Japanese Joints

In an extract from his new book, Dorian Bracht provides an overview of Japanese saws and describes a decorative dovetail joint

Wood sculpture with angular black pattern

Born in Los Angeles, Dorian Bracht spent his early years in California and Hong Kong. After finishing school, he embarked on an apprenticeship in Leipzig, Germany, to learn how to build Japanese shoji and fusuma sliding doors, as well as solid wood furniture. Throughout this time, he learnt both traditional German and Japanese woodworking techniques. Having a huge passion for joinery and woodcraft, Dorian has been working as a woodworker since 2012. He is now based in Berlin.

We first met Dorian F&C 296, in which he told us about his love of joints and his ambitious project to cut one of every type. Now he has written his first book, Japanese Joinery, in which he uses his extensive carpentry experience to provide readers with a comprehensive guide to the world of traditional Japanese joinery and its influence throughout the world on woodworking and joinery today. We share an extract from the book here.

Japanese saws

You can find saws, or nokogiri as they are called in Japan, as traditional handmade saws or as mass-produced versions with replaceable blades. Traditional saws are forged out of high-carbon steel and are selectively hardened so they can be resharpened. Mass-produced saws have blades made of modern steel with impulse-hardened teeth: they are very hard and cannot be resharpened. There are essentially two cutting directions in woodworking: with the grain and perpendicular to it. Sawing with the grain with a ripcut saw means splitting the fibres down their length, so the layers have to be ‘peeled’ off. The ripcut saw acts like a lot of miniature hand planes, shaving off layer by layer. Sawing perpendicular to the grain with a cross-cut saw means severing the fibres with sharp points. The cross-cut saw’s teeth have sharp points and a knifelike quality. Most saws have a set, meaning the teeth are bent outwards slightly, making the width of the cut wider than the saw blade. This prevents the saw from binding in the cut and reduces friction. One exception is the flush-cut saw known as kugihiki. This saw is designed to cut objects such as dowels flush to a surface without damaging it.

There are a host of different types of saws for different purposes. In general, saws can be differentiated into single-sided and double-sided. A double-sided saw such as the ryoba saw is very good for making many different types of cuts, making it useful for a construction site. For finer or more dedicated work, there are the one-sided saws known as kataba. The dozuki is a type of back saw that has a very thin blade for very fine cuts. Speciality saws for cutting joinery include the azebiki, a double- sided saw with a convex blade. This saw is designed to be able to start a cut in the middle of a board. There is also the minature kataba or keyhole saw. These are practical for curved cuts or when there is not enough space to manoeuvre a saw blade.

Japanese saw with bamboo handle

1. Mass-produced replaceable blade saw
Illustration of crosscut and rip saws.

2. Ripcut blade (top) and cross-cut blade (bottom)
Traditional Japanese woodworking saws with wooden handles.

3. Handmade mini kataba (keyhole saw, top) and handmade azebiki (double-sided saw, bottom)
Abstract geometric line drawing with squares
4. Sawing from both sides
Three Japanese saws on white background.

5.
Handmade kataba (single-sided saw, left), ryoba (double-sided saw, centre) and dozuki (back saw, right)

Using a saw

When cutting joinery, you should make as many cuts as possible with a saw. When using a saw, it should be sharp and you should be able to guide it without using pressure. If the saw does not bite without pressure, the blade is dull and should be sharpened or replaced. As you cut, use the entire length of the blade to make sure it dulls evenly and as many teeth as possible engage with the wood, thereby cutting faster. Make as many cuts as cleanly as possible to the line, which will reduce the amount of paring with a chisel or hand plane needed, saving time and keeping the surfaces crisp. With practice, you can use a saw easily and quickly to establish planes that need at most just a little clean-up and won’t require using a jig.

If sawing to a line that spans three or four faces of a timber, start the cut at the back of the piece (viewed from the person cutting). Make a shallow cut and bring it forward and past the arris closest to you. Then draw the cut down the front face at a diagonal angle. Continue the cut from the other side, using the first kerf (the slit left by the saw) as a guide to keep the cut straight. If you are sawing to a line that spans two faces of a timber, it will be impossible to start from the back. Here, with care, start the cut on the arris between the two lines to be cut to. Constantly keep the cut in sight over the back of the blade to make sure the cut stays on the line in both planes simultaneously.

NEJ IRE KUMI TSUGI

Scarf joint woodworking diagram connecting two pieces

6. Making the neire kumi tsugi joint: this orientation should be used to transfer the positions of the pins or tails to the other piece
Diagram showing zig-zag pattern with angles and labels.
7. Diagram of the nejire kumi tsugi joint
Wooden dovetail joint on display
8–10. The nejire kumi tsugi joint
Dovetail joint in light and dark wood blocks.
9.
Two interlocking wooden joinery pieces, light and dark.
10.

MIZU GUMI – DOUBLE SUNRISE
DOVETAIL JOINT

Found in furniture or on the corners of hoppers at temples, this joint is a part of the mizu gumi family. In English, this joint has been named sunrise dovetail. It is a strong aesthetic joint that is assembled diagonally, which conforms with all the other joints in the mizu gumi family. Like the nejire kumi tsugi, the sunrise dovetail can resist more mechanical forces than a standard dovetail joint and offers more surface area for glue.

As it is comparable to the nejire kumi tsugi, the sunrise dovetail is marked and cut in much the same way. However, the degree of precision when fitting and transferring the dovetails must be extremely high, since the faces of the pins are especially slanted, which can cause binding if the fit is too tight. When making the joint for the first time, it’s almost impossible to avoid a lot of fitting.

Escher-inspired impossible cube drawing

11. Making the mizu gumi joint: using a flat reference lightly loaded with coloured wax or graphite can show high spots that need to be addressed to ensure a good fit
Diagram showing geometric pattern with angular lines.
12. Diagram of the mizu gumi joint
Wooden corner joint with dovetail design.
13–15. The mizu gumi joint
Wooden dovetail joint, one light, one dark
14.
Wooden dovetail joint comparison, light and dark samples.
15.

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