Just drilled my canopy holes three weeks ago. Used a 1/8" Plexi bit, then a plain ol' #30 countersink, then enlarged with a 5/32 Plexi bit. No troubles at all. BTW, I tried the standard #30 countersink a lot on scrap pieces before I followed friends' advice to do so. They told me not to fret over the pricey ceramic/stone countersinks. At least 4 local builder/friends had used a standard #30 countersink with no trouble.
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Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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