The knobs on my reels have just been simple cylinders. They might look better with some shaping, perhaps a “waist”.

Here is a material blank mounted on a mandrel, ready for turning.

I want to make a concave arc cut on the cylinder, and the setup is to use the mill as a lathe.

The mill headstock is horizontal and a tall toolpost is fastened to the rotary table. I have used a similar setup to cut convex spherical surfaces on counterweights and center screws.

This plan view sketch may help to explain.

Here is the shaped cylinder.

New knobs on reels under construction: