On Sun, 29 Jul 2012 05:00:32 -0700 (PDT), phaedrus
wrote:

Hi guys,

I've seen pictures of threaded tapers being machined on lathes and was
wondering what the hell use they are? I mean, since the diameter of
the threaded section is constantly varying, what can it possibly be
screwed into? I cannot imagine any nut or internal thread that would
accommodate such a piece of work.

Kindly disabuse me of my ignorance if you can, thanks.

P.
Steeply threaded tapers are used sometimes to connect things like the
drill stem used for drilling oil wells. Once they have loosened just a
little bit they unscrew fast. So only a few turns will engage a long
length of thread. Look for API threads.
Eric