Making Odate’s Japanese Transom Part 3: Mitered tenon and final assembly

This is the final post on making a Japanese transom with asanoha pattern. If you’re just joining in reading than might I suggest that for your own satisfaction you start at the beginning. Up to this part I’ve assembled the kumiko and asanoha pattern, mortised the rest of the main frame, and cut the boxed mortise for the frame.

Mitered tenon joint

I cut the tenon shoulders and cheeks the same way the boxed mortise was cut. As a general principle in shoji work blind mortises should be cut as deeply as possible without breaking through.  I don’t think I came quite that close, my sokozarai-nomi (bottom cleaning chisel) was getting stuck on its sides and I’m currently ambivalent about grinding metal off of it to give it more clearance side to side.

Marking tenon length

I used the depth gauge used when cutting the mortises to mark the tenon length about 1/16″ shorter than the total mortise depth. Once again I trimmed the end of the joint on my shooting board to give a reliable square surface for transferring the rest of the marks.

Marking tenon width

I transferred these marks with my marking knife, and then grabbed the marks with my wheel gauge and marked down the cheeks of the tenon. Most of the tenon width marks will be cut off when the tenon is cut to length, but if you wait until then it will be much harder to directly transfer the tenon width. I left my wheel gauge set to the outside mortice width, and marked the top of the tenon immediately after cutting to length.

Mitered tenon layout

Now the rest of the layout can be completed, marking the mortise for the box that houses the tenon. It feels like you’re almost done at this point but things slow down considerably to cut the mortise. It helps if you’ve had a chance to cut half blind dovetails. There is a lot of similarities when it comes time to pare the interior surfaces.

Mortising mitered tenon

I used my sokozarai-nomi to pull the chips from the mortise as they packed in there. If you don’t clean them out you’ll loose depth of cut and have a lot more work paring the bottom to the line.

Mitered tenon with box mortise

After finishing with the mortising I pared the tenon cheeks of any material that the mortising left behind. All that’s left now is to get the tenon to width. And as Odate says “In making this joint, one section will be particularly hectic. You’ll have to dig behind the 1/4″ (6mm) tenon, which is a very small end-grain area”. Of course Odate is old school and uses a gimlet. I’m a little less fortified of spirit and used a 1/4″ forstner bit and cordless drill.

Diggin behind tenon

A bit of masking tape on the bit tells me when I’ve cut ever so slightly past the bottom of the end grain in the mortice. If I left it slightly above the mark I would be at a pain to make a paring cut on end grain back there.


Here is my sokozarai-nomi, or bottom cleaning chisel, that cleans up the end grain of the mortise after paring down the mortise width. I like this chisel so much that I made a miniature version of it for cleaning the bottom of tiny blind mortises in kumiko work. If you can deal with the hassle of ordering from Japan Woodworker, I highly recommend getting one.

Finished Mitered boxed mortise and tenon

Don’t ask how long it took to cut all four of these joints, the time is not important. Hopefully when I’m an old man and look back on these nice tight miter joints I’ll smile with a bit of satisfaction that even when young and in a hurry about life I did something right.

Japanese adjustable chamfer plane

The frame pieces were cleaned up with my Tsunesaburo kanna and the inside edges chamfered with my adjustable chamfering plane. These two planes are a great example of the difference between Japan Woodworker and The Tsunesaburo came lovingly packed in bubble wrap in its own beautiful little box. Japan Woodworker shipped me the chamfering plane loose in a box with other items, a piece of packing paper hastily shoved on top, banging back and forth all the way from WVA and getting dinged and chipped before I even opened the box.

Partial assembly of japanese transom

With everything lovely and polished up off the kanna, the rails were placed on the kumiko tenons and glue applied to the mortises. I started the tenons into the mortises on both sides and (having previously tested the fit on the mitered corners) tapped the joints home with my light hammer and a wood block.

Japanese Transom

None of my practice joints came out as well as the miters on this frame, and I was tremendously relieved that they came together well. I have a slight gap on one side of the tsukeko between the frame where I took too much material off in finish planing, but overall I’m still going to hang this and show it off.

My next project coming up are shoji inspired garden gates, and I’m definitely going to integrate the asanoha pattern as a central feature. What garden couldn’t do without a symbol of growth and vitality, the hemp leaf? Please comment and tell me what you think, I know there are others out there who have taken this transom on and I’d be most interested to know any differences in how you got it done.

3 thoughts on “Making Odate’s Japanese Transom Part 3: Mitered tenon and final assembly”

    1. I’ve actually been working on the garden gates for the past two days. Lots and lots of planing. The “garden” these gates go to is actually a 1/4 acre – one tenth hectare food forest. Our zone 0 project from before this spring. It has an eight foot deer fence around it, so each of the gate panels is about 4×8 foot. Large! I’ve never built a mortise and tenon frame this big before so I’m excited to see how it ages in the weather.

  1. Well done with Excellence – Odate would probably be proud to see US wood workers adopting traditional Japanese techniques and tools with concentration and good work.

    Dude, you’re an inspiration.

Leave a Reply

Your email address will not be published. Required fields are marked *