On Sat, 14 Feb 2009 07:16:27 -0700, Lew Hartswick
wrote:
snip
Havent
used them yet but need them to hold some threads without
"buggering" them up.
snip
--------
You may be working too hard here, depending on the thread size,
work piece length, TIR required, etc.

Easy way is to get 3 nuts to fit the threaded piece. Thread 1
nut, a washer and two more nuts on. Space the last two nuts so
they clamp at the front/back of the 3 jaw chuck, with the front
projecting very slightly in front of the jaws. Run the nut on
the other side of the washer down against this nut and torque to
suit to prevent the part from turning. If runout is excessive try
different nuts or shims between jaws and nuts. Not suitable for
production, but fine for a typical hobby shop one-off.

As a safety tip, if you are machining threaded bar like Allthread
and it extends through the headstock and out the back, be very
careful of "whip" that will likely develop. In this case you
will more than likely have to cumshaw up some sort of bar support
from a piece of pipe and some stands to restrain the part that is
sticking out if it is more than a few inches, depending on the
workpiece diameter. You may also find it helpful if this is thin
stock to make some sort of bushing to restrain the stock inside
the spindle and keep it centered.

Good luck and let the group know how you make out.


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).