In one of the older annual Dropbox archives, there was an improvised lathe
turning setup by Ted Edwards (very bright guy, a former RCM regular), where
he added a plate to the cross slide to extend the toolpost forward (toward
operator), and to the left of the cross slide, to turn the circumference of
a large diameter part.

BTW, I forgot to mention earlier, wrt machining chuck adapter backplates for
spindles with flange mounting, the flanges generally have a protruding
shoulder (raised center section) which registers the chuck body to be
centered.
The shoulder also adds to the security of the mounting, so that the chuck
isn't just held in place by studs or bolts passing through the spindle
flange.

Machining a chuck backplate (or other accessory) would include cutting a
matching undercut recess to closely fit the flange feature.

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Jim Wilkins" wrote in message
...
On Feb 12, 9:09 pm, "Michael Koblic" wrote:
...
Here is a question then: Say you have a 9" swing lathe and a 8" diameter,
...
Michael Koblic,

One of my old books shows an offset spindle added to a lathe to turn
oversized disks. A gear or pulley on the main spindle turns the
faceplate on the new spindle at a reduced speed. The geometry is
difficult with pulleys but the planetary reduction off a burned-out
electric winch might fit well, bolt the large internal ring gear to
the faceplate and drive it with the small sun gear.

The added spindle goes above and behind the main one so the tool post
is still in the right front-rear position.

jsw