"jk" wrote in message
...
"Karl Townsend" wrote:



The tech. fella told me this is one of the few machines that will cut pure
diamond. Anyone need their SO's diamond cut in half?

Karl

Is diamond conductive enough???
jk

Polycrystalline diamond compacts, which are the basis for most diamond
cutting tools, have enough electrical conductivity that they can be wire
EDMed -- just barely. It's a slow process, but it's used to make shaped
cutters for commercial woodworking, and to a lesser degree, for
metalworking.

The compacts are sintered with a small amount of cobalt, usually, but it's
not quite like the cobalt binders in sintered tungsten carbide cutters. I'm
not up on the details but the cobalt serves more to dissolve the diamond, or
to aid in the diffusion of diamond-to-diamond, rather than acting like a
matrix, or binder, as it does in tungsten carbide.

But a small amount of metallic cobalt remains in the diamond compacts and
that aids conductivity. It also makes polycrystalline diamond compacts
slightly less hard (but more shock resistant) than single-crystal diamond
tools.

Even pure diamond has some conductivity, and various forms of synthetic
diamond can be quite conductive. But the wire EDMing is generally applied to
the compacts rather than to pure, single-crystal diamond. There are wire
EDMs made exclusively for the cutting diamond compacts to shape. They have
specially tuned power supplies.

The really old Andrew machines used a conventional (for the time) RC
relaxation circuit, so I'm not sure why it would be especially good for
cutting diamond. Is this one of the granite-base machines with the moving
head?

--
Ed Huntress