Drilling Hard Steel help

D

Dan308

Joined
Jan 5, 2012
Messages
104
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?
 
What type of steel?

By heating to critical and slowly cooling, some steels will create lamelar pearlite which is bands of harder steel through soft steel. I'm thinking that these are the hypereutectoid steels, but I'm not sure. These have to be annealed by heating to critical, then cooling to black heat (?) which is 900 degrees F (?) and then quenching.

Someone smarter than me please confirm.

Eta: I think I misread the question. I still want to know if I'm right though.
 
What is the steel you are using? and what is your method of heating and cooling?
 
The steel is 1095. I heated it to non-magnetic and let it cool first. I thought that would anneal it sufficiently.
 
Turn off the lights and heat with a torch until very dull red then allow to cool. Do this several times and it should be soft enough to drill. Use Carbide tipped masonary bits from any hardware store. They are cheap and easy to find. Start with a small pilot hole (1/8) then work your way up from there. Speed your drill up for the smaller bits. Press firmly then let off and repeat until you have your hole. That works for me, anyways.

If you need to, you can use a cone shaped drimel stone bit to enlarge your hole.

Jason
 
jawilder said:
Turn off the lights and heat with a torch until very dull red then allow to cool. Do this several times and it should be soft enough to drill. Use Carbide tipped masonary bits from any hardware store. They are cheap and easy to find. Start with a small pilot hole (1/8) then work your way up from there. Speed your drill up for the smaller bits. Press firmly then let off and repeat until you have your hole. That works for me, anyways.

If you need to, you can use a cone shaped drimel stone bit to enlarge your hole.

Jason
Click to expand...

"I heated it to non-magnetic and let it cool first. I thought that would anneal it sufficiently. "

Did it. I also used carbide tipped masonry bit, Bosch blue brand. Tip broke off 1/2 way through, oil was used. I was using short pecking pressure. If I could drill a 1/8 pilot hole, I would.
 
heating to non magnetic once and letting cool is not the same thing I suggested. Non magnetic is not the same temp as dull red with the lights off. Try it and do it several times before you try to drill again. If the tip broke off you might have been using too much pressure.
 
You can always buy some Full Carbide Jobbers Bits, they are brittle and cost A LOT... But they will get through the material.
 
Dan308. I normally just back out of these posts because the OP did not have his profile filled out. If you are near a maker they might be able to help you out. If you live near me I would be happy to put a couple holes in your steel for you. You could even mail it to me if you like with return postage attached. Please update your profile.
 
A C Richards said:
Dan308. I normally just back out of these posts because the OP did not have his profile filled out. If you are near a maker they might be able to help you out. If you live near me I would be happy to put a couple holes in your steel for you. You could even mail it to me if you like with return postage attached. Please update your profile.
Click to expand...

:thumb up: Class act as always Chuck!
 
I was having the same problems, drilling through hardened 1095. solid carbide drill bits are great. they cut through the hardened 109 like a regular bit going through mild steel. they are not cheap, but im still using the first ones i bought 2 years ago.
 
thanks Mr. Richards, but it's the old "give a man a fish, teach a man to fish" thing here.

mxlj what are the carbide bits you bought? I'm thinking Carbide Straight Flute Drill Stub Screw Machine Length. Do you think this would be a good choice?
 
well i cant remember the exacts, but they are solid carbide straight flute about 3" or so long. depending on where you buy them, some are made/listed to drill through harder materials than others. I think some are for ceramic, some are only for drilling through maybe 50rc hardness material. I bought ones that were for drilling through hardened steel up to 65rc.
 
Dan yes those will work. The problem with drilling with carbides are they require a very rigid set-up. They have to be in a vise and the drill press must run true. They can be used in less than ideal conditions but they will frequently break. I use my mill and carbide end mills to put holes in hardened steel quite frequently. If you have a machine shop in the area go in and explain your dilemma. When I worked at a shop I would punch a hole for a guy just cause. Offer still stands if you can't get it drilled I would be happy to do so. Oh and thanks for updating your profile.
 
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