Cycloid toothed gears with 4th axis.

[JustinO]

Hi Bob,

I think we're thinking about different things.

I'm talking about where the "bottom land" and the "flank" surfaces come together. If you cut the gear with 2.5D, the fillet will be the same radius as the mill, or bigger. If you cut with a square end end mill, with a fourth axis, you will leave virtually no fillet, which is what you see in old clocks and watches. Nice square corners. It's part of the look.