Re: Seven-sided die (was Re: This just in)

From: Dominikus Scherkl (
Date: Tue Jan 12 2010 - 15:40:52 CST

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    Am 10.01.2010 21:43, schrieb Marcin 'Qrczak' Kowalczyk:
    > 2010/1/10 verdy_p <>:
    >> Hmmm.. due to the spacial distribution of weight, the center of gravity will be WITHIN the half-sphere,
    > Not necessarily if the pyramid is long enough, and/or the half sphere
    > is actually less than half. Then resting on the top of the half sphere
    > would be an unstable equilibrium.
    > Instead of half sphere we can also have 7 faces with wider angles,
    > such that the dice laying on one of them has the center of gravity
    > above a point lying outside the face. Then the only stable resting
    > positions are on the remaining 7 faces.
    The usual way to design odd-sided dice is to take twice as many sides
    and number them double (so two sides bearing the "1" and so on).
    And than you can build a long stick with that many edges and rounded
    ends. So a slice of the stick would be a simple 14-hedron.
    This is easy to design equaly distributed (Laplace).

    The other way would be paste two seven-sided pyramids turned a half
    face against each other and "smear" the pasted edge into a zig-zag line.
    For 10-sided dice this is so common that you can buy such in any fantasy
    shop - they are called "gems". Take a look.

    Best regards

    - --

    Dominikus Scherkl
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