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Re: [hobbicast] pattern smoothness

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  • Daniel C Postellon
    Slick is good, but I have pulled sand castings using unpainted expanded polystyrene patterns. If you have some draft, it is not real critical, but is
    Message 1 of 4 , Aug 6, 2007
      Slick is good, but I have pulled sand castings using unpainted "expanded
      polystyrene" patterns. If you have some draft, it is not real critical, but
      is desirable.

      > I just spent the weekend making some casting patterns and I was wondering just how smooth they need to be. I sprayed them with Krylon Triple Thick clear glaze today and they look pretty smooth, except for the edges, which are pretty smooth to start with, but no nearly as slick as the other surfaces. So I was just wondering, just how slick and shiny do casting patterns need to be in order to work really well?
      >
      > Chris
      >
      >
      >
      > Chris Reynolds
      >
      > http://builderofstuff.com
      >
      > "Computers are like air conditioners - They can't do their job properly if you open windows."
      >
      > [Non-text portions of this message have been removed]
      >
    • Chris Reynolds
      thanks for the input everyone. Rupert Wenig wrote: Hello Chris, Any imperfections in the pattern will show
      Message 2 of 4 , Aug 7, 2007
        thanks for the input everyone.


        Rupert Wenig <rwenig@...> wrote: Hello Chris,
        Any imperfections in the pattern will show up in the casting. Wood
        grain and even figure prints in the last coat of paint will show up. How
        clear the imperfections show up depends to some degree on the coarseness
        of your sand. The finer the sand the better they show up. Conversely,
        the coarser the sand the less they show.
        This only applies to surfaces that won't be machined as machining will
        remove any imperfections.
        That's my 2� and what I've found with my patterns.

        Rupert

        Chris Reynolds wrote:
        > I just spent the weekend making some casting patterns and I was
        > wondering just how smooth they need to be. I sprayed them with Krylon
        > Triple Thick clear glaze today and they look pretty smooth, except
        > for the edges, which are pretty smooth to start with, but no nearly
        > as slick as the other surfaces. So I was just wondering, just how
        > slick and shiny do casting patterns need to be in order to work
        > really well?
        >
        > Chris
        >
        >
        --
        yvt

        Rupert Wenig
        Camrose, Alberta, Canada.

        http://www3.telus.net/public/rwenig/





        Chris Reynolds

        http://builderofstuff.com

        "Computers are like air conditioners - They can't do their job properly if you open windows."

        [Non-text portions of this message have been removed]
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