On 4/15/2012 5:23 AM, David Lesher wrote:
So I broke off a M3 tap in a block of 0.5" aluminum.

Its tip is barely emerging on the far side, and broken below
flush on the feed side.



I've often had luck by grinding a O-1 drill rod of the right diameter to
fit into the flutes of a 2,3 or four flute tap. Harden the rod and draw
it back to dark straw. Then, carefully unscrew the tap.