On Tue, 15 Jul 2003 19:33:56 +0000 (UTC),
(Tina Marie) wrote:


(I've got a certified airplane, so I hope you guys won't run me out
of here on a rail, but...)

I need to replace some of my fairings on my Tripacer. They're all simple,
mostly flat aluminum, some with one or two bends in them. I can form
them (I bought my SO a metal bender/shear/break for Christmas. He never
uses it, but I just love it) without too much trouble.

Here's my problem. After I make 'em, I have to attach them to the plane.
And this nearly always requires making holes in them - and no matter
what I do, the holes in the new fairing never line up with the holes on
the airframe. I don't know how to mark where to drill - if I hold it
up to the airframe, the airframe holes are behind the fairing and I can't
see them. Measuring works sometimes, but then I end up off by 1/16, and
it gets worse by the time I get all of them done.

There's got to be a magic trick to making the holes the right size, in
the right place, and I figured I'd be most likely to find it here.

Thanks!

Tina Marie
--
Life is like an analogy. http://www.tripacerdriver.com

Tina, sounds like you need a tool called a "hole finder". It's two
long spring steel straps that are welded together at one end. One
strap of the open end has a nub on one that has a hole in it. The nub
is sized to fit tightly into the hole you need to duplicate. The
other strap goes on the outside of the material and has a hardened nub
in it too that is the proper size for a 1/8" drill, or something like
that.

You fit the new fairing over the airframe, then slide the hole finder
in place and pop it into the hole you need to drill. Or, fit the hole
finder first, then insert the fairing between the piece that's lodged
in the hole you want to duplicate and the drill guide piece.

Once all is in place, drill through the drill guide. The drill will
center in the hole you want. Then you remove everything and step the
now created guide hole out to the size you need using a step drill or
whatever works for you.

Alternately, there are hole finders that have the nub that goes into
the hole you want to drill acurately, and a point on the strap that
goes on the outside. You put the guide into the hole, get the
fairing in place and then tap the outer strap with a hammer and the
point dimples right centered in the hole you want to drill. Then you
just have to drill on the dimple to the size you need.

Will this tool do the trick? I've seen them in Wicks, Aircraft Spruce
and Aircraft Tools. I have several sizes in my shop.

Corky Scott