On Thu, 12 Apr 2012 05:03:43 -0500, Bob-tx wrote:

How to drill square holes and several other interesting mechanical
principles.

http://www.youtube.com/watch?v=L5Azb...eature=related

http://www.youtube.com/watch?v=9qEhy...eature=related

Check out "rotary broaching"
http://www.slatertools.com/sales-sup...ry-broach-and-
tool-holder-demostration