Hi John C,
That's a BIG gnomon! It will be enormously heavy if it is solid so I would opt for a fabricated design. Although you can make a cone by rolling up a circle with a slice cut out, that would need a sheet of material large enough to draw at least part of a 24' diameter circle - not easy to come by.
As an alternative to a circular cone, how about tapered cylinder based on a regular polygon for the cross-section? The base could be, for example, a 20-sided polygon and the sides would be 20 long, thin isosceles triangles, 12'+ tall. You could either get a sheet metal worker to weld it up, or make it out of fibreboard and soak the surface with epoxy resin.
For stiffness, you might need a series of progressively smalled polygons distributed up a central rod to form a backbone and ribs to the structure.
Sounds like an interesting project - how robust is the client's budget?
Regards,
John D
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John Carmichael <[EMAIL PROTECTED]> wrote:
John Carmichael <[EMAIL PROTECTED]> wrote:
Hello All (esp. sundial makers):I need some help on something. (what else is new)...I'm designing a huge horizontal dial for Cordera Elementary School in Colorado Springs. The face is 120' wide and the perpendicular gnomon will be 12' (3.65M) tall. I'd like to talk the builder into using a giant cone gnomon, but I have no idea how in the world you would construct one! I don't think I have ever seen a giant cone gnomon on a monumental sized sundial. Would it be easier to make it out of concrete poured in a mold, bent sheet metal or some other material? Any ideas Tony or anyone?Maybe I could find a surplus rocket nosecone somewhere!Do you think it would be really difficult and expensive to fabricate a giant cone?If we can't use a cone, we will have to use a blunted pyramid (obelisk) instead.thanks for any ideas,John---------------------------------------------------
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