Now that all the nut plates are installed, it is time to countersink for the big ol #8 screw/dimple from the tank skin. This was pretty straightforward as the #30 cutter fit well In the nut plate and kept nice concentric holes, just like vans said. It's almost like they have done this before ;). The wing access panel nutplates also got countersunk after all the #8's were done. Gosh I think that was like 400 freaking holes to countersink, sheesh. Once that was complete, time to spot prime all the open metal countersunk holes. I made a little “jig” to spray primer into the holes ( just a slightly bigger hole cut in a piece of small cardboard with tape on it so the cardboard didn't get soggy from the primer). Worked well and made the job speedy. Ohhh, and to clean/roughen the holes I came up with a little tool to make it speedy as well. I have a video, but it won't load on this site sadly, but I took a screen shot of the video. It's a hex drill extension bit with some maroon scotch bright jammed into the end. Worked grrrrreat! I also deburred, upsized and dimpled the wing access panels.