Review on Enhanced Aerospace Precision with Hardened Tungsten Fractional Tools by John Clark

Had to remove a set screw which not only had a fully rounded hex hole but also looked like a meteorite! (Yes it was SO hard.) Tried drilling this thing with HSS, TiN, Co and even left handed bits but it just made fun of it. So it was until finally THIS bit was used. Smash in and through like it's aluminum. However, be aware that sintered carbide drills are VERY brittle and break easily unless you hold the drill with vise-like hardness. And the fact that one of these babies leaves a broken tip at the bottom of the hole is the LAST thing you want to deal with. Don't ask me how I know that. :)