[MFchief]

I believe you are right about the straight flute cutters, the pics I've seen show those, and the geometry of the cut probably requires it.

Of course I know you you can cut non round holes already with CNC, but the corner radius is limited to the size of the tool, so tight corners require small tools, then you get into the whole depth of cut-tools diameter issue. The Watts tools cut very tight radii with tools close to the size of the hole.

[mountaindew]

I believe you are right about the straight flute cutters, the pics I've seen show those, and the geometry of the cut probably requires it.

Of course I know you you can cut non round holes already with CNC, but the corner radius is limited to the size of the tool, so tight corners require small tools, then you get into the whole depth of cut-tools diameter issue. The Watts tools cut very tight radii with tools close to the size of the hole.

Tormach sells a roto broach that cuts squares or other shaped holes. Is this what your describing or something similar