In October 2003, Bernard Lalanne sent me photos of a hinged octagon-to-square table that he had built. The top of the table (made out of oak) swings out and then back in, making use of my 7-piece swing-hinged dissection of an octagon to a square. A big thank-you to Bernard for taking the pictures and sending them to me!
The table forms an octagon on the left, and then a square on the right:
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Here we see the pieces swung out from the octagon:
Then the pieces are ready to swing in to form the square:
Neat!
Bernard is an aerospace engineer in the south of France, at Pau, where Wilbur Wright founded the first school of aviation. Not surprisingly, he has designed a sophisticated bracing mechanism to give support to the chain of hinged pieces when they are fully extended.
As Bernard describes it, the upper part of the table is on a rotating circular plate. The plate is mounted on a roller bearing to allow free rotation. The smallest triangle in the chain of pieces is attached to a retractable runner under the rotating plate. Expanding the runner causes the plate to rotate. Two revolutions will transform the square into an octagon. Reversing the movement creates a square from the octagon.
As Bernard observes, his two boys like this dissection application, and his wife claims not to understand it. His friends have ignored this hobby, but will discover it soon on this web site!
Photos courtesy of Bernard Lalanne.
All else copyright 2003, Greg N. Frederickson.
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Hinged Dissections: Swinging & Twisting
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Last updated October 6, 2003.