thanks!
DoN. Nichols wrote:

In article kq1Dd.15980$hc7.11564@trnddc06, AJ wrote:

I have a piece of rough round aluminum stock that I want to insert into
the 3 jaw chuck. The stock is kind of rough, do I insert it all the way
into the chuck until it firmly touches the end? It spins kind of wobbly.
What can I do to correct it?


You don't mention the ratio of diameter to length. If the
length is at least as much as the diameter (assuming a diameter large
enough to require you to reverse the chuck jaws to grip it), here is
what I would do. (And what I *have* done, with a 6" diameter by 6" long
workpiece on a 12" swing lathe.

What *I* would do is to insert it most of the way in, snug it up
lightly, and check runout at the free end. Tap it a bit as it slowly
rotates, until it is pretty close to true. then center-drill the end,
and put in a live center to support it.

Once that is ready, slack the chuck a little, use the tailstock
live center to push it deeper into the chuck, and re-snug it firmly.

Once you are there, up the speed a bit, and face the end, from
the outside at leat as far in as the jaw steps would contact. I would
probably go as close to center as I could manage with the live center in
place.

Also -- Turn the OD down enough to make it smooth all the way
around, for at least enough length so the chuck jaw steps will grip on a
nice cylindrical and centered surface.

Then, once it is faced cleanly, reverse the workpiece, pushing
the faced against the chuck jaws, and tighten. Check runout again at
slow speed, and adjust that if necessary until true. (If you turned the
OD as well, you will probably be pretty close without tweaking.

Center drill that end, and bring the live center in again to
support the free end.

Face that end as close to center as you can get, then back out
the live center and finish to full center. Redrill the center hole if
you've taken too much off the length. Replace the live center, and use
it to support while you turn rest of the diameter clean.

If you need the full diameter to be a single clean turning, what
I would do to accomplish this is to drill a hole into one end off-center
far enough to line up with a faceplate slot, and thread a stud into the
workpiece to drive it by the faceplate while holding it between centers.
That way, you could finish the OD full length in a single pass.
(Assuming that it is small enough in diameter to pass over the carriage
on a Sherline.) Of course, this is a bit of a problem if you can't
allow a hole in one end for the stud.

Good Luck,
DoN.