I countersunk the holes in the aileron counterbalance pipes then used those as the female component to dimple the leading edge skins. I broke off a piece of Boelube and rubbed it into each hole before I began to drill. I rested the pipe on the edge of a 2X4 and gave it a couple of whacks with the male die installed in the shaft that came with my pneumatic squeezer. This worked out well. Then I made a shallow dimple on all the holes of the spars, which I will finish off with a countersink. This system worked fine on the aft wing spars and the spar thickness is the same on the ailerons.
