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Cracks at the cho: PICTURES ON Pg 3

Discussion in 'Himalayan Imports' started by SkagSig40, Jul 22, 2015.

  1. SkagSig40

    SkagSig40

    Feb 1, 2001
    If you look close in picture 1, you can see the crack extend down from the side of the blade down into the cho. I cant get the other photos to show this clearly but it is like this on all the knives and that is why I believe they are cracks and not surface "marks"

    Do you guys see what I'm getting at? Check yours closely. It is hard to see these and may take magnification. On a side note a fine needle tip with catch on the crack.

    From a structural stand point the blade would be more sound with out the cho or squared edges. Bill agreed with me and we both agreed it would ruin the historical and cultural significants of the cho and the kamis would not make the knife without it. We had a good laugh about that!
     
  2. mtngunr

    mtngunr

    Apr 10, 2005
    No huge test....scuff clean area and squirt with with a couple of cans of aerosol....most any machine shop and many mechanics have the stuff.....if i suspected a crack i would first attempt to clean up area and see if it went away with a couple of small files and fine grit sandpaper and crocus cloth.....then if i were unsuccessful and had that widespread a problem on a huge percentage of knives, i would have quietly let my friend know he had a huge problem possibly brewing and that he might start making plans for a large number of replacements equal to half his production...and income....

    But again, THE MARKS ARE NOT FOLLOWING NORMAL CRACK BEHAVIOR, and UNTIL proven otherwise, i would not be calling them cracks at all until i had gotten to the bottom of the issue....A LINE RUNNING AROUND A CORNER AND AT ANGLES TO GRAIN IS NOT NORMAL CRACK BEHAVIOR....A LINE RUNNING ACROSS THE CHO FROM ONE SIDE TO THE OTHER WOULD BE NORMAL BEHAVIOR, but NOT a corner.
     
  3. SkagSig40

    SkagSig40

    Feb 1, 2001
    How do you explain picture 1 then, when it clearly extends down into the cho from the side of the blade? All of these do this. I just cant get the dam photos to show it clear enough. A crack acts and looks just like picture one....I could be wrong but how do you explain that it is not a crack when it clearly appears to be?
     
  4. mtngunr

    mtngunr

    Apr 10, 2005
    Extend the problem in 3D.....you have a washer and it cracked from the center hole outward....the crack extended from side to side......make the washer 5 or 10 or 50 times thicker and the crack will still extend from side to side.....machine it out of a solid block of steel, and would it crack only on a corner of all places?...and at times run at a weird angle away from the radius of hole or grain direction of the steel?......is this illustrating the problem of the suspect "cracks"....

    Until a dye penetrate or at minimum a magnified visual inspection AFTER attempts to clean away suspect "cracks" is done, calling any of the marks "cracks" is premature....period.

    I posted above and also other places, and many others have as well over time, that the cho is what makes a khukuri and to remove it is to admit why not carve it out of stainless sheet and stick a micarta handle on it.......even if an engineer would scream if not taken to at least 1/2" radius and 30 micron finish.
    ..but cracks are not self limiting and i still see a near void in posts of cracked or broken blades....
     
  5. J W Bensinger

    J W Bensinger

    Mar 26, 2009
    From the pics, my guess is that the ones in the body of the blade are partial scratches from previous grits.
    The ones actually on the edge of the cho cut, I'm guessing are cold shuts-tiny bits of steel flashing from the cut (or from forging) that get pounded into the surface of the steel-those are reeeeeaallylittle ones.
    Bear in mind, I'm looking at these on a 4x2-1/2" screen-so cut me some slack :)
    I've had one or two hairline cracks in my blades over the last 20 years or so-they don't show up until 320 grit or so, but they're unmistakable at that point.
     
  6. Dobe_1

    Dobe_1

    813
    Jun 19, 2013
    A good explanation mtngunr, and done in a respectful manner too. Personally, I appreciate the detailed explanation. I'm hoping that is what SS40 was seeking.
     
  7. Dobe_1

    Dobe_1

    813
    Jun 19, 2013
    Was there a pattern of where these cracks appeared, or is it more random?
     
  8. Steely_Gunz

    Steely_Gunz Got the Khukuri fevah Moderator

    May 9, 2002
    Thanks for posting pics, Chris. I really dunno what they are, but I would guess that if they really caused an issue, kamis would have axed the cho centuries ago.
     
  9. mtngunr

    mtngunr

    Apr 10, 2005
    As i said too many times, there are gonna be problems no matter WHO makes the blades, given enough of them, and any smith will tell you so....some occlusion in the metal unknown to all, acting as a stress riser, a blade pounded just a bit too long past proper temp, whatever....too many ways possible to have things go wrong to list.

    But for a smith to see these in huge percentages of blades and send them on while knowing his job was on the line, for the blades to be looked over by several sets of critical eyes knowing full well the financial disaster of passing along huge numbers of flawed blades to customers, well....the entire thing is preposterous short of a ring of moles committing sabotage....especially in a small single product company.

    And good job on Mr Bensinger who knows anybody can smear over a crack with a coarse enough grit.
     
  10. Dobe_1

    Dobe_1

    813
    Jun 19, 2013
    And you were doing so well...I was asking J. W., if he had seen any patterns in those he had come across in the 20 years of his experience.
     
  11. mtngunr

    mtngunr

    Apr 10, 2005
    I was addressing Mr Bensinger and and was not clear if the blades were ones he made or were HI products. Him going to 320 on them causes me to guess his own blades and if so, doubt very much they were sold.

    Went back and viewed old original 2003 thread and really only one or two broken blades from poor heat treat, and 3 or 4 suspected cracks by owners which Bill replaced in most cases...not very many at all, in short...and we will never know how many were ever judged to be truly cracks by a competent authority....and total lack of concern on most parts anyhow, which is rather strange still to my ears....as was the original poster not hinting around replacement nor Bill offering one, as if an old hat discussion now gone public or something.

    The chos appear to be something added rather late in the process considering how clean they appear, as for the metal itself...so i am having trouble figuring out what would cause any crack to appear there in first place on knives of zero or little use...perhaps someone could point out exactly when chos are added? I would think after major gross work, heat treat, and then cut during final grinds and polish, which should not cause metal to suddenly give way on a corner of an edge.
     
  12. J W Bensinger

    J W Bensinger

    Mar 26, 2009
    The ones I've seen were all in very thin differential hardened blades, Generally where the spine got hotter than it should have and pulled the edge apart as it contracted. (That's not in any way science, just some forensic investigation so it didn't happen again). Nothin that really bears relevance to a largely unhardened section of a 3/8"+ thich khukuri.
    I think I've had five knives crack since I started (which was a LOT longer than 20 years ago) and they were all either thin, or I was stupid and quenched in water/brine when I shouldn't have, and those just exploded in the quench.
     
  13. mtngunr

    mtngunr

    Apr 10, 2005
    Mr Bensinger, do you forge blades?....i need to look you up next time i brave Atlanta traffic....i do not live even 2 hrs away but still generally skip the show just due to hating Death Race 2000.....that is, you do do Blade, correct?
     
  14. davidf99

    davidf99 Platinum Member Platinum Member

    Sep 27, 2011
    In fairness, SkagSig40 really hasn't claimed that these tiny imperfections (I don't want to call them cracks) are a problem, he just seems to be curious about them. I wouldn't call his posts badmouthing HI, although I can see how they might be interpreted as such. There have been a few other people in the past who criticized HI in a passive-aggressive way, or "damning with faint praise," but I don't get that impression from SkagSig40's comments.

    The fact that SS40 continued to buy many HI blades has been interpreted as contradicting his claim about cracks. I rather see his continued patronage of HI as a sign that he has never considered these "things" (whatever they are) as a real problem.

    The photos are inconclusive. They seem to show something, but I highly doubt that they are cracks. Maybe tiny byproducts of the way that the kamis make the cho. Tiny file marks or sandpaper scratches, perhaps?

    We don't know under what conditions SkagSig40 stores his blades. Maybe repeated expansion and contraction of the metal with changes in temperature and humidity might create microscopic imperfections in the small-radius curve inside the cho. It is a bit of a mystery that he sees them on so many blades. Maybe he lives in a part of Colorado that has extremes of weather.

    I have a question that seems relevant: What tools and techniques do the HI kamis use to form the cho? I see on my own blades that some of them have the inside curve of the cho fairly well finished, while others are pretty rough inside.
     
  15. Dobe_1

    Dobe_1

    813
    Jun 19, 2013
  16. mtngunr

    mtngunr

    Apr 10, 2005
    Thanks Dobe, i don't facebook at all....i still am not clear but appears he is discussing only his own blades and chos do not enter there at all......i was reviewing the recently and blessed Howard Wallace shop tour video and it seems the chos might be showing already there in rough form during tang forging but blade already shaped by then so no idea still when cut, and assume water quench done after tang....but also sure ricasso area far away from target of a quench so still scratching head over what would cause a crack on a corner of the metal in the cho, if anything at all...i do love a mystery.....i wish i had one here with such a manifestation and by golly we would ALL know then what was going on....if anyone else turns up one and wants to play, please let me know...

    As for how chos formed, i have seen cleanly and roughly finished and rough ones obviously cut or filed out...at least in later stages....for all i know, they do part of it hot and finish later and i doubt i shall ever know that manner of detail...all i CAN know is that if i ever get my hands on one such as the original poster has, is if those are cracks or not....too easy to not find out, and probably only with files and sandpaper....
     
    Last edited: Jul 23, 2015
  17. Dobe_1

    Dobe_1

    813
    Jun 19, 2013
    I've seen YouTube videos showing kamis using a file. Those of mine seem to be somewhat rough, and also appear to have been cut by a file. That of course doesn't mean all are.
     
  18. mtngunr

    mtngunr

    Apr 10, 2005
    Do you recall how finished/final shape the blades were forged when chos were cut?....i would think they would need be about done by then as how else even to know where to put the thing, and not as if these guys are making knives out of cookie cutter blanks and just forging edges into them....nor would they be filing away through unforged full thickness if any way around it....and if you don't mind another question, where are these you tube HI videos stashed? Thank you muchly....
     
  19. Dobe_1

    Dobe_1

    813
    Jun 19, 2013
    I do believe, as you have suggested, that they the blades are in a finished state. I'll look for the videos, and post what I find.
     
  20. J W Bensinger

    J W Bensinger

    Mar 26, 2009
    Here's my take on the making of the cho-the HI's I own (and the old ones with an open cho) appear to be filed,the closed cho (gelbu special/chitlangi/ old eye of the dove cho) on the ones I have are hot cut/punched.
    When I make khukuri the open cho's are cut in with files, the closed ones (I do mostly eye of the dove, known to westerners as a "hole" lol) i often punch 'em hot.
    MtnGunner-pretty much everything I make is forged.
     

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