Why Shobu Zukuri?

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Apr 15, 2020
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There's a lot of katanas out there, and I remain amazed at how few of them are any good. All too often, historically accurate Japanese swords are little more than expensive ornaments. Which is fitting, because that's exactly how those swords were used in antiquity. Swords were worn to denote status, rank, and (essentially) one's worth in society.

Only samurai were allowed to wear two swords. Others could wear one and there's the rub: battle swords rarely survived in pristine condition through the ages for us to emulate today, unlike the ornaments which never saw the light of combat, and remained in perfect condition for centuries.

There are two sword styles, however, that are not only combat-oriented, their very design was conceived in battle: the tachi and (later) the shobu zukuri. The translation is linear, as the tachi led to the shobu zukuri.

The tachi is a cavalry sword, deeply curved, and much longer than a standard sword; the better to reach down from the mount and strike a foot soldier dead with. This extra length, and heft, was never an issue because the horse's ass was carrying the weight; not the cavalry man.

Enter the Mongols (the Masters of War.) The first time the Mongols invaded Japan, things were NOT looking good for the natives. The Mongol's superior organization, strategy, and wealth of supplies very nearly ended Japan. However, a freak storm not only destroyed the Mongol's ships and equipment; it completely demoralized them as they no longer had a way back home, and were left with whatever each man had in his pack.

This "Divine Wind" (kamikaze) is the only reason the Japanese survived that first invasion. In assessing the situation after the fact, all discerning minds realized the tachi outperformed every other sword in its ability to cut through the Mongol's superior armor. However, all anyone did was complain about the damned tachi: it was too long, too heavy, and required an inordinate amount of sharpening due to the narrow profile of the blade not allowing for a whole lot of room to bevel. An abrupt, acute beveled angle does not last long in the crash of battle.

The Japanese had a feeling the Mongol's would be back (they were correct), and immediately began fixing the tachi into something the infantry man could use. That's how the shobu zukuri was born. Deeply curved, like a tachi, but shorter, lighter, and with a wider blade with a bevel that practically ran the full width from spine to edge.

The kissaki was eliminated altogether for three reasons: 1) it takes a considerable amount of skill to shape an effective kissaki, inhibiting the production of a large stockpile of blades, 2) while the kissaki allows for excellent snap cuts from maximum distance, those cuts were ineffective against armor 3) deep, body-splitting slashes (which is where the shobu excells) requires one to drive the sword completely through the target, and the blade would typically snag in the target at the kissaki; making a fluid cut more difficult.

The shobu zukuri's massive, damn near full-length bevel was accentuated by the sword makers of Bizen with a "clam shell" edge, which bit so well that the spine of the blade would typically disappear into the target it was cutting; not typical of other katanas.

When the Mongol's returned, just about every Japanese infantry man was armed with a shobu zukuri. This time, the Japanese were winning the day on the battlefield when another storm wiped out the Mongol fleet...AGAIN!

After hundreds of hours of cutting practice, I can attest that nothing cuts like a shobu zukuri. While other blade designs have features of dubious effect, every aspect of the shobu zukuri helps it do one thing and one thing only: slash deeply while driving the whole of the blade through the target, from belly to tip.
 
I've always been interested in the real life Masamune blades. In terms of historical knowledge
 
Masamune and Muramasa both made blades that have not been equaled using modern technology, which is a huge statement given the primitive implements they each had to work with.

Masamune's intricate system was that of 3, overlapping "diamonds" (3D triangles), each made of a different steel composition, forged together for effect: one diamond's linear plane would protrude at the edge (the hardest steel), another edge would protrude at the sides of the blade (more flexible steel), a third plane would protrude at the spine (softest steel); he made several swords with up to 7 protrusions of different steel alloys, varied for effect. People have tried to make swords like that today, using state-of-the-art equipment; they're not even close.

Muramasa believed in geometry, specifically, the arc of curvature relative to the tip. Muramasa used the "clamp" method, whereby the hardest steel was encased in a shoe of slightly softer steel, and both would fit in a shoe of steel softer still. He would use up to 4 "shoes" of different steel alloys to cover the edge steel; 5 different kinds of steel total. He reached the same conclusion as Masamune, but relied on a different method to get there. Muramasa's innovation, however, was in the belly of the blade.

Masamune's bellies were dead center of the blade, practically identical geometry from the center towards both the tip and the pommel; can't argue against that.

Muramasa's bellies were deliberately asymmetrical, located closer to the handle. Think of a kukri: it's straight for a short length from the handle before developing into a massive curve. More leverage is generated from the straight portion (longer lever) after the belly, and the rear-ward location of the belly meant that all too often the weight of the sword alone was enough to split a torso.

Accordingly, Muramasa's blades are considered wicked, bloodthirsty, and spiritually unclean -.- while Masamune's blades were noble, honorable, and (obviously) divinely inspired =)
 
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Be careful looking up either of them as there's a lot of legend beyond the metallurgy.
yes, that is why i wanted to hear it from you, sensei

lots of video games have used these swords. I have known only that Masamune and Muramasa had a legend regarding their swords, the latter being a bloodthirsty sword, and the former being a "sword of life" so to speak

Thanks for telling me. Can you write some more interesting Japanese sword history?? I'll live in this thread for a while.
 
Those swords are mentioned in video games? I guess I shouldn't be surprised, I'm sure Excalibur has been in a 100 games...
 
Those swords are mentioned in video games? I guess I shouldn't be surprised, I'm sure Excalibur has been in a 100 games...
Hey, I bet you know a lot about Miyamoto Musashi. Wanna talk about The Way Of Walking Alone, Dokkōdō ?

I read The Book of Five Rings in middle school. I didn't absorb what I should have out of it, but I bet I absorbed some things from it. I wanted to read it because I respected Musashi, for someone who fought, he was so wise and............. honorable!!!! Go figure. An honorable Japanese dude.

Now I'm thinking of reading it again. Found out about The Way of Walking Alone that way.
 
The Five Rings is masterpiece, and it's hard to believe someone like that actually lived. He was on the losing side of two wars, and fled both battlefields by covering himself in the blood of others, pretending to be dead.
 
In the first three paragraphs of the book, he admits luck played no small part in his survival. That's common among warfighters: "why did I live while others died?" They all ask that question, and only idiots think it's because they were smarter, faster, or genetically superior.
 
For those NOT familiar with the original M&M, he killed every single famous swordsman of his day using wooden swords: THEY used live steel blades, honed to a razor; HE used a curved stick. When asked why, he said it was to make it fair.
 
Masamune and Muramasa both made blades that have not been equaled using modern technology, which is a huge statement given the primitive implements they each had to work with.

Masamune's intricate system was that of 3, overlapping "diamonds" (3D triangles), each made of a different steel composition, forged together for effect: one diamond's linear plane would protrude at the edge (the hardest steel), another edge would protrude at the sides of the blade (more flexible steel), a third plane would protrude at the spine (softest steel); he made several swords with up to 7 protrusions of different steel alloys, varied for effect. People have tried to make swords like that today, using state-of-the-art equipment; they're not even close.

Muramasa believed in geometry, specifically, the arc of curvature relative to the tip. Muramasa used the "clamp" method, whereby the hardest steel was encased in a shoe of slightly softer steel, and both would fit in a shoe of steel softer still. He would use up to 4 "shoes" of different steel alloys to cover the edge steel; 5 different kinds of steel total. He reached the same conclusion as Masamune, but relied on a different method to get there. Muramasa's innovation, however, was in the belly of the blade.

Masamune's bellies were dead center of the blade, practically identical geometry from the center towards both the tip and the pommel; can't argue against that.

Muramasa's bellies were deliberately asymmetrical, located closer to the handle. Think of a kukri: it's straight for a short length from the handle before developing into a massive curve. More leverage is generated from the straight portion (longer lever) after the belly, and the rear-ward location of the belly meant that all too often the weight of the sword alone was enough to split a torso.

Accordingly, Muramasa's blades are considered wicked, bloodthirsty, and spiritually unclean -.- while Masamune's blades were noble, honorable, and (obviously) divinely inspired =)


Just wanted to say that I had the chance to closely inspect a Masamune sword, and I believe there was also a Muramasa, along with about a dozen on display, all of them made by masters. They were all jaw-dropping, but the Masamune stood out amongst them. I really wish I could see them again. This one low-quality photo is all I have of that moment, other than what's in my head:

xMfuD0o.jpg


Concerning shubo zukuri, a professional katana mounter who test cut with one of mine said that I should do shobu zukuri, and furthermore could make them with no shinogi at all (no blade flat, just full height grind), and that this type of sword was a cutting MACHINE!

Edit: I believe the Masamune is the only sword pointed to the left.
 
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You guys have too much fun in here. First the end of the world thread, now impressive japanese sword lore.

It's almost inspiring me to take up some form of martial art.

However, truth be told, my heart condition means no matter what my only prayer in any kind of fight would be getting to a gun as fast as possible.
 
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