This video is very information-dense. I apologize, but: nature of the beast.

However! Astound your friends with how much you'll know about gears!
Amazing before-seen footage of Indexing, dividing, and gear cutting!
Stop making due with plain text video descriptions: Watch for yourself!

More than you wanted to know about gears: 0:00-10:50
Gear Cutters: 10:50
Indexing & Dividing: 14:18
Dividing Head: 19:43
Actually cutting a gear: 24:42
Metal gears in the mini-lathe: 26:28

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The musical blip at the end: Green Hills - Jingle Punks