One necessity in the machine shop is the ability to turn a part a specific amount.
For instance, to mill a hex you must make a cut, turn 30 degress, cut again, repeat until all 6 sides are done.
I found myself with a couple of 72 tooth brass gears and made myself this indexer. A spring loaded ball
bearing clicks down between the teeth on the gear to give 5 degree increments. Not as precise as a
rotary table or dividing head, but a big help on a great many projects.
Some day I'll get around to making a stand for it.