Japanese Saws: Ryoba, Dozuki and Flush-Cut Saws

A Western saw cuts as it is pushed away; a Japanese saw cuts as it is pulled back. The difference matters because of what each stroke does to the plate (see the plate above). Pulled from the handle, the plate is in tension, and a plate in tension has no tendency to bend sideways. Pushed, it is in compression, and a thin strip in compression tends to bow unless something stiffens it.

That is why the two traditions stiffen their saws differently. A Western handsaw relies on the thickness and taper of its plate; a Western backsaw relies on its spine. A Japanese saw can rely on the stroke itself, so its plate can be very thin. The published figures show the range: Gyokucho gives 0.5 mm for its #610 ryoba and 0.3 mm for its #370 dozuki, against 0.020 in (about 0.5 mm) for Lie-Nielsen’s backsaw plates and 0.024 in (about 0.6 mm) for Veritas’s tenon saws.

The comparison is worth reading carefully. A Western backsaw is not a thick saw — its spine lets it be thin. What the pull stroke adds is a thin plate without a spine, as on the ryoba, and an even thinner one with a spine, as on the dozuki.

The ryoba’s two edges make it a general saw, but they need to be used the right way round: the rip edge for cuts along the grain, the crosscut edge for cuts across it, as with the rip and crosscut teeth explained in the handsaw guide.

Why a flush-cut saw has no set

Set bends the teeth outward so the plate clears the kerf. On a flush-cut saw, set would scratch the surface the saw lies on. With none, the plate can be laid flat on the work and flexed against it, and it cuts a protruding dowel or joint off level with the surface without marking it.

Many Japanese saws, including the Gyokucho saws above, have impulse-hardened teeth. Hida Tool describes Gyokucho’s process as heating the cutting edge with an electric current for 0.003 to 0.005 seconds, which hardens the surface of the teeth while leaving the steel behind them flexible. The teeth stay sharp for a long time, but they are harder than a saw file, so they cannot be resharpened. When the teeth dull, the blade is replaced; many saws are made so the blade can be changed in the handle.

Saws with unhardened teeth, including most traditional Western saws, are sharpened with files instead. Which system suits you depends on how you work.

A thin plate makes a narrow kerf, which removes less wood and takes less effort to push through — or pull through. It also makes a saw that responds to the slightest twist of the grip. That is the other side of the thin plate: it bends if it is forced, twisted or pushed on the return stroke, and a kinked plate may not come straight again. Let the pull do the cutting and let the saw ride back without pressure.

Japanese saws are also sensitive to technique in the same ways as any saw. The start, the stance and the line decide the cut; the guide to cutting straight covers them for every saw.