2 D so the rivets ended up short. On the other guage, the shop head wasn't filling the round hole so I adjusted the squeeze until it filled the hole which in turn over drove the rivet. That should have raised a red flag at the time but it didn't so now I get to drill out a bunch of rivets.

Morel of the story...pay attention to what you are doing and take the dimple into concentration when selecting rivet sizes and bucking them. I am glad I had the chance to have someone look them over before I got much farther.