Hardened Carbon Steel

[Chief]

A couple of threads down the topic of drilling stainless steel was discussed.   Carbide spade brills seemed to rule the day for that material.  Is the same true for the hardened high carbon steel (specifically the Nicholson knife blanks they sell on e-bay)?  I never did figure out how hard the blanks are treated to but my dad says he can't get a bit through the them except right on the tang itself.  I haven't tried to drill them yet but was wondering if those diamond bits for dremel tools or maybe dental burrs would do the trick.  Dad says he tried carbide drills but I don't know if they were carbide spade (or if there is even a difference).  Any thoughts?

[Will52100]

Carbide bits should drill it, though you have to go slow and they are fragile.  Anougther way is to "spot" aneal, take a worn out drill bit or round bar of the size you need and use a drill press to drill the spot you need drilled.  Let friction heat the spot till it's a light red color and let air cool, you should be able to take a good drill bit and drill it then.  You can also take a torch and heat a rod to an orange heat and hold the hot rod to the spot you want sofened and watch your colors and when the spot gets blue/gray cool the blade down with a little water and drill.

Hope this helps,