@lewdfinger:
What i do to taper the hub is i take a 3/8ths drill bit,or what is close to the crank diameter.
Then i hold it at an angle against my grinder and put a taper on the bit that matches the crank taper.
Then i chuck the hub stock in my 3 jaw chuck.Use the tail stock with the drill chuck attachment.
Use slow speed and drill this out.
Just to about the depth i need.
then i thread it.
Then i use an old crank ive made up as a mandrill,then i turn my hub down.
Most of my hubs come out at .0015 and less.One i had only had 1/2 of .001.