I finally got to work on the project again. Today I finished countersinking the T-407 platenut attach holes. Then I moved on to get the tank ready for sealant. I drilled and countersunk the holes for the fuel cap flange and also drilled the holes for the VA-112 drain flange on the bottom of the skin.
Then it was time for deburring. I deburred all the holes in all the ribs and then dimpled the ones for the skin attachment. I then deburred all the holes in the skin and used the C frame to dimple all of those holes.