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.
Billh

wrote in message
oups.com...
Just got my new chuck-- Questions-- When I spin the chuck onto the
inboard side of the lathe, it only contacts about three threads (1 x 8
tpi) The adaptor came with two threaded holes for set screws, but no
screws. I think I would feel better if I were able to use the set
screws.
Should I worry about this?
Should the chuck adaptor have come with the screws? If not, does anyone
know the specs of the screws? ( dia & tpi)
Thanks, Phil