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Post by randomnobody on Mar 23, 2017 21:15:28 GMT
It's hard to capture on video, really. Most iaido videos, for instance, I've seen frame the subject several feet back from the camera, so as to display the full form. One can sometimes hear the whistle, sometimes more of a woosh, but actual sword-swinging is so infrequent and generally far away.
Despite how loud it might seem to the user, it's actually quite faint to anybody a safe distance away. I'm not, personally. 100% convinced the sound produced by most bohi is even really the "right" sound to begin with. Of the few katana I have, those without actually make more pleasant, albeit quieter sounds than those with, though admittedly the latter is certainly louder.
Of the lot, those with aren't even consistently lighter than those without. Much more than hi or no hi goes into a blade's weight, never mind balance...
Oh, and as for my personal opinion, as far as aesthetics, I like clean hi. Crisp termination, some of the less common styles like naginata-hi, soebi, etc. I don't like poorly-executed hi at all. I'm indifferent otherwise, or I'd like to think I was, but I do tend to like swords without a little better than swords with...
Of course, my interest in Japanese-style swords these days isn't what it once was.
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Post by seriouslee on Mar 23, 2017 21:45:47 GMT
The sound is a defect in a sense. A perfect blade would not disturb the air as it cut through it. Like Red October it would allow air to pass through the front of the blade and then pass from the rear almost silently. A nano foam blade?
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Post by benvk on Mar 23, 2017 21:49:04 GMT
Thanks for that, its interesting to hear an opinion of a martial arts practitioner.
From the collector point of view, hi can be the result of a special order blade or the result of "repairs" during it's lifetime time to correct faults and/or damage. Good luck with deciphering the difference.
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pgandy
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Senior Forumite
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Post by pgandy on Mar 23, 2017 21:59:12 GMT
And no one has mentioned they make the blade sing. From my post yesterday “ In the beginning the sound helped helped...”.
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Post by AndiTheBarvarian on Mar 24, 2017 2:33:46 GMT
I don't know wether the sound is caused by the bo-hi or by the tip which can be moved faster on a lighter bo-hi sword. My Hanwei TacKat, light, with bo-hi, makes this sound, but also two of my lighter longswords without fuller and a rapier.
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Post by seriouslee on Mar 24, 2017 3:36:04 GMT
And no one has mentioned they make the blade sing. From my post yesterday “ In the beginning the sound helped helped...”. My apologies, I missed it.
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Ifrit
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More edgy than a double edge sword
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Post by Ifrit on Mar 24, 2017 3:41:04 GMT
My Kris Cutlery had a very noticible singing to it. Could hear three different sounds of swung correctly. I have yet to test this with my ronin
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Post by seriouslee on Mar 24, 2017 5:05:47 GMT
All my blades have a voice. The ones with bo-hi make sounds easier - less force required in the swing to produce sound. Fascinating article on the science of the sound a sword makes. blogs.scientificamerican.com/assignment-impossible/the-science-of-swords-the-sound-of-approaching-doom/So according to the article "thickness noise" is produced by any blade to some extent and "loading noise" is accentuated by the groove(s). Now the statement - "Since the back part of a katana is not tapered, "it would have a very similar vortex street, like a cylinder's."" is out of place with the Unokubi Zukuri since the spine changes width - thick at either end (a diamond shaped winglet at the tip) and a very thin carved out spine from the tip back to the first 10 inches of the blade. It would be interesting to capture and compare no bo-hi to a katana with one and then with two bo-hi to see if there is a perceptible difference in the sound, frequency etc and not just the ease of making noise. "The thickness of a sword and the geometry of its edge are also key factors regarding how easily a sword will generate tachikaze when swung. Intriguingly, the biggest factor behind tachikaze is whether or not a sword has a groove along its backside known as a bo-hi — swords with this groove are louder than swords without it." Backside?
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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 24, 2017 5:44:56 GMT
I got a noticeable sound with a no bo-hi sword, but my KC had a tri-tone sound. Sounded like 3 whistles. Interestingly, ot had an almost diamond shape to its cross section, the spine thinner than the central ridge, and a very smoothed out bo-hi. It had a geometric yokote, and even the width of the blade had a distill taper. It was a beautiful sword
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Post by randomnobody on Mar 24, 2017 14:30:05 GMT
I missed the bit about no taper past the bevel. That's just outright wrong. Even outside unokubi and it's cousin kanmuri-otoshi, any given katana (wakizashi, tanto, tachi, whatever Japanese style blade) could easily exhibit taper from the shinogi to the mune. Some have more than others, thus "high shinogi" and sport a very diamond-esque cross-section. As for comparing bohi to no bohi, that would require two blades that were otherwise completely, perfectly identical. Same length, thickness, bevel, taper, etc., except one has a groove carved into it and the other doesn't. I have an old Hanwei Practical Katana, a remounted Dynasty Forge Musha, a Musashi Swords Zetsurin, a Slavedge Katsujinken (which I keep forgetting I'm supposed to review, because I keep forgetting I have it) and some random Chinese katana with a bohi. Of those, two have bohi, three don't. I get satisfactory sounds from all five, but prefer the sounds of the blades without bohi. On top of these, and a few euro models, I also have Musashi Shirakawa line blade mounted in a basket hilt. I don't really count that among either Japanese or Euro, because it's both as much as neither. It's sound is... awkward? I'm also in possession of two antique wakizashi, one shinogi-zukuri with no hi, one naginata-naoshi with a short maru-bi. (I've seen that used before to describe bohi with a rounded end, but Google is failing me now) Both make adequate sound, comparable actually. My T-section blades are the weird ones, but we aren't talking about them...
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Post by Faldarin on Mar 24, 2017 14:49:24 GMT
I'm far more into European longswords than katana - but this is very much a thing when training with longswords. Every single one I have sounds a little different depending on the tip geometry, more than anything else. The ATrim is very quiet, but a unique sound. The rest of my longswords have unique sounds that let you know when you have the edge alignment right or wrong. Personally, I love the H/T bastard. Properly delivered, it has a beautiful 'swinging voice'.
My bo-hi katana are nearly as quiet as the ATrim. (This may just be me - I don't seem to cut with katana nearly as well as longswords.)
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Post by randomnobody on Mar 24, 2017 15:25:06 GMT
Some interesting points brought up on tip geometry. Speed is absolutely a factor, as much as alignment.
I wonder if a narrower tip creates a sharper sound, or is it thinner? Should we think of blades as airfoils? Perhaps, in a sense, there is relation. That science goes beyond me, and is probably not the direction this thread was intended to go.
I think, originally, aesthetics were the focus. I do enjoy the looks of some styles of grooving, especially on European medieval type swords. Particularly, among those, the wider blades. Unfortunately, a wide, double-edge blade with no fuller(s) holds little aesthetic appeal to me, personally. Single-edge, curved or not, I can do with or without just as easily. Oddly, in a European sabre, I like fullers more than I do on katana...
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Post by connorclarke on Mar 24, 2017 16:56:26 GMT
Wouldn't make a difference. Muscular exertion and speed of making a cutting motion mostly depends on how much sound the blade will make. Now for the actual bo-hi itself, the deeper and more consistent the grooves are means more noise will be produced from swinging it. Shallow cut bo-hi and no-hi blades all make noise as well but not as loud.
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Post by Faldarin on Mar 24, 2017 17:47:12 GMT
Wouldn't make a difference. Muscular exertion and speed of making a cutting motion mostly depends on how much sound the blade will make. Now for the actual bo-hi itself, the deeper and more consistent the grooves are means more noise will be produced from swinging it. Shallow cut bo-hi and no-hi blades all make noise as well but not as loud. That's for a different topic - but different geometries certainly make a huge difference with longswords. Back to the bo-hi at hand though - definitely deeper ones make a bit more of a sound.
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Post by wazikan on Mar 24, 2017 17:57:49 GMT
when I watch people make cuts the bohi allows me another way to monitor their movement,and my own for that matter. you can tell by the sound of they are making a good cut. sure you can watch the body but sometimes the body looks right but maybe their hand positioning is off. for instance. a gyaku kasagiri cut if you don't shift your right hand at the end of the cut it will take the blade out of alignment. its hard to see this but you can hear it. when im doing cuts it allows me to self correct easier. we might think we are moving correctly but in truth we aren't. so its a great teaching tool.
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Post by seriouslee on Mar 24, 2017 21:51:56 GMT
From a forging or engineering perspective - why do some blades have both bo-hi starting all the way back, beneath the habaki and some start the grooves an inch or two further down the blade?
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Post by Timo Nieminen on Mar 24, 2017 22:41:27 GMT
The grooves/hi on a katana are cut, not forged, so it doesn't affect the forging at all.
- If the hi runs under the habaki, having a nice termination doesn't matter.
- Some blades have been shortened, and hi that originally stopped short of the habaki now go all the way.
- Stopping short of the habaki leaves you with a stronger tang-blade transition.
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Post by seriouslee on Mar 25, 2017 0:24:05 GMT
The grooves/hi on a katana are cut, not forged, so it doesn't affect the forging at all.
- If the hi runs under the habaki, having a nice termination doesn't matter.
- Some blades have been shortened, and hi that originally stopped short of the habaki now go all the way.
- Stopping short of the habaki leaves you with a stronger tang-blade transition.
Thank you.
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Post by seriouslee on Mar 25, 2017 3:38:11 GMT
This is why I thought they were part of the blade before heat treating was complete. Not a great video but...
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Post by Timo Nieminen on Mar 25, 2017 4:16:49 GMT
Lots of ways to do fullers: forging them in with a fuller (the tool is also called a fuller), grinding them, and cutting them are the usual old methods.
Japanese-style:
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