On Tue, 13 Sep 2011 10:38:39 -0400, "Ed Huntress"
wrote:


Right. It's not that they can't be EDMed (Sumitomo even makes, or made, a
conductive ceramic that can be EDMed), but the speed, settings, overburn and
wire reaction (and deflection) get tricky with refractory metals.
Superalloys and other refractory materials have been wire-EDMed for decades,
but I suspect that pure niobium is a very rare one, if anyone does it at
all.

It's not unheard of. I know at least four places that have done it
successfully to a relatively high standard. As you say, it is going to
take time to optimize the setup.

It's nasty to machine conventionally. I'm told, gummy like copper.