Osaka Castle Gate Repair

[Stanley Covington]

This picture is of a repair made to one of the large columns supporting the gate to the Osaka Castle in Osaka Japan. I am not sure of the size, but it is in excess of 2 feet square. The base of the column was replaced at some point with new wood using the interesting connection shown. The same dovetail shape appears on the backside of the column.

The solution can be seen in the sketch in the following post. Try to figure it out before you look at the next post.

Stan

[Stanley Covington]

The solution to the connection can be seen in the attached sketch.

Stan

[Metod Alif]

Stanley,
Thanks for sharing. A nice example of Japanese joinery.
I would like to know of examples how such 'large scale' joinery can be utilized in furniture (small scale') situation. Getting good at such joinery would mean high level skills - in laying out and execution.
Best wishes,
Metod

[Harlan Barnhart]

What would be the purpose of the "button"?

[Stanley Covington]

Here are links to a couple of pages with more pics.

The square plug at the top of the dovetail hides the end of a bolt connecting the beam to the column.

http://blogs.yahoo.co.jp/warenabee/57225499.html

http://galleryimpossible.com/outemontugite.htm

Stan

[Stanley Covington]

For those of you that enjoy strange joints I found a better diagram with ratio dimensions.

Stan

[Peter Pedisich]

Brilliant stuff, thanks for sharing. If I was 20 again (1985!) I'd change my major and study these techniques.

[Pat Barry]

How exactly does it go together? It looks impossible based on those drawings

[Andrae Covington]

How exactly does it go together? It looks impossible based on those drawings

This is cool! Thanks Stanley for sharing. Here's a page with some pics of a small folded-paper version that might make it easier to see how it slides in place.

[Pat Barry]

Oh, I see now. Didn't notice the dovetail orientation wasn't exactly the same for each side. Thats very crafty

[David Wong]

Here are three pictures of the joint that I took at the Takenaka Carpentry Museum, in Kobe. The third picture shows the joint sliding together.

P7131190.jpgP7131191.jpgP7131192.jpg

[Kesh Ikuma]

This is pretty cool. For those of you who can't read Japanese, the writeup in Stan's links says that this joint has been a mystery for years. A newspaper featured this joinery in 1979 as a mystery joinery. They received a number of "solutions" from readers and ran a followup article the next day to share them to the readers. The actual construction of the joint was not revealed until Dec. 1983 when they took an X-ray photo of the joint. Apparently, there are at least 2 alternative ways to cut the joinery and get the same outside look.

FYI, I've read somewhere that Japanese carpenters are known to use a tricky joinery for a handful places in their job to passive-aggressively show off their skill (while using simpler joinery for the majority of joints).

[Bryan Ericson]

A while back, I found a scan of a book called "Wood Joints in Classical Japanese Architecture". It was linked to from a Japanese woodworking forum, and you can read a copy here: http://www.scribd.com/doc/37922205/W...e-Architecture (I don't think this is an illegal link, but if it is, a moderator can edit this post). The book is amazing - it analyzes dozens of joints that are similar in nature to the joint above, and the authors then go on to analyze the joint's strength and typical failure modes. It's well worth your time to check out the link and read the book, even if you're not particularly interested in Japanese joinery.

[Jim Matthews]

I can't decide if it's a Mensa intake challenge puzzle or one of those "Betcha can't unscrew this" noob traps at a bar.

I get the feeling somebody really clever had way too much time on their hands.
Perhaps it was a way to slow people down at the gate, so the guards had more time to check ID?

[Stanley Covington]

This is cool! Thanks Stanley for sharing. Here's a page with some pics of a small folded-paper version that might make it easier to see how it slides in place.

Thanks, Andrae. The paper model makes it very clear. Good to hear from another Covington!

Stan