I have read a number of articles on machining ball handles; every one involves either manufacturing an accessory to turn the ball in the lathe or making a radius form tool with all the problems that brings (making the tool, chatter, etc). An alternative simpler method would be to generate the ball in a milling machine; this method uses standard workshop equipment and does not require any special fixtures or tooling. The inspiration for this idea came from a catalogue I saw some years ago illustrating large ball valves being manufactured on a special purpose machine by using a hollow milling cutter and revolving the component in a chuck, this machine generated the spherical part of the valve by milling. At the time this struck me as being a good way of generating a ball, and although in the intervening years I've had no use for the application in my professional life, (I was a production engineer) the idea stuck. What do I mean by generating a ball? I will give a couple of instances. If a flat surface is milled on a milling machine by fly cutting, then that surface is generated. Also a cylindrical surface is generated on a lathe when turning a shaft. The dictionary definition of generate gives "to trace or form by moving a point, line, or plane in a specific way: circular motion of a line generates a cylinder" (Collins English Dictionary). In other words the cylinder in the lathe is generated by the circular motion of the lathe spindle and the straight motion of the tool slide.
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