Gyokucho Razorsaw Seiun Saku 300 mm Ryoba Saw

The Seiun Saku 300 is the largest ryoba in the series, made for timber framing, landscape timbers and big rough stock. Its 300 mm blade is 0.7 mm thick and cuts a 1.1 mm kerf; the crosscut edge has a 3.0 mm pitch and the rip edge runs from 5.6 mm to 3.5 mm, so each long pull stroke removes a lot of wood. A ryoba carries crosscut teeth on one edge and rip teeth on the other, so a single saw cuts across and along the grain; the rip teeth are progressive, finer near the handle for an easy start and coarser toward the tip for speed.

Seiun Saku is Gyokucho's standard-width ryoba series on a traditional rattan-wrapped handle. The teeth are impulse hardened, an electrical heat treatment that makes the cutting edges much harder than the body of the blade, so they stay sharp far longer than conventional teeth. When the teeth finally dull, the blade is replaced rather than sharpened; a fresh blade restores the saw to new condition at a fraction of the cost of a new saw; the blade is held in the handle by a single screw that can be loosened with a coin, so changing it takes a minute.