I need to make a special grinding head for another hobby. Spindle will be 3/8" diameter with a ball at the end. Diameter of balls will range from about 9mm to 25 mm. How do I make a spherical head at the end of the spindle? All I have is a completely manual machine, no CNC, no CAD/CAM, just Mark 1 eyeball, good hands, and good calipers.
Scott