To cut the ellipsoid shape into the top ring section I've programmed the ellipse in g-code so that the lathe table will follow this shape. The cut gets incrementally closer to the final cut. In the diagram, above, the solid white lines are the tool paths yet to be followed and the red ones are the paths already done.
On the final cut I increase the lathe spindle speed to give the finest finish.
Going back over the photo's I remembered that I'd forgotten to include this bit, apologies about the 'part 10.5' but it fits between the part 10 and 11.
I'd like the edge of the watch-glass shelf to have some curvature so that it doesn't just end abruptly with a square edge. I'm going to use the lathe and some cnc to cut the curve.