LOL Old endmills have a multitude of uses. Make excellent boring bars for lathes too
Here's a recent recent 2nd lifes for old old cutters.
1st 2 are threadmills including the one in the video (HSS) the smaller threadmill is an old solid carbide cutter, I use that for 0.75mm pitch internal threads on model aero engines.
The other pic is a form drill which drills for 1/4" whit tap, chamfers the hole and creates a spotface all in one operation.
Wayne....