Drilled nutplates on W-423 joint plate. Dimpled #8 screws on tank skin - 3 hours

Using a nutplate jig I drilled the W-423 joint plate for the K1100-08 nutplates. I drew a line down the center of the #19 holes to provide a reference. I then used the jig to drill the holes.


Then, I dimpled them with the #8 screw dies. I was sure to use scotchbrite on the holes to be dimpled. The goal was to smooth out the hole as best as i could to mitigate the risk of cracks. After the hole was dimpled, I went over the hole with scotchbrite again to smooth the hole.

Everything turned out well. So I decided to give the tank skins a shot. I started off with the T-701/W-423 attachment holes. I repeated the process, but low and behold...I have 1 cracked dimple. Crap...
So I carried on. I completed the dimpling the spar attachment holes...About 1 hole in 10 is cracked. Crap! Not sure what to do now.