Hey G'day,JohnHaine wrote: More conventionally, hobs have the teeth on helical profiles, rather like a tap, and the gear blank rotates at the same time as the hob, with a ratio between the speeds so that the blank moves through one tooth angle per rev of the hob. The hob is fed slowly back so that all the teeth are formed in one milling operation. The benefit is that triangular teeth on the hob with a pitch equal to pi times the gear module, will generate involute gear teeth of any tooth count except for small counts where the teeth need undercutting. You can use a tap as a hob.
Thank you for the courtesy of a reply, well bugger... that's something worth trying using a tap :)
Cheers and avagreatday...