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cantenary(?) arch

updated wed 16 feb 05

 

Cindy in SD on wed 16 feb 05


Tarrant, Derek wrote:

>How can one generate the numbers and plot the points for a cantenary
>curve where the base can be varied for experimental purposes.
>
>
Hi there,

I'm not a mathematician, but an old college art prof did show me his
method of figuring out just what you want to know. I don't know if it's
a pure "cantenary" arch, but it makes a very pretty arch, and it's easy.
Just get a chain like you would use for a reasonably sized dog or a
swing set. Fasten one end of the chain to something (perhaps a wall).
Fasten the other end to a spot level with the first spot, and the
distance of your base away from the first spot. The chain will form a
graceful arch. The pitch will, of course, vary with the length of the
chain. It's fun to experiment with. I'm not sure whether the pitch of
the cantenary arch is critical or whether you can eyeball it. Once
you've settled on a satisfactory curve, you can slide a large piece of
paper or a sheet of board or whatever you like behind the chain, fasten
it in place, and spraypaint over the chain onto the paper in order to
convert the curve into a workable pattern.

Best wishes,
Cindy in SD