leo is right as to the purpose. But he is mistaken in that not all metal
lathes have a groove for such a use - for example my metal lathe does not -
it has 2 1/4X8 threads but no groove - and the chucks that go with it don't
have the set screw either (and a little setscrew wouldn't do much against
the forces a metal lathe sees anyway)

My wood lathe will turn in reverse, and I have not had any problem with the
chuck unscrewing with a finished piece on it - so I'm not convinced the
little screw is needed - I have had the chuck start to unscrew if I brake
too fast with a heavy piece on the lathe (e.g. 50 pounds or 100 pounds), but
that's a different matter, and it's why I keep the tailstock in place when
roughing big pieces.



wrote in message
oups.com...
Hi Bob

The treaded hole is for keeping the chuck spinning off of the
headstock when you have a lathe that can turn reverse or one that can
be stopped quickly.
These lathes have a groove turned for the setscrew to tightened to,
metal lathes all have those grooves.
As your lathe does not have a flat groove, you probably don't need the
setscrew, but if you want to use one than the easiest way would be to
use a nylon/plastick setscrew, it will not damage the spindle thread,
or you could use a plastic plug between the setscrew and the spindle.

Have fun and take care
Leo Van Der Loo



On Mar 4, 2:44 pm, "Bob Daun" wrote:
I have used my chuck for quite awhile but I was just wondering why there
is
a threaded hole in the back end of the adaptor (the side facing the
headstock when mounted). The threads in the hole are quite fine but
there
is nothing in the hole. If I shine a flashlight into the hole I can see
the
threads from my headstock. Is this meant to use as and additional hold
down? I would hesitate to do that as it would ruin the headstock
threads.
Any thoughts on this?

--
Bob Daun





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