"Roy" wrote in message
...
I am in the process of making an item for my sal****er setups, and
have to thread the inside diam of a 3" socket joint (happens to be
correct bore needed for my application and only needs threads) which
are 13 tpi. My biggest problem is if I tighten the piece up in the
chuck it distorts it. I ruined a bunch of pieces trying to find a
sweet spot n chucking prressure with out distortin oor without having
it slip. Even with light cuts its gone wrong. Perhaps I need to put it
all away and give it a try on anaother day, unless someone can suggest
something that may work to hold this piece in the chuck without
distortion or slipping. I have played with super glueiing it, double
faced tapes, but one thing I have not tried net is to glue two or
three lugs on the outside of the piece I am turning and allow them to
hold against the chuck jaws sides.........hmmmmmmmthat idea just hit
me, is there anything else that may work?

PVC is neat to machine, but it can get awfull flimsey and such when
chucked up.....


I'd suggest you measure the ID of your socket and the OD of any PVC pipe you decide to use
in a few places first. If it's anything like the 4" piece I used to make a housing a while
back, it ain't round to start out with. I ended up turning a wood plug as a pilot.

You may want to get a cleanout adapter to slip inside or over the piece you're threading
and work from there...