On Sun, 19 Dec 2010 22:41:32 -0500, "Wild_Bill"
wrote:

While checking about what other 9x20 lathe users who have implemented larger
sizes of (heavier) conventional chucks, you might inquire if they are making
chatter-free facing cuts on fairly large diameter workpieces, without the
use of the tailstock for support.

If you ask a male golfer how far he hits his driver the answer is
never less than 240 yards.

If you ask a fellow 9x20-er if his pieces chatter the answer is never.
Under any circumstances!

When I had issues with the finish of my disks I was sent photos of
similar items to show me "how to do it". The finish was worse than
mine :-)

An additional factor could be if the other users have variable speed motors,
which can be a significant factor in chatter-free finishes.

Indeed. Many do have them.

I haven't priced the cheap generic lathe chucks recently, but the last cheap
chuck I bought was a 6" 4-jaw for about $55 +s/h from JTS Machine(?) in
Mentor/Cleveland Ohio.
I bought that chuck for a different machine that had a 8" 4-jaw, which was
much larger than I normally needed.

But then a 4-jaw independent would defeat the purpose of the pie jaws.

I don't doubt that the 9x20 could handle running a heavier 5" or 6" chuck,
however, I doubt that with the additional distance from the spindle nose
bearing (2-3" more overhang) it would be trouble-free to face moderately
large diameter workpieces without chatter.

A variable speed drive (AC or DC) would give the operator a better chance of
tuning the cutting speed to avoid chatter, but otherwise I would be
expecting to have problems attaining smooth finishes.
I expect that many, more experienced (than I) lathe operators would adjust
the angles on the cutting tool and have everything dialed in rather quickly.

I guess the YMMV comment applies here.

I have learned some of that, not being able to go lower than 150 rpm.
In fact the differences from tool to tool can be striking. I am still
struggling with consistency.

Oddly enough the finish matters less on these pieces: Some get a brass
face anyway which covers a multitude of sins underneath, others get
sanded anyway as I found that unless the face is absolutely smooth,
the transfer of patterns is only partially successful.

What I was thinking is "that'll be the day".. when I buy a $500 chuck to put
on a ($600 when bought) Chinese lathe.
The chucks don't necessarily assure better quality parts.. they're mainly
just a convenience, easier than working with only a faceplate, dog and
centers, and a mandrel for items like the sundial faces.

I think it mat have been Harold that commented that just about any 3-jaw
chuck would be suitable for using pie jaws with.. since the workholding
surfaces are cut in place, they're already concentric with and perpendicular
to, the spindle's centerline (even if the chuck itself had previous accuracy
problems).

As Harold is about to say: "Only if they have two-piece jaws".

The best to you and yours this season, Michael

And yourself.

Michael Koblic,
Campbell River, BC