How to Repair Split Tenjin?

[pboman]

I received my used Tsugaru Shamisen today from Japan. It requires wood repair to the Tenjin before I can use it. Any advice is appreciated.

BTW- I don’t blame the shop from whom I bought this Shamisen for any of the damage to the Shamisen. They have outstanding customer service and were very responsive to any questions that I asked and made the purchase fair. I am fully satisfied with the purchase. This just means I get a little introduction to the Shamisen and some joint making before I try to make one from scratch using Kyle’s book.

The fitting of the Kamizao into the Tenjin is loose because the Tenjin is partially split on the side where the Sawari should attach… It looks like the previous owner tried to glue everything together at that location but the wood split and now the Shamisen cannot be played…

!
The two wood pieces flop apart because the split Tenjin does not grip the Kamizao tightly.

20211018_154600|375x500 !

Should I file off this old glue? What if I file too much and the joint is no longer tight?

Would using a heat gun help remove the glue by scraping rather than filing as long as I don’t burn the wood? Would that help ensure I don’t remove wood and maintain a tight joint?

Is there a type of solvent I could use to dissolve the glue without damaging or softening the wood?

20211018_154636|375x500

Should I file out the previous glue and try to make the Kamizao and Tenjin fit tightly together? I wonder if filing the Kamizao smooth removing the old glue and the pieces of torn wood will make the Kamizao no longer fit the joint tightly. Any advice on how I should repair that location to make a tight fit but not to glue the Kamizao to the Tenjin?

I am wondering what type of Sawari I should install. Kyle’s store shows two types. Which do you recommend?

Are they installed after I re-glue the Tenjin? Is the Sawair also glued in?

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Different Approach?-- What type of wood do you think this Shamisen is made from?

-Would it make sense to just rebuild the Tenjin from scratch trying to match the old wood?
-Would it be easier and stronger than trying to repair the broken Tenjin?

What is this hole for in the front of the Tenjin? Is it for the “ichi-no-ito”?

[Brown]

Hi there.

I cannot answer specific maintenance questions as it is beyond my expertise, but I can offer some other data.

Your shamisen’s tenjin already has a square hole suitable for an azuma sawari. The en sawari is round and so may not fit properly. Round peg, square hole.

The small, round hole is there to hold the kamigoma or nut to the tenjin. Some kamigoma (particularly those made for azuma or en sawari) have a small spike that is inserted into a small hole on the tenjin and further fastened with adhesive.

Your shamisen is probably, but not definitively, kouki (紅木) which is often translated as Red Sander, Redsanders, or Red Sandalwood. It is a hard, dense lumber from India. It is also possible that it is Shitan (紫檀), which is a slightly softer lumber [and a rosewood] … but I’m leaning towards the former based on what I can see in the grain. If this is the Etsy shamisen, the details of the auction/listing might have more information.

[pboman]

Thanks much Christopher Brown for this info. My used Shamisen is missing the Kamigoma (nut) I wonder which type I should get. the measurement between the two holes is about 16 mm, but they put the right side hole right between the seam of the Kamizao and Tenjin which means you would not be able to take it apart without moving or damaging the kamigoma…

If I install the missing Asuma sawari which nut should I buy to match that?

[Brown]

If you take a look at the image I linked, you want a kamigoma that looks like the bottom one.

It will go all the way across and will have small indentation where the first string will sit. If buying from bachido, it is the one listed as “Kamigoma (Tsugaru/Minyo)”

[pboman]

Thanks Christopher. I will order one from Bachido.

[Stefanie]

Hello Paul!
Lucky lucky, you got your shamisen. However, what a challenge!

About the glue, I can´t tell from the photos what kind of glue was used.This is what I would try:

1. Does the glue hold fast to the wood, or can you easily scrape it off? If not, then
2. I would try the heat gun, maybe dampen the glue with hot water. See if the glue gets sticky or soft - then it could be hide glue. If nothing happens, then
3. it is possible that the previous owner used a “modern” glue, something like super glue or epoxy In this case, you would need to do a test with acetone. (Should be fine on wood, as it evaporates). Apply acetone with a cotton swab directly on the glue and see if it softens. I haven´t done this procedure but I believe that it probably won´t be soft right away and one should wait for a couple of minutes.

Personally, I would find 1. the easiest, however, I can see a challenge in not filing away the hole that holds the sawari. Regarding filing too much of the other sides, you can always use splines to adjust the fitting of the tenjin joint.

All in all, you should take into consideration that it won´t be a fast repair and it will require a lot of your patience for best results. Take you time (I expect to go through a similar process in two weeks or so…)

Good luck, let us know what you have found out.

[pboman]

Thanks much Stefanie, your posts are always so helpful.

The previous owner told me he used Titebond III to try to glue the tenjin joint.

I will try to remove the glue.
I scraped off some of it yesterday with a box cutter knife. It tried to be careful to only remove glue. I also tried mineral spirits before I knew what kind of glue it was. That may have helped soften the glue a little…

I think the first step is to use some contact cement in the split and then clamp it to dry.

The previous owner is not certain what kind of wood the Shamisen is made from but suspects it may be any oily type wood and maybe that is why the glue didn’t hold well. I think there are a couple of problems that I need to address.

The slot for the joint is almost vertical on one side so it won’t hold the Kamizao. it just slips out.

Even after super gluing the spilt I think the joint will be weak without me widening the joint and slanting the joint so it holds better by itself without falling apart. The second issue is the bottom right corner of the Kamizao seems to be missing its edge to grip the joint in the Tenjin. I will need to glue on thin strips of wood onto the Kamazao and make the joint tighter before regluing…

I ordered some Japanese chisels and some saws based upon pictures you previously shared
Okyo Japanese Chisel Set with Storage Box - 10 Piece

Razorsaw - Dozuki for Dovetail

I also ordered a keyhole saw but it is on backorder. Now that I am spending so much on tools I will have to build a complete shamisen in the future to justify the cost…

GYOKUCHO - 9-1/2" DOUBLE EDGE (RYOBA) RAZORSAW

Maybe I can use one of those chisels or the Razorsaw - Dozuki to help increase the flare of the joint…

[Prose]

My landlord is a failrly well known luthier here in the states and she recommended hide glue…the kind that you can heat…workinging like a dream

Pierre Rose
Seattle, WA

[pboman]

Ok thanks Prose for the tip, I didn’t know hyde glue could be used to repair and fasten together wood.

[pboman]

Ok so I super glued and clamped the cracked Tenjin. Hopefully that will hold.

I then scraped off the old glue:

But the final fit is a little loose:

It wobbles a little and there is a gap of wood in one lower corner:

Is it better to glue some thin wood to the Sao Tenjin or should I add wood to the Tenjin slot to fill the gap?

Should I use hardwood or softwood to fill the gap to make it a tight fit? BTW I don’t know what the wood is and I don’t have an exact match… I may have to add some stain to the patch to make it a better match…

[pboman]

I bought a Sawari (Azuma) from Kyle to see how it will fit.
Is this how it would normally look on the back side where it it curved?

Here’s what it looks like on the front or top. Does that look ok or is it sticking out too much?

there is quite a bit of extra space where the slot was cut out around the sides of the Sawari.

What should I fill the gaps in with to make a tighter fit? Since it wont be seen from the outside after I re-glue the Kamizao to the Tenjin joint should I just fill in the gaps with sawdust mixed with wood glue and apply it like a wood paste? Should the Sawari also be glued in before attaching the Kamizao?

[Stefanie]

Hello Paul!
Nice job!
I won´t be able to give you advise regarding how to make things more tight as I don´t have enough experience. The only thing I can say, if the azuma sawari fits the way it is, I believe it is ok. Here are some pictures for reference:
as you can see, it is not always “nice and neat” I guess it depends on how the maker was able to drill the hole for the azuma and at what angle.

On the other hand, the front is always flush. The first picture is when the maker put in a new azuma sawari and in the second picture, he filed it to be flush. The filing would be the last thing I would do, after having all the wooden parts and the azuma secured as one has only one go at it.

Hope it was of some help!

[pboman]

@Stefanie

new azuma sawari

Thanks much Stefanie for your tips. Is the new azuma sawari glued in once it is filed down? I assume you would put it in loose, then mark the sides, take it out and cut and or file it down and then reinsert it. What holds it in place without it falling out?