The cutting edge of a knife can have different angles. The smaller the angle is, the sharper the knife. Therefore, the cutting edge of a very sharp knife, is very narrow. Japanese knives are made of very hard steel (starting from 60 HRC) and can be made extremely sharp, when sharpened under a small angle. Other, for example German knives (55-58 HRC), often are made of slightly softer types of steel and are sharpened under a wider angle.

The angle of the cutting edge of Japanese knives is usually 30 °. For normal knives you can use an angle between 36 ° and 40 °. The sharpening angle for your knife is half the angle of the cutting edge (after all, you will sharpen on 2 sides). The sharpening angle of a Japanese knife (please find a few examples below) is therefore 15 ° (30 °/2) and of other knives 18 ° to 20 °.

If you notice that your knife becomes dull or damages quite quickly, then maybe you are sharpening the knife too thin and then we recommend to use a larger sharpening angle.

Examples of brands which carry knives made of hard steel (sharpening at an angle of 15 °) Böker, Eden, Global, Kai Shun, Robert Herder, Sakai Takayuki Myabi, Zwilling

To determine the sharpening angle for pocket knives, we recommend to follow the next general rules:

For heavy use 46 °

For normal use 36-40 °

For light use only 30 °

The grinding angle which you will achieve, is determined by the height of the back of your knife against the stone. You can determine the correct height with a simple formula. If you have determined the required grinding angle, measure the width of the knife. Then look in the table below how high you must keep your knife against the stone.

Width of the blade | Sharpening angle 12° | Sharpening angle 15° | Sharpening angle 18° | Sharpening angle 20° | Sharpening angle 23° |
---|---|---|---|---|---|

10 mm | 2.08 mm | 2.59 mm | 3.09 mm | 3.42 mm | 3.91 mm |

15 mm | 3.12 mm | 3.88 mm | 4.64 mm | 5.13 mm | 5.86 mm |

20 mm | 4.16 mm | 5.18 mm | 6.18 mm | 6.84 mm | 7.82 mm |

25 mm | 5.20 mm | 6.47 mm | 7.73 mm | 8.55 mm | 9.77 mm |

30 mm | 6.24 mm | 7.77 mm | 9.27 mm | 10.26 mm | 11.72 mm |

35 mm | 7.28 mm | 9.06 mm | 10.82 mm | 11.97 mm | 13.68 mm |

40 mm | 8.32 mm | 10.35 mm | 12.36 mm | 13.68 mm | 15.63 mm |

45 mm | 9.36 mm | 11.65 mm | 13.91 mm | 15.39 mm | 17.58 mm |

50 mm | 10.40 mm | 12.94 mm | 15.45 mm | 17.10 mm | 19.54 mm |

55 mm | 11.44 mm | 14.24 mm | 17 mm | 18.81 mm | 21.49 mm |

60 mm | 12.47 mm | 15.53 mm | 18.54 mm | 20.52 mm | 23.44 mm |

If you don't want to work with a ruler, there are two handy helpers which we can recommend. First off, we offer a "sharpening rail set" on our website. Another solution is to try it first with a pile of coins to match the correct height.

The sharpening rail is clamped on the back of the knife. The small sharpening rail creates a fixed height of 4.5mm. The bigger sharpening rail creates a fixed height of 6.5mm. This means, that when using a sharpening rail your are less flexible with your angle than if you choose the angle manually. In this table below we show the possible heights:

Width of the blade | Sharpening angle 12° | Sharpening angle 15° | Sharpening angle 18° | Sharpening angle 20° | Sharpening angle 23° |
---|---|---|---|---|---|

10 mm | 2.08 mm | 2.59 mm | 3.09 mm | 3.42 mm | 3.91 mm |

15 mm | 3.12 mm | 3.88 mm | 4.64 mm | 5.13 mm | 5.86 mm |

20 mm | 4.16 mm | 5.18 mm | 6.18 mm | 6.84 mm | 7.82 mm |

25 mm | 5.20 mm | 6.47 mm | 7.73 mm | 8.55 mm | 9.77 mm |

30 mm | 6.24 mm | 7.77 mm | 9.27 mm | 10.26 mm | 11.72 mm |

If you use a sharpening rail, we recommend to apply a strip of adhesive tape on the back of the knife before clamping on the sharpening rail, to prevent damage of the blade.

If you want to use Euro coins to measure the correct height for sharpening, follow these steps:

1) Determine the sharpening angle which you want to use

2) Go to Step 2 and find the correct height

3) Measure the thickness of the blade in mm

4) Calculate as follows:

The height in mm - half of the thickness of the back of the knife. This is the height that you are going to fill up with coins.

Example: You are going to sharpen a Böker Saga Cook's knife with an angle of 15 °. The blade has a width of 52 mm, the thickness of the back of the knife is 2.4 mm, the height which you find in the table with step 2 is more than 13 mm. The calculation which follows is approximately 13 mm - 1, 2 mm = 11, 8 mm. This is the height that you can measure out with euro coins.

Coint | Thickness |
---|---|

1 penny (1971-1991) | 1.52 mm |

1 penny (1992-present) | 1.65 mm |

Two pence (1971-1991) | 1.85 mm |

Two pence (1992-present) | 2.03 mm |

Five pence (1992-2011) | 1.89 mm |

Five pence (2012-present) | 2.38 mm |

Ten pence (1992-2011) | 1.85 mm |

Ten pence (2011-present) | 2.05 mm |

Twenty pence | 1.70 mm |

Fifty pence coin | 1.78 mm |

1 british pound | 3.15 mm |

2 british pound | 2.5 mm |