Todd Rich wrote:
(...)

P.S. The part that needs an external thread also needs a smooth through
hole in the center.

Ah! Now I see what you are doing.

Just through - drill these in a lathe 'soft collet' for the inside part:
http://store.hamiltonmarine.com/browse.cfm/4,13248.html

Your pilot hole is the center of the cup.

--Winston
--

Don't *faff*, dear.