On 1/19/2010 7:43 PM, Pete C. wrote:

I expect you probably have to break it down into 4? separate arcs and
cut each one in a separate setup with the part and mill positioned the
proper distance from the center of the rotary table.

I was looking at the 5 centered arch graphical method, thinking that
given an ellipse bounded by a rectangle, one could mathematically
determine offsets and radii. My head hurt. It then occurred to me that
someone in the bad old days before CNC must have done this. Hence my
appeal to the collective knowledge pool.

Kevin Gallimore