To Bo-hi, or not to bo-hi?

[Kichigai-no-Okami]

Can someone please shed some light on this for me? In the market for a new katana, and doing some work in Bujinkan Biken jutsu , I got a feel for different type of blades. Love the feel of a lighter blade (bo-hi), but was advised that if doing Tameshigiri (love doing this !) that a "bo-hi-less" blade, although forward-heavier, would be more advisable. Can you cut [ temeshigiri] with the bo-hi just as well as a katana without the bo-hi?

Thanx for your help.

 

[Grenadier]

In my experiences, yes.

I've owned both a Last Legend Mark V (with bohi), and a Mark II (with no bohi), and both did a very nice job when cutting tatami. I haven't seen any rolling of the edges on either.

 

[Sukerkin]

This has ever been a thorny topic of discourse, with a division of practitioners and metal-workers both favouring either one side or the other as to whether a bo-hi weakens or strengthens a blade (or lightens it with no loss of strength).

As to whether a bo-hi blade would be more at risk for tameshagiri, that depends almost entirely on the skill level of the wielder. For someone with no prior experience of cutting practice then it would be advisable to go for a sturdy blade without a bo-hi (for the simple reason that a 'meatier' blade is more likely to survive a botched cut).

 

[Cryozombie]

I found that cutting with a sword that had a bo hi created more... drag? On the blade and I had trouble keeping the blade from "wobbling" when I swung it. But Im also not the most experienced cutter in the world, so take that as nothing more than a beginners opinion...

 

[howard]

As to whether a bo-hi blade would be more at risk for tameshagiri, that depends almost entirely on the skill level of the wielder. For someone with no prior experience of cutting practice then it would be advisable to go for a sturdy blade without a bo-hi (for the simple reason that a 'meatier' blade is more likely to survive a botched cut).

I'd fully agree with Sukerkin about this.

A well-made katana with a bohi will work well as a cutter. On the other hand, a katana with no bohi but that is not that well-made could give you trouble. Likewise, a beginner is going to have teething pains whether he's using a top-shelf katana or something much farther down the quality spectrum.

I believe I've seen some precautions against using certain very light katana with bohi on large-diameter bamboo (and they may have also taken the user's skill level into consideration), but if you're planning on cutting tatami, and you have some level of skill already, I think you'd be fine with a blade with a bohi.

 

[Kichigai-no-Okami]

Cool. Thanks to all for your input. Greatly appreciated. Was thinking about getting a Chennese Oniyuri.

 

[Sukerkin]

I found that cutting with a sword that had a bo hi created more... drag? On the blade and I had trouble keeping the blade from "wobbling" when I swung it. But Im also not the most experienced cutter in the world, so take that as nothing more than a beginners opinion...

Cryo, the most usual cause of 'kippering' when cutting is using too much right hand in the technique - trying to 'muscle' the cut so to speak.

To counter this tendency, try to make sure the 'power' comes from the left hand and 'direction' from the right.

The notion that the technique of cutting generates much more of the impact than muscle input is quite an odd one at first and the desire to 'put your shoulders behind it' is one of the more difficult things to let go of in sword work (well, that and the idea that you should not hold the sword too tightly ).

 

[Chris Parker]

Hi,

I would first say that your choice of sword should depend on your intended use. The bo-hi has long been a controversial topic amongst sword discussions, most notably with swift repercussions for anyone daring to use the term "Blood Groove" around me...

From my perspective, the use of the groove is best suited for someone wanting to get their cutting technique absolutely right, whether that is in Iai, solo training at home, or otherwise. The reason is that if your technique is correct (with the back of the blade following directly behind the edge), the groove in the blade catches the air, and makes a "whistling" sound. If there is no sound, then your cut was off, and on a real target would have resulted in (at best) a scalloped cut, or (at worst) a badly damaged sword.

But if you have already got a pretty good cutting technique, and want to get into a more practical approach by adding Tameshigiri practice, then you might want to get a "Full Bladed" sword, just for extra safety. If you pick a good, well-made sword (I would probably go for a modern one like the Cheness, at least to begin with), then you should be fine with either type.

 

[pgsmith]

Was thinking about getting a Chennese Oniyuri.

If you do, please have someone with experience take the handle off and inspect it before you use it. Many of the inexpensive Chinese made swords come with pre-cracked handles due to how they are assembled.

My experience with bo-hi versus not is as follows ...

1) Although a loud tachi kaze (whooshing sound) is an indicator of decent hasuji, it does not mean that your hasuji is totally correct. Once you begin tameshigiri, it is very common for people that have a good tachi kaze to totally thump the cut because their hasuji was just a bit off, but not enough to cause a difference in sound.

2) Swords that I've handled without bo-hi tend to be more forward weighted than those with bo-hi. This makes cutting easier because it is much easier to lay the sword out and let its weight and momentum make the cut. With bo-hi, it requires better technique and more tip speed to compensate for the forward weight and get enough momentum to cut well.

3) Swords that I've used with bo-hi tend to bend easier than swords of the same thickness without bo-hi.

4) The only benefit I've seen to having bo-hi is that it brings the balance back toward the tsuka. This makes repetitive practice much easier on the wrists and elbows, and helps prevent repetitive stress injuries.

These are just my opinions based on my experiences. Other's may vary.

 

[Flying Crane]

For someone with no prior experience of cutting practice then it would be advisable to go for a sturdy blade without a bo-hi (for the simple reason that a 'meatier' blade is more likely to survive a botched cut).

Is a Japanese sword so delicate that a botched cut could actually damage or even destroy it? It seems that in actual combat, with armor-wearing soldiers, and the chaos stemmed from weapons of all sort getting thrashed about, you must assume that the weapon will take some level of abuse. So could a botched cut on tatami mats really be so dangerous to the weapon?

 

[Erik Tracy]

Is a Japanese sword so delicate that a botched cut could actually damage or even destroy it? It seems that in actual combat, with armor-wearing soldiers, and the chaos stemmed from weapons of all sort getting thrashed about, you must assume that the weapon will take some level of abuse. So could a botched cut on tatami mats really be so dangerous to the weapon?

It depends.

One can not just categorically lump all "Japanese Swords" together when it comes to questions of performance.

But - historically speaking and even today with production katana or custom ones - you will find that the quality varies.

In general the ability of a given blade to withstand the inevitable 'bad sword day' that everyone eventually has is mostly due to the quality of the smith's heat treating of a blade.

It has less to do with the steel used - so just because a maker claims it is tamahagane, L-6, or 1086, or 5160, or whatever - means less than the reputation of the smith who made it.

In general, when speaking of modern production katana specifically designed for cutting (wide/thin blades) then, in general, they will be more prone to bending than say a blade with a more traditional shape that is not as wide, not as thin.

In general, the consensus of most practitioners I've talked to who actually compete in cutting events, and to polishers who see these types of blades quite a bit - is that, in general, for the SAME blade, the one with bo-hi will bend easier than the one without bo-hi.

But - that is not to say that just because a blade has bo-hi that it will be easy to bend. Which brings us back to who made the blade, how good was the heat treat, and to some extent the geometry of the blade in question - all factoring together that could result in a blade WITH bo-hi that is NOT easy to bend.

It depends - but a good quality blade made by a skilled smith with a quality heat treat will not be easy to bend.

Bear in mind - that ANY blade can be bent - there is no such thing as an indestructible blade....yet (even the L-6 blades by Howard Clark can bend or chip - just under extreme conditions that you will not likely encounter in a typical cutting environment).

YMMV,
Erik