Date: Mon, 20 Dec 2004 12:10:52 -0800
From: Anthony Thompson
<thompson@...>
Subject: Re: lost styrene & wax casting

Larry Jackman sez:

I must correct this one statement. There is always

shrinking in brass

investment casting. It is 1 1/2%. Melted brass

always shrinks I cast

brass for 20 years and it always shrinks

I remember talking to Stan Schwedler up in Phoenix
some time ago (he and his brother Sheldon run Coronado
Scale Models) and he explained the process like this.
You built a master 8% oversize. There is 4% shrinkage
per generation and you ran parts in two
generations...one to build up enough parts to build up
a sprue, and a second to cast the sprue. So you build
your masters 8% (two times 4%) oversize to compensate.

=====
Bill Daniels
Tucson, AZ



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