Just an observation on HI kaudi/cho....

J

JimmyJimenez

Joined
Sep 30, 2005
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I've been admiring the DOTD photos that Yangdu puts up.

One thing that I have noticed, at least by comparing them to the many older HI photos on the internet, is the apparently different kaudi/cho sizes.

Many of the older photos of HI products seem to show somewhat larger cho/kaudis than what is usually seen today. Then again, it may just be my imagination, in which case............ scratch my observation altogether ;)

I do believe that there may be some benefits to a smaller kaudi/cho area.
The most obvious would probably be that the less metal displaced or removed from this area, the ever so slightly stronger that area of the blade may be (at least it would seem to make sense that that would be the case).

The other "possible" advantage is the less chances of causing what "I" now believe may be pretty common with products coming from KP, KH, and NKH, which is kaudi/cho fractures.

I'm sure many of you have seen videos or pictures of how they set this notch in during the forging process. It involves pounding a piece of steel (the cho tool?) into the blade to form the notch. This may be the main reason the kaudi/cho fractures develope. At one time I wondered if it was probably more a situation caused during the heat treatment of the knifes edge, but after watching a video of how this area is initially pounded in, I can see this step being more of a culprit. When one takes a look at a cho, one notices that it is not only the pounding of this cho tool that makes the final shape, but also that some filing is involved to finalize it.

This being the case, it would make sense, at least to me, to have one's kamis not overdo the pounding of the cho area. Less pounding will obviously cause less chances of forming fractures in the cho area, and besides, an extra little bit of final filing will still result in whatever kaudi/cho is desired.

The other advantage may be appearance. While some may like it small, some may like them a bit larger. By making them smaller from the get go, you can please both parties. The person that likes it small, can leave them as received. The person that wants them large, can carefully open them up with the proper small files. They can also ever so slightly reshape them to their liking.

The company that overdoes the cho size, does not leave any option for the person desiring a small one. And if by making it larger during the forging process, they also cause more chances of forming decent sized fractures, well then they can really make a lot of folks unhappy.

I don't know if HI has a policy to make their knives with smaller kaudi/cho areas, but I can see some benefits if they have :)
 
I've not personally ever seen a cho fracture from a HI product. I don't believe in the rare documented blade failures of HI products that has ever been a particular problem. I'm not the all seeing eye; it may have happened, but I can't recall any. It makes no sense to re-engineer something that has not been a problem.

I've a older HI Malla with a cho going halfway through the breadth of the blade. Bura knew what he was doing and adjusted for that in the spine on that particular blade. Today's Mallas aren't like mine.
I'm glad you like Yangdu's pictures of the DOD anyway.


munk
 
Munk,

I surely can't claim that the hairline fractures I'm talking about are a serious functional problem in any makers knife, only that I've seen these fractures in the knives I mentioned above.
I had also discussed these fractures before on this forum, and there were "some" members who also stated that they too had seen or purchased HI products with these fractures (probably not as prevalent or as pronounced as with the other makers products). It's probably a much more rare thing to encounter this in a HI product, but I also imagine that whether or not it makes much, if any functional difference, most folks would opt to not have this in their knives.

Here is a photo of a NKH (Nepalese Khukuri House) Ganjuwal I had to send back because of some defects, one being cho/kaudi fractures:
http://img357.imageshack.us/img357/1286/dscn06400qg.jpg
If only the cho would have been smaller, there could have been salvation by filing out the fractured area. With the cho already being pretty deep, filing out the fractured area would have made this cho way too deep, IMO.

Again, maybe my observations of seeing the current crop of HI DOTD knives with smaller kaudi/cho areas is incorrect, but it just seems that way to me. You that have been purchasing these knives for quite some time, will most definitely be better able at determining if the chos have really gotten any smaller on the HI product :)

There may be nothing to this at all, but if this is the way that most, if not all HI products will now be, I'm saying that there may be some advantages to it (for them and the customer).
Even putting the fracture issue and possible large cho size/strength diminishing issue aside, like I said in my other post above, you can make a small cho bigger, but you can't readily make a big cho smaller :)
 
Oh, by the way.....

I have fun calling this notch a "CHO"!
I know it is said that the meaning of this notch may be in honor of a goddess' female part, and others say it may be for the hoof of a sacred cow, but in any case............... "CHO" is the first word in a two worded slang that Hispanics use for the female organ (strictly a street slang).

The first time I was discussing these knives with my wife (we are both Hispanic), she burst out laughing when I repeated the word "cho".
Again, it is the beginning of a slang for us, so it is a bit strange to say it amongst other hispanics. In most areas I just say "kaudi or kauri" to keep it respectable............ LOL!! ;)
 
Some people have mentioned that they thought that some of the deeper chos as found on the gelbu and chitlangi and malla might cause a weakening of the blade, but I have yet to encounter that problem. I agree that the size and depth can be overdone by some mfrs.

I have had something in the neigborhood of a couple hundred HI knives with chos pass through my hands at one time or another, and have never seen any fracture issues at all. I suspect fractures are caused by stenciling out the chos after the blade has started to cool, which could stress the metal and cause fracturing. Cutting it out of a hot blade should have zero affect in creating fissures, so I suspect it's simply a process issue.

The only issue I have seen is on the more complicated and encapsulated heart shaped/double kidney shaped chos, is some roughness by not being able to get into the tight area to polish out the metal, which is to be expected. (That is roughness and not cracking.) Also sometimes rouge from the final polishing will get up in there and need to be cleaned out. That's about it.

Norm
 
Norm,

The truth is that I have only seen photos and video of how firms like NKH and KH put their chos in. For all I know, other firms may even be using less impactive methods of achieving the cho.

The NKH and KH method (which may be very traditional) involves them pounding in a piece of steel to form the cho during the blades forging process. This pounding in of the tool looks to be pretty harsh overall.
Maybe it is a combination of too much pounding and too little heat in that area when it's being done. Metalurgist I'm not, but it's obvious that the firms that are having more trouble with this could probably find an easy fix, (if they only made a concern of it).

There are probably all sorts of possible methods that one can end up with a proper cho. If using the forging in method, then I would guess that even a little less pounding and a little more filing could easily solve any cho fracture problems. Heck, all filing alone will give a desired cho as well, but I imagine that may be too time consuming, even in a country where the labor cost is very low.



As I mentioned before, if HI has standardized with a small cho for their knives, then even with the functional issues aside, IMO, a small cho makes more sense, as it simply is a great way to fill everyone's needs :)
 
I've not noticed any change in size...nor do I doubt that HI holds the kamis to the highest standards...nor do any of my HI khukuris have any fractures anywhere.

Even if they did, the HI policy would exchange it without question.
 
JimmyJimenez said:
Norm,
The NKH and KH method (which may be very traditional) involves them pounding in a piece of steel to form the cho during the blades forging process. This pounding in of the tool looks to be pretty harsh overall.
Maybe it is a combination of too much pounding and too little heat in that area when it's being done. Metalurgist I'm not, but it's obvious that the firms that are having more trouble with this could probably find an easy fix, (if they only made a concern of it).

There are probably all sorts of possible methods that one can end up with a proper cho. If using the forging in method, then I would guess that even a little less pounding and a little more filing could easily solve any cho fracture problems. Heck, all filing alone will give a desired cho as well, but I imagine that may be too time consuming, even in a country where the labor cost is very low.
QUOTE]

You've hit the classic argument between knife makers here. The forgers vs. the metal removal crowd. Like everything else there are purists on both sides, and the majority who could care less about the argument in the middle. I'm in the middle and want to know how to do it all. Both sides of the isle is populated with talented blademakers.

Steel takes a pounding all over every part of it during forging. This creates stresses within the steel, so it is normalized to relax those stresses. This normalizing takes time to do and could be skipped by inferior companies. This is speculation, but it could cause the checks you're speaking of, and worse too.

Since we last discussed this same problem I got a knife (ebay) that has these tiny fractures. It is not an HI knife. I took that knife outside and literally beat the snot out of it with no negative effect. It will take my body weight laterally. This means only that in this particular case these little cracks had no effect on blade performance.
Click to expand...
 
I think Jimmy has hit on it, and I'm sure that Nasty is right as well. I'm sure HI uses a stamp like everyone else, but it makes sense to me that you would get fractures if you wait a bit too long and then use it on steel that has already hardened too much. I'm not a metalurgist either, but it makes sense.

Andy's anecdote about fractures not spreading also makes sense, but it is equally as possible in another knife that such cracks might spread dramatically. I don't think there is any hard and fast rule either way. I have a Tora knife with a ware crack in it, that is very small and I missed it at first, but it seems to have zero affect on performance. Maybe it's due to the steel they used, but I have never seen one in an HI product. However I am sure Dave Hahn wrote about a ware defect that was in an HI Bag Bhairab he had I believe. (?)

Norm
 
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