Rod wrote:
Frank Erskine wrote:
On Mon, 24 Mar 2008 19:59:37 +0000, Dave
wrote:

Just talking from an engineering point of view, I was always taught
that a bolt had a plain shank between the threads and the head and
that a screw was threaded all the way up to the head, minus a thread.

AIUI, a bolt is intended to be held still while a nut is tightened on
to it (a bit like a stud), whereas a screw is intended to be rotated
into the nut (or casting, or whatever).

So I can follow this to the concept of a ship's propellor being called a
screw. But what about things like lead screws? (Leave the magazine out
of it... :-))

I think the bolt word comes from smooth sliding shafts, and the screw
from rotating spirals..

The problem comes when its both smooth and threaded.