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Thread: Kumidachi with steel blades?

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    Nathan, interestingly my original zinc-beryllium iaito balances & swings almost exactly the same as the Bizen Nihonto I use in SMR Jodo training. The shapes aren't close at all, but the balance is so close that I'm not sure I could tell them apart in my hands if I was blindfolded. But its mune developed a string of tiny divots along one edge that feels & acts much like a file when I do noto, so that's why I moved to steel.

    My steel Tozando iaito, although a very nice training weapon, doesn't feel at all the same as any of my shinken or Nihonto. Not sure why that is. But I agree that zinc-aluminum blades are not the best choice for serious iaido training from a safety aspect. Our dojo with only 12 iaidoka has experienced five blade breaks over the past two years: three at the habaki & two at the yokote. None of the blades had any floor contact, BTW.

    That said, as a long-time engineer & metallurgy expert, when I ran some quick calculations on the force it would take to break/shear a Zn-Al blade with those dimensions, it came out to nearly 1,000g (gravities)!! Although I like to think that my swings are fairly powerful these days, I doubt that they come anywhere near that much force, & the same applies to our other students. So that makes me wonder whether modern Japanese manufacturing processes - or at least their quality controls - are as good as we think & expect.

    But even using steel blades for kumidachi, I'm going to continue to try & convince Sensei not to go in that direction.

    Ken

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    Hi Ken,

    Interesting about your nihonto vs iaito. I could see the balance being the same, but usually the difference in weight is significant. But good for you if they feel the same.

    As far as breakage goes, I always assumed that swinging aluminum iaito strongly gradually causes stress/stretch to the blade (just ahead of the front grip), which over time, continues to weaken the blade until it breaks. I remember checking the grain pattern inside the broken iaito we had, and I didn't observe any irregularities that would indicate a manufacturing flaw. But yeah, it could be an inconsistency with the mix of aluminum & zinc (or whatever). That being said, I've heard from people who do slower forms of iaido that they never have any problems with breakage, so I guess it depends a bit on the style of swordsmanship you study.

    Live blades for kumitachi? Some arts, including koryu, use blunted shinken at the most advanced levels. Ono-ha itto-ryu, for example, use what they call "Habiki" blades for this. I've used live blades a handful of times for kumitachi with my most senior/trusted students, and if feels kind of like (to me) like facing a partner with loaded guns. Definitely keeps you focused, but very dangerous on all accounts, and I would only do it under certain circumstances and with the right partner.

    Regards,
    Nathan Scott
    Nichigetsukai

    "Put strength into your practice, and avoid conceit. It is easy enough to understand a strategy and guard against it after the matter has already been settled, but the reason an opponent becomes defeated is because they didn't learn of it ahead of time. This is the nature of secret matters. That which is kept hidden is what we call the Flower."

    - Zeami Motokiyo, 1418 (Fūshikaden)

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    Nathan, my Kunimune Nihonto has a thin & rather elegant blade, so the weight differential is almost nil. Fast & fun to train with, but incredibly sharp, so my attention is always well-focused. But I think that is exactly why my SMR Sensei (Menkyo Kaiden) prefers us to train that way, outdoors on a mountain, in as "real" an environment as possible.

    Thanks for your input on live-blade kumidachi. My other (MJER) Sensei thinks that these blades will work better than our current bokken with saya, but based on the input in this thread, I'm increasingly sure that the potential for injury far outweighs any possible benefit. There are four of us who are senior enough to conduct training, & I would rather keep that number constant, rather than thinning our ranks!

    Ken

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    Ken,

    Nice looking sword! Yeah, I admit to using heavier blades, so that's probably a big factor in my opinion.

    Some koryu that use live or blunted swords for contact training include edge-to-edge contact, others do not. I was trained that at advanced levels it is not necessary to have edge-to-edge contact, except in an emergency hard-block, so my live blade work involved shinogi deflections against thrusts and cuts (within the context of pre-arranged kumitachi forms). The shinogi gets scarred a bit, but there should not be chips of steel flying at you or nicked edges. Ono-ha itto-ryu appears to avoid edge-to-edge contact from what I've seen, but others, like Jikishinkage-ryu (at least one branch) appear to perform edge-to-edge contact kumitachi with steel blades (nihonto or habiki - not sure which). This obviously results in chips of steel flying around, and rows of saw-teeth where the edge used to be.

    So from a practical standpoint, if your kumitachi involves edge-to-edge contact, one argument against it could be that the chips of steel that result are dangerous to the eyes, and that the swords become ruined after becoming chipped. Obviously, expensive to replace on a regular basis, and once critical flaws are created in a sword, the odds of complete failure are greatly increased (resulting in broken sword flying across the room).

    If you don't have edge-to-edge contact, then I guess you could just stick to the idea that you all don't want to die while practicing kata, and remind the teacher could easily be sued for any injuries students obtained from such practice, based on negligence / unsafe training methods.

    BTW, I'm also a big fan of training outdoors. There was a period of months where my dojo space was being restored, and we trained outside in the grass at night time. One thing I used to like to do is practice kumitachi on hill sides, both vertical and horizontal to the slope. Also, doing forms around trees is a lot of fun for the zanshin as well. We also used to do extra training at the beach for bonus training. Outdoor surfaces, reduced lighting, etc. are GREAT experiences to have for any martial art. IIRC, the original ryu-ha used to practice outdoors, and only at some point later took to training inside a dojo. I'd have to dig through a bunch of notes to find details about that though...

    Regards,
    Nathan Scott
    Nichigetsukai

    "Put strength into your practice, and avoid conceit. It is easy enough to understand a strategy and guard against it after the matter has already been settled, but the reason an opponent becomes defeated is because they didn't learn of it ahead of time. This is the nature of secret matters. That which is kept hidden is what we call the Flower."

    - Zeami Motokiyo, 1418 (Fūshikaden)

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    Sensei has us doing full-speed, edge-to-edge TUNK much of the time, Nathan, & I shudder thinking about my pristine steel iaito getting clobbered by another blade! And now that I think about it, I've had other sempai whack various of my body parts during training, & I've likely returned the favor. Nice bruises from a bokken, but the potential is for much worse, as you point out, using metal blades of any type. I'm not sure that Sensei has ever used a live blade except for tameshigiri practice &, up to now, he has not allowed them to be used in the dojo. That's why I was so surprised when he suggested using them for kumidachi, & even more so when my other sempai agreed. I'm glad that I publicly disagreed, even though I got chewed out. I'm sticking to my guns on not using metal blades at all for paired martial arts.

    Our MJER dojo had to train outside for a few months about 10 years ago while the recreation center we use was repaired from storm damage. My wife & I had a great time because we were used to it from SMR, while you'd think some of our other students were made of cotton candy & afraid that they'd melt. Linda & I were sorry when we had to move back inside. Of course Hawaii & California have relatively pleasant weather for outdoor training, Nathan - not sure I'd be so gung-ho if we still lived up in Wyoming!

    I'd be interested in those IIRC notes if you happen to run across them.

    Ken

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    Quote Originally Posted by Ken-Hawaii View Post

    . Not sure why that is. But I agree that zinc-aluminum blades are not the best choice for serious iaido training from a safety aspect. Our dojo with only 12 iaidoka has experienced five blade breaks over the past two years: three at the habaki & two at the yokote. None of the blades had any floor contact, BTW.
    There is something severely wrong with either the source of your blades or the training method.

    I've hit a steel joist with my Tozando Zinc-alloy blade and it's still going strong 8 years later.

    I'd love to see the positions of the left hand when the breaks occurred.

    "Serious" Iaidoka nearly always use Zinc-alloy and only use steel variants if they are shinken.
    Mat Rous

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    "Serious" Iaidoka nearly always use Zinc-alloy and only use steel variants if they are shinken.
    Interesting comment, Mat. I wonder what your definition is of "serious." Of the five iaidoka who had zinc-alloy blades break, all but one are yudansha, & Sensei is kodansha. Like my wife & I - also yudansha - they have all switched to steel iaito.

    Are you of high enough rank or possibly heading up your own ryuha that you can make a blanket statement like this for all iaidoka? As you have chosen, by your own words, to "hit a steel joist" with your blade, I rather doubt that this is the case....

    Ken
    Ken Goldstein
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    Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
    Fencing Master/NRA Instructor

    "A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."

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    Ken, yeah - sounds scary. I would opt out if possible.

    Mat, as far as the longevity of zinc-alloy iaito, sure, there are plenty that last a long time, and never break. However, I think it is worth taking in to account that not all arts swing the same way, or, practice the same way. Even within a given art there are those who train more seriously / realistically, and those that are more philosophical in their training approach. It doesn't mean that one Way is necessarily wrong, just that some approaches may be harder on a zinc-alloy iaito than others. I think it is only fair to allow for such a possibility, rather than just make blanket attacks against others you know nothing about, don't you?

    Regards,
    Nathan Scott
    Nichigetsukai

    "Put strength into your practice, and avoid conceit. It is easy enough to understand a strategy and guard against it after the matter has already been settled, but the reason an opponent becomes defeated is because they didn't learn of it ahead of time. This is the nature of secret matters. That which is kept hidden is what we call the Flower."

    - Zeami Motokiyo, 1418 (Fūshikaden)

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    Quote Originally Posted by Ken-Hawaii View Post
    Interesting comment, Mat. I wonder what your definition is of "serious." Of the five iaidoka who had zinc-alloy blades break, all but one are yudansha, & Sensei is kodansha. Like my wife & I - also yudansha - they have all switched to steel iaito.

    Are you of high enough rank or possibly heading up your own ryuha that you can make a blanket statement like this for all iaidoka? As you have chosen, by your own words, to "hit a steel joist" with your blade, I rather doubt that this is the case....

    Ken
    Now now Ken, you were the one who made a blanket statement first about Seriousness. If you dish it out, you've got to expect them back

    Re hitting a beam - that was in my first six months of practice. I don't consider myself an expert at all. I put it out there as a humble statement.

    I have trained in the US, Japan and Australia for 10 years and trained with over 150 other iaidoka from other styles apart from my own.

    Apart from Apocryphal tales, I've never know anybody to break their Iaito.

    5 in one dojo is an anomaly, hence my statement re supplier.

    Nathan, if you re-read my comment, there is no blanket attack. Perhaps you aren't getting the tongue in cheekness of an Englishman......
    Mat Rous

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    I don't think that any of us got our iaito from the same supplier. Well, my wife & I got our steel blades from Tozando, & had our original zinc-beryllium blades custom made at a small Tokyo shop near NHK, but none of those blades failed. Sensei had offered to buy low-cost Zn-Al iaito for several new students, but none of them took him up on that, so I can't see the failures being manufacturer-based unless they're all in cahoots.

    Ken

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    Quote Originally Posted by Nathan Scott View Post
    Personally, I've always considered aluminum alloy iaito to be, technically, unsafe pieces of crap. The weight is all wrong, and they swing "funny" , compared to live / steel blades, IMO.
    Not their fault if you bought only cheap ones!

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    Quote Originally Posted by Ken-Hawaii View Post
    I don't think that any of us got our iaito from the same supplier. Well, my wife & I got our steel blades from Tozando, & had our original zinc-beryllium blades custom made at a small Tokyo shop near NHK, but none of those blades failed. Sensei had offered to buy low-cost Zn-Al iaito for several new students, but none of them took him up on that, so I can't see the failures being manufacturer-based unless they're all in cahoots.

    Ken
    Mine is also Tozando.

    Which particular cut is the predominant culprit?
    Mat Rous

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    You know, Mat, that's a good question. I have to admit that when that chunk of Sensei's blade flew across the floor at me, I wasn't considering which cut had caused the break. We were in MJER Okuden, but that's all I recall. I'm fairly sure it was a kirioroshi cut as that puts the most strain on the blade.

    I wasn't at the dojo when two of the other breaks occurred, & I was leading a different group of kohai when the fourth break happened. Not sure about the fifth. I'll ask Sensei on Saturday if he recalls what he was doing when his iaito broke.

    Ken

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    Okay, Mat, I have an answer for you. Still another Zn-Al iaito broke at iaido training this evening. I stayed home to help my granddaughter with a project, but my wife said one of our other yudansha was doing kirioroshi (as I expected) in plain old Shoden when his blade snapped off two inches in front of the habaki.

    Not a cheap one, either. It was one of the mid-range iaito from e-Bogu, who makes decent equipment, & cost about $700. Sensei has suggested that he buy a steel blade to replace it.

    Ken
    Ken Goldstein
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    Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
    Fencing Master/NRA Instructor

    "A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."

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    Not their fault if you bought only cheap ones!
    Yeah, but I've played with plenty of iaito from different manufacturers over the years. Koshirae is a good value, but the weight and "flex" feeling of the blade have always been big turn-offs. We use shinken far more than iaito, so the difference going back and forth for us is very noticeable. But as I say, this is just my experience / opinion.

    I bought a Tozando Iaito for $500 maybe 15 years ago. Rarely use it, but it has served me well so far. Personally, I only use iaito for teaching students about sword etiquette, how to put on and take of the sword, and how to draw and resheath. We use bokken or shinken after that for solo kata practice.

    As far as Kirioroshi, I could see how such a "casting" swing could create quite a bit of stress around the habaki area. The blade is thrown forward, then pulled down, then stopped fairly abruptly. While a bad swing of any kind, or a sharp cut-and-reverse (tsubame-gaeshi) type technique could easily place stress on such a blade, breaks at the habaki from an Iai Kirioroshi makes the most sense to me. Why it doesn't happen to everyone who cuts that way is interesting, but probably varies mostly on the amount of power generated vs. the sharpness of the swing completion. I know that the iaito that broke at the dojo I was training at broke from a straight downward swing, and we swung with a lot of power and stopped the blade pretty sharply at the end of the swing.

    Regards,
    Nathan Scott
    Nichigetsukai

    "Put strength into your practice, and avoid conceit. It is easy enough to understand a strategy and guard against it after the matter has already been settled, but the reason an opponent becomes defeated is because they didn't learn of it ahead of time. This is the nature of secret matters. That which is kept hidden is what we call the Flower."

    - Zeami Motokiyo, 1418 (Fūshikaden)

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