I didn't get much done tonight...had a pounding headache by the time I got home from work. So I decided to just do a few dimples. My friend, Greg, has the skinny bar with the countersink in it which I used for dimpling the aftmost holes of my elevator ribs, so I decided to try a different approach. I wasn't completely happy with the results of using a male dimple die and a countersunk hole to do the dimpling anyway. Here's an example of one of the ribs that needed dimpled.

I got out my pop-rivet dimple die set. I had tried using these with the pop rivet tool, but the shank always seemed to break before forming a nice, crisp dimple. This time I'm going to use the female half of the set in my rivet squeezer. I applied a little piece of tape to hold it in place while getting setup.

Here's the female pop rivet die taped over one of the holes.

I clamped the pneumatic squeezer in the vise so I wouldn't have trouble holding the whole apparatus steady.

Then carefully wedged the nose of the squeezer yoke along with the pop rivet die into the rib.

The holes came out great! The only thing that would've made this better is if I had a "tank die" pop rivet dimple set. I've been using the tank dies for all the skeleton structure. I guess I'll just have to be satisfied with having these aftmost holes dimpled with regular sized dimples.

Note that for the flap ribs, I needed to use my no-hole yoke with a few washers behind it (to keep the pilot of the male dimple die from protruding through) in order to fit between the flanges of the aftmost holes. In that case, I also had to stack a few washers between the male die and the squeezer ram. Apparently the opening of the no-hole yoke is somewhat larger than the regular yoke.