On Sun, 19 Dec 2010 13:56:29 -0500, "Wild_Bill"
wrote:

He certainly has options available with his existing tooling/accessories.

Double-sided tape (not the thick stuff, with foam in the center) is somewhat
commonly available in 1/2" and 2" widths. I've seen 1/2" DST available in
stores that stock winterizing/weatherproofing products as a method of
applying plastic film to window openings, and the 2" width is often
available as a product for working with carpeting.

Enco and various other suppliers generally have DST in larger length rolls,
and made by 3M.
The DST method of securing thin workpieces should be adequate (it's a fairly
common shop practice) as long as the workpieces don't get too hot, as the
adhesive grip will weaken at elevated temperatures.

As Michael has mentioned that he has (I think) 2 faceplates available, each
of them could be adapted for sundial plate machining, if they're not
frequently used for other purposes.

Right now if (and it is a big if) I continue with this line there are
three sizes I make. The miniatures are no problem, they get done on
the Taig and bored in the 3-jaw on the 9x20. The 4.5" and 5.5" could
be standardized and each face plate dedicated to one size. If I can
make it work it would be far and away the cheapest solution even if I
had to buy more face plates.

I think we've been discussing the generic 9x20 lathe in this instance. My
experience with owning one of these light duty lathes, is that it doesn't
take much to induce chatter with these models.
That's why I've been making suggestions for faceplate or the supplied 4-jaw
chuck for turning/facing the sundial plates, as the working diameters are
relatively large for these lathes.
These existing accessories will keep the workpieces close to the spindle
nose bearing, which will likely minimize the risk of chatter, whereas I
believe the addition of a new chuck will likely increase the likelyhood of
chatter due to the extended overhang distance from the spindle nose bearing.

That is a consideration. I did check with other 9x20 users and some
seem to like 5" chucks better than 4" chucks, however, this may be
related to the quality of the manufacture. None reported any problems.
One even run a 6" 3-jaw.

Either way the cost of a Polish 5" 3-jaw, back plate and pie jaws is
$500 give or take. Not something to undertake lightly.

An interesting point: I see that many manufacturers make the chucks
with plain backs but also with threaded backs. I can see the need to
turn the back plate to fit one's particular lathe to make the chuck
run true but I am not sure how this works with a chuck that has
already been threaded unless it is a "Set-through" chuck which these
are not.

Machining these sundial workpieces seems as though it would be very much
like working a bowl on a wood lathe, since the workpiece is free-hanging
from the spindle/workholding accessory.

Protecting the precision lathe parts from wood debris isn't very troublesome
by just using some disposable material such as newspaper or aluminum foil
and possibly some masking tape. Paper products covering the lathe bed
wouldn't be especially suitable if hot metal chips are present.

I use cling film when working with abrasives. One would hope that wood
chips would not be *that* hot...

I shall be looking at this in the New year. Right now it's the turn of
other manufacturing processes.

Michael Koblic,
Campbell River, BC