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Thread: Question on katana dents

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    Question Question on katana dents

    I have a zinc-beryllium iaito that I had made in Tokyo about 10 years ago that gets swung for 5-6 hours each week in MJER & Shinto-Ryu. On the left side of the mune (while holding the katana), there are hundreds of tiny dents going the entire length of the blade. There are no dents at all on the right side of the mune. I'm right-handed, my saya is made of the usual ho wood, & there is nothing but wood at the koiguchi. I don't really notice the dents when doing noto, but am starting to wonder if they might cause eventual blade failure.

    I've been a professional engineer for 40+ years, & have worked with metals for most of that time, but I'm absolutely stumped. One other student in our dojo has a few dents on his mune, but nothing like mine.

    Any ideas???
    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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    Hey Ken,
    Could it be flaws in the copper or chrome plating? As long as the plating is not actually flaking off, it should be fine as long as it doesn't bother your practice.
    Paul Smith
    "Always keep the sharp side and the pointy end between you and your opponent"

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    Paul, as far as I can tell, there isn't any difference in the plating in & around the dents. I know there's some question on whether zinc-beryllium blades are plated at all, but in any case, the dents are far deeper (1/16 inches) than could be accounted for by plating problems. And of course with dents only on one side of the mune, plating problems wouldn't make much sense....

    I'm not yet panicked about the blade breaking, although our Sensei's last iaito did fail catastrophically a few months ago, & I had to (literally) jump over the piece that went skittering across the dojo floor towards me. I just can't imagine what would be causing the dents in the first place!
    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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    Quote Originally Posted by Ken-Hawaii View Post
    I just can't imagine what would be causing the dents in the first place!
    Do you have a significant other with a wicked sense of humor?
    David Sims

    "Cuius testiculos habes, habeas cardia et cerebellum." - Terry Pratchet

    My opinion is, in all likelihood, worth exactly what you are paying for it.

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    Ha, ha....

    We actually had our iaitos built at the same time & place, David, & although she doesn't swing hers quite as much as I do mine, there's no sign of dents on her blade.

    Truly strange.
    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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    That is truly strange. I don't think I've ever had an iaito develop dents in it.

    For what it's worth, my beryllium iaito (from Nosyudo) has copper, then chrome plating on it. Found that out after I managed to stick my kissaki into a wooden wall support at home (no more practicing in the house for me!). It badly bent the end of the kissaki and I had to file it down to repair it.
    Paul Smith
    "Always keep the sharp side and the pointy end between you and your opponent"

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    Quote Originally Posted by Ken-Hawaii View Post
    I have a zinc-beryllium iaito that I had made in Tokyo about 10 years ago that gets swung for 5-6 hours each week in MJER & Shinto-Ryu. On the left side of the mune (while holding the katana), there are hundreds of tiny dents going the entire length of the blade. There are no dents at all on the right side of the mune. I'm right-handed, my saya is made of the usual ho wood, & there is nothing but wood at the koiguchi. I don't really notice the dents when doing noto, but am starting to wonder if they might cause eventual blade failure.

    I've been a professional engineer for 40+ years, & have worked with metals for most of that time, but I'm absolutely stumped. One other student in our dojo has a few dents on his mune, but nothing like mine.

    Any ideas???
    As a professional engineer, I reckon you have two choices:

    1. Recognize that the gremlins or another supernatural force have induced tiny dents in your iaito.

    Or... ruling out magic and the fey....

    2. Ask you kids or who else (including you) who has access about it.

    Lance
    Lance Gatling ガトリング
    Tokyo 東京

    Long as we're making up titles, call me 'The Duke of Earl'

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    Here in Hawaii, they call gremlins "menehune," Lance, & they're supposed to only do good deeds .

    Our kids are grown & long gone, & one grandkid swings her own sword, so I kinda' doubt that she'd sit there with a tiny hammer & make dents in mine. I've been trying to take a digital photo that shows the dents, but so far I haven't been successful.

    I've also been using a 20X magnifier in bright sunlight trying to find any sign of copper, or even plating, in my iaito, but again no luck. Just looks like plain old metal with no bubbles or imperfections, other than the dents. If I could just figure out why they're only on one side of the mune, I'd be a lot happier!

    Well, as long as I can keep swinging it, I guess a few (hundred) dents are't going to make much difference . Thanks for the comments.
    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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    what are you cleaning it with, perhaps some reaction with the chrome??? I have seen some pitting before on chrome like this, and it is possible you always leave it with one side down... be good if you put it under a scope and took a look to see if it is corrosion or dents.

    Or is it you have spiky hair and a bad chiburi????
    Tim Hamilton

    Why are you reading this instead of being out training? No excuses accepted...

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    My, aren't we hilarious today...?

    Nope, just plain, old choji oil on a soft piece of toweling, Tim, same as I've been using for 20+ years. And with dents, rather than pits or corrosion, as seen under my 20X loupe, I'm still in the dark. If they weren't just on one side of the mune, I'd probably drop the whole thing. I generally keep the iaito in the saya, edge up, although if I'm going to train the next day, I do tend to leave them in my waterproof case, either standing on end or lying down.

    Oh, yeah, if my chiburui was that bad, I'd likely have scalped myself by now, as I train with shinken in Shinto-Ryu !!
    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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    I know it is a long shot, but have you tried peering into the saya aided by a small flashlight? Could you be knocking the edge of your koiguchi when doing noto? I'm just throwing out guesses here, since it is an intriguing mystery!
    Best regards,
    Bruce Mitchell

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    I guess its possible you have something hard bouncing around in the saya, maybe a metal chip, or a bit of grit??? Give it a good tap onto a white piece of paper and see what comes out.. just a thought, but the chrome isnt bubbling up due to something going on underneath by any chance, and you are taking the top off?

    in the meantime, avoid spiky hair...
    Tim Hamilton

    Why are you reading this instead of being out training? No excuses accepted...

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    Hey, guys, I just realized that this thread has been on e-budo for DAYS without a single person saying "Ask your sensei!"

    That must be a record!
    David Sims

    "Cuius testiculos habes, habeas cardia et cerebellum." - Terry Pratchet

    My opinion is, in all likelihood, worth exactly what you are paying for it.

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    That must be a record!
    Nah, it's just that we know Ken has been around long enough to know the more obvious answers. Now we're trying to come up with really obscure answers ... like spiky hairdos!
    Paul Smith
    "Always keep the sharp side and the pointy end between you and your opponent"

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    Could it be related to the technique shown in this illustration? Always popular with pirates, IIRC.
    David Noble
    Shorinji Kempo (1983 - 1988)
    I'll think of a proper sig when I get a minute...

    For now, I'm just waiting for the smack of the Bo against a hard wooden floor....

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