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Reduced diameter countersink cutter for gear intersection fairings

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iamtheari

Well Known Member
This might be an oversight in the otherwise very nice tool set I bought when I started building my RV-14 back in 2018. I don't believe I ended up with a reduced-diameter #40 pilot countersink cutter, which is specified for the first and only time in the plans in the section on the landing gear fairings. You use it for the countersinks on the landing gear intersection fairings, which are cut perpendicular to the underlying pieces (wheel fairings, fuselage, and lower cowl) but not parallel to the surface you're cutting.

Am I setting myself up for disaster if I attempt to do these countersinks with a normal diameter tool? I can order a new tool but would rather be flying again this weekend than waiting for the slow boat from China to show up with a countersink.
 
RV7A Flyer said:
You mean the countersink cutter *cage*?
Click to expand...
Negative. The RV-14 plans call to use a reduced-diameter countersink cutter with a #40 pilot to countersink the holes for the #6 (and one #8) AN507 screws that attach the landing gear intersection fairings to the wheel pants and to the fuselage/cowl. No cage is used. The reason is because the countersinks are done at an angle not parallel with the surface of the intersection fairings, so the reduced diameter cutter will cut less unnecessary material than a normal diameter cutter.

Here's an example of one:

I believe that Isham now includes one like this in their RV-14 toolkit, but did not when I ordered my kit back in 2018.

I think I'll just finish the fairings without countersinking and accept the loss of 1/4 knot or so while awaiting the tool. I have grounded myself for a month to finish the gear fairings and I miss flying. :)
 
I'm not quite there yet, but would this work? It's made by Perma-Grit, you can order direct from Great Britain or Wicks Aircraft sometimes has them in stock. It's my go-to for countersinking the canopy and fiberglass parts. It doesn't chatter even if the hole is larger than the pilot.

1719880117398.jpeg
 
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