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Date: Thu, 02 Sep 2004 08:11:52 -0600
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
From: Bill Dube <bdube@al.noaa.gov>
Subject: Re: [FlyRotary] Re: foam-sicle (new ducts)
In-Reply-To: <list-389782@logan.com>
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I've built a bunch of stuff with composites. For large objects that will 
retain the foam inside, the moldless construction is a very practical 
option. Conversely, for hollow objects of any manageable size, I have found 
that it is best to go the extra step to make a mold. The finished part 
comes out so much better. You can also make duplicates.

	In your situation you would coat the plugs you have made with a couple of 
thin layers of epoxy and cloth. You then finish the surface to look like 
the final part. (I like to put a coat of automotive clear coat on last.) If 
needed, make some sort of parting line (flange) with Formica sheet. Wax it 
up. Spray on some PVA.

http://www.fibreglast.com/showproducts-category-Mold+Releases-23.html

	Next, spray on (or roll on) gel coat. Then build the mold using chop 
and  polyester resin. Pop off the mold with compressed air.