Made a Worden, many years ago. Enables drills to be kept sharp and accurate (Made up a holder for ER20 collets) using four facet method. having a square holder, enables the drill to be turned over after every cut, so that the lips are the same length, and it will cut to size.
Have also ground a few End Mills, and with a diamond wheel, an inserted tooth carbide face mill.
Superb for tool bits for use in the lathe, or a flycutter.
Obviously,, not used every day; but invaluable when needed.
Am in process of making one for the Water Works Museum, so that they can sharpen their drills and tooling better. (Had forgotten how much work involved, but satisfying to see it taking shape).
Howard