I'm attempting to countersink the #8 screw hole for the nutplates holding the fuel tank. I'm having a great amount of difficulty getting a nice round countersink with no knife edge. The countersink tends to wander producing a square countersink and/or oblong hole. Any ideas on a method for getting a nice round countersink.
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Spar countersink problems
- Thread starter findane
- Start date
Turn the cutter slowly. I use low speed range on a dual speed cordless drill.
A knife edge is exceptable and expected in this instance (it is not possible to machine countersink deep enough for the dimples and not have it knife edged and the hole enlarged.
rapid_ascent
Well Known Member
The material is thin so the pilot doesn't have much material to ride on. Take a piece of scrap, clamp it under the flange, drill a through #40 hole. Then use that piece as a guide for the countersink pilot. I just used this same method on the fuse bulkhead platenuts. Works great. I actually just held the backup piece with my free hand without clamping it while doing the countersinks.
Not my idea BTW.
Not my idea BTW.
Av8torTom
Well Known Member
I second this...
