Drilling Hardened Steel

M

me2

Joined
Oct 11, 2003
Messages
5,105
Does anyone have a way to drill hardened steel? I have a couple of blades I'd like to drill holes in, but I cant mark them with a punch, let alone get a drill to cut them more than halfway through. One is 440A, the other is Carbon V. I've also thought about ordering some other alloys already hardened, stuff that is too complicated for me to heat treat. Thanks for any ideas. I mainly just need to drill holes for handles and pivots etc.
 
Only way to drill hi rockwell hardened steel that I've found is with a carbide spade bit. Or you might try spot softening. A spade bit is only suposed to drill half it's dia. if I remember rite. Spot softening is where you chuck up a nail and set your drill press at the highest speed and try to drill with it. It'll make the nail glow and the spot where you want to drill heat up and start changing colors. When that spot gets blue a little around where you want a hole stop and let it cool. Try center punching, if it'll punch drill with a cobalt or Titanium Nitride bit. If it's still too hard you may have to repeat the spot softening a couple more times. Easist way by far is to grind and drill and file the sofened steel and then send it out for heat treat, that's what I do with stainless steels since I don't have the equipment to heat treat them myself.
 
I do not know how big a hole you need but I have found that a masonary drill can do the trick. You know, the type they use for drilling into concrete.

The tip is carbide. You just get it sharp on the grinder (better if you have a green stone) and it will work. Screams like a banshee but what the heck.
Otherwise a solid carbide bit.

Good luck.

Mike
 
Another carbide drill alternative is called a "Hi Roc". It is a two flute 135* point that cuts a cleaner hole and is a little less fragile than a spade bit. Expensive.

Google "Hi Roc drill".
 
Try annealing the spots with HD/Lowes Blowtorch.
In a dimly lit room, heat the spots up to bright red,
back off the flame slowly, don't water quench, let it
cool in the air.

And of course be careful not to anneal the blade's cutting
edge itself.
 
This works ever time.

torchcu1.jpg
 
I dont know that spot annealing will work on the 440A, since I think it's air hardening. A cutting torch may work on the CV, but I'm not very good with one. Looks like its off to find a carbide bit. Thanks guys. There have been some suggestions that spot heating and drilling while hot would work. What do you think? I'm hoping for a method that will work on M2 as well.
 
Me2,
I cannot resist after reading about the M2 as well but you had to see it coming...
You may want to drill the holes before you harden these things. Sorry...:foot: :D :D

Mike
 
If you use a carbide drill, be sure that you back your work up with another piece of soft steel. If you don't, when the drill breaks through your work it will grab and break the carbide drill.
 
If you go to the expense of a carbide drill, don't forget to use cutting fluid like tap magic. It does wonders at little expense. Also don't be tricked with a Chineese TIN Coated drill. They are Junk. A good HSS American drill will do a better job than they do. Now an American Made TIN Coated drill is a different story. Also don't waste your money on a Chineese made Carbide drill or their inserts either. You will get much better results with a Quality American Made drill I promise. I finally learned the hard way myslelf. You can buy a 113 piece TIN coated set of american drills for around $100 compared to $35 for the Chineese set. The American set will last you a long time
 
longline charlie said:
If you go to the expense of a carbide drill, don't forget to use cutting fluid like tap magic.
Click to expand...

With carbide, unless you're able to flood it, run it dry. It works better. Remember to clear chips away and don't push too hard.

Jamie
 
I recently drilled some bolster holes in a hardened blade using an 1/8" carbide bit I bought from Northcoast. The bit looked like a a refurbished electronics industry bit. It had no point and I needed to clamp the blade to the table but I did cut two holes O.K. The bit was advertised as brittle and it seemed to break up as it cut. They claimed it would do 2 or 3 blades. Maybe I can do another. It cost $1.80. The hole ended up a little oversized.
 
I sometimes grind a slot in hardened tangs for pins...for a pivot pin hole I have used grinding points in a Dremel for a half hour...true and polish the hole with a tapered pin and valve grinding compound.
 
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