Cracks Near the Cho of my Ang Khola?

M

Maltheus

Joined
May 14, 2001
Messages
4
Ok, I just received my first Kukuri two days ago. I went with the 15" Ang Khola as I wanted it for backpacking. I love it it and promptly went on to order a 25" Kumar Kobra today (I'm sure that'll be it though...hehehe).

I haven't used my AK for much of anything, so I'll assumed they were there when shipped, but I've noticed two little hairline cracks extending a little less than a quarter inch from the cho towards the spine. They don't make it all the way through the knife as they are only visible on one side. Should I be concerned with these?

I know there is a lifetime warranty and I don't plan to hack into any oil drums, but I do want this to be my indestructible wood chopping knife and I don't want to put myself at unneccessary risk. I've read about other peoples' concerns over the chos on some of these knives and I think that has me a bit paranoid now. I'm planning some longer, more remote, camping trips in the near future and it's very important to me to have a knife that won't fail so I'd appreciate some of your opinions of this.

Thank you!

--maltheus
 
I would suggest you fix up the knife using any of the recommended methods i.e superglue. Take it out and test it to see if it suits your needs.

Will
 
The AK is pretty beefy. I don't think you have anything to worry about.

If it were my knife I would take it out for some heavy chopping and prying, trying as hard as I could to break it. If it survived, I would keep it and trust it. In the unlikely event it broke, I would send it back to Bill.
 
Maltheus, I'd go along with Howard's suggestion and test it out now, rather than wait until you're out backpacking before testing it. Better to have it fail now rather than spoil a good backpacking trek. I am assuming that the hairline cracks are in the steel of the blade rather than the wood. If in the wood, then Will Kwan's suggestion is a good start.

Take care and let us know how your testing goes,

Harry
 
Those tiny cracks near the cho are cosmetic and should never cause a problem. Testing builds confidence. Put the knife thru some rigorous testing, more severe than you'd ever encounter under normal circumstances and see what it tells you. I'm betting the AK will survive the tests.

And welcome to the Cantina, Mal!

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Blessings from the computer shack in Reno.

Uncle Bill
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[This message has been edited by Bill Martino (edited 05-14-2001).]
 
Yes, welcome to the cantina Maltheus
smile.gif

I'm betting on the HI Ang Khola smiling at you the entire time your testing it.
 
I suggest for extreme testing that you wear heavy gloves (welder's gauntlets if you can find some) and some safety glasses (available at your local home-improvement store). Khukuris can be replaced, most body parts can't.

Hope the safety officer approves of this!

--Mike L.


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What goes around...comes around.
 
I still haven't run a stress test. I live in an apartment, and probably won't get a chance until the next time I go hiking. But I can now include a picture:
KukCrack.jpg

They don't extend beyond the diameter of the circles I've marked. They don't really look ornamental. But they don't look that bad either.

By the way, does anybody know which Kami this mark belongs to? I've checked the FAQ and it doesn't seem to be any of the symbols listed.

Well, I'll report back on the stress test when I get the chance to run it. As I said, it's kind of hard in an apartment. I don't have enough wood lying around. Does anyone have a good suggestion for a safe prying test (other than prying open a safe, that is)?

Thanks!

--maltheus
 
Sorry, I misunderstood where the cracks where. My guess is that these will not cause you any trouble.

You could try using it as a lever in the apartment. For example try lifting a desk by putting the blade underneath one of its legs. Support the blade on a book and push down on the handle. Bear in mind that a lever can amplify the forces and keep it within human limits.

Will
 
Maltheus - The mark is the butter lamp, for the kami with no name. I have a 12" AK which has indentations at exactly the same locations as in your pics. They looked to me to "witness marks", to locate the position for cutting the cho.
BTW, a 25" Kobra is one whale of a blade. While I would (if I could still navigate) carry it into the woods, I'd do it out of the feeling that I couldn't get a much more powerful blade. It ain't no l'il plastic handled "hiker's special" - it is a KNIFE. No other way to spell it.
Uncle - I noticed (while "cho checking") that the dish portion of Mal's maker's mark is plain, and the mark on my AK has a "/\" in the center of the dish. Do these guys come in togother and collaberate on one knife at a time, or work singly and modify the mark they share? More trivia to add to Khukuri lore
smile.gif
 
Maybe some technical remarks on what happened here are interesting.

The blades of the HI khukuris are edge quenched with water. This method is not as rude as but in it's effect still very similar to the method used by the japanese bladesmiths. During the hardening process first the entire blade is heated. During this heating process the structure of the steel changes from cubis room centered to cubic face centered. This means that the carbone atoms move from their position in the center of an iron atom "cube" to the faces of the same "cube" forcing the iron atoms outwards. That's why the cubic face centered structure is bigger than the cubic room centered.
During the edge cooling process the steel of the edge part of the blade is "frozen" in this bigger cubic face centered mode, making the edge hard and brittle. The slow cooling spine part of the blade returns to the cubic room centered mode and shrinks at the same time.
Now if the edge stays big and the spine shrinks, guess what happens? Yes, the blade bows upwards! A japanese katana blade for example is dead straight before hardening and has a bow up to 2.5 inches deep after hardening.
The problem with the cho is that it acts as a stress collector for the whole shrinking stress of the upbowing blade. So if the place around the cho is hardened together with the rest of the edge these small stress cracks in this part of the blade are very hard to avoid. I think that it is not new to the old members of this forum that the cho is a major flaw in the construction of a khukuri blade, but is still an important part of these blades in a more historical way.

I would NOT think that these small cracks would weaken such a blade to an extend, as the spine of the blade is very thick and soft at the same time. If you want to be sure to get no problems get yourself a small hard metal or diamond coated file (one of these small round diamond hones will work) or some medium grain sanding paper around a small stick and just grind the cracked place until there is no more cracks visible on the surface.

I hope you could follow my explanations.

Achim
 
I thought it was the sweet spot that was hardened . . . I figured the cho was uniform hardness spine to leading edge (that hardness being very soft, if you can follow that.) Is there a gradient of hardening down by the bolster, or is it all just about dead soft?
 
Test the khukuri. Even if you get a "perfect" one you won't know for sure until you put it through its paces. Plus its fun
biggrin.gif
!
 
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