VS Spar, Countersink or Dimple?

[Roy25101]

I assume the answer is in the details but it is not readily apparent. Should the holes on the forward and aft VS spars be dimpled or countersunk? These are the holes the skin will attach to. The metal sure seems thin to countersink but It seems like that many dimples is going to change the shape of the spars. Thanks in advance..

[tgmillso]

I am building a -7 but the VS is the same. These spars should be dimpled. So long as you don't over dimple, you will not stretch the material and induce any bows. Only countersink 0.040" or thicker material, infact many times 0.040" can also be dimpled, but any thicker and the material will distort.
Cheers,
Tom.

[johnbright]

Here are a couple pages from the construction manual circa 1997... I circled some paragraphs on pages 5-2 and 5-6 having to do with dimpling.