Invest in some good carbide drills, and a carbide burr/ rotary file to grind a dimple in the center of the tap if need be. Drill it out a little at a time, go slow. If you know someone that is a kick a&$ welder, they can weld a chunk of steel onto it to apply torque like a wrench.
Tap extractors rarely work well, they work only if the tap is somewhat loose already. This hardly never happens because the tap is tight when it breaks.
To cheat it out with a hammer and punch, changing directions can break the chip and loosen it up.
A worn or dull tap will be more prone to breaking. Investing in new high quality taps is worth the money, and this is the reason why.
Feral cat waterboarder
Last edited by primer1; 08-13-2013 at 06:37 AM.