"Alun Saunders" wrote in message
...
billh wrote:
You don't need the screws for regular turning since the force of the
cutting tightens the chuck on the thread. The number of threads
contacting is plenty. You should use the screws when you are cutting with
the lathe in reverse. Light sanding should be OK in reverse without the
screws but as a precaution they are a good idea when doing anything in
reverse.
The screws do not come with the chuck and they are metric M8 setscrews. I
think the M8 specifies the thread pitch as well as the diameter but am
not 100% positive about that.

Nope ... there's a coarse (1.25mm pitch) and a fine (1.0mm pitch) version
of M8 and upwards. See

http://www.metrication.com/engineering/threads.htm

That having been said, I'd bet on it being the fine version.
--
Alun Saunders

Thanks for the info. After peering at 10mm worth of thread under a magnifier
lamp I think it is actually the coarse thread but I wouldn't want to be my
life on it. As usual, best to take the threaded piece to the store!
Billh