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Thread: Mekugi, a week point on katanas ?

  1. #1
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    Question Mekugi, a week point on katanas ?

    Is the mekugi (wood peg that holds the handle) a week point in katanas ?
    Let's say that during a fight the sword get's stucked in a enemy, in armour or some other object. When the swordsman ned to pull out the katana, the wood peg breaks.
    Working in an enviroment that requires redundancy, my first thought would be to equipe the katna with 2 mekugis.
    Or a mekugi with steel core.

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    The subject was discussed alot, please try to use the search function, and be amased at the result...
    What I have gathered from reading alot of things on this forum and elsewhere, is that in a properly made katana, tsuka shouldn't depend on mekugi alone to hold it in place, but on the friction fit with the nakago for the most part...
    Also, mekugi are made from bamboo because when bamboo brakes, it doesn't snap, it has fibers that can still prevent the blade from moving, well, some at least... Also, it can absorb some of the shock, and be pushed to fit snug... Steel mekugi would be too rigid, might fall out from shock, and if it failed, that's that then... But, if I rememeber correctly, iron and brass mekugi pins are found historicaly, but not that often...
    If I didn't get something right, there's people here that will be able to correct me, I'm sure...

  3. #3
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    Quote Originally Posted by jorn olav View Post
    Is the mekugi (wood peg that holds the handle) a week point in katanas ?
    Let's say that during a fight the sword get's stucked in a enemy, in armour or some other object. When the swordsman ned to pull out the katana, the wood peg breaks.
    Working in an enviroment that requires redundancy, my first thought would be to equipe the katna with 2 mekugis.
    Or a mekugi with steel core.
    Hi Jorn,

    Welcome to SFI

    Mekugi can be a potential weak point, but the tendancy is to inspect them each time you choose to use the sword. Bamboo, being a type of grass doesn't snap in the same manner as wood, with bamboo mekugi tending remaining in place and providing some hold until replaced.

    Hrvoje's pretty well bang on in his description
    Careful thought, consideration & communication is well worth the effort and end result.

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    Problems with metal mekugi would surface if they would bend in use; they would be very difficult to remove. Also, since metal mekugi would not break they might damage the tsuka if exposed to extreme stress.

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    mekugi alternatives

    Ive experimented with a few materials trying to find a viable alternative to
    bamboo mekugi - but up to now ive always came back to bamboo for function , fit ,and tensile strength

    I have a wakizashi with a custom tsuka that uses a steel mekugi pin that tapers
    correctly like mekugi should - the maker put it there so ive left it in place .

    ive tried cherry wood that pipe smokers use in their pipe bowls , its dense and hard but does not have the tensile strength or fibrous construction of bamboo .

    a lot of people favour a nylon polymer called delrin - its exceptionally tough and strong - ive even read of fuchi being made from it , but ive yet to come across it in the UK - if anyone knows a source for delrin please share it.

    bamboo was used traditionally as it was probably the best thing available to
    medieval japanese craftsman -

    In the 21st century we have a host of materials from steel alloys to any number of abs/nylon based polymers to try and use

    I am trying to track down some stuff called ZYTEL made by the french DUPONT company - this was a nylon that if I remember correctly was practically indestructible when used to create BMX bicycle wheels - I could
    sit on a wheel rim till it was flat and when I stood up the rim would spring back
    true , I could jump off the parents garage roof and the wheels would be ok -

    now thats what I call tensile strength .

    Mick
    " Put on the full armor of God so that you can take your stand against the devil's schemes. For our struggle is not against flesh and blood, but against principalities, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms."



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    After a deeper search in the forum it seems like bamboo is the way to go.
    Interesting that they have found old catanas with brass mekugi.
    Perhaps this was done'n because of a bad experience ?
    Brass sounds perfect, stronger then wood and still soft.
    Or perhaps drilling a hole in the mekugi and put a iron neil inside
    easy a fast and easy fix.

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    Bamboo is very well suited to this purpose because of its fiber structure. Bamboo grows long, dense fibers that stretch from one growth ring to the next. The bamboo used to make mekugi is mature, smoked bamboo. The smoking process removes water and further hardens the bamboo The bamboo is then split out.

    If the mekugi peg should break in use, it will crush rather than crack. The fibers will seperate along the grain rather than breaking across the grain, This still leaves long fibers running from one side of the sword to the other, preventing the tsuka from flying off or the blade from flying out. Because the peg is wedged tightly into the ana, the fibers will be compressed into the space, making it unlikely even should they completely seperate into a frayed mess, that they will actually fall out without being pulled out. Going further, in a battle, the samurai's hands are going to be sweaty and wet. The end-grain of the bamboo is going to take up this moisture and swell the peg even more, making the fit even tighter. This will only be more pronounced if the peg frays.

    Yet another point. Wood and metals all move a little with changes in temperature and in the case of wood and other biological materials, moisture and humidity. Thus the exact size of the holes in the nakago, and tsuka ho are going to change in relation to one another as the climate and environment changes The mekugi ana of the nakago is going to change the least of all. A metal or delrin peg isn't going to react nearly as much as a wooden one, it is going to stay about the same size and shape, So as the tsuka ho contracts and expands due to heat and humidity, the metal peg is going to get looser and tighter in that mekugi ana of the tsuka wood putting a lot of splitting stresses on it, and possibly slipping when the fit is looser. By contrast a bamboo peg driven tightly into the holes will be compressed into the various ana. It will also swell and contract at more similar rates to the tsuka ho wood, so it will tend to loosen less, if at all. It will also place less splitting stresses on the tsuka ho wood.

    Also critically important is the fact that bamboo menuki are readily replaceable. A metal pin would need to be very carefully lapped to fit. A huge task on a previously made sword. A bamboo peg can be made at an approximate taper and driven in until tight, then the excess ends cut off. You can achieve a tight, secure and lasting fit in just a few minutes of work.

    One thing we know about the Japanese is that while they are inherently conservative in many ways, they are not afraid to try new things, and if they work, to embrace them and perfect them. I am absolutely certain that they tried any number of other methods to fix tsuka to nakago and ended up discarding them or using them only sparingly because the bamboo mekugi worked as well or better.
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    A rose by any other name..

    Quote Originally Posted by michael wilson View Post
    a lot of people favour a nylon polymer called delrin - its exceptionally tough and strong - ive even read of fuchi being made from it , but ive yet to come across it in the UK - if anyone knows a source for delrin please share it.
    Mick
    Delrin is a trademark of DuPont company an it seems it is not marketed with that name in Europe. (At least I have not managed to find it.)

    You could try asking around with a more general name for the material. These include (but are not limited to) polyoxymethylene (POM), acetal resin, polyacetal, acetal plastic, polytrioxane and polyformaldehyde.

    The basic composition is the same, but some products have fillers thay may affect their mechanical properties. The fillers vary depending on material and manufacturer. If you find a seller, they should be able to help you with these.

    Here in Finland the stuff is most commonly called "polyasetaali". The most commonly found brand name seems to be "Ertacetal C". Teollisuus Etola sells it in round bars in various diameters both white and black. The white looks a bit too "plastic-y" for my taste, but the black polishes up a bit and looks like horn. Costs about 2€/m depending on diameter.

    The material is very tough, but I personally find bamboo strong enough and easier to work with. (I'm limited to hand tools. A small lathe would work wonders with this polyacetal stuff.)

    Ari-Matti

  9. #9
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    Engineering pet peeve irritated:

    Quote Originally Posted by michael wilson View Post
    ive always came back to bamboo for function , fit ,and tensile strength
    . . .
    does not have the tensile strength or fibrous construction of bamboo .
    . . .
    now thats what I call tensile strength .
    Tensile strength is a measure of the strength of a material specifically in tension. That occurs when directly loaded in tension (i.e. pulling on opposite ends) or on one side of something being bent. What's important in a mekugi is shear strength, as the majority of the stresses are shear stresses.

    In a typical bicycle wheel, the spokes are in tension, so tensile strength is quite important. However, the ability to spring back from large deformations isn't actually indicative of high strength, which refers to the stress, but to high strain limits on the elastic region.

  10. #10
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    Perhaps I should read up on this more before commenting, but I trained in Iaido for almost a year. I never practiced tameshigiri formally, but I do cut with my swords all of the time, and have so for at least six years. I've never once had any mekugi on any of my katana splinter, break, or loosen to the point of falling out, or to any substantial point at all. In fact, I've only had them swell slightly. I have one mekugi with a small dent from the blade, but that was due to me trying to remove the tsuka while the mekugi was still in the ana. I thought I'd taken it out. And yet it holds fine. So has mekugi strength really ever been an issue? I mean i've seen several old nihonto, and countless in books. Some were in terrible shape. Ito frayed and falling off. Chunks of missing same, chipped, rusted blades. I've seen a habaki splitting in two, but the mekugi, while very old, still appear to hold true. Perhaps they replace them, but if these swords aren't going to be used, then what is the point? I just don't know any instances of a katana failing due to any manner of mekugi failure.
    Last edited by R.S. Miller; 12-23-2006 at 01:15 AM. Reason: misspelled "trained"
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  11. #11
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    While very rare, mekugi related accidents do happen...
    This was not due to failure, but due to the mekugi falling out:
    [09/19/1981, Kashima, Japan]

    6th Grade Student Killed While Watching Practice:

    KASHIMA. On September 19th at around 8:35pm, Mr. Sakamoto Katsu (45 yrs old) was practicing Iaido in the Kashima Central Public Community Center when the mekugi [retaining pin] of his sword fell out. He swung the sword down and the blade flew out, striking the nearby eldest son of Mr. Nishi Toshikatsu, Takao (12 yrs old). A sixth grade student, Takao was killed when he was pierced in the left side of his chest. He was immediately rushed to the Japan Red Cross Hospital in Kumamoto City where he was pronounced dead on arrival. Takao had just finished practicing Judo, and was observing Mr. Sakamoto's Iaido.

    - Reported by the Kumamoto Daily Newspaper, Sunday, 20 September, 1981. Translation courtesy of Guy H. Power.

  12. #12
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    Quote Originally Posted by Hrvoje Samija View Post
    What I have gathered from reading alot of things on this forum and elsewhere, is that in a properly made katana, tsuka shouldn't depend on mekugi alone to hold it in place, but on the friction fit with the nakago for the most part...
    Bingo. Just a couple things to add to this though. The traditional file markings on the nakago, a proper fitting of the tsuka, the tsukamaki, and the spacing from the tsuba, seppa, and fuchi all play a part in keeping the blade secure. With a well made tsuka the mekugi are literally there just in case, and bamboo is the perfect choice. That's best case scenario however. Needless to say though as previously mentioned they still need to be inspected before each use whether cutting or practicing forms. Especially since many tsuka aren't as well made as they should be. If you're speaking about the production katanas then yeah I'm sure the mekugi tend to help hold the blade in.



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  13. #13
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    Quote Originally Posted by Hrvoje Samija View Post
    While very rare, mekugi related accidents do happen...
    This was not due to failure, but due to the mekugi falling out:
    [09/19/1981, Kashima, Japan]

    6th Grade Student Killed While Watching Practice:

    KASHIMA. On September 19th at around 8:35pm, Mr. Sakamoto Katsu (45 yrs old) was practicing Iaido in the Kashima Central Public Community Center when the mekugi [retaining pin] of his sword fell out. He swung the sword down and the blade flew out, striking the nearby eldest son of Mr. Nishi Toshikatsu, Takao (12 yrs old). A sixth grade student, Takao was killed when he was pierced in the left side of his chest. He was immediately rushed to the Japan Red Cross Hospital in Kumamoto City where he was pronounced dead on arrival. Takao had just finished practicing Judo, and was observing Mr. Sakamoto's Iaido.

    - Reported by the Kumamoto Daily Newspaper, Sunday, 20 September, 1981. Translation courtesy of Guy H. Power.
    Even if I think the above is the exception that confirm the rule, (I'm assuming
    some mistake was made either by the owner or by the maker of the tsuka)
    maintenance of a sword isn't sheer oiling.
    If the sword is used intensively for a long time, might be it needs a new
    tsuka rather then a new mekugi. The whole handle and sheat should be
    periodically inspectioned especially if Tameshigiri is involved.
    Best is to have a "beater" for training and "the good one" for public events.
    Please forgive my english.

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