It is not as easy as just getting up one day and saying, “ah, let me build that dividing head” or “So I was making a dividing head the other day when I saw this weird thing.” It takes a little bit of planning and ingenuity on your part.
You may choose to use a spin indexer or a wormhead; although there are many other different approaches for this.
When you choose to use a spin indexer, you will still have to borrow some complete parts. I recommend the Gingery dividing head collection. Use Book 6 to get a better, in-depth discussion of the matter.
For a quick and dirty walkthrough, you will need:
1) A hand crank. This can be obtained from the gingery dividing head
2) A fraction plate or two – you can make this, although it is inexpensive
3) A spin indexer.
From here, you will build the following:
1) A worm carrier
2) A carrier for the fraction plate
3) A frame that mounts the worm carrier and the fraction plate to the spin indexer
4) A worm wheel and gear
5) Shaft for holding the worm gear.
You will need an instructable to take you through putting together the whole thing. Here it is