Drilling into hardened steel

[Risser]

would like some tips on a good drill bit product for drilling into hardened 440c stainless.

 

[KenOnion]

Carbide spade drills, coolant and appropriate speed faster for small holes 1/16-1/8 slower for larger

 

[Dr.Lathe]

Carbide drills are the only thing that will work! If I have to drill into hardened blade steel, I use a high quality carbide drill and Cool Tool 2, cutting fluid. Both available from MSC. I run the drill at about the same speed I would if I was drilling soft tool steel with a High Speed bit. Don't spare the cutting fluid either. If the hole is over 1/4" I would go through with a 1/8" hole first. I always have access to a diamond grinder to resharpen the carbide drills. I average about 2 holes between sharpenings with a fully hardended knife blade. The best thing is to not wind up having to do this!!!!
Good Luck!

 

[george tichbourne]

For the rare times I have to drill hardened steel I use the cheap cemented carbide masonry drills available at the corner hardwarre store. I run them dead slow with lots of oil. They have to be sharpened after 2 or 3 holes but that is no problem on a diamond stone.

Don't get them too hot or the brazing will melt and you will lose the carbide insert.


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george
www.tichbourneknives.com
sales@tichbourneknives.com



[This message has been edited by george tichbourne (edited 02 September 1999).]

 

[T. J.]

One trick to using carbide spade bits is to use a backing piece of scrap steel to keep the bit from chipping when it exits the work piece. Just be sure not to drill too deep into the backer, because spade bits are depth sensitive. If you go too deep, it's gonna break on ya. I'm gonna have to try the masonry bit ideal, it's gotta be cheaper than 7 or 8 bucks a pop.
James