Roughing Out Ball Shapes on the Lathe
It bugged me that when I needed a number of uniformly sized wooden balls for bedpost finials, the only way to make them was to turn each ball from scratch a painstaking operation. So I came up with this router-based fixture that whips out a rough ball in less than a minute.
To make the fixture, attach a simple plywood box, open at the top, to your lathe bed. Install a pivoting router base, as shown in the top part of the drawing. If you want to make perfectly round balls, carefully locate the pivot points right on the axis of the lathe centers. You can also make some interesting eccentric shapes by lowering the pivot point below the centers.
To attach the ball blanks, screw a block of wood to a faceplate and turn the block so that you have a truncated cone, roughly 6 in. long. Rough out a ball blank on the bandsaw and attach the blank to the cone with a large lag screw that runs through the back of the faceplate and into the ball.
To make a ball, start with the router in a horizontal position. Turn on the router, turn on the lathe and swing the router through its arc slowly to shape the ball (see steps 1 and 2 in the drawing). You should be able to rough out about 90% of the ball, leaving a small, unfinished section where the ball attaches to the cone. Part the unfinished section off the bottom of the ball, and mount the ball using the lag-screw hole.
If you want a perfectly round ball with no hole such as a croquet ball make up a longer blank, so that when it is attached to the cone, the lag screw doesn’t penetrate the ball. Rough out the ball, leaving a stem. Separate the ball from the stem and finish the ball by turning it 90ยก and chucking it between two cone-shaped centers so that you can waste away the stem. By chucking the ball in two or three positions and sanding the surface, you will achieve a virtually perfect sphere.
Timothy Dalton, Middleton, Wis.
Fine Woodworking Magazine, April 1999 No. 135
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