Message-Id: <3.0.3.32.19981017020441.0072da8c@olsusa.com>
Date: Sat, 17 Oct 1998 02:04:41 -0400
To: lancair.list@olsusa.com
From: Marvin Kaye <marvkaye@olsusa.com>
Subject: Pre-preg coring tool
Mime-Version: 1.0

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          <<  Lancair Builders' Mail List  >>
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I received a post last night from Bill Gradwohl which outlined the
construction of a simple yet effective tool for the removal of core
material from pre-preg.  The letter which accompanied his photos is
included here, and it's also on the LML homepage in textfile form located
in the Attachments area
(http://www.olsusa.com/Users/Mkaye/maillist.html#attach) along with a
composite of several of the photos.  Enjoy!

>>>>>>>>>>

Date: Fri, 16 Oct 1998 22:55:46 -0500
From: "Bill Gradwohl" <Bill@YCC.COM>
To: marvkaye@olsusa.com
Subject: PrePreg coring tool

I don't know if anyone else would find the attached interesting, but it is
a tool to uniformly remove an 1/8" core from a piece of prepreg. The depth
is a matter of choice during tool construction. Coring is obviously
required prior to forming a cap strip or in general bonding prepreg pieces.

I found that removing the core material from prepreg prior to filling with
micro a hit an miss proposition. Using a miniature die grinder took too
long and didn't give a consistent depth. Sometimes a slight body movement
would cut a hole through the side of the piece I was working on. Other
times I would plunge to deep and end up needing too much micro (weight).

I put this tool together in about an hour. It makes coring quick and easy
and always to a consistent depth. It's just a piece of 2x4 with six hack
saw blades buried in it with one end of the blades flush with the 2x4
surface, and the other end raised up 1/8" above the surface. There is a
small fence to act as a guide to push the prepreg piece past the teeth on
the hacksaw blades. The distance between the fence and the hacksaw blades
is the thickness of one skin of the prepreg material. The hacksaw teeth
make quick work of the core material after a few passes. It will core out
standard 1/4" prepreg material and will also core out larger sizes by
flipping the piece you are working on.

I cut a kerf in to the 2x4 deep enough so that one end of the hacksaw
blades was flush with the surface. I just positioned the blades at the
other end so that 1/8" was above the surface. The width of the kerf is just
enough to squeeze the blades in. I poured in epoxy and waited for it to set
up. Then I mounted the fence with a few screws. I found that positioning
the hacksaw blades with the teeth pointing towards the raised end was
better than the other way.

I sent this to you because I'm not sure it's worth distributing. I'l let
you be the judge. If dimensions are needed. I'll supply them.

Bill Gradwohl
IV-P builder
N858B