On Mon, 17 Nov 2008 18:46:39 +0000, Mark Rand wrote:

What's special about ball and radius endmills? The same (to some extent)
applies to all endmills doesn't it?

Only when plunge cutting. With side milling (climb or conventional) the center
of flat bottom endmill does virtually nothing. With a ball end the center is
still cutting *some* material.
--
William