Drilling hardened steel

F

Frank Skufca

Joined
Nov 1, 2002
Messages
4
Bought a 7/32 Cobalt drill bit to enlarge bolt holes in stainless steel tang. Set the drill press to 620 rpm. Used oil to cool it.

All I get is a HOT drill bit, smoke, a squealing sound and very little actual drilling. Am I using too much/little pressure? Too low/high speed? I'd appreciate any help or advice - as you can tell I'm not a machinist!

Frank Skufca
fskufca@utech.net
 
Just a couple of red hearings
1. You may be able to buy a small abrasive dremel bit with a point.
You may be able to come from each side.

2 if you have a gas touch you may be able to heat the hole red hot put the tang over a harger hole and drive a tappered rod through pushing out the size of the hole. I have done this with larger black smithing projects. However such a small hole you may just end up locking the tappered rod in the hole and then you would want to stick the sharp end in my blunt end.

3 very similar to 2 but you would not use a tapper you would just punch a larger hole with an oversize flat end punch. naturally you would have to be carefull not to over heat the cutting section and loose the heat treating.

The tang area to be punched or streched would need to be past red heat. Try it on some scrap first.

Good luck
 
Frank you need a carbide drill bit. Run it as slow a possible. If the bit gets hot it will break. hope this helps.
 
Carbide will work but it will have no flex at all and will break very easily. I drill stainless all the time where I work. You want drill bits that are marked HSS. They are silver in color and will drill stainless much better than the black jobber drills. You want high speed steel bits.
 
Well Guy's i can Honestly say been there done that !! I Use Solid Carbide Drill Bit's Used in Construction Of P.C. Board's They are Brittle But They will Drill Most Any Steel With R.C. up to 65 !! I THink I Saw some at the Local H.F store here !! The size Selection is not Great But you will find a "Bit" that will drill it
Good Luck !!
 
I would grind the holes out. Worst thing you can do to a drill bit is try to ream a hole. This puts the cutting pressure on the margins of the bit while the center bearing area is over empty space.
 
Believe it or not, a masonry bit works as well as carbide, for drilling hardened steel. Cheaper too. The only problem might be, finding it in the right size.
BTW, Frank, welcome to BFC.:D
 
I sent some 440c blades to paul bos & forgot to drill them. When I got the hardened blades back, I used 135 degree, 2 flute solid carbide Atrax drill bits from MSC to drill the holes - no problem. Watch your speed and use a coolant/lubricant.
 
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