joe greiner
3rd November 2011, 09:03 PM
Wobbler 2.0 is a successor to Wobbler 1.0, which was a study sketch in Spruce, about 4 1/2" (115mm) in diameter and unfinished.
They're both loosely derived from David Springett's "Ribbon Streptohedron" in "Woodturning Full Circle," but with a circular cross section of each torus.
I call them "wobblers," because when rolled on a table top or the floor, they traverse an S-shaped path defined by cones tangent to a large and a small arc. There are four such cones available, but only two operate in a single rolling.
Wobbler 2.0 is 11" (280mm) in diameter, limited by my lathe's 12-inch swing, with allowance for cutting the outside and support for cutting the inside. The torus body has a diameter of 1 5/8" (41mm). The small rings are about 6 1/4" (160mm) in diameter.
There are 132 segments altogether, 66 each in Spruce and Mahogany. The large ring has 60 segments of 6 degrees; the two small rings have 36 segments of 10 degrees. I chose those values to make the outside width of the segments almost equal, for ambiguity in the exact location of the transition between large and small. The junctions lie at the corners of a hexagon.
The finish is clear semi-gloss polyurethane.
Cheers,
Joe
They're both loosely derived from David Springett's "Ribbon Streptohedron" in "Woodturning Full Circle," but with a circular cross section of each torus.
I call them "wobblers," because when rolled on a table top or the floor, they traverse an S-shaped path defined by cones tangent to a large and a small arc. There are four such cones available, but only two operate in a single rolling.
Wobbler 2.0 is 11" (280mm) in diameter, limited by my lathe's 12-inch swing, with allowance for cutting the outside and support for cutting the inside. The torus body has a diameter of 1 5/8" (41mm). The small rings are about 6 1/4" (160mm) in diameter.
There are 132 segments altogether, 66 each in Spruce and Mahogany. The large ring has 60 segments of 6 degrees; the two small rings have 36 segments of 10 degrees. I chose those values to make the outside width of the segments almost equal, for ambiguity in the exact location of the transition between large and small. The junctions lie at the corners of a hexagon.
The finish is clear semi-gloss polyurethane.
Cheers,
Joe