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Post by Deleted on Mar 29, 2017 3:05:43 GMT
I could take or leave bo hi.
The term "no hi" drives me up the wall. It's worse than katana being faster / sharper than longswords or being able to cut machine gun barrels, or whatever other myth you like. I would rather hear it called a blood groove. I would rather hear a magazine be called a clip. I would rather spar. I hate the term no hi.
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Post by Faldarin on Mar 29, 2017 13:08:06 GMT
The myth was propagated by the US army putting it in their manuals about bayonets and knives Interesting, Croccifixio - I was wondering about this. I've heard a lot of people repeat it, and wonder where it came from. A fuller or bo-hi does subtract from the weight of the sword (by removing material). This weakens the sword in both directions, the flat and the cutting plane. Some people say 'But it works like an I-beam!'. I'm no structural engineer (despite an engineering degree), but this statement to me is both true and false. It works like an I-beam for the cutting plane - so the strength stays roughly the same (despite material removal) for direct edge-on-target contact. The sword will be weaker to pressure from the side, though, having more flex. It's not pronounced on a katana, because the fuller is at the spine, which is fairly thick... and not exactly bad on a katana either. At least with a differentially-hardened blade, giving the spine more flex will help it absorb shock a little more. That said - I'm kind of on the fence about a bo-hi. Most aren't well-carved enough to make a great difference with sound on lower-end production blades in my experience. .... I do like fullers on my longswords though, just saying. Mmm. (From an aesthetic standpoint.)
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Post by AndiTheBarvarian on Mar 29, 2017 14:14:28 GMT
I could take or leave bo hi. The term "no hi" drives me up the wall. It's worse than katana being faster / sharper than longswords or being able to cut machine gun barrels, or whatever other myth you like. I would rather hear it called a blood groove. I would rather hear a magazine be called a clip. I would rather spar. I hate the term no hi. I read it so often that I actually thought it would be the official japanese term for "no bo hi". In the future I will use "no blood groove"!
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Post by randomnobody on Mar 29, 2017 18:41:51 GMT
Well, "hi" in this case is just the general (Japanese) word for "groove" and can refer to any applicable style. Bohi, futasuji-hi, naginata-hi, etc are all "hi" in this sense.
Thus, a sword without any of these is a sword with "no hi" is it not? I'm not aware of a term that specifies a sword without hi, otherwise. Therefore, "hi or no hi" is equally valid to "with or without hi" unless we should shift to "mu-hi" to stay all Japanese-y with it?
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Post by MLanteigne on Mar 29, 2017 19:22:57 GMT
Some swords I don't mind having hi if the termination follows the shape of the kisaki. Otherwise I am not a huge fan. I think they really became popular when Iai experienced a. It of a bloom in members in the mid 2000's.
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Post by AndiTheBarvarian on Mar 29, 2017 19:25:13 GMT
hi hi (german for heh heh)
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Post by randomnobody on Mar 29, 2017 20:08:55 GMT
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Post by Deleted on Mar 30, 2017 0:04:42 GMT
Sine hi? Para hi? Hi yanai?
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Post by randomnobody on Mar 30, 2017 0:42:56 GMT
Hi ja arimasen?
I should really get back into Japanese...
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pgandy
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Senior Forumite
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Post by pgandy on Mar 30, 2017 0:46:01 GMT
There is disagreement as to the effectiveness of a bo-hi, not only here but elsewhere and what characteristics it gives a blade. I was wondering if the method used to make a fuller might have some effect on the end result, granted blade width and thickness also play a part. The two methods that I am aware of is hammering it in as the man did in the video and milling it. Hammering it in does not remove material but rather rearranges the metal, pushing it around and relocating it if you will. Milling is cutting the metal away and thereby making the blade lighter. I have no idea as to how these two methods differ regarding effects on stiffness. If anyone has thoughts on this your input will be welcomed. Another thought crossed my mind and that is the shape of the fuller. That is the two parallel walls of the fuller could be more perpendicular the blades sides on some blades than others, giving more of an ‘I’ beam shape.
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Post by vermithrax on Mar 30, 2017 0:55:14 GMT
All, I am sorry I started all this but glad we are all getting to know a LOT about the bo hi!
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Ifrit
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More edgy than a double edge sword
Posts: 3,284
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Post by Ifrit on Mar 30, 2017 1:07:35 GMT
At the moment, its my favourite discussion thread
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Post by vermithrax on Mar 30, 2017 1:13:52 GMT
At the moment, its my favourite discussion thread Agreed. I think I should start another one about gimei swords of same era.
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Post by seriouslee on Mar 30, 2017 2:08:28 GMT
"About those hammered fullers So the I-beam profile created by a fuller isn't responsible for any increase in stiffness over an equivalently sized solid section. But what if the fuller wasn't created by removing material, but rather by moving material around?
This is actually pretty simple: In that case, because of conservation of mass, the outer dimensions of the piece will no longer be the same. So it is possible for a hammered fuller to increase the stiffness, because you are not removing material... assuming that is that you don't grind that excess off to make an edge."
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Post by Croccifixio on Mar 30, 2017 2:17:22 GMT
Fullers/grooves/hi are all about the weight. Reducing weight somewhere, while maintaining 1. a good angle for the cutting edge, 2. enough thickness at the spine or ridges to maintain some stiffness, and 3. making the blade easier to wield (for instance, single handed swords from the 10-12th century of the type X-XIII variant can still be wielded with speed and grace despite having massive, 30+ inch blades due to their deep fuller/s). Of course, they also affect the harmonics of the sword but I think that's mostly tangential and related mostly to mass distribution along the parts of the blade OTHER than the fuller.
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Ifrit
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More edgy than a double edge sword
Posts: 3,284
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Post by Ifrit on Mar 30, 2017 2:17:57 GMT
Interesting theory. Perhaps that, likewise, it can lighten the blade, but only if the fuller is ground out.
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Post by Timo Nieminen on Mar 30, 2017 2:24:43 GMT
I was wondering if the method used to make a fuller might have some effect on the end result, granted blade width and thickness also play a part. The end result (mostly) only depends on the final cross-section. The stiffness and weight only depend on the final cross-section. Yes, forging a fuller/hi doesn't remove material, so doesn't reduce weight, but if you compare finished blades of the same cross-section, the stiffness and weight will be the same. Strength and appearance of laminated/pattern-welded blades is affected by forging vs cutting/grinding. Another thought crossed my mind and that is the shape of the fuller. That is the two parallel walls of the fuller could be more perpendicular the blades sides on some blades than others, giving more of an ‘I’ beam shape. This makes a difference. A rectangular fuller of the same width and depth removes more material than a round fuller, and only reduces the stiffness by a tiny amount (the extra material removed is closer in to the centre plane of the blade). You can remove about 30% more steel, and only increase the reduction in stiffness by less than 10% (depending on how deep the fuller is). The most extreme fullers are T-spine blades, which can can think of as wedge-section blades with very wide and deep rectangular (triangular?) fullers. Not quite an I-beam, but a T-beam. (Offset fullers where each fuller is deep enough to go through the centre plane of the blade are pretty extreme, too.)
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Post by seriouslee on Mar 30, 2017 2:28:19 GMT
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Post by randomnobody on Mar 30, 2017 4:00:01 GMT
The most extreme fullers are T-spine blades, which can can think of as wedge-section blades with very wide and deep rectangular (triangular?) fullers. Not quite an I-beam, but a T-beam. What about T-section with fullers either side?
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Post by Timo Nieminen on Mar 30, 2017 4:45:56 GMT
The most extreme fullers are T-spine blades, which can can think of as wedge-section blades with very wide and deep rectangular (triangular?) fullers. Not quite an I-beam, but a T-beam. What about T-section with fullers either side? :o If you mean this: then it's just a fuller-within-a-fuller. Fullers on these tend to be narrow and shallow, decorative more than functional. Some T-spin blades are pretty thick (like modern repro Khyber knives) - not really extreme fullers. Note that I didn't say that T-spine blades are the most extreme fullers! If you mean this: then it's just the double-edged version of the T-spine blade. The "blade" is usually much thicker than a thin T-spine blade.
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