You might grind a shim out of HSS (piece of lathe bit) and
silver-braze it in place -- or silverbraze it in place and then grind
to dimension and shape.

HSS doesn't seem to lose any hardness from the heat of silverbrazing.
That isn't based on any measurement, but cutting tools I've made
that way seem to keep an edge as well as unbrazed ones do.

Carbide can be silverbrazed also, but it might be too brittle for your
purpose.

On Sun, 15 Aug 2004 16:44:35 -0700, Grant Erwin
wrote:

I haven't yet. I'm going to do what I came up with above, i.e. grind away
a bit of the fixed jaw and make up a hardened shim to replace it. The shim
will be held securely in place by the movable jaw of the chuck. This may not
work well for some reason as yet unknown, and I may just make an entire new
file rod which is bored at the end to receive 3/8" round file shanks, and
then make up 3/8" round shanks for my parallel files, using the method
described by Andy Lofquist with his MLA die filers.

Grant