The Murphy Builders Site

Craig,
If you try to flatten the creases the holes will move apart from each
other in the direction perpendicular to the crease. That will move them
out of alignment with the ribs.

If you elect a new skin there are several ways to transfer the holes. In
any case cleco as you go, start at the leading edge, and do one side and
then the other back to the rear spar. Be sure to get a proper start at
the leading edge with the first holes correct as you can't recover if
wrong.

Method #1
Use a long strap hole finder of the type that puts a pin in the existing
hole and allows a spot drill start on the new skin. Do not drill into the
hole finder. After spotting you can remove the hole finder and drill
through.

Method #2
This can be used where the hole finder reach is insufficient. There are
small "buttons" with a #30 (or #40) pin on one side and a short but sharp
point on the other. The pin is inserted in the hole to be copied, new
sheet positioned on top and a LIGHT tap on the new skin will leave a drill
place mark on the under side of the new skin which is then drilled out.
It might be useful to put some layout blue on the new skin to show up
drill locations better. Support under the rib during tapping would be
good if accessible.

Method #3
To replace #3, you might be able to back drill the holes nearest the
leading edge with a small right angle drill.

In any case, good luck. We have all remade parts, in some cases several
times although those persons shall remain anonymous.
Ralph Baker



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From: snowyrvr@mtaonline.net
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] fin problems
Date: Mon, 10 Dec 2007 22:34:54 -0900

Thanks Jesse,
That's a good idea I hadn't thought of. Not sure how to figure out exactly
what the dimensions are, though; the only clue I have is the skins-and they
aren't flat. One suggestion was to put the creases in a brake and make them
less prominent. That and your tip might do the trick. Being so new at this
I'm very tempted to just order new ones. On the other hand, I wonder if MAM
could give me the exact dimensions.



-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Jesse
Jenks
Sent: Monday, December 10, 2007 7:51 PM
To: Builders list
Subject: [rebel-builders] fin problems


Craig,
I just looked at the pictures of your fin that you posted, and it reminded
me that MAM wants you to layout and build the framework on top of one skin.
I found this to be a really bad idea when I was building the tailfeathers.
Instead, I drew out where the framework should go on my work table and built
it flat on the table I used small pieces of wood screwed right to the table
as clamps and jigs to hold everything in place while drilling all the
brackets. Worked great for me. I can see how you got in trouble trying to
build on top of that potato chip of a skin. Just build it flat on the table.
Jesse

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