Bo-hi and Tameshigiri

[M.Clay]

Hello,

Does Bo-Hi have any effect on Tameshigiri. In Iai the Bo-Hi is nice,but does it interfere with cutting?

Best regards, Mike

[socho]

Hello,

Does Bo-Hi have any effect on Tameshigiri. In Iai the Bo-Hi is nice,but does it interfere with cutting?

Best regards, Mike

No.

Dave

[Brian Owens]

Does Bo-Hi have any effect on Tameshigiri. In Iai the Bo-Hi is nice,but does it interfere with cutting?
Someone asked the same question a few weeks ago. If I me be forgiven for quoting myself, here was my response:


If the blade has a good cross-sectional profile then that shouldn't be the case. If you consider the profile to be a sort of diamond shape, with the ha and the mune being the bottom and top "points" and the left and right shinogi being the side points, then the section where the bohi lives -- the shinogiji -- would actually be recessed from the shinogi and so wouldn't be in solid contact with the target.

That's is my understanding, anyway.

[M.Clay]

Thank you guys, Mike

[kdlarman]

To clarify a bit...

Not all swords are created equal in terms of cross sectional geometry. Some have parallel shinogi-ji surfaces, other have what is called a high shinogi meaning the thickness of the blade at the shinogi is greater than thickness at the mune (creating the more diamond like cross section). This latter shaping is a typical feature of the Yamato school of swords for instance.

But all that said many blades have very much parallel shinogi-ji surfaces. The way that blade passes through a target is different from a blade with a high shinogi. There is less drag with a high shinogi blade since the shinogi-ji are both angled in from the target as they pass through. A bo-hi in that would have little effect on the feel as it passes through the target.

If the shinogi-ji are perfectly parallel you'll have a bit of a "grab" on the mune side of the bo-hi as it goes through a target of any weight. But it would be minor.

Not all bo-hi are created equal. I've seen some cut into swords where the bo-hi "edge" was a bit too low. Meaning it was starting to cut past where the shinogi would have been. This isn't uncommon especially when we're talking about production sword makers that use mills and the like to cut them in. These type tend to be very deep (which is a dead giveaway for how they were done and is in general a very bad idea). Anyway, what can happen is if the original blade has shinogi ji that are parallel and if the bo-hi is cut in a half mm too low, the end of the groove near the mune is actually thicker than the blade at the other side of the bo-hi. So basically the blade will kinda of "thunk" as it goes through targets.

Well done they don't make much difference. However, I have had a few people over the years tell me that they feel bo-hi (well done ones) sometimes with very large soft targets. On a small target the blade will cut, lift and separate (sounds like a brassiere commercial) the target as it passes through. But a larger, heavier targets will tend to "squeeze" the blade since it takes a lot more to make the target "jump" when you go through. And in that case the bo-hi is "felt" as a bit of drag.

Of course all of this is a "all things being equal" sort of discussion. And they never are anyway... ;) And lots of this has to do with subjective interpretations of the feel as a blade passes through a target.

[M.Clay]

[QUOTE=kdlarman]To clarify a bit...

Hello Kdlarman,

Thank you for the input. I can't afford a Japanese shinken now...I'm currently Looking at the Bugei "Dragon Fly Katana" it looks to have the proper diamond shape you desribe. Where the bo-hi drops below the cutting edge. Or do you think that for a first shinken I would be better of w/ a mid-range Chen like the "Wind and Thunder" or the "Tsunami", there $500 dollars less expensive.

Thank you for your time,
Mike

[chrismoses]

[QUOTE=kdlarman]To clarify a bit...

Hello Kdlarman,

Thank you for the input. I can't afford a Japanese shinken now...I'm currently Looking at the Bugei "Dragon Fly Katana" it looks to have the proper diamond shape you desribe. Where the bo-hi drops below the cutting edge. Or do you think that for a first shinken I would be better of w/ a mid-range Chen like the "Wind and Thunder" or the "Tsunami", there $500 dollars less expensive.

Thank you for your time,
Mike

I would assume anything coming from Bugei will be shaped to cut well. Even if some of their offerings are not listed as 'heavy duty' cutters, their swords have a very good reputation for cutting well. Bugei also does a better job than other importers of Chen blades with their quality control (since they know what to look for). I really like the way the Dragon Fly Katana feels and looks in particular, and while it is a bit lighter than some of their other offerings, I personally wouldn't hesitate to cut with it (I primarily cut tatami omote, not bamboo however).

And as always... Aks yer Sensei! ;)

[kdlarman]

[QUOTE=kdlarman]To clarify a bit...

Hello Kdlarman,

Thank you for the input. I can't afford a Japanese shinken now...I'm currently Looking at the Bugei "Dragon Fly Katana" it looks to have the proper diamond shape you desribe. Where the bo-hi drops below the cutting edge. Or do you think that for a first shinken I would be better of w/ a mid-range Chen like the "Wind and Thunder" or the "Tsunami", there $500 dollars less expensive.

Thank you for your time,
Mike

First off I have to say that a diamond cross section is not "proper" in the sense that other shapes are "improper". Many (most?) shinogi zukuri designs do not have a high shinogi and the shinogi-ji surfaces are basically parallel with each other. That is "correct" as well. Some styles will taper them towards the mune and that is "correct" too. There are a lot of subtle details and variations in shapes among various smiths, styles, etc. That's why experienced people can sometimes so quickly and accurately identify when a blade was made, in what province, and sometimes even by who even if the piece is unsigned. A high shinogi for example will make someone immediatley think of the Yamato den. Not always and other things will have to support that, but it is an identification point. But many other schools do not use a high shinogi hence the shinogi-ji surfaces are for all intents and purposes parallel.

With respect to the Bugei dragonfly you also need to realize that I'm one of the guys who helps design their swords and perform QC.

I have two dragonfly katana in my shop right now. My personal training blade is a dragonfly with bo-hi. I have no problem cutting with it. Super sharp and I think it is a really nice blade. I wanted bo-hi on my blade because I tend to suffer from tendonitis in my elbows due to abuse from sword polishing and sword training. So anything to reduce the stresses on my elbows. And I have cut a lot of targets with my sword and I don't notice the bo-hi. Remember that when I wrote I said some people claim they feel the difference. And I've felt a difference with a bo-hi on some blades I've tried usually due to the target being really thick or the bo-hi not being well done. But it is *MINOR*. The bo-hi would have to be horribly done to be felt as anything less than a "what was that tiny feel I had" sort of impression. Of course bo-hi introduce other issues with tameshigiri especially with less experienced swordsmen attempting larger, harder cutting. Don't screw up your cuts.

Anyway, I have two in my shop right now. One with bo-hi (mine) and one without. The one without bo-hi has perfectly parallel shinogi-ji. It has a very flat ji surface and would make a strong, aggressive cutter. I don't think I'd attack bamboo with these blades as they were made to be flatter with less edge support (I'd call it hira niku to use the proper terminology). Many blades were made this way or polished to this point in history and they make excellent soft target cutters. And the dragonfly has become very popular with martial artists because they are aggressive cutters.

With respect to the other swords by Hanwei, I really don't comment on them. I haven't seen enough of them recently or looked at them close enough to really have an informed comment.

[socho]

huge difference between the dragonfly (df) and the wind & thunder (wt). Very much depends on what you want, are used to or are looking for. I have a df with bo-hi that I sometimes use. very nice light iai blade, good for forms (repetitious training), very nice cutter. And the Swedish powdered steel makes nice hada. One of my students just won a wt (no bo-hi) at the recent Arizona tai kai, brought it to the dojo tonight for some cutting. Very good cutter, much heavier blade. Nice lines (much improved over the earlier models. I like the hamon (suguha) and the o-kissaki, feels very strong in the cut, but weighs about twice as much as the df, does not have much sori, so I would not recommend it for forms, or as an 'all-around' blade. Your mileage may vary.

Dave

[Maro]

The W&T is indeed a beast. I'm of large build and rarely use it for forms - it's much too tiring.