Seiun Saku are the standard ryoba for carpentry and joinery work, the angle between the centreline and the toothline is carefully calculated to give a rapid yet smooth cut and the heat treatment is optimised for springiness, i.e. the degree to which the blade can be distorted and still return to its original shape.
| Model No. | 660 | 661 | 622 Fine tooth | 663 | 664 |
| Blade Length | 210mm | 240mm | 240mm | 270mm | 300mm |
| Blade Depth | 70 - 87mm | 77 - 97mm | 77 - 97mm | 90 - 115mm | 95 - 120mm |
| Overall Length | 530mm | 560mm | 560mm | 645mm | 680mm |
| Blade Thickness | 0.45mm | 0.5mm | 0.45mm | 0.6mm | 0.7mm |
| Pitch CC | 1.5mm 16.9tpi | 1.7mm 14.9tpi | 1.3mm 19.5tpi | 2.5mm 10.2tpi | 3mm 8.7tpi |
| Pitch Rip | 3.7-2.5mm 6.9-10.2tpi | 3.8-2.4mm 6.7-10.6tpi | 3.8-2.4mm 6.7-10.6tpi | 5.6-3.8mm 4.5-6.7tpi | 5.6-3.5mm 4.5-7.3tpi |
| Set per Side | 0.125mmm | 0.125mm | 0.125mm | 0.125mm | 0.125mm |
| Max Depth | ∞ | ∞ | ∞ | ∞ | ∞ |
| Replacement Blade | S605 | S610 | S611 | S615 | S616 |
Gyokucho razorsaws, the original replaceable blade Japanese saws, have long been renowned for their cutting efficiency and excellent durability. The latest generation of Gyokucho saws have blue handles made from TPE (thermoplastic elastomer) a remarkable material that is simultaneously hard and resilient yet feels velvety to the touch and affords a superb grip. Rest assured that TPE is an eco-friendly alternative to rubber, and isn't harmful to the environment as it is completely recyclable.
The blades of Gyokucho saws are treated using a process called electroless nickel plating, this has three functions. Firstly, it protects the blade against corrosion, secondly it provides a nice shiny mirror surface so you can gauge your cutting angles, and thirdly its low friction properties inhibit resins and sap from building up on the blade - anything that does manage to get stuck to them can easily be washed off with warm soapy water.
The teeth are differentially impulse hardened, one by one, bringing the outer surfaces to RC68 or more whilst still leaving the 'root' of the tooth soft and therefore much less prone to fracture - not unlike tiny Japanese sword blades. They are equally happy working in softwoods or temperate hard woods and can, with care and a light touch, be used on exotic timbers too.
Ryoba are double edged saws (Ryo = Two, Ba = Edge). They have different tooth patterns on either side of the blade, usually one for ripping and the other for crosscutting.
Here's an interesting video by David Walton, YouTube's Unplugged Woodworker, on Ryoba Saw basics using a Gyokucho TPE saw.
