Brief Description: Drill for nutplates, machine c/s wing root
I used a #8 nutplate jig to drill holes for nutplate attachments in the wing root—did upper and lower holes from the main spar aft. Then I used a deburr tool to put a small countersink in the skins for use with NAS 1097 rivets. The plans show to rivet on the nutplates on the top of the wing skin and then use a #40 piloted countersink centered in the nutplate to machine countersink the 3 layers of skins. Well, a #40 pilot still doesn’t completely fill the nutplate hole thus allowing for some wobble of the countersink. Instead of Van’s method, I used a piece of 1/8” aluminum and drilled a #19 hole in it, then used my nutplate jig to drill #40 holes like I was going to attach a nutplate. I clamped this guide to the inside of the wing root. Then, I inserted some NAS 1097 rivets thru the skin into the guide and clamped the guide to the wing root flange using a couple of miniature vice grips. Then I machine c/s the hole—came out perfect—no chatter at all. This method seems slow and tedious, but sure makes a nice c/s in the skin. I dimpled a piece of scrap and screwed it to the wing—this is going to work out nicely.