Tang Hardness

[i4Marc]

What is best practice with tangs? Can tangs be left the same hardness as the blade? Is it ALWAYS better to spring temper or go full-soft? In this particular case I am thinking of a hidden tang but the question applies to all tangs.

 

[Richard338]

It's an interesting question although I can't imagine anyone destruction testing one of your knives.
People who are into abusive testing like CPK, to my knowledge treat it uniformly, although those are mostly full tang.
My guess is that unless you need to pass a bladesmith test involving large bends, you should be fine at full hardness. It would be interesting and horrifying to do some FIF type testing to see where it fails first...

 

[Sam Wilson]

I have done a tremendous amount of abusive testing and some destruction testing, on the majority of the knives tested (my own), the tang wasn't the point of failure. The vast majority of the knives had the tangs at the same hardness as the rest of the blade.

I typically leave the tangs hard, unless I am drawing the temper back for a reason (hardware, threading, etc.) The tang is (on hidden tang knives, anyway) fully or almost fully encapsulated in micarta/G10/steel and epoxy, so it is reinforced rather well, if the knife is made properly.

Sam

 

[i4Marc]

Great, thanks guys. The tang in question at the moment is for an A2 chopper, 10.5" blade. The handle is paper Micarta. System Three T88 epoxy. pin through handle. The tang is quite robust, seen here:

https://www.instagram.com/p/CGjPxApjJ_a/

Sam, it is reassuring to hear that full hardness tangs have held up well for you. I will leave it full hardness then. But I'll need that carbide drill bit to make the pin hole.

 

[Sam Wilson]

That tang looks pretty robust, I don't think I'd be concerned in the least. Carbide is the way to do it, zip right through. Sounds like a good plan, looking forward to seeing it.

As to the destructive testing, the only time I had the tangs themselves break is when I intentionally broke them. The rest of the time, the blade bent or snapped elsewhere, depending on the stress load. There will always be an exception, but I'm not really concerned about it anymore.

Sam

 

[i4Marc]

It's an interesting question although I can't imagine anyone destruction testing one of your knives.
People who are into abusive testing like CPK, to my knowledge treat it uniformly, although those are mostly full tang.
My guess is that unless you need to pass a bladesmith test involving large bends, you should be fine at full hardness. It would be interesting and horrifying to do some FIF type testing to see where it fails first...

Richard, my concern isn't really an immediate one. I think most of the folks who acquire knives from me directly know what they are appropriate for. In this case I am building this knife for an elderly gentleman. He'll probably do some test cutting with it to play with it but it will likely spend most of its time in a safe. My concern is that since the knife will end up in someone else's care eventually(hopefully not too soon), it may not be treated with the same respect as the original owner might. Of course ALL my knives are built to do work but the customer has requested a Micarta handle which will seem more like a user than a collectible. And that is fine. I wish more people used them. I know I'm over thinking it but I have visions of the knife being handed down to some dopey kid who tries to cut an I-beam in half with it. Thanks Forged In Fire! I just want to make sure this knife won't come back for warranty repair in the future.

 

[Richard338]

I understand, I send mine out for HT, and I always discuss it with them and ask for a tough protocol. Some of them like a chopper I made get used hard, and some not, but I always want the capability to be there. I don't sell mine, so other than my kids I don't have to worry about how someone else might use it.

 

[Robert Erickson]

Looks great Marc, I don't think you'd have to worry about that tang. A2 should have pretty good toughness at RC60 so that should help as well. What hardness did you get?
With A2 being air hardening, what would your procedure be for drawing back the hardness in the tang? Just use a torch?

 

[AVigil]

. I know I'm over thinking it but I have visions of the knife being handed down to some dopey kid who tries to cut an I-beam in half with it. Thanks Forged In Fire! I just want to make sure this knife won't come back for warranty repair in the future.

Most the knives on "Forge in Fire" look horrible.
Yours will be a gem in comparison and end up in a drawer and brought out to oogle over.

 

[i4Marc]

Thanks Adam! Yours will be oogled. Mine will be traded for a pack of smokes. I don't mind my knives getting used at all. I just hope they are educated users.

Rob, I got almost 66Hrc out of the dry ice. I tempered down to 60.5. Yes, if I were to soften the tang I would use an O/A torch.