drilling holes in hardened steel

clint c

clint c

Joined
Aug 21, 2001
Messages
397
I screwed up and didn't drill enough pin holes in the tang of two ATS-34 knives befor heat treating them. They came out at RC 60.5, so are mighty hard. Tried localized heating the area w/torch, but cobalt bits still skate around instead of grabbing. Is carbide the answer , or it there a better/cheaper way to do this?:(

Clint Chisan
 
Made trhe same mistake myself. Tried everything I had and then- bought some carbide drill bits from MSC - did the trick.

Bob
 
Gotta go with carbide. Cobalt will just cost you wasted money on ruined bits. I've also ruined a many a ginding stone trying to ream out that stuff.

At least you know you hit the heat treat

RL
 
there is one other way if you don't feel like running to the store. take a old drill bit and grine the end flat. put in in the chuck and press down with just a little pressure until the tang gets red hot. let it air cool and it should be annealed enought to drill with the cobolt drill bit.
 
I'll give you the same advise as I gave for drilling stellite, use Hi-Roc carbide drill bits from MSC or one of the other suppliers.These bits are designed to cut materials up to 65Rc I believe. The have saved the day for me when I have had to put a few extra holes in a hardened blade. I have not had very much luck in spot annealing or torch heating and air cooling any of the air hardening steels that I have used. They simply will not get soft enough to drill with even the best cobolt bits. Only you can decide if the carbide bits are worth the price.
 
The hi roc are the way to go, you won<t regret buying them Just use them with care, In a emergency try masonary bits they have carbide tips and some brands cut quite well but usually a little oversize.
 
The way I got let in on, when I made this type of mistake, is this:

Go to the local hardware store, and buy some of those glass-drilling bits, in whatever size you need. They're shaped like a little spear, and coated in diamond dust, or bits of Excalibur, or something, but they do the job. You may only get a few holes out of each one, depending how much pressure you use, etc., but it's usually cheaper than Carbide, and easier than spot-annealing.

Just my two coppers. Hope it helps!

:D
 
Thanks guys. Carbide it is then. L-6, thanks for your personal e-mail help also. This post is related to my other current post about sheep horn handles, by the way, just in case your interested in how I got in this stupid situation!

Clint Chisan
 
Hi Clint.
when i did the same thing a while ago i wrapped the tang in wire about 1/2" thick where i wanted it annealed. and then got it red hot with a torch, this allowed the steel to cool more slowly and anneal to a state that can be drilled easily.
 
Hagar,

You can clamp the knife close to where you want to heat it in a heavy vise for that too. Clamp tight to sink the heat away from unwanted areas of the knife.

RL
 
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