Thanks for all the info last year awerby.

I am re visiting this..... so I am assuming that the 2 or 4 flute ball-nose endmill does not actually have a spherical radius to match my radius - and putting very large concave or convex spherical radii on metal is done by clamping the part on a table - the table turns and the end mill projects further into the stock as is goes toward center in the convex piece and opposite for the concave piece. Kind of acts as a bit cutting stock on a lathe - is this about correct? I would assume the most economical way to have it machined is by a CNC machine? If I was running several dozen or a hundred parts or so?