I used to sharpen tools in a tool crib, but now work with SWX all day.
I made a 1/2" end mill model last year while teaching a tool grinder how to use SWX.
Extrude the shank first, then drew a profile centered on the shank of a single flute combined with its "core" diameter.
The core diameter I would describe as smallest cross section between the flutes which I simply transferred into a circle.
The whole profile resembles one half of a yin-yang symbol.
Then I established a helix to use as a guide.
Then with the flute/core profile I used a sweep feature along the helix.
The next feature cut away a little more material to get center cutting geometry. I may have also gashed out a little more relief on the end.
Then I patterned everything since the initial shank feature to make a 2 flute end mill.
