Posted by Ron V on December 26, 2013 at 15:19:34:
Necessity is the mother of invention.
The blank would have first been gashed in a milling machine.
The gashes are required so as the hob's lead can pick up on the gashes causing the free wheeling blank to then rotate.
Something that's also interesting in the video is that the hob looks like it has been made from an original worm shaft.
Here's the link - http://youtu.be/C3hXM5jd-pY