Mekugi-ana Rationale

[Shamsy]

If there is an existing mekugi-ana in the nakago, who would a new hole be drilled when remounting? Doesn't that weaken the nakago? Wouldn't it be easier to use an existing hole and adapt new mounts to fit?

 

I read that; "when remounting, the position of the tsuba and areas of the handle ito wrap are different on each mount, so the same holes cannot usually be used" but couldn't a skilled craftsman adapt the tsukamaki to match? That just makes more sense to me, though I have no experience with which to form more than an impression. 

[Wolfmanreid]

I have often wondered the same thing...  what I’ve been told is that there is an ideal point on the tsuka for the mekugi ana to be placed from the standpoint of geometry for the strength and stability of the tsuka when fighting and such, so a different length tsuka was put on the sword (for fashion, swordsmanship style, height, or simple personal preference) it would require a different mekugi ana placement. Just as it would if the sword geometry changed because it became suriage or machi okuri for example. 
 

I look forward to more knowledgeable persons than myself enlightening us if I’ve been misinformed or misunderstood. 

[dkirkpatrick]

This never made sense to me either given how most swords dont fit random saya very well so using an existing koshirae always seemed strage to me.  I could see if a field expedient was needed but surely there were enough craftsman that a new tsuka could be quickly put together in a non emergent situation.

[micah]

the one  reason you know how hard it is to to guess were to drill a hole and if you    miss you  messed up month's  work

[DoTanuki yokai]

It gives information how often a blade was shortned, so why change.

 

I dont think there is a problem with weakening the nakago. The mekugiana is only preventing the blade from going in one direction but in a actuall combat nobody tries to pull your sword out. The tsuka has a tight fit that takes the forces of impacts as a whole and the same, fuchi-kashira and ito is preventing the wood from spliting apart.

 

And how can someone know if they never used existing holes for new koshirae ? what would be a sign for that ? There was more reason for a new koshirae then only shortening.

[Shamsy]

Thank you all who contributed. There re some valid points and perhaps most of all the last one, that it wouldn't be possible to know whether a pre-existing hole was actually reused.

[John A Stuart]

As to it weakening the nakago. Some old swords have huge ana where the drilling/punching overlaps, with sometimes a square ana is melded with a round one. No worries, a properly fitted tsuka relieves a significant portion of the shock caused during a strike. When one's life depends upon a proper fitting the expert must take precedence. John

[Ken-Hawaii]

No weakening of the nakago, as the yield strength of steel is 53700 psi (370 MPa).

[micah]

9 hours ago, Ken-Hawaii said:

No weakening of the nakago, as the yield strength of steel is 53700 psi (370 MPa).

that depends on the steel some have more than others  considering this is older i would guess it would be less

[Shamsy]

I'm no metallurgist, so I'll take your word for it regarding overall strength of the nakago. I like to see several holes, it does suggest some history to the blade, it just seems an unusual approach, but the arguments made are logical and hard to argue with.

[Jacques]

Some swords were worn either as katana or as tachi, as the tsuka of these koshirae are different, a second mekugi-ana is necessary.

On the battlefield it is easier and faster to drill a hole to fit a recovered tsuka than to make a new one.

[Tom Darling]

Applying additional mekugi-ana can give a false appearance of period/age. I had a signed, kijimoma-gata, hira-zukuri ubu shinshinto tachi with five mekugi ana,  pointing to kamakura period.

[Andi B.]

On 3/3/2021 at 9:35 PM, Shamsy said:

..it wouldn't be possible to know whether a pre-existing hole was actually reused.

Good point!

As long as only the the old tsuka has to be replaced by a new one, there is no need to change the mekugi ana...

But if you cut the blade you can also drill a new hole - the 'damage' has been done already.

[Dave R]

This lead insert and new mekugi-ana has always intrigued me. (not my latest blade anymore).

[micah]

On 3/11/2021 at 12:06 PM, Andi B. said:

Good point!

As long as only the the old tsuka has to be replaced by a new one, there is no need to change the mekugi ana...

But if you cut the blade you can also drill a new hole - the 'damage' has been done already.

not really damage if they did it so they could have a working sword because there handle broke

[Andi B.]

...that's why I wrote 'damage' with ' '.

 

Actually I had shortened blades in mind (cut off to get a more practical lenght - not a 'rescue-cut' due to hagire or broken off nakago to keep the blade alive at least as weapon).

 

I think it's a difference whether a blade has been altered during its active years as weapon or nowadays as part of a collection (which I would reject).