Full Color Sandstone Question

Discussion in 'Design and Modeling' started by Nickola, Jan 13, 2018.

  1. Nickola
    Nickola Well-Known Member
    If I would like to design a sphere with diameter lets say 2cm what diameter for the escape hole must I design? Of course I cannot design an escape hole of 10 or 20 cm! Or for a small model till 5cm for example diameter an escape hole is not needed
  2. mkroeker
    mkroeker Well-Known Member
    Without an escape hole, the model will simply be solid gypsum, which will not matter much in terms of price and weight. For bigger spheres, an alternative to using escape holes would be to split the model into two hemispheres, so that the opening acts as an escape hole for production and is invisible on the finished model. (I think there are a few models of planets and baubles in the shops, also figurines split at the waist)
  3. Nickola
    Nickola Well-Known Member
    so for 2-3 cm in diameter model an escape hole is not needed?
  4. draw
    draw Well-Known Member
    The only reason to add escape holes to sandstone (and most other material) models is to make them hollow and cheaper. For small items you probably don't need to do that except for the most expensive materials. And fortunately I think sandstone is generally the cheapest material.
  5. mkroeker
    mkroeker Well-Known Member
    Depends on what you are trying to do and how much it should cost - a sphere of 3cm diameter has a volume of 14.14ccm (4/3*pi*r^3), which means the material will cost $10.60 and weigh about 30g (density of gypsum is between 2.2 and 2.4 according to various sources, as shapeways' material is glued it is probably on the low end of that range)
  6. Nickola
    Nickola Well-Known Member
    So I won't get any type of distortions to the model or any other defects if i don't add an escape hole if i understood correctly. This will only affect the price of the model
  7. draw
    draw Well-Known Member
    It's possible that a hollow print has a better chance of slightly warping depending on its overall size and shape, but for small things I've never had any serious problems either way with sandstone. Of course it might depend on what you consider to be a serious distortion.

    Nickola likes this.