Quick question: whats the best drill bit for drilling really hard steel?

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Hi,

There is a bit more to hard drilling than just carbide drill run slow. As a machinist, I do hard machining more than I want to sometimes.

First, you will need a rigid setup. Hand drills are worthless, cheap drill presses almost so. The drill needs to have good power. Your work needs to be clamped down firmly so it can't move. While drilling hard can be done dry, flood coolant is to be preferred. Don't use oils, it won't carry heat away fast enough. Use water soluble/based coolants.

Be careful of your speed and feed rate. Too slow rpm's can be as bad as too fast. Feed rates need to be fast enough to cut well without breaking down the cutting edge. Yet too light a feed rate causes rubbing and excess heat also ruining the cutting edge. Everything needs to be "balanced".

dalee
 
The reason I ask is that I can't find any 7/32 bar stock locally to match the holes in my Fallkniven F1. So I thought I'd just bump that up by 1/32 to 1/4. You wouldn't believe how tough the steel in that knife is...I think my best bet is to just order some nice 7/32 pins...thanks again guys.
 
Or you could ask somebody with a lathe to chuck some larger stock and turn it to 7/32.
 
Been searching for an answer myself for this one. I've broken punches trying to mark old Cold Steel scalper blades, which Rockwell tested at 59-60 HRc, and spent about an hour trying to get through some M2 hardened to about 64-65 and I'm about half way through on 1/16" thick stock. Finally I said forget it, its time to learn hidden tang construction anyway.
 
I have attempted and failed at this too. I have ruined over a dozen drill bits trying to bore out tang holes. Clamped down on the drill press cutting with a variety of speeds with pricey carbide bits and coolants. If the bit loses its edge and binds inside the hole, the bit just snaps. And if it doesn't snap, once you lose that cutting edge, its garbage.
 
You need to grind it out! As mentioned earlier you will not be able to drill it without specialized tooling.
 
scotchleaf said:
The reason I ask is that I can't find any 7/32 bar stock locally to match the holes in my Fallkniven F1. So I thought I'd just bump that up by 1/32 to 1/4. You wouldn't believe how tough the steel in that knife is...I think my best bet is to just order some nice 7/32 pins...thanks again guys.
Click to expand...

The 7/32" holes in the F1 blank are for 5/16 Corby screws.
Jantz supply sells Corby screws.


Regards
Mikael
 
For detents I have used a 1/16 inch diamond ball in the dremel. I too am trying to drill a hole in a knife--to convert the BK13 into a friction folder.
 
I would add that, in my limited experience in machining, making existing hole bigger using carbide bits (even with a proper fixture in a CNC mill) is not advisable- a small misalignment or off centre entry and the bit snaps like a dry twig. In that scenario I'd recommend spiraling the hole to desired bore with end mill on a CNC machine...
 
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