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Thread: Question on katana dents

  1. #16
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    It was a good idea to look down the saya with a flashlight, but I couldn't see anything except the ho wood. And when I tapped the saya onto some paper, nothing at all came out except some cat hair (not tremendously unusual as my wife has eight very hairy Maine Coon cats). Hmm...would you call it a dust bunny or dust kitty...? And as my koiguchi is wood, I can't see how that would dent the metal mune, especially on one side.

    Tim, I'm really trying to find any sign that the chrome is bubbling or something similar, but I'm just not seeing that. No sign of chrome plating at all, really. I'd love to find out exactly how they manufacture zinc-beryllium blades, BTW. From a metallurgy standpoint, it's not a very hard alloy - which is why they can't be sharpened - but I haven't been able to find any info on how shiny it is without plating.

    Oh, & I did ask Maeda-Sensei about my iaito, who had no ideas at all.

    Okay, since I have a 13-foot tsunami bearing down on me out here in Hawaii, I think I'll focus my energies on how to re-anchor my boat !
    Ken Goldstein
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    Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
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    "A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."

  2. #17
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    It was a good idea to look down the saya with a flashlight, but I couldn't see anything except the ho wood.
    I had been thinking maybe there was a hard knot or an inclusion in the wood of the saya that might have come to the surface with wear. The good news is that we are eliminating potential problems as the diagnosis progresses.
    And as my koiguchi is wood, I can't see how that would dent the metal mune, especially on one side.
    I was thinking that some saya have a metal band that reinforces the koiguichi, or sometimes horn or hard wood (I've also seen plastic). My thoughts were that if this material was harder or as hard the surface of the iaito it might account for dents. If you are fairly consistent in how you bring your sword to the koiguchi to do noto it is plausible that you might always strike the same side of the mune (long shot guess here).

    Okay, here goes another shot in the dark. Do you were a reinforced knee brace on your right knee? If so you could be knocking the edge of the mune when doing the first part of the noto during Ukenagashi (when you place the back of the blade against the right thigh above the knee).

    Or, maybe some of those crazy cement eating termites you have on the islands have been gnawing on it?
    Best regards,
    Bruce Mitchell

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    Metal-eating termites?? That's almost as scary as thinking about cats with hands !!!

    I mentioned in passing that my wife & I both had our iaito made at the same time & place, & that we both train in MJER. Her iaito has none of the same problems that I'm seeing. And, no, she's not more gentle than I am!

    Strange.

    Awaiting the wave... 15 minutes away.... The water supply has been turned off on all islands; how long can you subsist on ?
    Ken Goldstein
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    Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
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    "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 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???
    You didn't say - where they there when you bought it, and simply didn't notice them?

    Or, not metal-eating termites, but those critters from The Day the Earth Stood Still. They're just chilling out because they're in Hawaii.
    Lance Gatling ガトリング
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    Long as we're making up titles, call me 'The Duke of Earl'

  5. #20
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    Also, are you sure that's zinc-beryllium? Beryllium is nasty stuff, its dust is toxic. I work in the aerospace business, dealing with it is a necessary pain.

    AFAIK most iaito blades are brass, zinc, aluminum alloys of some sort.
    Lance Gatling ガトリング
    Tokyo 東京

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

  6. #21
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    Tim Hamilton

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

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    Quote Originally Posted by Lance Gatling View Post
    Also, are you sure that's zinc-beryllium? ...AFAIK most iaito blades are brass, zinc, aluminum alloys of some sort.
    You said it yourself; most iaito are zinc-aluminum alloys. Zinc-beryllium iaito do exist. (Possibly they are zinc-aluminum-beryllium or some other combination.)

    Adding beryllium is said to increase the stiffness of the blade, at only a small cost in increased brittleness.
    Yours in Budo,
    ---Brian---

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    Quote Originally Posted by Lance Gatling View Post
    ...Or, not metal-eating termites, but those critters from The Day the Earth Stood Still.
    That movie was an abomination!

    This is the only true TDTESS: http://www.imdb.com/title/tt0043456/

    Last edited by Brian Owens; 1st March 2010 at 02:27.
    Yours in Budo,
    ---Brian---

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    My wife & I think your attack cats are hilarious, Tim! Thanks for a good laugh. But I'm not showing it to our clather of cats, either !

    I certainly would have noticed any dents when I had my iaito made, Lance; it was my first custom blade! But I don't have any idea when they showed up, either. I was watching an old Musashi rerun a few weeks ago & was giving the iaito a full cleaning (tsuka removal, etc.), when my fingers noticed the line of dents. I had Linda check her blade, but no dents on hers. I suppose they could have been there for quite awhile. The dents aren't at all noticeable when I do noto, but that could be because Sensei has been working on Okuden with us sempai for the past six months, & there's not much mune that hits my hand.

    When I had our blades made, I checked at length to find the best materials, & zinc-beryllium was at the top of the list. I wasn't aware that the beryllium increased the stiffness, though, so thanks for that tidbit, Brian. I know about its toxicity, Lance, but that doesn't matter once it's alloyed, thank goodness, metal-eating critters notwithstanding :.
    Ken Goldstein
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    "A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."

  10. #25
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    I think I NEED a photo now, you have piqued my interest...

    Does it look like chatter marks then?
    Tim Hamilton

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

  11. #26
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    Quote Originally Posted by Ken-Hawaii View Post
    Metal-eating termites?? That's almost as scary as thinking about cats with hands !!!
    ...........
    Awaiting the wave... 15 minutes away.... The water supply has been turned off on all islands; how long can you subsist on ?
    So, how was the tidal wave? Water still off?


    "

    On the subject of iaito, there are a lot of opinions, & here's another from a chemical engineer. The two primary types of "true" iaito are made from either a zinc/aluminum or zinc/beryllium alloy. There are advantages to each of these, primarily for density (weight) & balance; & of course neither can be sharpened. It's bloody hard to stick chromium chemically to either of these alloys, so as several iaito manufacturers have explained to me, they "direct anodize" that nice shiny surface, but it's not chrome because it doesn't have any chromium in it. I can figure a couple of ways to actually chrome an Al-Zn surface, but it would take several intermediate metals (nickel & either steel or gold), which would drive the iaito prices even higher than they are now. I stick with Zn-Al primarily because I happen to know that beryllium is one of the most poisonous metals we're likely to encounter; check out www.webmd.com/hw/health_guide_atoz/nord481.asp if you want to get scared.

    "
    That makes more sense...
    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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    They turned the water back on after about eight hours, but as I haven't run out of beer yet, I don't much care . We had about a four-foot surge in Kaneohe Bay, & my boat looked rather strained, but no damage in our neighborhood, thank goodness.

    So you're another ChE, Lance? I took a dual major in that & petroleum engineering, & so of course haven't been doing much of either for the past 30 years.... I used to design & build nuclear reactors, & we used beryllium tools to prevent sparks, so I'm akamai about its toxicity (new Hawaiian word for ya').

    Tim, chatter marks are a good way to describe the dents. They start about 2-1/2 inches in from the munemachi & wander down one side of the mune to about 3 inches before the boshi. I've been trying to take a good photo of the area for about a week, but haven't succeeded as yet; to see the dents, the amount of light I need to use causes 'way too much glare. Even Photoshop hasn't helped, but I'll keep on trying. I want to send a photo back to the manufacturer to see what they have to say, & of course will post it.
    Ken Goldstein
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    Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
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    "A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."

  13. #28
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    Quote Originally Posted by Ken-Hawaii View Post
    ...I've been trying to take a good photo of the area for about a week, but haven't succeeded as yet; to see the dents, the amount of light I need to use causes 'way too much glare. Even Photoshop hasn't helped, but I'll keep on trying. I want to send a photo back to the manufacturer to see what they have to say, & of course will post it.
    To reduce glare, change the angle of the light; angle of incidence equals angle of reflection.

    Also, the larger the light source the better, all else being equal. A soft box would help, or shooting outdoors on an overcast day or in the open shade on the north side of a building.

    A tripod is almost a must have for sharp images at the low shutter speeds you'll need in dim conditions, since you'll want a moderate or small aperture for sharpest focus.

    HTH.
    Yours in Budo,
    ---Brian---

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    Brian, I've been a professional photographer since about 1970, & have pro-level gear, but still haven't been able to capture the damn dents clearly. I've tried a soft-lightbox, but then I don't get the specular highlights on the dents. I've played with depth-of-field, of course, along with a small spotlight, reflectors, & a dozen other things....

    It's a lot easier to shoot Nihonto !
    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."

  15. #30
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    Quote Originally Posted by Ken-Hawaii View Post
    ...I've tried a soft-lightbox, but then I don't get the specular highlights on the dents.
    You may have tried this, but just in case...

    Aim the soft box quite a bit downward, and set the stand so low that the "ceiling" of the box is just barely above the level of the blade. You'll be feathering the light to skim across the blade. (A strip box works even better than a square- or octa-box.) If you have grids for your box, use one.

    Mount the camera just above the box, with the lens axis not quite parallel to the light-to-blade axis.

    You won't have specular highlights, but you should get strong shadows in the "bowls" of the dents that will reveal their depth and contours.
    Yours in Budo,
    ---Brian---

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