Thread: Kintaro Yazawa Box with Key Hole Joint

Originally Posted by Ironwood

I think the round, dowel shaped bit will be at 45 degrees to the sides, you cannot see this as it’s completely hidden.
If they are all cut and drilled at 45, all 4 sides will be able to be pushed together simultaneously, creating the illusion that you can see from the outside.
This is the only way this joint can be accomplished using solid timber.

Originally Posted by Mobyturns

A variant of the "impossible dovetail" technique??? ...

Originally Posted by GraemeCook

That was my first reaction, too, .... I have tried drawing it multiple times with variant angles - 45°, 50°, 60°, etc, but none worked. ....

Yazawa has confirmed that it is not a varient of the angled dovetails, twisted dovetails, rising dovetails, etc. but has otherwise remained stum.

I am pretty sure it is not a variant of an angled dovetail, aka impossible dovetail.

Originally Posted by Ironwood

Possibly.
.....
Not sure if my explanation is understandable, if not I could draw a picture and post a photo of it. I don’t have any CAD program to draw it up.

A hell of a lot of variations have been tried; none has worked so far.

If you can draw your idea, I might be able to convert it to a CAD drawing so we can look at it from all conceivable angles.

Originally Posted by GraemeCook

PS: The Yazawa keyhole joint has been discussed extensively on many forums starting about 15 years ago - including Woodworkform and FestoolOwnersGroup and others.

I'm trying to ignore this little fact but I know all the thoughts I'm having have been thought before.

Nevertheless I'm going out on a limb to say there are only two initial moves possible when disassembling the joint and I think only one of those allows the complete disassembly of the joint. Just need to work out how to disassemble it and run it in reverse. If he'd left a clue, such as the top and bottom fingers being on different boards that would have eliminated one of them. But I think I might be up to where you are Graeme, now working out how to put words into joinery

Good luck!

I have got so close so many times ....

Originally Posted by mic-d

I'm trying to ignore this little fact but I know all the thoughts I'm having have been thought before.

Yeah; a lot of "solutions" that did not work.

Also an incredible amount of brain effort invested.

We haven't advanced very far. I have a hypothesis that I want to test but cannot work out how to craft stage 1.

As stated before, I do not want to reveal my "magic" stage 2 at this point in time. None of Yazawa's dramatic: "My secrets will go to my grave"; I just do not want to add to the long list of "solutions" that did not work.

My big question is: How do I cut the joints depicted below?

Originally Posted by GraemeCook

I have been fascinated by that joint and have been attempting solve it for almost 20 years. I think that I may have a workable solution in two parts:

1. Craft the pins and tails of the joint, then
2. Make an elegantly simple variation so that it may be assembled.

I do not want to reveal step 2 in case it is an intellectual dead end. However, I am stuck on Step 1. How do you actually cut that joint with the needed level of precision, and lack of tool room?


Attachment 535805

Attachment 535806

Remember, this joint cannot be assembled until I work some "impossible magic" on it. However, I cannot test my hypothesis until I make a pair of joints as above.

If it just for testing the possible ways to assemble the joint, perhaps you could concentrate on assembly only by dummying up the fingers first by drilling holes in the appropriate mortise locations, then cutting a standard finger joint followed by inserting some dowels into the locations of the cylindrical tenon locations?

Originally Posted by GraemeCook

We haven't advanced very far. I have a hypothesis that I want to test but cannot work out how to craft stage 1.

As stated before, I do not want to reveal my "magic" stage 2 at this point in time. None of Yazawa's dramatic: "My secrets will go to my grave"; I just do not want to add to the long list of "solutions" that did not work.

My big question is: How do I cut the joints depicted below?

My answer to that without giving away what I'm going to try for the first part of cutting the joint is to truncate the 'dowel' part at about the depth of their diameter, then you only have to shape maybe an 8mm deep circle. It's pretty clear that the joint can't go together with the dowels in the guts of the joint. As far as how to cut the joint, I'm keeping my idea close to my chest until it's added to the list of failures.

Setting aside compressing the small section remaining as a last resort...

Here are the obvious things I repeat to myself which help limit the path the assembly must take. The internal corner is a perfect corner, there are no cuts beyond the lines of the corner. The only path the dowels can take is in through the part of the joint that will be buried or exactly through the hole from the outside. The through fingers on the top and bottom cannot be moved 'out of the way' by bending, splitting along the grain etc. Ultimately the assembly method must be compatible with box construction - you've got to make a rectangle/square.

Thanks, Franklin

My first reaction is that is great idea for proof of concept. I will do a CAD drawing - should verify its validity.

But after we prove the concept, we are back to the original question:
How do we cut the complex keyhole tenons and mirror mortices?

I have drawn Franklin's concept and it looks feasible.

Dowel Trial 1.jpg Start with two sides of timber


Drill dowel holes Dowel Trial 2.jpg

Dowel Trial 3.jpg Cut finger joints

Assemble finger joints Dowel Trial 4.jpg

Dowel Trial 5.jpg Insert dowels

But we didn't really want dowels Dowel Trial 6.jpg


Thanks, Franklin, this has proved how it might go together and has given me some ideas on how I might actually cut it. Need to think it through a little more. And the level of precision required is daunting.

Graeme did you receive my pm?

Originally Posted by mic-d

Graeme did you receive my pm?

Yes; I am thinking .... Will get back to you.

Originally Posted by GraemeCook

Yes; I am thinking .... Will get back to you.

Never sure the electrons get to the right place

Originally Posted by GraemeCook

I have drawn Franklin's concept and it looks feasible.

Dowel Trial 1.jpg Start with two sides of timber


Drill dowel holes Dowel Trial 2.jpg

Dowel Trial 3.jpg Cut finger joints

Assemble finger joints Dowel Trial 4.jpg

Dowel Trial 5.jpg Insert dowels

But we didn't really want dowels Dowel Trial 6.jpg


Thanks, Franklin, this has proved how it might go together and has given me some ideas on how I might actually cut it. Need to think it through a little more. And the level of precision required is daunting.

That is certainly one way to imitate the look but there are no advantages structurally over a plain finger joint, nor creating the "howhedodat" factor. In the original photos there is perfect end grain match across the "dowel" portion into the remainder of the fingers, so definitely not how they were done.

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.

Originally Posted by Mobyturns

That is certainly one way to imitate the look but there are no advantages structurally over a plain finger joint, nor creating the "howhedodat" factor. In the original photos there is perfect end grain match across the "dowel" portion into the reainder of the fingers, so definitely not how they were done.

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.

I was never suggesting this as a method for actual construction. I was simply trying to suggest a way of constructing prototype mortice and tenon elements that can be played around with (and modified as required) easily enough to test possible assembly methods. Clearly these profiles can't be cut from solid timber as is and assembled as the final joint.

Work out how to assembly the joint first, then worry about how to cut the joinery.

Just sayin..