Catastrophic blade failure

Discussion in 'Himalayan Imports' started by ferguson, Oct 6, 2006.

  1. spiraltwista

    spiraltwista

    Nov 29, 2002
    Ive Never handled a good genuine all antique metal kora handled one. {I think N2S has though.};)

    So far Just copies faked as old & retreads, putting old blades & handles together.

    But original tulwar & kora sword grips are cast & have a small central hole for the tang & some laha. It is a friction fit in places though.

    The end cap & pommel is then forge welded to & or from the tang.

    It seems safe to assume to me that thats how the tulwar & kora grip kukris were constructed as well.

    The tang needs closer support.

    Some tulwars also have a single pin through handle & tang as well.

    So That might be the blade to handle join problem, but the blade break starting with the black piece shows it was old damage.

    Thats a differnt beast.

    All IMHO. of course.

    Spiral
     
  2. munk

    munk

    Mar 22, 2002
    Spiral, point taken about testing.

    Forged metal has nothing to do with the source you mentioned; worn springs. Metal forged from this is a new metal.

    Take care,

    munk
     
  3. munk

    munk

    Mar 22, 2002
    To all;

    I know Yangdu is resuming a testing regime in Nepal. HI khuks have always been hammered hard. Other khuk manufacturers say the khuk is not the tool for hard chopping.

    I'm wondering aloud; would HI be better off with less of a assurance about use?

    Seems like HI has long carried a heavier load, doesn' t it?


    munk
     
  4. spiraltwista

    spiraltwista

    Nov 29, 2002
    Thankyou, i realised you had misunderstood me. glad you re read it.

    But I dont understand your meaning Munk? Whats new metal? the blade? The handle? Or do you mean forging makes it new metal?

    Forging doesnt make old metal new at the temprature they use in Nepal,

    Can you elucidate please.

    Take care,
    Spiral
     
  5. munk

    munk

    Mar 22, 2002
    Spiral,



    You have good hi carbon spring steel. You reforge it. It is not what is was, now, it is 'renewed'. It has changed. IT has no more relation to 'busted worn out springs' (quotes mine) than good carbon sheet steel from Whobunk Asia. Sheet steel forged is changed also. It is now knife steel, right?

    Anyway, this kind of stuff is over my head. Other more knowledgeable folks who make knives and are more familiar with this have weighed in on this thread with similar views. My opinion may be crudely stateded, I don't know.

    munk
     
  6. munk

    munk

    Mar 22, 2002
    Oh, btw Spiral;

    I believe in forward progress. I'm not interested in tripping anyone up.
    I'll always speak my mind as I think best, but any sincere and good heart is always getting the benefit of a doubt from me.


    munk
     
  7. spiraltwista

    spiraltwista

    Nov 29, 2002
    Thanks Munk, I now I understand what you mean,

    I am not a metaraloligist but my understanding {which is fairly reasonable ,I would say.} is heating a blade to red hot & pounding it with a sledge hammer to shape wont repair any old cracks in the steel.

    Whether the steel was old or new if its cracked , Nepali style forging wont fix it. It would need to be very hot forged to do that, enough to forge weld it & that would reqire any crack to be cleaned & fluxed as well.

    Perhaps someone with more about forging knowledge than either of us {Dan or other bladesmiths , engineers. etc.}can give the 100% difinative on it?

    All kukri companys & all steel sources both old & new will have failures sometime. Thats why the Hi gaurantee exists.

    But i realy do think thats looks like a black old crack that worked as the stress riser. But thats like 1 in a 1000 or whatever incident. But I think its good for all companys to try & improve their product, rather than rest on thier laurals.

    Reliable Testing before kukris reach customers would do it.

    Spiral
     
  8. spiraltwista

    spiraltwista

    Nov 29, 2002
    Well if you need to give me "benifit of the doubt" thats your buisness.

    I want all kukri companys to succead & yes make better kukris. {thats not an insult, I can be a perfectionist about kukri at times though.}

    If Windlass made great kukri , i would be realy pleased!

    I like kukri & want thier popularity to continue to grow world wide.

    And with all companys some of the money reaches the kami & they need it.

    Cheers,
    Spiral
     
  9. Svashtar

    Svashtar Gold Member Gold Member

    Dec 28, 2003
    Spiral's point is well taken, and I did not take his comments for a cheap shot at all. Just because a leaf spring has a section cut off and is reheated and pounded into a new knife blade shape does not mean that there still could not be some internal flaw IMO. (Of course Dan or other makers among us would be able to comment more intellingently on that point.) The steel would have to be almost molten to eliminate that, and then completely reshaped. Hence the need for testing in any case.

    Other companies do make knives for heavy chopping. The difference is, HI is in a whole class by themselves when it comes to that particular activity, and I suspect we have become somewhat spoiled lets say as to what we expect from a knife. I imagine other folks might recoil in horror if they saw some of the chopping torture tests we routinely expect HI blades to pass!

    However, these failures appear to be because the tang was overheated when fitting the metal handle.

    On mine today I tested the hell out of it, just like Eric did, but in reading Sams comments maybe I was too hard on it. I don't know. Essentially what these have is a big Junge blade attached to an aluminium (edited: Steel! Thanks Eric and Mike.) handle with pommel and front ring brazed on. A blade that big should be able to take the chopping I threw at it in spades, also IMO.

    I donned my heavy welding gauntlet, boots, eye protection, body armor, gas mask, etc., and tested this thing this morning and about wore myself out. My right arm feels like a noodle. I chopped halfway through that old redwood 6X6, and then on an ancient creosote soaked railroad tie, then back through the 6X6 to clean off the blade.

    I hit very hard or as hard as I could over 100 times before I lost count. I chopped from the sweet spot to the tip, and then choked up on it and chopped from the cho forward, which is harder than it would seem, as the knife doesn't want to hit there. I slapped the sides of the blade as hard as I could 20 times per side, and then chopped with the spine first and blade up. I stopped every once in a while to check the blade with a 5X loupe to look for any cracks.

    The blade held up beautifully. When I was taking pics and getting ready to put up the blade, I detected the slightest amount of movement on the front ring. My loupe showed that the brazing on the rear of the front ring had slightly fractured, allowing the ring to move. I then hard tapped the spine on an anvil another 20 or so times, which then loosened the handle as the handle had no support. This also damaged the brazing even more. Not the smartest move on my part.

    What I see is that the front ring brazing has broken, which allows the handle to flex slightly in relation to the blade. The handle - bolster and blade connection still seems solid, but in a vice I can move the handle side to side mabe a 64th of an inch now.

    So I wanted to get your advice. The tang and bolster on this are fine as far as I can tell. It took a tremendous amount of use and abuse this morning and held up. Keep in mind that railroad tie is probably 70 or 80 years old at least, and is like iron. I still got 1/2 of penetration on each hit before the blade would bounce clear back out of the cut.

    Should I A) clean out the chipped brazing and just paste up both sides of the front ring with JB weld, or B) remove the handle, (which I have not done before), and fix it that way. It looks like I would file off the peened-down tang at the keeper, heat up the handle and tap the handle off to the rear, then clean up the front brazing material, and refasten the entire handle with JB Weld. I guess I'd have to file off the front of the handle a fraction to compensate for what I remove from the tang rear so I could peen it down again.

    This last would eliminate the 64th of play on the tang in the laha as well. But just doing "A" might be enough.

    It should be noted that had I not done those last 20 hits to the spine on the anvil, just doing "A" would probably have been sufficient. I realize now that stressed the handle badly doing that, as it had no front support. It still might be enough though.

    I probably should have read Sams post earlier before pounding the hell out of this, but frankly wanted to see what I had before I could really trust it. This blade and tang and bolster are 110% solid as far as I can tell. If I have to, I will send it to Dan in order to salvage this blade with a new handle, as it's that good.

    So I may be out some time, and maybe a little $ in the long run, but it's still a great knife.

    Here are a couple of post chopping pics.

    Thanks,

    Norm

    P.S. If Steve only write long posts when he's on painkillers then I must be totally stoned. :D Being a fast typist can be a problem I guess...

    [​IMG]

    [​IMG]

    Sorry for the blurry pic. I can't do decent closeups with this camera yet. You get the idea.

    [​IMG]
     
  10. spiraltwista

    spiraltwista

    Nov 29, 2002
    Thanks Norm, Glad you could read it in the way I wrote it.

    I agree if the handle has flex & movement that will have put loads more pressure on the blade, & help cause the fracture.

    Perhaps the kami should go & buy a cheap rusty old tulwar or kukri 7 take it apart & see how it used to be done.

    If the kamis are making handles from aluminium tubing, it should perhaps be filled with wood & the tanf fitted through that for stability?

    {None of my buisness, just offering possiible solutions.}


    cheers,
    Spiral
     
  11. Edward Teach

    Edward Teach

    174
    Jun 29, 2005
    Here's another glove supplier...with a few options that are not quite as dear as the stainless mail glove.

    I've worked with kevlar gloves similar to these (ex-fisherman) and they're pretty effective. You can take the knife and draw it across the palm of one of these gloves and it doesn't so much as make a mark (except with the rubber-coated ones it would cut into the coating of course).

    http://www.chefdepot.net/bonesaw.htm
     
  12. Edward Teach

    Edward Teach

    174
    Jun 29, 2005
  13. sams

    sams

    Apr 21, 2001
    I hope I didn't step on toes with my post. I certainly wasn't meant to upset the apple cart.


    I wish everyone would just use a little common sense using the khukuri.

    Kinda like a teenager getting a stick shift, running the car in first gear, red lining and pow! engine blown.

    It isan't necessary to "red line" a HI khukuri but if you must, for God's sake use a 20" AK.;)

    Sam S.
     
  14. Svashtar

    Svashtar Gold Member Gold Member

    Dec 28, 2003
    Wow, cool. Didn't know they made such things.

    Norm
     
  15. Svashtar

    Svashtar Gold Member Gold Member

    Dec 28, 2003
    Nasty's the man. Definitely Super-Mod material. I don't care what his mother says about him! What does she know anyway? :D;)

    (Sorry, old joke!)
     
  16. Svashtar

    Svashtar Gold Member Gold Member

    Dec 28, 2003
    There may be wood in there Spiral. Not sure yet. Although the very slight up and down movement of mine suggests you are right and there isn't. Looks like Steves and Mike's failure would have happened even if the handles were solid hardwood?

    Norm
     
  17. spiraltwista

    spiraltwista

    Nov 29, 2002
    I agree Svashtar I think Steves Blade would have broken sooner or later,To me Mikes looks like just a loosly fitted handle & bolster, brazed to hold, but . without enough interior inside bolster & handle against the tang to rigidly support it.

    & presumably one day Mikes handle will come off but hopefully the blade wont snap.

    But thats just going on the pix.

    If there is wood in there its to loose , to soft or the hole drilled is to large, if it allows tang movement.

    I always think close tang fit to the interior of the handle is a good start for longevity. Its what I see inside kukris that have lasted 80+ years.

    The bolster needs that support inside it as well. IMHO.

    Thats why i didnt like those Habaki bolsters.

    Spiral
     
  18. Svashtar

    Svashtar Gold Member Gold Member

    Dec 28, 2003
    Well, this leads me to think my best course of action on this would be to completely remove the handle and clean it all up and then re-epoxy the whole thing together. As long as the blade and tang are solid and in good condition I shouldn't have any further problems.

    Norm
     
  19. spiraltwista

    spiraltwista

    Nov 29, 2002
    I think that would be my approach. But I like seeing how there put together inside, anyway. ;)


    Spiral
     
  20. Nasty

    Nasty Chief Cook & Bottle Wash

    Nov 11, 2003
    Thank you gentlemen...exactly the response I desired and expected of you all.

    I will *now* go back to sleep...
     

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