On Tue, 29 Mar 2011 00:32:29 -0400, "Wild_Bill"
wrote:

Very nice setup, Michael.

There are some workholding clamps that grip laterally as the fastener is
tightened, which may work well for holding the rings by their edges.. while
allowing you to make light facing cuts.
Since the rings are captively held by the undercut, I wouldn't expect there
to be much likelyhood of clamping devices distorting the rings (WAG,
mostly).

There seems to be enough surface area around the threaded holes in the plate
to support those kinds of clamps, although the jaws of the clamps could
leave marks unless the tips of them were biting into brass shims (definite
maybe).
Grinding an appropriate radius into the clamp "jaws" could be worthwhile.

The types of clamps I'm thinking of (but can't remember the notable brand
name) could turn your workholding plate into a 3 or 4-jaw chuck, for that
specific size of rings.

Some metal blocks with screws in them (located around the ring area) could
potentially work about the same as those clamps, but screws perpendicular to
the lathe spindle's axis won't also push the workpieces into the workholding
plate.. which is what those clamps do.

I had a look at some of them. Firstly, only the smallest ones would
hold the ring without sticking up above the surface of the ring and
interfering with facing. Secondly, the smallest ones have only very
limited range of gripping. Thirdly, there is the issue of centering
the workpiece accurately.

In the end I was not sure that they would not do the job any
differently than a 4-jaw chuck. Plus they would add complexity and
cost to the existing project (e.g. I doubt that I could get away with
just a 1/4" aluminum plate).

I am keeping them in mind for a similar project in the future, though.

Michael Koblic,
Campbell River, BC