Snowblower Motor driveshaft

[InFlight]

Depends on what machining capability you have access to, and what other sprockets you have in hand.

If you have some 1/2 hex sprockets-

1) Best bet would be to water-jet a DD Hex insert
2) Mill a DD insert in Hex Shaft Stock.
3) Not the best fit, but you could also try just a 10mm center hole in a lathe. And then use preferably two set screw against the two flats.

[chapman1]

A good machinist with a milling machine could make easy work of modifying a hub to DD