So 15n20 is some tough stuff

Justin Schmidt

Justin Schmidt

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Feb 18, 2016
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Just got some .120 15n20 from chuck the other day. Tried drilling 2 .257 (cobalt F drill bit from USA knifemakers) and it burned up the biit. I started on the slowest speed 660rpm and got nice curly Q' s. Got halfway through the material and the bit would lock up. Upped it to the next set of pulleys. 1100 rpm. Chart said it would be good at this speed for hardened steel. Then it wouldn't cut at all, no chips or anything. More pressure and it squealed and smoked. I used cutting fluid and chicken pecked the entire time.
Tried a dewalt gold hss. 250 bit. Nothing .
Put it in my hand drill. Nothing. Man this stuff is tough!
Should I anneal it? Just ordered 2 more bits from Tracey
 
Use the slowest speed possible and some oil for coolant while drilling. Stinks but I have used gear oil in the past because it is good and thick and stays on the bit longer before it thins out from the heat. I can believe the 1100 rpm if it was 1018 steel, not 15n20.
 
Have you hardened it? I drilled the stuff from Aldo last night and it drilled like butter. If its hardened you probably need to do a local anneal or use a carbide bit.
 
when that happens to me with some 5160 i spot annealed with a torch. After that the steel drilled very easy. It is very important to use correct pressure/ pecking and keeping that heat in the chip and away from the work piece. If also like to use jobber drills or sink the drill up in the chuck far enough so that you are not getting any deflection. Having a rock solid base with zero movement is also key.
 
Most 15N20 is harden to 45-47 Rc and is hell on drill bits. I anneal it when I need to drill holes.

Aldo has the only annealed 15N20 that I know of. Chuck's might be, I don't know?
 
Don Hanson III said:
Most 15N20 is harden to 45-47 Rc and is hell on drill bits. I anneal it when I need to drill holes.

Aldo has the only annealed 15N20 that I know of. Chuck's might be, I don't know?
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That would make sense. Thanks for the replies Everyone I'll just spot anneal the steel before drilling
 
Be carful spot anealing 15n20. It can have a tendency to air harden if heated and left to air cool. I found this out the hard way on damascus. My 15n20 comes from bandsaw blades and sits at 42-43rc and drills fine. But the trick to drilling steel is to go as slow as you can. The charts are all well and fine but usaly end up being for perfect conditions in a ridgid machine like a mill with coolant. And even the on those machines I never pushed them that hard.
 
JTknives said:
Be carful spot anealing 15n20. It can have a tendency to air harden if heated and left to air cool. I found this out the hard way on damascus. My 15n20 comes from bandsaw blades and sits at 42-43rc and drills fine. But the trick to drilling steel is to go as slow as you can. The charts are all well and fine but usaly end up being for perfect conditions in a ridgid machine like a mill with coolant. And even the on those machines I never pushed them that hard.
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I only sped up the drill because the bit would "stick" but I see what your saying.
How should I anneal it? All I have is a 2 brick forge for heat treating.
 
I can drill it ok as is, getting the steel from chuck. I can usually drill about 5 blades per drill bit. The best I found so far are cobalt masonry bits from ace hardware. If I use enough cutting oil I can get a little more than 5. But the bits are about 5-7 bucks per bit. After that many, sometimes the cutting bit tears out. But I’ve tried many different bits, and these are the best I’ve found so far! But 15n20 is some really awesome steel!
 
rodriguez7 said:
I can drill it ok as is, getting the steel from chuck. I can usually drill about 5 blades per drill bit. The best I found so far are cobalt masonry bits from ace hardware. If I use enough cutting oil I can get a little more than 5. But the bits are about 5-7 bucks per bit. After that many, sometimes the cutting bit tears out. But I’ve tried many different bits, and these are the best I’ve found so far! But 15n20 is some really awesome steel!
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Jeez this stuff is crazy tough then. Wonder how I should anneal it without having it air harden on me
 
sounds like its hardened and tempered, the stuff I have certainly is. heat it up to nonmagnetic and put it in a bucket of vermiculite overnight to soften it. Then soak it in vinegar (white wine) for another day to remove the scale.

-Jeff
 
valknut said:
Jeez this stuff is crazy tough then. Wonder how I should anneal it without having it air harden on me
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Drilling 3v is a little tougher! But everything I buy, and drill seems rough as hell on drill bits. I couldn’t imagine drilling and grinding s110v or something like that!
 
It's not difacult and no need for special bits. Heat the blade in you forge till it's a nice red forging temp and quickly take it to the drill press and drill a hole. It's called hot drilling and works amazing. No pecks and don't go slow. I'm not saying to ram it home but don't hesitate in the steel. There has not been a steel for me that this has not worked on.
 
I have had the same problem as the original poster too. I had good success heating the spot to red with a torch and then quickly drilling - like JT says. But it is still a pain. I just annealed my last batch of blade blanks in my furnace and now they are super easy to drill. I plan to keep annealing all my 15n20 going forward. It also cuts so much easier on a bandsaw after annealing.
 
Bamph said:
I have had the same problem as the original poster too. I had good success heating the spot to red with a torch and then quickly drilling - like JT says. But it is still a pain. I just annealed my last batch of blade blanks in my furnace and now they are super easy to drill. I plan to keep annealing all my 15n20 going forward. It also cuts so much easier on a bandsaw after annealing.
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Wish I had a oven for stuff like this lol
I'll try hot drilling it and see what happens
 
We have a bunch of 15n20 . We anneal all of it in the kiln. If you don't have a kiln heat to a nice even red in your forge and bury in ashes or vermiculite. Will drill like hot butter
 
Kentucky said:
We have a bunch of 15n20 . We anneal all of it in the kiln. If you don't have a kiln heat to a nice even red in your forge and bury in ashes or vermiculite. Will drill like hot butter
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If I end up liking this 15n20 I'm gonna have to invest in vermiculite. I'll try tj method of hot drilling first
 
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