Low Cherry Tansu – Hidden Dovetail Joinery

When it came time to deciding what kind of joinery to use for the low cherry tansu my main concern was to keep the cabinet’s aesthetic in line with the two antique tabi-dansu that I planned to stack on top. The tabi-dansu have a very subdued tone so I wanted to maintain that feeling with the new cabinet as well. After thinking about a few different options I decided to use a clean miter for the corners. A miter is about as subdued and minimal as it gets. The problem with miters is on their own they are a quite weak. There are plenty of different ways to go about reinforcing them including using splines, biscuits, dominoes, etc., but in this case I decided to reinforce the miters on this cabinet using hidden dovetail joinery.

Hidden dovetails are really no different that standard dovetails aside from the fact that you cut each half of the joint only part way through. The remaining material is used to conceal the pins and tails, while also forming the miter itself.

Dovetail Layout

I started by laying out the pins first. With normal dovetails it doesn’t really matter which side you start with, pins or tails, and in a way it doesn’t really matter with hidden dovetails either. In either case you cut one half of the joint, then carefully align each side up with it’s mate and mark from the cut half of the joint onto the mating half. In this case I thought I would have a bit more room to mark out the second half of the joint if I cut the pins first, but looking back I think I could have started with the tails just as well.

Like all dovetails, when laying out the joints it’s crucial to consider the spacing of the pins and tails relative to the other cuts you will need to make. In this case I knew I would be cutting a groove around the back edge of cabinet to house the back panels. I also planned to cut a groove in the front side of the top and bottom to house the door. So when laying out the pins I took into account the locations for the grooves, and then spaced the dovetails accordingly.

In the picture below you can see a line running 3mm up from the very bottom corner, as well as 3 mm back from the ends of the pins. Those layout lines are crucial for hidden mitered dovetails, and the following pictures will hopefully make their purpose clear.

Sawing the Pins

To cut out the joints I used a really thin Japanese dozuki saw to cut along the layout lines. The saw is a Nakaya brand saw that I got for kumiko work a few years ago but have found it to be really handy for cutting joinery like dovetails. It leaves a really crisp cut making it easy to follow your layout lines.

I still remember the first time I was asked to cut dovetails by a Japanese woodworker, and he told me to split the line with the saw; no chiselling, just cut accurately with the saw. I thought he was joking. But really his point was to push me accurately saw along a line, and to treat the sawn line as a finished cut. If you can do so, you can reduce or even eliminate the amount of time consuming chisel work after sawing. Every time I cut dovetails I think about that experience. Yet as much as I want to I find it really hard to push myself to split the line. Instead I usually err on the side of caution and cut just outside the line. That leaves just a bit of fat to trim with a chisel afterwards, which goes pretty quick.

Roughing Out the Waste

After sawing along the layout lines I used a drill press to bore out a good chunk of the waste between the pins, making it easier for the trimmer which I planned to use next…

With the trimmer I removed even more of the waste and also accurately cut an even depth down to the 3mm layout line on the bottom.

After routing it was a pretty straightforward task to use a chisel to clean up the last of the waste around the pins.

Marking Pins to Tails

With the pins cut I carefully aligned each corner with it’s mating half and marked out the tails.

Repeating the Process for the Tails

Here are the tails with completed layout. My little v-shaped marks are there to remind me which side of the line to cut on. With so many layout lines it’s easy to get confused when cutting and I’ve cut on the wrong side many times in the past. Never hurts to add a little reminder.

I followed the same procedure using the drill press and laminate trimmer to knock out the waste material.

With the tails cut out the final step was to cut the ends of the pins and tails back. My layout line for this cut was 3mm, but I made the cut a bit fat at 3.5mm, to ensure that the ends of the pins and tails don’t run into the mating side; essentially leaving a 0.5mm gap on the inside of the joint. This cut is what determines where the pins and tails will sit in relation to the 3 mm of material I left on the outer faces of each joint. The remaining little tongue that sticks out is what gets cut back to form the miter.

Forming the Miter

To cut the miter along the tongue, I used a simple jig and a kiwa-ganna, Japanese rabbet plane. The jig is basically a board that I cut to an accurate 45 degree angle. The process simply involves aligning the 45 degree jig to the end of the board, then using the jig to support the kiwa-ganna as you plane down the tongue to form the miter.

Unfortunately I didn’t take any photos of myself using the plane, but here is the miter cut most of the way. I took each corner 95% of the way, and then started fitting each joint to see where I needed to make adjustments. Hidden mitered dovetails are particularly tricky because it’s easy to cut too much off the miter leaving an open gap along the finished joint. So it’s good to take the final trimming slow, and sneak up on a good fit.

Here I’m test fitting the joints on the right side of the cabinet.

All in all things went pretty smoothly. One unforeseen difficulty that popped up was I realized after cutting the first miter that the planer I used for milling down the panels wasn’t cutting an even thickness all the way across meaning my panel wasn’t an even 18mm thick (one of the downsides of working out of a shared shop, where the machinery is sometimes poorly set up). The planer was only off a tiny bit, but enough to create some problems with the miter closing. After doing a bit of tweaking to my kiwa-ganna corner jig I got things back on track.

That’s about it for the hidden mitered dovetails. Up next I’ll post some shots from the final casework details and door construction.

Thanks for following along,

Jon