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Thread: How to remove the little bit of play in the Tsuka

  1. #1

    How to remove the little bit of play in the Tsuka

    Hi there,

    I am fairly new to all this, so please forgive me if I do not use the correct Japanese terminology.

    I have a Ronin Katana Dojo Pro which I bought around end of Dec 2014. After some use, the wooden Tsuka broke, I advised Chris of RK about this, he sent me 2 replacement Tsukas (pulled off from other swords in his inventory, I think).

    The replacement Tsukas do not have the two peg holes at the same place as the original sword. The top one is slightly off by about 1/4 mm, which for all intended purposes is probably close enough (or so I thought). The lower hole is off by about 5 mm or so, so I had to drill new holes on the wood core.

    Now I confess I could not find any online tutorial that describes exact process of installing a Tsuka, so I just did it entirely on my own. It is likely that there may be some important steps I missed. Essentially, I viced the blade, slid on the tsuka, and pounded in the pegs. I did not glue the tang into the wood.

    Because the holes on the ray skin are not aligned perfectly with the holes of the wood core (I used the original ray skin from the broken Tsuka), I did not wrap the tsuka before installing the wood part. In other words, I wrapped the ito after the wood core was installed.

    Maybe because of this, I did not achieve a very tight wrap. Or maybe that has no bearing on the tightness, I was just sloppy.

    In any event, at first after wrapping the tsuka, the sword worked fine, I took it out for a couple uses. But now it developed a little play in the tsuka, it feels like the tang is not firmly secured inside the tsuka, there appears to be 1/6 to 1/4 mm of movement. I cannot feel it when the sword lay stationary, I can only feel it if I hold the tsuka and shake the sword forward and backward.

    Basically I have several question I want to ask you veterans, if you would indulge me:
    1, Is there a comprehensive online tutorial somewhere about how to install a tsuka properly?
    2, is that play normal?
    3, if not, what is the right way to remove that play?
    4, is wrapping after installing the wood OK, or is it an absolute no-no?

    Your input is appreciated.

  2. #2
    Join Date
    Sep 2006
    Location
    Järvenpää, Finland
    Posts
    3,241
    Hi Daniel, and welcome to SFI. I'll answer your questions out of order because it forms a narrative.

    4) It could be OK if you do it tight enough, but it's better to wrap it beforehand as it adds compression on the core. Then again, with a mass-produced core, that extra compression might crack your tsuka..
    2) It is absolutely normal to have play in a tsuka that was not made for your individual sword's tang, which is why mass-produced tsuka cores should not be used at all.
    1) Probably, but you had it wrong from the beginning with a mass-produced replacement tsuka core, and no tutorial can fix that.
    3) Having said that, it is possible to remove *some* play in the tsuka. You can insert shims (very thin wood shavings) to either side of the tang; remember to check the alignment of tsuka and the blade. This is often done even with high quality iaito. If there is much play, I would recommend replacing the tsuka altogether, but you could also try to fill the tsuka core with some epoxy/chemical wood/glue/stuff; see this thread for some suggestions. As a last resort, if you're not willing to have a proper tsuka made for your sword, you can glue the tang in permanently - you'll have to chisel the tsuka away if you ever want to replace it after this, though, and I would not recommend it for a number of reasons.
    Certified nerd; if you need an Excel sheet or an AutoCAD drawing done, just drop me a PM!

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