I could use some simple confirmation of the proper depth for this countersink.
I am checking my QB wings and found that the nutplates on the inboard top edge have not been attached. These take a #8 nutplates (all but 1 a double wing nutplate).
I drilled, deburred and countersunk the #40 rivet holes. I then drilled and deburred the #19 screw holes. I dimpled the most rear one per plans. The remaining get countersunk.
Using some scrap 1/8 bar, I countersunk the bar until the #8 screw sat flush. I then adjusted the countersink cage so the screw would then site 4-5 thousands deep as it states in section 5 of the plans. Using my test dimple sample, I found that that it did not nest nearly as well I wanted or expected. I tried fastening it together and did not like the results. It wasn't until I got to a .018 recess of the screw in the substructure that the two pieces nested and attached to any degree of acceptability. Is this normal for #8 dimple to countersink. It goes against VANS instructions. Pictures attached.
I realize the geometry of a dimple and countersink are different and a perfect nest will not be accomplished but I do not like the results using the VANS rules.
My test dimple
The two different countersinks One per VANs suggestions
One deeper but nests and fastens better, cleaner with minimum distortion
The shallower dimple (VANS specs) with fastened sample dimple. Notice how the pieces diverge
The deeper countersink with still some divergence but much more acceptable
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Tail Kit delivered 6-2013
Started building April 2014
QB Wing and Fuse Delivered December 2015
Finishing QB wings on September 2018
Dues Paid through 2018