Hex vs. Key

[Gabe]

Originally Posted by Cory

It's so much easier than using keys--nothing to lose, and unlike keys, the hex won't slip.

The key will stay in place if it is brazed to the shaft, which immobilizes it (adhesives might work). You can also cut a light groove around the shaft for a retaining clip or e-clip.

Most gears and sprockets with finished bores have a standard keyway cut into the instead of square or hex shafts, when purchased from sources such as McMasterCarr and Grainger. One reason why keys are so common.

[sanddrag]

There is also the option of woodruff keys which are stronger and will not slide out, but I will admit, hex is nice.

The only thing that is kind of annoying about hex is when you go from round shaft down to a smaller hex. Then you have to mill it with an indexing head (or 4th axis in the case of CNC).