⚙️ Shear Sharpening Training: Convex Edge Theory Module — Japanese Edge (Hamaguri)
The Convex Edge Theory Module introduces one of the most advanced and defining skills in professional shear sharpening — understanding and preserving the Hamaguri convex edge. This module focuses on the theory behind true Japanese edge geometry and why maintaining its natural radius is essential for precision performance and long-term durability.
Understanding the Convex Edge
The convex edge — also called the Hamaguri edge — is the hallmark of Japanese shear craftsmanship. Unlike beveled edges, which are flat and angular, the convex edge is smooth and continuous, allowing the blades to slice through hair with minimal resistance. Proper sharpening requires an advanced understanding of radius preservation, burr control, and surface polishing.
- Learn the difference between convex, semi-convex, and beveled edge designs
- Understand how the convex edge enables a true slicing action
- Recognize how improper sharpening flattens or destroys the edge geometry
What You’ll Learn in the Convex Edge Theory Module
- The structure and geometry of the Japanese Hamaguri edge
- Why edge radius and curvature determine shear smoothness and sharpness
- How to identify true convex vs. imitation convex edges
- The importance of proper polishing and honing angles
- How edge design affects performance for dry, wet, and slide cutting
Who This Module Is For
This module is designed for professional sharpeners and those training to become professionals who want to master the true Japanese convex edge. Whether you’re an experienced sharpener seeking advanced technical depth or a newcomer looking to build a foundation in high-precision work, this module provides the essential theory behind world-class results.
Why This Module Is Critical
The Hamaguri edge is what separates premium Japanese shears from all others — but without proper maintenance, it’s easy to ruin. By learning the theory and geometry behind the convex edge, you’ll gain the foundation needed to sharpen with accuracy, respect, and consistency. This module prepares you for advanced hands-on training in flat hone sharpening and edge restoration techniques covered in later courses.
This module is part of our complete Professional Shear Sharpening Training Program, available through our Shear Sharpening Academy.
Related Modules
- Edge Types Module – Compare convex, beveled, and semi-convex designs in detail.
- Sharpening Machines Module – Learn which systems best preserve true convex geometry.
- Oiling & Maintenance Module – Maintain smooth performance after sharpening and polishing.
Explore the Complete Shear Sharpening Program →
FAQ
What makes a convex edge different from a beveled edge?
The convex edge has a continuous curved surface, while beveled edges have flat angles. Convex edges cut smoother and quieter, ideal for Japanese shears.
What is the Hamaguri edge?
Hamaguri is the Japanese term for the true convex edge — a clam-shaped radius that allows the blade to glide through hair effortlessly. It requires precision tools and training to maintain properly.
Who should take this module?
This module is designed for professional sharpeners and those training to become professionals who want to understand and execute true convex edge work at an expert level.
Is this module part of the full training program?
Yes — the Convex Edge Theory Module is part of our Professional Shear Sharpening Training Course, available individually or within the full certification program.
