Holy moly, 150 or so nut plates have to be attached to the main wing spar. Each one requires 3 machine countersink holes. One hole for the bolt going through the nut plate and 2 counter suck holes for the nut plate attach points.
The larger hole was a major pain because the finished inner diameter of the hole is larger then the couter sink pileot.
I used aluminum bar clamped under the flange to capture the pilot to keep the cutter centered. I didn't use the Vans method of using a nut plate to capure the pilot.
