Mathematical Lathe Work

This week’s Math Monday on Make: Online is all about Bob Rollings‘ mathematical lathe work. George Hart writes:

Another example of Rolling’s lathe work has a spindle icosahedron assembled around a solid great stellated dodecahedron. Although the great stellated dodecahedron has flat faces and is nothing like a baseball bat, it was completely fabricated by turning on a lathe. Sets of five triangular faces are coplanar and so are turned in one operation. (A plane, though flat, has rotational symmetry, so can be cut on a lathe.) Twelve such planes are turned, on twelve different centers, with the piece held in a spherical chuck.