I setup my drill press with the countersink cage and a #40 cutter so that I could countersink all the 3/32 holes in the trailing edge where the rudder skins will get riveted to the trailing edge. The trailing edge is tapered and the plans call for the countersinking to be done perpedicular to the face of the trailing edge. I accomplished this by putting the left over peice of the trailing edge under the trailing edge that will be countersunk. This smaller support piece was oriented in the opposite direction to the trailing edge. The result was the face of the trailing edge was perpendicular to the countersink cage.
It worked great. The countersunk holes were all consistent and the depth was just right to accept the dimple in the skins. The holes in both sides of the trailing edge were countersunk in this manner.
I assume the larger holes in the trailing edge are lightening holes. A nice, light airplane is the goal!
