the Carpentry Way: Making Connections                                                          

Making Connections

I have a project for a west coast client to make Japanese joinery models, which I've been pecking away at here and there between other tasks. These models are at a large size, and it was tricky finding dry 16/4 materials appropriate to the task. I managed to obtain some Iroko and Bubiniga beams. The joints are made to have contrasting halves, and to be readily demountable. Apparently, the client, who is unknown to me, is fascinated by Japanese joinery mechanisms. We have that in common!

I thought I'd share a few pics of the two models I've made so far. The first is koshi-kake kama tsugi, the half-lapped gooseneck joint. This is a splicing joint often used on mudsills and purlins where they are adequately supported underneath. It is a tricky connection to fit properly as the head of the joint has sloped ramps which tighten the connection as it goes together.

The two joint halves, the Iroko on the left, and Bubinga on the right:

The joint assembles in one direction, which is a vertical drop in:

These are a couple of standard proportionings for this joint, and I went with the longer and skinnier necked version. There is also a tapered neck version, and some alternate shapes for the joint head as well, but the above is more or less standard.

As the joints slides down, it begins to tighten up:

A view from the other side:

I took these photos just prior to wrapping the joint for shipment, and did not push the joint all the way together. I had done so at the shop but omitted to take a picture. I resolved to be a little more organized in the picture taking for the next joint.

The second joint is a double wedged locking box joint, or shachi sen hako dome tsugi. This is a high class joint used for decorative alcove floor frame corners, and is seen on some temple mudsill corners. It is also used in framed furniture pieces on occasion, and it is a favorite of mine.

The two joint halves:


A view of the joint halves going together, the assembly rotated 90˚ up:


The two halves going together, conventional orientation of parts:


Completed joint, inside view:

The black locking keys, shachi sen, I made out of Gabon ebony. They have bulbous heads on them to make it a lot easier to pull the pins out. Normally, the wedging pins would not have such heads, and would be driven in with a hammer and likely trimmed flush. Once the shachi are driven in, this joint is tightened right up and the pins would be removed only by drilling them out. Finding the right position with fitting these pins so that the connection would tighten and yet not get too tight added a fair amount of time to the fitting process.

A view of the front, the intended position from which this connection is viewed:

Clicking on any of the images will render them in a larger format.

The joints are all hand planed clean, chamfered and then sent out. No finish otherwise. A very enjoyable project for me, and apparently providing much delight to the client so far. I hope the reader has enjoyed the look at these joints. I have about another dozen to make, give or take, depending. I'll probably post some follow up entries as these connection are completed. Thanks for your visit!

Update: after discussion with my client's representative, they would prefer no more blog entries of photographs on this topic. Sorry!