Product Features. 1/16 to 1/4 by 1/64ths (Does not skip any sizes) Niobium Nb41 Steel; Left Hand Thread (Flutes are Counterclockwise) Used for Removing Broken Bolt, Screws, and Studs ...

Cobalt left hand drill bits are also available, although not as prominent. These spin in a counterclockwise motion and can ...

Place your drill with the left-handed bit over the bolt and into the pilot hole you created. Once you start drilling, don't spin the bit too fast; this process works much better at a slow speed.

Used in a hand drill, it's not hard to break through the coating and then you just have a plain HSS bit.<BR><BR>I've used cobalt bits to drill the case hardened head on allen bolts for safety wire ...