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36465Re: lost foam core problems

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  • twright76108
    Aug 1, 2006
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      Kerry,
      It looks like your core failed because the walls of your gypsum
      heated, broke through and metal filled the void. I think you have a
      couple
      of options. (A)Cast the piece solid and machine the void or (B)use a
      solid
      core piece such as wood, steel, or resin bond sand to fill that
      space. Something needs to be there to provide more insulation between
      your side walls. Just my opinion, I'm sure others will have theirs.

      good luck,
      Tony

      --- In hobbicast@yahoogroups.com, "lord_kerry" <lord_kerry@...> wrote:
      >
      > Ok, did my first casting to a lostfoam pattern saturday.
      >
      > Cut out the foam, glued it together with low temp hot glue, pasted
      it
      > over with a pancake batter thick slurry of drywall joint compound,
      let
      > it dry for a day, cut off the top of the sprue and put the pattern
      in
      > a barrel of dry sand using the air from bottom method, jogged the
      sand
      > to make sure it was well settled, put a head preassure pipe above
      the
      > sprue, heated my aluminum, skimmed the dross, poured into head
      > preassure pipe, as it smoked and bubled I added more alluminum
      keeping
      > the pipe full. Let it cool and pulled the part from the sand rinsed.
      >
      > If you look in the photo file Kerry's Castings you will see that
      the
      > outside looks beautiful, my problem is the core, (which is
      currently
      > the area I was most concerned with for this piece) any thoughts,
      > Ideas, opinions?
      >
      > Help please
      >
      > Kerry
      >
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