[Chris Endres]

Over the summer, I did an extensive search for bevel/miter gears with .5" hex bore, couldn't find anything. It's not an industry standard, so they really aren't in demand.

You can find bevel and miter gears at SDP-SI: http://www.sdp-si.com/eStore/CoverPg/Gears.htm

You can also get bevel/miter gears from McMaster: http://www.mcmaster.com/#bevel-gears/=z2kqn1

Vex pro has 15t miter gears with a 3/8 hex bore: http://www.vexrobotics.com/vexpro/mo.../217-3344.html

But as Joe said, you'd either need to used the keyed bore, or broach your own.