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Figuring materials

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  • Figuring materials

    Wondering how to figure out my material list for a 34" casted dome, 3" thick cast of homebrew with ss needles.

  • #2
    Use volume of a sphere = 4/3 x Pi x r3
    calculate volume of sphere using outside diam (ie r = 20")
    Deduct vol of inner sphere using r = 17"
    Then halve the result because it's a hemisphere.

    Add 2% of the dry weight of castable of stainless steel needles.
    Also add around 2 grams of fine polypropylene fibres for every 10 litres (a bucketful) of castable
    Last edited by david s; 04-06-2017, 04:44 PM.
    Kindled with zeal and fired with passion.


    • #3
      Maybe this (in metric):

      diam radius volume
      outer 1.02m .51 0.56
      inner 0.86m .43 0.33
      difference (shell volume) 0.230

      divide by 2 (hemisphere) 0.115

      times 2000 (kg/m3 required of castable) = 230kg of castable = 9.2 x 25kg bags.

      Hopefully I didn't stuff it up.
      Last edited by AndrewT; 04-07-2017, 10:07 PM.


      • #4
        That sounds about right. The extra required for the entry equals approximately the same volume taken up by the oven mouth.
        Kindled with zeal and fired with passion.