Allen_Wrench
Resident Mad Scientist
Try again w/the heat,and maybe dry ice on the shaft for awhile befor heating the ring and droping it on,ir measure w/inside and outside mic's and see if it is even reasonable too try with out machining the gear
I'm with him. It's probably time for a micrometer, if you have or can borrow one. I worry too about the temper of the metal, what with all the heating and no quenching. I don't know what the Rockwell rating on a Chinagurl cog would be. Norman might know the Rockwell (harharhar). But I think repeated heating and cooling might make a bad situation worse.