Drilling Hard Steel help

Dan308

Active Member
Can someone help me out with drilling 3/16 holes in hard steel? I'm using tin coated bits with oil and slow speed and they are screeching and dull/breaking. My drill speed is slow, cutting oil is used. I heat to critical and cool the steel. then grind and shape. It's the small holes holes that are problems

I switched to cobalt drills. It made it easier but I can tell they won't last long. Any opinions on going to solid carbide spade bits?
 
Hello Dan , Boss has some C-4 carbide bits that are very reasonable . I use them all the time . Make sure you get some good cutting oil .
they work great..... Bubba
 
Carbide bits are the answer.....but carbide needs to be run at higher speeds, with constant flow lubricant/cooling when drilling hardened steel. Another approach you might think about trying, is to add an annealing step in there....then you'll be able to use standard high-speed steel bits.

You didn't mention the steel type your using, but even oil/water quench steels will experience some residual hardening when treated as you described.
 
Thanks for the info, I was heading the carbide direction. The steel is 1095. I heated it to non-magnetic and let it cool first. I thought that would anneal it sufficiently.
 
If we are talking about drilling holes in the tang you should be able to draw the temper enough to drill it. Stick the entire blade section point down into a can of wet sand far a heat sink and use a torch to heat the tang. You don't need to do it until you see color but you will want to keep the heat on the tang for a few minutes. To prevent this from happening in the future, only normalize the tang and try not to bring it up to a austinizing temperature when you are austinizing your blade prior to quenching. Then keep the tang out of the quenchant until a dark heat.

Doug
 
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I drill the handles before Heat Treat to get around this issue. I used to use Stainless Steels like CPM S30V or D2 Tool Steel and I didn't want to have to drill after Heat Treating. One guy recommended using whole milk as a cutting fluid, something about the fat in the whole milk helping the drill bits bite into the steel better??
 
I normally dont have a problem , especially with japanese blades because the tang gets coated with a heavy coat of clay and does not get that hard. I drill my holes after ht so I can line up the handle and mekugi with the ito cord . In your case It would be differerent. Drill them before ht ....... or use a Laser beam .........
 
when i use tin, or cobalt i use soapy water for a cooliant. but if the hole is in the tang and not to close to the blade i would just draw the temper down.
 
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