Hi , just curious how some of you guys drill square holes in a lathe and/or mill machine ?

Any special tools that you have made and would like to share some of the information and your own experience in drilling square holes??

Examples -

square hole drilling [ame="http://www.youtube.com/watch?v=9qEhyQfbImY"]YouTube - square hole drilling[/ame]

[ame="http://www.youtube.com/watch?v=270qEZKXAfQ&feature=related"]YouTube - How round is your circle?! www.howround.com[/ame]

cheers