A tsuba that just won’t fit right and wobbles back and forth and side to side despite how tightly the tsuka is on or how many seppa you have, is probably something most katana collectors have experienced at some point. This issue rarely affects the function of the sword but it sure can be annoying. In the past, I have used small pieces of copper or brass wedged into the space around the nakago to keep it still and while they did do the job, it was only temporary because they tended to shift and fall out when the sword was disassembled. Well, here is an easy and inexpensive way to solve this problem for good.
Traditionally, inserts made out of copper or other soft metals are pressed into notches cut into the top and bottom of the nakago-ana for a tight custom fit to a particular blade. This is done so the tsuba itself does not have to be altered and so that the softer metal now touching the blade doesn’t damage or scratch it. These metal inserts are called sekigane.
Traditionally made sekigane can be inserted into standard reproduction tsuba but would require copper or similar material, a jewelers saw, hammer and punches, and would also require cutting into your tsuba, not to mention some experience and a lot of patience. Once again, I needed to find a less expensive and less time consuming fix for the average budget sword sporting the average twenty dollar tsuba.
The method I will demonstrate is a hassle free and safe way to mimic the traditionally made sekigane and will function just the same. I wouldn’t recommend using this method on an antique or valuable tsuba. Even though it probably won’t damage anything, I’ve not tested what the chemicals in the epoxy might do to a fragile patina so it’s probably better to have an expert just add a more traditional sekigane in that case. With care, most traces of this insert can be removed relatively safely if you decide to do so later on.
Prep time – 10-30 minutes (excluding drying time)
What you will need
A loose fitting tsuba – If you didn’t have one of these, you probably wouldn’t be reading this tutorial right now
Rubbing alcohol – Your standard variety will do or any other product that will clean oil and dirt without leaving a residue
Masking tape – I use regular blue painters masking tape that doesn’t leave sticky residue
A piece of cardboard – I just use a medium stock piece from a box or scrap from packaging, etc.
A pair of scissors or a utility knife
High impact and hard curing epoxy
Needle files – Any standard set is fine
Before you begin make sure the inside of the nakago-ana is cleaned of any dirt, debris, or oil. I use q-tips and rubbing alcohol but you can use anything that will clean it and not leave behind any residue. if there is excess rust, file it off before cleaning
Step 1 – Apply tape
Place a piece of masking tape on one side of the tsuba covering the nakago-ana and surrounding area (seppa dai)
Step 2 – Cut out nakago-ana
Use scissors or utility knife to cut out the shape of the nakago-ana in the tape.
Step 3 – Apply more tape
Apply a piece of tape to the other side.
Flip it back over so the side with the cut-out is facing up
Step 4 – Cut cardboard strips
Cut a couple of strips of cardboard, one for the wider bottom and one for the narrow top. Each piece will have two bends in it and each strip should be a little wider than the thickness of the tsuba. The space between bends will obviously be larger for the one going on the bottom. (see pics below)
Step 5 – Place the strips
Go ahead and place the cardboard strips inside the nakago-ana leaving about 1/8″ – 1/4″ depending on how much larger the nakago-ana is than the nakago of your blade. You want to have a little extra filler so I usually go at least 1/4″ on the bottom. You can always file off some later if it’s too much.
Make sure the cardboard strip is pushed in so it touches the bottom piece of tape, but do this on a flat surface so you don’t force the tape away from the tsuba. You want to maintain a tight seal.
Then place the other smaller strip near the narrow end. (oops, I jumped the gun and applied epoxy on the bottom before I added the second insert so just ignore this for now)
Step 6 – Mix the epoxy
Follow the product instructions and mix enough epoxy to fill both open spaces.
A chopstick with a wedge cut end makes a handy mixer and spatula but you can use anything similar to mix and apply the epoxy.
Step 7 – Apply the epoxy
Apply the mixed epoxy as quickly and as neatly as you can to the two open spaces you’ve created.
Step 8 – Let it dry
Clean up any epoxy that might have gotten on the metal or anywhere you didn’t want it and then let the epoxy cure for the recommended amount of time.
Step 9 – Remove inserts and tape
Remove the two cardboard inserts and masking tape. Don’t worry if there is some remnants of the cardboard left on the cured epoxy, you will file this off anyway.
Step 10 – File to fit
With this step you need to take your time and constantly check the fit of the tsuba on your nakago. Make sure you have the habaki and first seppa in place when sizing the new epoxy sekigane since the point of this exercise is to create a customized and snug fit and that means the tsuba should fit tightly in the spot it will be when mounted.
File a little then check the fit and do this until it’s fully mounted and tight. If you do accidentally remove too much, you can repeat the above steps or just add a bit of epoxy to the filed surface, cure and then go from there.
In many cases the nakago-ana is too wide in addition to being too long, so if you carefully file a channel only as wide as the nakago, you will have epoxy left on the sides which will help fit it better. Also check the tsuba’s alignment from front to back and side to side to make sure it’s sitting where you want it on the nakago. Sometimes you will need to file notches in both the wide and the narrow ends but sometimes only one side will need to be adjusted, just pay attention to the final overall fit you need.
Now your tsuba won’t move around and you can mount and remove the tsuba without having anything shift or fall out
If you’ve enjoyed the tutorials and feel like buying me a cup of coffee, a meal or more tools, I’ll be super grateful. Thanks!
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