Ball-holder jig lets you machine a sphere in multiple ways
My friend Louis DeHan was making a decorative box with a top ornament composed of a turned ball held between two small posts. The problem was figuring out how to safely and securely hold the ball while cutting 1⁄4-in.-wide slots in it for the arms. We came up with a simple jig that stabilizes the ball and creates reference surfaces that could ride on a number of machines, such as a tablesaw, router table, or drill press, for safe machining or drilling. It’s made of 3⁄4-in.-thick Baltic-birch plywood. To grip the ball, cut stopped holes on both inside faces of the jig with a Forstner bit. The bolts that hold the jig together are inset on one side so the jig can run against a fence. We used the jig on the router table. We ran it over the bit, flipped the jig 180°, and ran it through again. Worked like a charm.
—Lawrence Killingsworth, Spokane, Wash.
From issue #266
Drawing by Dan Thorton