Thread: Kintaro Yazawa Box with Key Hole Joint

Originally Posted by Mobyturns

A close inspection of all the images I can find of these joints leads me to believe they aren't even glued, so appear to rely entirely on the mechanical design for the joints structural integrity.

Hell! I had not even considered that possibility.

Have just had a good look at high resolution photos of the jewelry box and you may well be right. Certainly not an excess of glue, but I cannot be absolutely sure.

The plot thickens.

Originally Posted by Swifty

Graeme, in your second post you showed a “disassembled” view of the joinery. Is that just your guess? Clearly it can’t be correct, there is your starting point! I am just bewildered, solving the problem might consume what’s left of my life!

Read the series of posts and all will be as clear as mud. That "disassembled" view is essential before my step 2 - which, inigmatically, I am withholding. We are trying to workout how to cut those shapes.

A lot of people have been trying to solve it for almost 20 years - many false "solutions" but ... you are very welcome to try.

Good luck! I’m leaning towards some 45 degree deception myself!

I have tried many options with variant degrees, none looked like working, and also Yazawa has stated that it is not a variant of the angled dovetail.

Originally Posted by GraemeCook

Hell! I had not even considered that possibility.


Have just had a good look at high resolution photos of the jewelry box and you may well be right. Certainly not an excess of glue, but I cannot be absolutely sure.


The plot thickens.

Grasshopper, like all the great masters the only way to learn their secrets is to serve an indentured apprenticeship with them and to accept the associated obligation to not share that knowledge.


So many secrets of wood working remain unsolved. Just look at Yosegi, Tunbridge ware, even Buffard Fereres inlay banding constructions, still lots of mystery about how the more complex designs were achieved or could be produced at a market competitive / acceptable price. Those secrets are earned but only if you are worthy.


If you look at the other complex joints Kintaro Yazawa makes they also appear to be the same - unglued. It's pretty difficult but not impossible to disguise the use of glue in a dovetail like joint.


I love the mystery and fully respect Kintaro Yazawa's playful teasing of potential imitators, such grace in acknowledging his own superiority as a maker whilst "seeing off any potential competition". At least he has passed on his knowledge and those guarded "commercial in confidence" trade secrets to his staff.


Another issue to consider here is the knowledge about how to construct that joint really is of curiosity or novelty value to us but it has significant commercial value and I might say adds a considerable premium to the unique work produced in Kintaro Yazawa's workshop and by him and his staff.


Intellectual Property Rights are difficult and expensive to protect, look up the numerous court cases involving glass artist Dale Chihuly. There is also no guarantee that the courts, or the court of popular opinion will side with the original maker either. It is indeed nigh on impossible to protect process IP, registered designs - yes, copyright - yes; process - no; patents - for a term. So the only realistic avenue to protect one's lively hood is through highly guarded "commercial in confidence" trade secrets and to demand loyalty from those entrusted with those secrets. The formula for Coke a Cola syrup is a testament to the value of a closely guarded trade secret - real or imagined.

What about this:
IMG.jpg
Not sure if he only uses hand tools, but the slot in the finger could be cut with a router (a bit at a time, with plenty of support, carefully!) then the piece with the keyhole shape could be steam bent to 45deg. I must admit though I have no experience with steam bending so I don't know how possible this is. The rest of the joint could be cut with a router like a standard finger joint (from the face of the board, not the side, and then then shoulders cleaned up with a chisel) but leaving a bit to be hand shaped round with a small file for the male keyhole part. The corresponding female keyhole part could be drilled with a small forstner bit. Then, the joint could be slid together at 45deg and the male keyhole shape be steam bent back into place, with something to fill the slot first if desired. Of course, it would have to be glued unless another solution can be found to hold the joint together. A bit hard to describe and I'm not saying this is necessarily how he did it, but it's a thought.

Originally Posted by mannetje

What about this:
IMG.jpg
Not sure if he only uses hand tools, but the slot in the finger could be cut with a router (a bit at a time, with plenty of support, carefully!) then the piece with the keyhole shape could be steam bent to 45deg. I must admit though I have no experience with steam bending so I don't know how possible this is. The rest of the joint could be cut with a router like a standard finger joint (from the face of the board, not the side, and then then shoulders cleaned up with a chisel) but leaving a bit to be hand shaped round with a small file for the male keyhole part. The corresponding female keyhole part could be drilled with a small forstner bit. Then, the joint could be slid together at 45deg and the male keyhole shape be steam bent back into place, with something to fill the slot first if desired. Of course, it would have to be glued unless another solution can be found to hold the joint together. A bit hard to describe and I'm not saying this is necessarily how he did it, but it's a thought.

I admire your drafting skill!

....remembered something from school..

I am moderately certain that the first move of the board without the through fingers on top and bottom (call this the short board and the other one the long board - just for ease of describing) is an oblique move. If you look at the detail closeup photo earlier, you will see deep shadows around some of the long board keyhole holes. This fits with there being a void into which the short board would move.
Next week I hope to have a new handtool to help cut the keyhole finger joints and then it should be a matter of relieving some hidden areas on both boards and drilling a path for the one set of key pins to exit. This is the step where I expect to fail.

Thanks Manetje

Mic-d suggested something quite similar in Post #12; it was trialed about 10 or 12 years ago but no one could make it work - they kept snapping on the short grain.

Short Grain.jpg

I never thought of using steam bending and am unsure of its applicability in this situation. It looks like the bend is too sharp.

Also, I did not understand your reference to assembling at 45° - as everything seems to be at 90°.

Still watching with interest mic-d. If you look at the photos of the inside of Yazawa's jewelry box, the corners are quite clear - no visible trenches which possibly would be needed for diagonal sliding joint. I have tried so many varients of this but none got close to working.

But you may come up with something I never thought of??

As to tooling, I have been thinking along the lines of miniature chisels, mini gouges, mini-scorp, etc, even dental instruments. My guess is that Yazawa's jewelry box has finger joints about 3 mm wide. That defines the size of the tools!

Look at the high level skill required in setting out then making the joints in his Hishigata box and the geometry of the joint set out.

Originally Posted by Mobyturns

Look at the high level skill required in setting out then making the joints in his Hishigata box and the geometry of the joint set out.

Diamond Joint 2.jpg Diamond Joint 1.jpg

Those "diamond" finger joints allegedly have fingers that are 0.3 mm wide - the kerf of a dozuki?

It is really hard to get your head around that joint. I have reasonable CAD skills and it took me two days to workout its construction and how to draw it. It is basically a mixture of a finger joint and a mitre joint.

Originally Posted by GraemeCook

Still watching with interest mic-d. If you look at the photos of the inside of Yazawa's jewelry box, the corners are quite clear - no visible trenches which possibly would be needed for diagonal sliding joint. I have tried so many varients of this but none got close to working.

But you may come up with something I never thought of??

As to tooling, I have been thinking along the lines of miniature chisels, mini gouges, mini-scorp, etc, even dental instruments. My guess is that Yazawa's jewelry box has finger joints about 3 mm wide. That defines the size of the tools!

With regard to the internal corners please revisit post 23. I made a list of observation in it, including normal internal corners. I’ve settled on 5mm fingers 8mm key pins which allows plenty of meat left on the keyhole fingers. Crawl before walking

Originally Posted by mic-d

I’ve settled on 5mm fingers 8mm key pins which allows plenty of meat left on the keyhole fingers. Crawl before walking

My thinking is also heading the same way.


My best guess is that Yazawa's finger joints are 3 mm wide, and the key holes are about 7 mm wide, but they are oval, so perhaps 7x4 or 7x5. That would certainly give you a lot more room for maneuvering tools.

Originally Posted by GraemeCook

My thinking is also heading the same way.


My best guess is that Yazawa's finger joints are 3 mm wide, and the key holes are about 7 mm wide, but they are oval, so perhaps 7x4 or 7x5. That would certainly give you a lot more room for maneuvering tools.

they are oval??. I know they look oval in the detail shot but I thought that was foreshortening. They look circular in the first photo to me. This is important to know!