Awl --
An unremovable setscrew left me doing the unthinkable: I ground the goddamm thing out with an 4.5" angle grinder, so there is like a gash half-way into the nose of the 3/16" toolholder. If you held the toolholder in the vertical, the ground-out region would be in the horizontal.
From previous responses, the whole holder is hardened, so drilling/tapping another hole will be semi-futile. If I *could* do this, this would work, even with this gash, as the tool would still be substantially supported.
So I figgered I'd mebbe weld this gash up with some soft rod, or even braze it, then drill/tap it. I thought I'd stick some old 3/16 carbide in the holder, to keep anything from "spilling" too far inward, and pray that nothing sticks to the carbide, or that nothing warps so bad I can't get the carbide out.
This toolholder doesn't have to be superstrong or super accurate, as it will doing lite stuff -- after all, these are only 3/16 tools, some engraving, etc.
Any tips, caveats in pursuing this? Best fill rod? Brazing better? Combo??
Heh, the good news is: At this point, I got nuthin to lose!!!