[parishht]

Ok, I have to jump in on this one.

My job as a heavy truck engineer requires that I know how to drill hardened metals,
i.e. 140,000 psi tensile.

A standard metal cutting drill bit will work, but, when you sharpen it
make the angle 15 degrees, do not force the bit into the metal,
it will only burn it.
do not run the drill at high speed, again burn up the bit.

Slow speed, 15 degree angle and constant pressure,
you will see a ribbon of steel being cut, this is correct.
You should not see chips.

Last but not unimportant, cutting oil or a little motor oil mixed with water.