centering threaded ron in lathe chuck

Wrongly posted this message at the Sherlinecnc list. Cross-posting it
here hoping to catch Chris H' or others attention.

Chris H's lead screw mount picture

<http://f4.grp.yahoofs.com/v1/gNQvP6e4g4VR5ZEdDJB4WqgI-
REgeZIBeYKKjJbebZl7Veuk8U-6-nEAt41kMEifVncYCb3M2C0phbvN/Chris_lead%
20_mount.gif>

Been looking at Chris H's screwmount picture, and toying with the
idea of turning a threaded rod down to fit into a thrust bearing, but
haven't attempted anytbing like that. If one uses the Sherline lathe
to turn the threaded rod, how can one ensure the leadscrew/threaded
rod and turned end are concentric (ie. how does one center the
threaded rod in the chuck) Does one clamp the rod into the self-
centering 3jaw chuck and safely assume that it is properly centered
or is there any precaution to be taken?

Thanks

Terra

BTW where does one buy threaded rod like the ones Sherline uses for
their mills and lathes?