National Pi Day

This morning, I heard a piece on the radio about National Pi Day featuring a mathematicians speaking of pi and its utility. He said there could be no technological sophistication without calculations involving pi: no automobiles, no space flight. I realized there would be no Weeks Rocker, or any of the chairs we build or plan to build. Or at the very least, they’d be hard to build and likely wouldn’t fit together so well. This is a great day of celebration.

Our chairs, comfortable chairs, are forms of curves and profiles that come together, and fit, at critical points. These points and the relationship between the mating parts cannot be easily described in a way that makes the making of the chair a relatively simple process of precision rather than a more lengthy and haphazard one of “cutting to fit.” But by taking a section (finding a plane) within the solid form, mapping tangents to curves, and solving triangles using pi (and trigonometry), we can build very exact jigs, fixtures, and tools to make parts that meet in space, surface to surface, glue-line tight. I love pi.

This week, I was designing a curved bench for a patron. To find the number of slats in this drawing, I used pi to find the length of the arc described by the intersection of the seat and back slats — a simple use of the formula: circumference = pi times diameter. The drawings are handy enough to post here.

End elevation of bench

Section -- center of all benches

Plan view of curved benchPi calculations for curved bench

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