I used my hand deburring tool with the countersinking bit to countersink all of the rivet holes for the access panel nutplates. I clecoed the standard jig plate behind the skin in order to have enough material to guide the pilot of the countersinking bit. I had to use the hand deburring tool rather than the microstop countersink because of the recess pressed into the skin for the access panel cover. Once all of the rivet holes were countersunk and everything was deburred, I riveted the nutplates to the skin.
Countersinking outboard bottom skin for nutplates for access
