Meet a Kakuri Artisan: Koide-san, Master Plane Maker
Kakuri was founded in 1946 as a wholesaler of carpentry tools and cutting tools. Later, the company established a manufacturing division with the goal of producing reliable in-house products. In 1972, the manufacturing division separated and became the independent company it is today, Kakuri Works. Since then, it has expanded its product range to include planes (kanna), chisels (nomi), and bonito shavers, creating high-quality products suitable for both beginners and professional woodworkers.
Our company works alongside Kakuri Works on joint development projects, blending traditional techniques with modern tool-making to meet today’s needs.
The Process of Creating a Plane Blade
The plane blades at Kakuri Works go through various stages to ensure ease of use and sharpness. The key to achieving that sharp edge is the final honing (blade sharpening), which requires a high level of skill and precision.
1. Material and Forging
The material used for the plane blades combines hard steel and softer iron into a composite material. This combination makes the blade easier to sharpen compared to fully hardened steel, while still providing excellent workability. Through the process of forging, where heat and pressure are applied to the materials, the blade gains strength. Afterward, a rough grind removes the oxidation created during forging, and the blade takes its initial shape.
2. Heat Treatment: Hardening and Tempering
The heat treatment process gives the blade its strength and resilience. The steel is heated to about 800°C and then rapidly cooled in water during the hardening process. This hardens the steel, and then tempering is done to add toughness and flexibility to the blade.
3. Blade Sharpening
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Insight
To ensure the blade does not leave marks on the wood surface, the blade's central line is slightly raised, while the corners are kept lower. This creates a convex shape on the blade, ensuring that the center of the blade contacts the wood first when the plane is used, effectively preventing any unwanted lines from forming on the surface. |
At Kakuri Works, the combination of machinery and skilled handwork allows for the production of around 5,000 plane blades each month. Some parts of the process are outsourced to specialized local factories in the Tsubame-Sanjo region, creating a strong horizontal connection that ensures efficiency. This setup allows Kakuri Works to focus on honing the blades to perfection, delivering high-quality, consistent results.
4. Leather Honing (Kawa-togi)
The last step in sharpening is leather honing (kawa-togi). In this final process, the blade is polished using cowhide leather, removing any burrs (kaeri) and ensuring a smooth edge. A special abrasive is applied to the leather, and the blade is honed to perfection, achieving a razor-sharp edge.
Kakuri Works' Commitment to Craftsmanship
The planes made at Kakuri Works are used by a wide range of people, from DIY beginners to professional woodworkers.
For DIY enthusiasts, the planes are designed to be easy to use, with a focus on being easy to sharpen and practical for everyday use.
For professional woodworkers, Kakuri Works uses Hitachi Metal's Aogami No. 2 blue steel, creating blades that maintain their sharpness for a long time.
The Difference Between Aogami and SK Steel Used in Plane Blades
Many plane blades are made from either Aogami (Hitachi Metal's Blue Steel No. 2) or SK steel. Each material has its own unique characteristics, and we recommend selecting one based on your intended use.
SK Steel Planes
SK steel is relatively affordable, offering ease of sharpening and low maintenance. For DIY users or hobbyists, it's an excellent choice, as it's easy to handle and requires minimal effort to maintain. This makes it especially suitable for beginners or those who don't use planes frequently.
Aogami Planes
While sharpening Aogami steel can be a bit more challenging, once sharpened, it is renowned for its long-lasting sharpness. This means the blade resists wear and retains its cutting edge over a long period, making it ideal for extended use or for those who want to reduce the frequency of sharpening. Aogami steel is one of Japan's highest-quality tool steels, and its quality is highly regarded by customers worldwide. While it's priced higher than SK steel, its durability and the trust in Japanese craftsmanship make it a preferred choice for many.
Both materials are available in Kakuri's product lineup, and you can select the one that best suits your needs, budget, and preferences. Aogami blades don't require specialized sharpening stones and can be honed with standard artificial stones, making them highly practical as well.
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Explore Aogami Planes |
Featured Planes from Kakuri Works
Replaceable Blade Planes
These planes are primarily offered for general users. While they're less commonly used by professionals, their ability to be mass-produced and the convenience of easily replacing the blade if it gets damaged make them highly practical. These planes offer excellent usability and cost performance.
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Ebony Mini Plane
The Ebony Mini Plane is ideal for detailed tasks like DIY projects or leathercraft. It uses a screw mechanism to secure the blade, which is made from high-speed steel (HSS) that's resistant to chipping. Although made in China, the design and quality control are handled in Japan, ensuring that it delivers excellent performance and quality.
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FAQ by Woodworking Enthusiasts
What Is the Purpose of the Chip Breaker (Uragane) on Plane Blades?
Originally, planes were single-blade tools, but for easier use when planing against the grain, two-blade planes with a chip breaker (uragane) became the standard. This feature helps make planing smoother, especially when working against the grain.
Learn More About the Chip Breaker
How Often Should I Sharpen My Plane Blade?
The frequency of sharpening depends on your usage, but since the blade's sharpness gradually decreases over time, it's ideal to sharpen the blade before every use to maintain smooth, comfortable work.
A good indicator that it's time to sharpen the blade is when you notice it's becoming harder to cut smoothly. If you wait until it's completely dull, the sharpening process becomes much more difficult. Additionally, minor nicks or damage to the blade should be addressed early to keep the blade performing well over time.
Can I Use the Plane Blade Forever? When Is It Time to Replace It?
Theoretically, a plane blade can last forever as long as it is regularly sharpened. While the blade does gradually wear down with each sharpening, very few people use a blade until it reaches its very end. For example, a plane from 50 years ago might still be in good working condition if it's only used a few hours per week. Even for professionals who use planes daily, it's rare for the blade to wear out completely. Thanks to the high-quality steel used in these blades, a few sharpening sessions are usually enough to restore their sharpness.
What Should I Pay Attention to When Sharpening My Plane Blade?
When sharpening your plane blade, it's recommended to use at least three stages of sharpening: rough, medium, and finishing. If your blade has chips or damage, you'll need to start with a coarser grit to remove the imperfections. This process can be time-consuming and requires focus.
Another important point is making sure your sharpening stones are flat. A worn-out stone will cause uneven sharpening, which can affect the blade's cutting performance. Regularly flattening your stones is crucial for achieving the best results. Additionally, maintaining a consistent angle while sharpening is key, so using an angle guide or jig can help ensure accuracy.
Explore Sharpening Stones and Guide
For more guidance on sharpening Japanese kanna blades, you may also find this video helpful:
Pride in Craftsmanship and Vision for the Future
"I always try to create blades that make our customers say, 'This is a great tool.' That's my daily motivation," says Koide-san. "I also don't want to be the one to stop the traditions that my predecessors have worked so hard to continue. It's important to me to pass these skills on."
Koide-san, along with the rest of the team at Kakuri Works, is dedicated to ensuring that the craftsmanship and techniques passed down over generations continue into the future, despite the changing times.
The Future of the Tsubame-Sanjo Craftsmanship Town
The Tsubame-Sanjo region in Niigata Prefecture is home to a large number of small factories, creating a unique atmosphere where close-knit collaborations are the norm. Kakuri Works works closely with specialized local factories to manufacture a wide variety of products efficiently and at high quality.
The planes produced by Kakuri Works carry the wisdom and techniques passed down over the years. The shapes and thicknesses developed through trial and error by previous generations are carefully maintained to guarantee the quality of each product.
At Kakuri, we are committed to continuing the production of high-quality woodworking tools while preserving the traditions of the Tsubame-Sanjo region. Our mission is to support the future of craftsmanship, working alongside the region's legacy to pass on the value of traditional handicrafts.