The Thin Grounding of Knives

Knives must be periodically ground thin to achieve optimal cutting performance. This thin blade shape minimizes cutting resistance. Discover more about the process of thin grounding of knives

Why should Knives be ground thin?

Two things happen during cutting:

1: The knife’s sharp cutting edge slices through the object being cut. To achieve this, it is necessary to have a finely ground knife.

2: As you push the knife further into the object, the material beside the blade gets compressed, necessitating the creation of space for the knife.

To ensure that as little material as necessary is pushed away, the knife blade must be as thin as possible. Then the resistance is minimal. This is achieved by grinding the blade thin.

The knife’s sharp cutting edge effectively slices through the object by applying pressure. Achieving a fine grind on the knife is crucial for obtaining this sharp cutting edge.

When the knife penetrates deeper into the object, the material surrounding the blade compresses to create space. To minimize the displacement of material, the knife blade needs to be as thin as possible. This thinness can be obtained through proper grinding.

Many manufacturers do not produce knives with thin blades, making it beneficial to grind new knives to achieve optimal sharpness. Even knives that have been sharpened multiple times can benefit from being ground thin. This is because the conical shape of knife blades causes the cutting edge to gradually thicken with each sharpening.

Drawing 1 in the above figure shows a common cross-section of a knife. The blade tapers slightly and becomes thinner towards the cutting edge. Then a cutting edge is ground at an angle of 40 degrees on the blade.

Drawing 2 shows the cross-section of a thinly ground knife. By grinding away a small piece on both sides of the knife, the knife encounters less resistance, especially with harder objects. The angle of the cutting edge remains unchanged. This hardly changes the strength of the knife.

A knife is therefore not ground thin over the entire blade, but only directly over the cutting edge.

This is how thin grounding of Knives is done:

By thin grounding of knives, a relatively large amount of material is removed. Therefore, not all grinding methods are suitable. Below you will find information on three common practices.

1: On a coarse Grindstone

The knife is ground at a smaller angle than usual. After it has been ground thin, the knife can be resharpened on a finer stone. This will remove scratches caused by the coarse stone and form a new cutting edge.

Of course, the question arises: which grit size is best?

On a coarse grindstone, the knife is ground at a smaller angle than usual. After thin grinding, the knife can be resharpened on a finer stone to remove scratches and create a new cutting edge. It is recommended to use a stone with a grit size of about 220 for initial thin grinding, as it balances material removal and scratch depth. While this process may be time-consuming, it is ideal for regular knife maintenance.

2: With the aid of an electrically driven Grinding Belt.

Knives can be ground thinly on an electrically driven grinding belt. However, such grinding machines are often not available.

The best machines are those that allow you to grind on the part of the belt that is between the drive rollers. This area can be slightly bent, which gives a better result. For grinding on the roller, it must have a relatively large diameter. Ideally, it should be covered with a slightly springy layer.

When grinding electrically, make sure that the blade is not overheated. When the temperature rises to around 200 degrees, the knife becomes softer. This can happen in small places faster than you might think.

3: With a slowly rotating Whetstone

A slowly rotating whetstone (ideally placed in a container with water) also offers the possibility to grind out knives thinly. However, it is very difficult to achieve a good result with this method. This is especially true when grinding on the curved side of the stone. Grinding is easier with the side of the stone.

Why are Knives ground to a thin Edge?

The thin grounding of knives is essential because it allows for better cutting performance. Grinding knives to a thin edge ensures that they can penetrate materials more easily, resulting in cleaner and more precise cuts. It also reduces friction and resistance, making the knives more efficient. So, the thin grounding of knives improves their overall functionality and performance.

Is a full flat Grind better than a Saber Grind?

A full flat grind and a saber grind have their own advantages and disadvantages. A full flat grind provides excellent slicing performance and is easier to maintain, while a saber grind offers more durability and strength. The choice between the two depends on the specific needs and preferences of the user.

What does it mean to thin a Knife?

Thinning a knife means reducing the thickness of the blade behind the cutting edge. This process helps to create a thinner and more acute edge, which enhances the knife’s cutting performance and precision. Thinning a knife also reduces drag, making it easier to slice through materials with less resistance.

What is the benefit of a Scandi Grind?

A Scandi grind provides excellent control and precision during cutting tasks. It features a flat primary bevel that extends all the way to the cutting edge, making it easy to maintain and sharpen. The Scandi grind excels in woodworking and bushcraft applications, offering superior edge stability and efficient carving capabilities.