Just joined, hobby level

[Jonathan]

At first it looks like just simple sin/cos ... but if I may there's one thing I think you might be missing out? When using a ballnose cutter, unless the cutter is kept perpendicular to the finish part's surface (impossible on a bowl without 5-axis) the cutter will cut more material off than intended. That's because the cutter is not a point, it has a finite diameter and the outer edge will cut more from the surface. It gets worse as the surface is steeper. This diagram will hopefully make it obvious:



It's a fair bit more difficult to work out the co-ordinates for that...