What we did: Tightened the nut on the axle and measured the angle from the gear leg to the flat of the nut where we wanted the cotter pin (forward and up), marking the flat. Then we removed the axle nut, counting the number of full revolutions. To be sure, we re-tightened and recounted a couple of times. Then we removed the wheel and put the nut back in place, counting and then adjusting until the marked flat was at the angle we had previously measured.
Now to the Bridgeport. Clamp the leg in place and position the tool so it goes cleanly through the hole in the nut. Then remove the nut and cut the hole in the gear leg. Use a file to clean up the threads, replace the nut, turn the leg over to position it to cut the other side, and repeat.
I used an angle drill on the -6A and went through several bit and got an ugly hole, taking a long time to get it done. The mill was cheaper and more accurate, but even a drill press would be better than hand drilling these. You can apply more pressure and control the speed better. It's even better if you have a cutting bit rather than a drill, because they are too long and can wander slightly.
Another thing, I notice that there is potential interference between the cotter pin and the valve stem on my RV-10 mains. I will be counter-sinking the holes in the nut slightly to allow the cotter pin to fit closer; we also enlarged the cotter pin holes very slightly to allow an easy slide fit (but not loose).
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
EAA Technical Counselor #5357