Woven Kumiko Cabinet – Dovetails

Before diving into cutting the dovetails for this cabinet, there’s one last bit of work for the wedged tenon joints that I didn’t show in last week’s post, and that is slotting the tenons to accept the wedges. I like to do this work with a hand saw, and typically just eyeball the cut. No layout lines needed, though I try to keep the angle and location of the cuts as uniform as possible. To hold the piece for sawing I simply clamped the board vertically to a planing beam so that the end of the board was hanging off the end of my bench.

The Japanese method for slotting tenons to accept wedges looks like this. The cut is intentionally angled toward the center of the board. Doing so helps prevent the tenon from splitting, and I have to say it’s been an effective method in my experience. (The other cruicial detail to prevent splitting is to ensure the you have a snug fit between the tenon and the inside, narrow side, of the flared mortise.)

Now on to the dovetail work. The cabinet only has dovetails on the upper corners, so cutting these went fairly quick.

I’m a tails first guy when it comes to cutting dovetails, so that’s where I started doing the layout. There is 6 mm deep by 10 mm wide groove near the front edge of the underside of the top panel. There’s also a 3mm wide x 4 mm deep groove towards the back edge of the panel to accept the back slats. I had to consider the spacing of the dovetails relative to both grooves when laying out the tails, ensuring that the first and last tail would effectively cap off the end of each groove. I’m fond of dovetails that have graduated spacing so starting from the edge of each board I gradually spaced the dovetails farther apart as I moved towards the center, then repeated the same spacing from the opposite edge so the layout was symmetrical.

Here’s a close up of one half of the tails layout.

From there I used a super thin kerf Nakaya rip saw to cut the tails. When I first got into Japanese woodworking I had the opportunity to help Yann Giguere of Mokuchi with a sukiya style restaurant project. We needed to cut a few dovetails and I remember Yann telling me to split the line with the saw… as in there’s no time for chisel work, saw it once, and get it right on the line. That was a mindblowing moment. Up to that point I always evisioned handsawing as being a rough kind of task, and when it came to sawing joints I would err well outside my layout lines for safety sake. But Yann taught me that with practice and skill it’s possible to develop the ability to split a line with a handsaw. It’s not easy but it can be done, and once you develop the skill to do so you can save a ton of time by not having to chisel and pare each joint. I’m still not nearly as skilled as Yann with a handsaw but I have gotten better and I push myself to get as close to the line as possible. I still can’t split a line consistently, but I’m able to consistenly cut just outside of the line which still saves a lot of chisel work (joints that won’t be visible are good practice for aiming to split the line).

After sawing I jumped over to the drill press to bore out a good chunk of the waste. Before drilling I also lightly chopped just beyond the shoulder line with a chisel to prevent the grain from blowing out when drilling. After drilling the remaining bit of waste could be popped out easily with a chisel and hammer.

Then I used a 90 degree paring jig once again to guide the chisel for cutting right on the shoulder line. I worked about half way from one side, flipped the board over, reset the paring guide and cut the opposite side’s shoulders. Working from both faces makes getting the shoulder lines perfectly square to one another slightly more challenging, since any tiny misalignments of the guide from one side to the other will result in a shoulder that isn’t square. But I’ve also found it relatively easy to make adjustments when necessary. And the benefit of working from both sides is that the shoulder will be much more crisp and clean on each side. If you chop the shoulder all the way through from one side to the other, there’s always a chance that you may end up with a bit of tearout.

These are my dovetail chisels. On the right is a 6mm Ouchi shinogi-nomi that I bought many years ago from Suzuki tool. The one on the left is a flat carving chisel from Konobu. I bought this chisel back when I toured Konobu-san’s shop with the Somakosha crew, and at the time I didn’t know what I would use such a chisel for, but I had a feeling it would be handy to have. It’s turned out to be one of my favorites. Being a chisel made for carving the blade itself is short and super delicate with the sides tapering down to a near knife edge, making it great for getting into tight spaces and cutting tricky areas like dovetails.

Here are the dovetails after trimming the shoulders. You can see a few spots where my layout lines are remaining, but since I’ll be marking and cutting the pins to fit, I wasn’t too stressed about trimming those areas. For the tails I only trimmed the sides if they looked out of square, otherwise I focused on cleaning up the shoulders and inner corners.

With the tails cut I lined up the ajoining board and used a marking knife to scribe the location of the pins. The groove you see below is for the sliding door. Before laying out the dovetails I cut the groove and ensured that the location of the first dovetail would cover that area once assembled. Now is also a good time to mention that before scribing and cutting the pins I planed the inside of this board. The sides of the cabinet with tails can be planed afterwards, but any boards with pins need to be finish planed (or sanded) before cutting the pins. Planing afterwards has the effect of loosening the fit between the pins and tails, and it’s a big bummer when that happens.

And some once again I busted out my handsaw for the pins.

To remove the waste between the pins I started by chopping and splitting out the waste….

…. but soon got tired of that and jumped over to the bandsaw to cut out the waste instead. Once again, prior to sawing, I lightly scored the grain just shy of the shoulder line to prevent tearout. This ash was a bit crumbly, so I was trying to be extra conscious of the possiblity of tearout around the shoulders.

From there I used my 90 degree paring block one more time to pare the waste down to the shoulder line, again paring halfway down from each face of the board.

With the tails cut and shoulders trimmed I could start test fitting the dovetails. A few light taps with a dead blow mallet and everything started to go together pretty well, but there were a few areas that were just a bit too tight. Japanese ash is slightly softer than the white ash I’m used to from N. America, and I figured I could get away with a decent compression fit between the pins and tails. But how much compression comes down to your intuition.

After the first test fit things seemed a bit too tight so I pulled the boards apart to make some fine adjustments. You can see a bit of compressed grain on the upper half of the pins below. It’s suble but it’s there.

After a light trimming on the sides of the pins that needed it, I did another test fit. This time I was able to tap the joints closed without too much trouble. In the case of compressible woods, as long as the fit isn’t overly tight, you can get away with a decent amount of compression between the pins and tail, especially on pins and tails towards the interior of the boards where splitting is less likely to happen. It’s the outer most pin that you really have to watch out for though, and the fit needs to be much more dialed in with minimal interference between the pieces to prevent splitting.

Things are looking pretty good. The first pin and tail on the far right look a touch gappy but I was able to clamp things tight when I did the final glue up.

And here’s the other side.

And that about wraps up the dovetails for this cabinet. With the joints dialed in I disassembled the parts and proceeded with the final details, namely the back slats, prior to final planing and assembly. More on that next week.

Thanks for reading.