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  <title>Shapeways: Bring your creativity to life in 3D</title>
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<item rdf:about="http://www.shapeways.com/forum/index.php?t=rview&amp;goto=50798&amp;th=10084#msg_50798">
  <title>Best material for a master to be investment cast</title>
  <link>http://www.shapeways.com/forum/index.php?t=rview&amp;goto=50798&amp;th=10084#msg_50798</link>
  <description><![CDATA[I am starting a project  to make a steel investment cast part.  About 2&quot; x 1&quot; x 0.5&quot;.<br />
<br />
I'm thinking in the few hundred parts range, it will end up fitting in an assembly of mechanical parts in a machine, so here are my initial thoughts.<br />
<br />
1.  Shapeways makes a master.<br />
2.  I build a form and cast it in RTV silicone.  <br />
3.  I got a little wax injection molder, so I shoot waxes<br />
4.  I send them off to a foundary to get cast in tool steel<br />
5.  I finish machine (reaming a pivot hole, and touching a surface grinder to clean up one edge).<br />
6.  Send out for heat treat.<br />
<br />
So, my questions I can think of are:<br />
<br />
1.  What material is best for my master?  Presumably I want the best surface finish, though I could clean it up by hand.<br />
2.  Shrinkage.  I assume 4%, though I would not apply shrinkage to my pivot hole, so it is 4% undersized, leaving enough meat for the reamer to clean up.<br />
<br />
What am I missing?]]></description>
  <dc:subject></dc:subject>
  <dc:creator>ShootingSight</dc:creator>
  <dc:date>2012-07-04T14:02:45-00:00</dc:date>
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