Intro: Giant Steel Ball Sculpture
Rotating magnetic sculpture made out of decorative hollow steel spheres and magnets
Step 1: Deriving the Geometry of Cuboctahedron and Vector Equilibrium
The Vector Equilibrium is the only geometric form wherein all of the vectors are of equal length. This includes both from its center point out to its circumferential vertices, and the edges connecting all of those vertices.
Another way of deriving the geometry of the VE is by using 13 spheres of the same diameter. one sphere magnet as the center point, twelve steel spheres around the nucleus. The centers of each sphere will be equidistant from all of their adjacent neighbors
Step 2: Going Bigger Scale
Fascinated by this form I decided to explore its unique geometry on a bigger scale. I glued a magnet to each 12 hollow stainless steel sphere (diameter of 18 cm) hence allowing them to be attached to the solid metal center sphere (diameter of 12 cm). 3 cm of magnets and metal parts were added to compensate the smaller diameter of the middle sphere.
Step 3: Center Sphere, Axle, Magnetic Suspension Bearing and the Stand
Metal rod was welded to the central sphere. The smaller 1 1/16 inch metal ball welded at the other end of the rod acts as a magnetically suspended bearing and allows the structure be rotated. The stand is made out of two table pedestals (same 4cm diameter as the axle) fastened with screws to one wide board at the bottom and one narrower overhead board. Three powerful neodymium magnets are attached to the uppermost board. The magnets add up to a total of 330 kg of pull force. The upper ball bearing on the magnets is held up with just magnetism. The structure weighs 10 kg. Keeping that much weight up magnetically is possible to accomplish with a lesser amount of magnets - it would require also one magnet in the axle, underneath the lower 1 1/16 metal ball.