Lathe Ball Turning Attachment Turn Ball. This fits straight onto the cross slide of your lathe machine for Quick Turning of Cones and Balls.Comes with a 1 Index able TNMG16 Insert for best turning finish and results. Maximum Ball Diameter possible is. The Head can be adjusted for different Ball Sizes. A ball turning attachment is really just a mechanism that cause the cutting edge to follow a circular path which is the outside of the ball being cut. The cutting edge can turn in the horizontal plane or it can turn in a vertical plane lying along the axis of the lathe.