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Thread: Cutting a machine gun barrel

  1. #16
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    Originally posted by The Coffee God
    Actually in John Yumoto's book "The Samurai Sword, a Handbook" he mentions that the way a katana is forged, by the time it has been folded 10 times, it exceeds 300,000 layers. He gives a very specific number in the 300,000 range, but I don't have the book any more so I'm just paraphrasing at the moment.
    1 fold 2
    2 folds 4
    3 folds 8
    4 folds 16
    5 folds 32
    6 folds 64
    7 folds 128
    8 folds 256
    9 folds 512
    10 folds 1,024
    11 folds 2,048
    12 folds 4,096
    13 folds 8,192
    14 folds 16,384
    15 folds 32,768
    16 folds 65,536
    17 folds 131,072
    18 folds 262,144
    19 folds 524,288
    20 folds 1,048,576
    21 folds 2,097,152
    22 folds 4,194,304
    Yours in Budo,
    ---Brian---

  2. #17
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    Hi

    I also read in a book I have - too many to search through to find which. That if the metal is folded more then 21 times it is so soft you could bend it in your hands.

    Folds may make it stronger but only if the layers are thick enough to add any strength.

    Also the amount of time it would take to create 21+ folds would be very time consuming and not production. When I met Sumitani he told us on average most smiths do between 9 and 12 folds these days
    Paul Richardson - Shidoshi
    Bujinkan Lincoln Dojo

  3. #18
    The Coffee God Guest

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    If you're starting with a single piece of iron unlayered to beging with, those figures are correct, if you're starting with a layered piece of iron to begin with, then it depends on the number of layers the piece has.
    Take for example: [we'll use a modern steel as to not confuse you]
    A piece of twisted steel cable
    Let's say it has 5 strands, each strand is made up of 10 smaller strands, which equals 50 strands of steel; a nice round number.
    If you start with that number, it goes up quite quick as you see...

    50 fold 100
    100 fold 200
    200 fold 400
    400 fold 800
    800 fold 1,600
    1,600 fold 3,200
    3,200 fold 6,400
    6,400 fold 12,800
    12,800 fold 25,600
    ect, ect...

    Now, let's just give an example, let's say the broken pieces of iron ore on the spatula equal about 32, should that be folded 10 times, that would make 16,384 layers...for just one block of steel. In the makings of a katana in traditional fashion, there are two blocks folded in half and put together to make the blade. That makes 50,786 layers.
    See where I'm going with this?
    Last edited by The Coffee God; 5th October 2003 at 12:57.

  4. #19
    Ford Hallam Guest

    Default The evidence

    Gentlemen,

    I`m surprised that no-one has mentioned any more recent tests of the Japanese forged blades ability to cut steel.
    There exists a profesionally produced ( one of the Japanese TV stations, I think ) video which features a sword made by the well known smith Yoshindo Yoshihara being used to cut into a steel kabuto. The result was that the blade suffered no damage to the edge while the helmet recieved a ventilation slit about 3 inches long. If some unfortunate soul had been wearing it at the time i imagine that they would have suffered a somewhat impacted neck and a splitting ( sorry, poor pun! ) headache but perhaps only a relatively minor gash in the skull.

    The gentleman who actually performed the test, whilst being the very wealthy induvidual who commisioned and paid for the sword ( and I rather suspect the actual documentary. ) was probably not the most qualified to best demonstrate the swords capabilities.
    The look of relief on Yoshihara san`s face when he realizes that his work has survived is very telling. Had things gone badly his reputation would have been seriously damaged and I imagine we would not have seen the footage.

    The actual cutting of the helmet is in best cliff-hanger tradition, right at the end of the tape. At the beginning however we see a demonstration which compares the cutting ability of a gendaito and an older blade, koto i think. The result was predictable. The tubular steel frame of a beach chair was cut cleanly in two with no visible damage to the older blade. ( the edges of the cut were distorted though, which was to be expected. ) The gendaito did`nt fare so well, it failed to sever the pipe, merely denting it while sustaining a severe bend. I don`t recall if the steel of the sword was actually chipped or not. I really should dig the video out and watch it again. Various sundry items which routinely had to be dealt with by working samurai are also mutilated by the valiant tester, I seem to remember a motorbike petrol tank and a metal container of milk!

    Hope this adds a little to the general discussion on the capabilities of these fine weapons, which are after all only as good as the men weilding them.

    Regards,

    Ford Hallam

  5. #20
    The Coffee God Guest

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    Surprisingly enough, In 1994 using a newly made katana by Paul Champagne and the same late 16th-early 17th century Hineno style kabuto, Obata Toshishiro Kaiso beat the record of 12 centimeters held by Terutaka Kawabata in 1986 with Yoshindo's blade. The katana was used as a bare blade with only nylon rope as the handle, leaving a 13 centimeter gash in the kabuto and an unmarred blade.
    Last edited by The Coffee God; 5th October 2003 at 15:33.

  6. #21
    The Coffee God Guest

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    Also interestingly enough, staying inlines with modern test cutting, Michael Bell tests his forge-welded steel cable swords on free-hanging cable.

    Except taken out of a '97 Tactical Knives magazine

    I started cutting cable about 4 years ago. Anytime you set out to develop a new material, you invariably end up with blades that are a failure for one reason or another. I quickly learned to forge-weld logging cable, and I made any number of knives out of it and found out that it was easy to heat treat and was very aggressive in cutting. So I started making progressively longer and longer swords out of it. As I played with the material in a wakizashi length, I was finding that they would heat treat just like a piece of traditional Japanese steel, with a nice hard edge. So I started testing their cutting ability. I started off fairly gentle with the stuff, cutting 1-inch aluminum pipe in two, then copper pipe, all sorts of bush and trees up to 2-inch alders and 3-inch bundle of green bamboo using the Kesa stroke, cutting downward from the shoulder and out the bottom of the rib cage.

    Then I started cutting various thickness of mild steel rod, until I could cut through a ¼-inch rod in one swipe. Then it occured to me that since cable was such tough stuff, that it might be an interesting test to try and cut cable. So I tied some 3/8-inch steel cable up in a tree and did a free-hanging wire rope test. Not every sword would cut it 100 per cent, but the better ones did.

  7. #22
    MartialArtist Guest

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    Originally posted by Yagyu Kenshi
    I've never heard of a katana with "millions" of layers. Typically a sword blank was folded 10 or 11 times, resulting in 1024 or 2048 layers. Occasionally you might see 12 folds resulting in 4096 layers. But millions? I don't think so. 4 million layers would require 22 folds, and after that many folds you'd have nothing left of your blank but a smudge on your anvil.

    I also suspect you'll get a good number of people disputing the superiority of Swedish powdered steel for swordmaking. As long as it wasn't heated beyond 1100 degrees or so, Japanese steel was excellent. During the shinto period forging at temperatures over 1500 degrees to make forging easier resulted in a decline in quality, but that was the forging process, not the lack of good iron ore in Japan.

    But, as usual, that's just my opinion. Others may differ.
    Nihonto usually don't advertise how many layers they have, and neither do katanas made by reputable people such as Howard Clark.

    However, some stainless steel katanas are advertising the 4 million layers and so on and they are the same people who are spreading "a katana can cut through all European swords, cut railroad tracks, cut through trees".

    Japanese steel usually had a lower carbon content than steel from Europe, and like you've said, the amount of ore was rare.

  8. #23
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    Originally posted by The Coffee God
    If you're starting with a single piece of iron unlayered to beging with, those figures are correct, if you're starting with a layered piece of iron to begin with, then it depends on the number of layers the piece has. Now, let's just give an example, let's say the broken pieces of iron ore on the spatula equal about 32, should that be folded 10 times, that would make 16,384 layers...for just one block of steel. In the makings of a katana in traditional fashion, there are two blocks folded in half and put together to make the blade. That makes 50,786 layers. See where I'm going with this?
    I could be mistaken on this, but aren't the "broken pieces of iron" on the spatual melted into a single ingot prior to forging?

    I suppose if you want to do a microscopic examination you could come up with some really high numbers, but when I think of the "layers" in a Nipponto, I'm thinking of the forge-welded layers...which number in the hundreds or thousands, not millions.
    Yours in Budo,
    ---Brian---

  9. #24
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    Yoshindo's blades are amazing in their strength. He forged them in the old style from a single type of steel, differentially heat-treated, rather than the mass production oriented "jacketed core" method that he considered an "abomination."

    I wish I could afford one!
    Yours in Budo,
    ---Brian---

  10. #25
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    Default Correction

    Originally posted by Yagyu Kenshi
    Yoshindo's blades are amazing in their strength. He forged them in the old style from a single type of steel, differentially heat-treated, rather than the mass production oriented "jacketed core" method that he considered an "abomination."
    A correction to the above post: I was thinking of Yasuhiro Kobayashi, not Yoshindo Yoshihara. Yasuhiro uses one piece forging; Yoshindo uses kobuse forging. Sorry if I confused anyone.
    Yours in Budo,
    ---Brian---

  11. #26
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    But speaking of Yoshindo:

    Originally posted by The Coffee God
    Actually in John Yumoto's book "The Samurai Sword, a Handbook" he mentions that the way a katana is forged, by the time it has been folded 10 times, it exceeds 300,000 layers.
    I haven't been able to find a copy of the Yumoto book you mention, but here is what I found in The Craft of the Japanese Sword by Leon & Hiroko Kapp, and Yoshindo Yoshihara:

    There is no prescribed number of folds, although in Yoshindo's case it is usually about thirteen times in all.
    And in the next paragraph:

    The forged metal, having been folded thirteen times or more, becomes a kind of metallic pastry dough, consisting of layer upon layer--some 16,000 or more--per inch of steel.
    It appears that the method of counting layers and the number of layers itself is subject to some variability. However I think most here would agree that advertising a stainless steel, made in Spain "katana" as having 4,000,000 layers and being a superior blade is probably marketing hype, not fact.

    But I'd still like to see someone cut off a machine gun barrel!
    Yours in Budo,
    ---Brian---

  12. #27
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    Question Mass production? ...

    How does kobuse method of forging translate to mass production? From what I understand, it is more time consuming and difficult to produce a blade using kobuse method. There is some debate over whether you actually gain much that way, but I've never heard it referred to as relating to mass production.

    Cheers,
    Paul Smith
    "Always keep the sharp side and the pointy end between you and your opponent"

  13. #28
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    I think it comes down to the heat treating process. To get a good blade from single piece forging is very difficult and time consumming. By using two different types of steel you can get the same effect more easily; a sort of short-cut.

    But that is a constroversial statement, to be sure. Not everyone agrees. Yasuhiro thought kobuse swords were "an abomination." Some felt that it was good for swords made more for viewing than to be used in battle. But obviously not all would agree.
    Yours in Budo,
    ---Brian---

  14. #29
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    Hi all,

    I'd like to add a few things:

    John, that's what you get for reading books by Daniel Furuya!

    Steel and steel contact would cause nicks or chips on the blade.
    This is not necessarily correct, and is perhaps the subject of this thread. Metal can cut metal without damage, as long as the cutting metal is sufficiently harder than the metal being cut. I have a few Strider Knives that proove this. Other examples are the aforementioned kabutorwari by kenshi like Obata Sensei, in which a heat treated helmet was partially split, but the blade used was not damaged (didn't chip of bend).

    As a more common example, tin snips are metal scissors that are made to cut tin.

    So the question remains, what type of barrel was split (not cut) by a Japanese sword in this propaganda video? Even if it was a non-functional barrel, painted black and made of annealed alluminum or tin or something, it would have given the apperance of a sword having cut a gun - even from up close. chances are more likely that it was painted bamboo or wood though. There has to be copies of this footage around somewhere, don't ya think?

    Also, there has been much written about folding swords and what it does, both here and on swordforum.com. Please do a search instead of speculating about it in this thread.

    Folding does not make a sword "stronger" from a literal standpoint, it removes impurities from the steel and makes it more uniform. Take out too much carbon and impurities, and the steel becomes too soft. In fact, folded or unfolded swords has nothing really to do with this subject!

    Glad to see a thread dedicated to this myth though.

    Regards,
    Nathan Scott
    Nichigetsukai

    "Put strength into your practice, and avoid conceit. It is easy enough to understand a strategy and guard against it after the matter has already been settled, but the reason an opponent becomes defeated is because they didn't learn of it ahead of time. This is the nature of secret matters. That which is kept hidden is what we call the Flower."

    - Zeami Motokiyo, 1418 (Fūshikaden)

  15. #30
    The Coffee God Guest

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    Originally posted by Yagyu Kenshi
    It appears that the method of counting layers and the number of layers itself is subject to some variability. However I think most here would agree that advertising a stainless steel, made in Spain "katana" as having 4,000,000 layers and being a superior blade is probably marketing hype, not fact.

    But I'd still like to see someone cut off a machine gun barrel!

    And indeed, I would agree as well.
    I never said anything about millions of layers, just a few hundred thousand, nor was I discussing steel from Spain. I was merely posting what I have read in a valuable sourcebook on Japanese swords(though a bit dated).

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