Precision Grinding -_Nenohi Record Vol_3

In the last chapter of Nenohi Record, we explained the structure of a single-edged blade.
At Nenohi, we have introduced "precision-grinding" into our manufacturing process in order to maximize the advantages of the single-edged blade.

This time, we will guide you on our commitment to this process by comparing the actual 3D scan data of a blade that has been precision-grinded and one that has not.

Please refer to the previous Nenohi Record for a better understanding of the contents.
If you haven't seen it yet, please click here.

[What is precision-grinding?]

The term "precision-grinding" may sound mechanical, but Nenohi's precision-grinding is 100% handmade by Nenohi's ace craftsmen.
We believe that the ultimate in handwork is to process delicate steel materials that cannot be processed by automatic machines with a precision that is superior to a machining process.
The grinding and polishing process are repeated at such a high degree of difficulty that a single mistake can render the entire product useless, and grinding stones are used to create a beautiful shape to a near mirror finish.
*The polishing process with a buffing wheel is used only very slightly in the final stage because it ruins the shape.
This is the precision-grinding process of Nenohi.

[Reasons for precision-grinding]

(1) To improve sharpness.

When cutting food, there is no friction (resistance) due to unnecessary unevenness on the side of the blade, which greatly affects the sharpness of the blade.

(2) To make the blade strong and light.

The extra weight of the knife can be scraped off by the "hollow-grinding (concavity)".
As a result, the blade remains strong and light, especially at the cutting edge (tip), so you can handle the knife for a long time as if it were an extension of your own hand.

(3) To sharpen easier.

Since the knife has an accurate blade from the beginning of use, it can be sharpened accurately by simply tracing the blade. And above all, it does not lose its shape, so you can save unnecessary sharpening time.

(4) For beautiful appearance.

No matter who sharpens it, beautiful "shinogi" and "ura" can be maintained.

[Comparison between with and without precision-grinding]

This time, we acquired 3D scan data of blades with and without precision-grinding.
How much difference is there between the blade surface with and without precision-grinding? We will show you how the difference affects the blade surface.


The precision-ground blade has a precise hollow in the center of the Hira. This hollow allows the blade to maintain a clean line of shinogi. *If the Hira is not shaped accurately, the shinogi will not be set straight, even though the sharpening is done correctly.


Precision-grinded blades have a precise hollow in the center of the back.
This hollow allows the blade to maintain a beautiful back edge. The "line of the blade" does not collapse, so the performance of the knife can always be brought out.
*If the hollow of the backside is not shaped accurately, the blade will have a mixture of thick and thin areas, i.e., a mixture of poor cutting ability and a brittle blade, which will adversely affect the sharpness of the blade.


By precision-grinding, you can experience the best sharpness from the beginning. When sharpening with a whetstone, the entire blade immediately hits the whetstone, allowing for uniform sharpening.
Knowing the knife's original sharpness from the beginning will clarify the target performance to be maintained.
*Without precision-grinding cutting edges do not hit the whetstone evenly, resulting in a longer sharpening time.

By introducing this "precision-grinding" into the knife manufacturing process, Nenohi is able to make knives that are beautiful and maximize performance .Another major advantage of precision-grinding is that it allows customers to easily maintain their own knives even after they have been delivered to them.

Nenohi's Japanese knives are completed through this grinding process and then a handle is attached to the knife.

In the next chapter, we will elaborate on the final process, "handle attachment".
Please look forward to the next chapter, as Nenohi's Japanese knives are filled with meticulous dedication to detail right up to the very end of the final process!