A knife sharpener allows you to keep your kitchen tools in working condition. The sharpness of the blade depends on the quality of the metal. Gradually, knives become dull, so sooner or later they still need to be sharpened. For this purpose, special devices and power tools are used. When choosing, take into account the parameters of the knife and the type of blade material. The cost of a sharpening tool depends on its functionality.
Manual (left) and electric (right) knife sharpener.
Sharpening theory: profile and type
The blade profile (geometry) refers to the contour formed by sharpening. The profile outlines the part of the blade that will be in contact with the material while using the knife. Different tools have different blades and their own characteristic profile.
Its shape is related to the properties of the material used and the purpose of the tool. Using blade processing, the following types of profiles are formed:
- A simple blunt wedge. The blade is durable, but rough. It creates significant cutting resistance, and cutting rather viscous materials leaves a ragged mark.
- Sharp wedge. It is poorly suited for cutting, quickly becomes dull, and may chip. When cutting tough or fibrous materials, the result may be worse than with a dull blade due to high friction and cutting resistance.
- Ogival (bullet-shaped). The slopes (the sides of the cut line) have a characteristic convex shape. Such a blade is expensive and difficult to make even in production conditions. Tools with a bullet-shaped sharpening are made for special equipment (for example, medical equipment, when studying the thinnest tissue sections).
Model of a desktop sharpener with the ability to change the sharpening angle Source ytimg.com
- Faceted. Faceted geometry is used for disposable safety razor blades. The cutting part ends with edges (straight segments). Hex sharpening is considered universal. A profile with 3-4 edges is suitable for coarse hair, with eight – for the finest hair.
The most common is traditional double-sided sharpening; its variety is lens sharpening. It has high cutting efficiency and is considered the best choice of blade options. However, it is quite difficult to implement, which increases the cost of finished products, regardless of whether it is a kitchen tool, hunting, folding or tourist. There are knives with other, more specific blade shapes that determine the functionality and ease of use of the tool.
What types of electric sharpeners are there?
The best manufacturers have filled the market with a large number of special devices for processing cutting elements. On sale you can find inexpensive and expensive products, of elementary design and with additional functions, universal and directly for Japanese products. However, all manufactured products are divided into the following types:
| Kinds | Description |
| Sharpener - keychain | The most basic device. Belongs to the mobile category. They differ in shape, size, and color. According to buyers, it is an indispensable item for fishing, picnics, hiking, and hunting. There are models with an original design: in the form of a regular pocket keychain or a bank card. |
| Folding | They are called "balisong" in honor of the region where they first appeared. This happened in the province of Batangas in the Philippines. It is believed that it was in this province that the first folding knives and sharpeners, which were rectangular in shape with an awl and a rod, arose. Fishermen, hunters and travelers doted on them. |
| Grindstone | It is primitive and easy to use. It may resemble a bar, cylinder, rod or disk in appearance. The manufacturer chooses the shape of his brainchild. Products with a handle, base and body made of wood or plastic go on sale. There are double-sided products with different abrasives. This sharpener is unpretentious, compact and mobile. Able to handle a blunt edge in any conditions. |
| Mechanical | Stationary devices with advanced capabilities. Products with adjustable angles are available. You can install any abrasive at your discretion. Refers to professional equipment. Suitable for tidying up kitchen units. A review of reviews shows that experience and skills are required to work with this product. It is convenient to use the product, as it belongs to the universal category. Step-by-step instructions posted on the Internet will tell you how to sharpen blades yourself with such a device. |
| Electrical | Modern products. Available in both compact and bulky versions. Not suitable for home. Often found in catering establishments. They are distinguished by productivity, reliability, and long service life. |
Sharpening theory: angle
Each specific blade has its own area of application, even if it is kitchen appliances. During manufacturing, they are sharpened at different angles, which is especially noticeable on new tools (after manual sharpening of knives, the differences often disappear).
Blade parameters affecting its functionality Source klinok.zlatoff.ru
The sharpening angle is a fundamental characteristic. It is always indicated in half, since many products are sharpened on one side (for example, a bayonet). The purpose of the knives can be determined by the following angle parameters:
- 10-15°. Straight razors, medical scalpels, and tools for artistic carving are taken to the sharpest corner. This sharpening makes it easy to cut hairs, but quickly becomes dull when trying to cut unsuitable material.
- 15-20°. This is how food tools, vegetable and pastry (cake) knives are sharpened.
- 20-25°. The angle is typical for bread and fillet knives (although on fillet varieties the angle is often adjusted to 15°).
- 25-30° (sometimes up to 40°). The corner is torn out for a hiking and hunting tool. The edge is sharp enough to cut through wood, open a tin can, or chop a bone.
- 30-35°. Meaning inherent in general purpose household products.
- 35-40°. Sharpening is performed on specialized (carpentry) tools, axes, shoe knives.
Full and half sharpening angle Source 2proraba.com
- 30-50°. This angle is typical for a special-purpose tool, such as a machete. You won’t be able to cut bread evenly with its help, but it can deal with thick undergrowth and vines just fine.
There are blades with different types of sharpening in different parts of the blade. Such a tool becomes more versatile in use, but it is much more difficult to manufacture. The angle of sharpening determines how convenient and useful the knife will be. It becomes clear that the correct device for sharpening knives should allow you to set the required sharpening angle. This is the main difficulty in its manufacture.
Optimal one-and-a-half sharpening
Almost all (except special) knives are sharpened with a one-and-a-half profile during the manufacturing process. During operation, such a blade is easy to straighten, and it is suitable for household work with a variety of materials. For blades with one and a half sharpening, it is much easier to make a sharpener, since there are no edges in the profile geometry.
A simple way to restore sharpness to a blade Source ytimg.com
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The straightening and finishing of blades with one-and-a-half sharpening is carried out using a sharpening device and an abrasive. Abrasives vary in material and grain size. The abrasive number indicates the number of grains per square millimeter, that is, the degree of grinding of the metal surface. Processing is performed depending on the purpose of the tool:
- For straightening and finishing kitchen tools, abrasive No. 800-1100 is used.
- If the quality of the cut is important (for example, for a straight razor), pre-treatment with an abrasive is carried out. Then the surface of the blade is polished using a leather whetstone until it is mirror smooth. GOI paste for fine or fine polishing (dark green color) will help you get the desired effect.
- Finishing is usually not used for tourist (hiking) and hunting knives. Firstly, with such a tool it is often necessary not to cut, but to chop or file, and a knife copes with this more easily without finishing. Secondly, a cut on the skin from such a weapon is not smooth, but slightly ragged, which reduces bleeding, speeds up healing and reduces the likelihood of infection.
Compact mechanical sharpener Source ice-people.ru
What to sharpen: grit
The main characteristic of whetstones (brushes) used for sharpening knives is grain size. It is designated differently in different countries; It is more convenient to define grain size as the number of grains per unit area, but the designation in English terminology is also accepted. The classification of stone grain size is as follows:
- Rough (coarse) stone. Sharpening is carried out using sharpening stones No. 300-350. The coarse abrasive helps form the correct angle (geometry). Often used if the cutting edge has visible damage.
- Medium. For it, choose abrasive No. 400-500. The metal surface is ground to the required smoothness.
- Fine. The most common type of material suitable for household use. Restores the sharpness of knives that have become dull during normal use.
- Very fine (extra or ultra fine). Final finishing is carried out if necessary; The connections are polished to a mirror finish.
Sharpening stones with different grain sizes Source top-nozhi.ru
What to sharpen: a variety of materials
Sharpening stones can be divided into materials of natural and artificial origin. Natural stones are slates, quartz, chalcedony and corundum of various types and colors (for example, black Brazilian slate). They wear down faster than their artificial counterparts; the grain size is often uneven and rarely fine. Artificial ones include ceramic and diamond varieties.
The most durable and hard sharpening device for knives is considered to be a diamond whetstone. It is based on metal or plastic, with a thin layer of diamond coating applied on top. The device cannot be called cheap, but it will serve for a very long time, since it practically does not wear down. The diamond stone needs time to grind in and produce excellent results, and can be cleaned under running water.
The market offers technological varieties of material, for example, CBN sharpening stones. They have a continuous working layer made of cubic boron nitride, are characterized by high hardness and resistance to the chemical components of alloys and steels.
Stones with two types of grain size Source ytimg.com
The most convenient type of whetstone is an elongated whetstone, as this makes the sharpening process easier. Ideally, the length of the bar should be greater than the length of the blade. At home, it is enough to have two medium-grained bars (different), and one or two fine-grained ones. The option with double grain has proven itself well; on one side it is coarse, on the other it is finer (for example, grain 125/100).
To improve the quality of sharpening, natural stone is moistened with water (or soaked in it for a short time) before use. Water is absorbed into the structure of the material, and during operation it is released and mixed with particles separated under the pressure of the blade. A mixture of water and abrasive forms a paste that improves sharpening quality.
Water can be replaced with mineral oil. Knives are always sharpened using oil on Arkansas stone, which has different textures. Hard varieties are used for additional grinding and the sharpest sharpening, medium - for sharpening the tool, soft - for quick grinding. After work, Arkansas stone is cleaned with a brush, hot water and soap.
Wetting with water increases work efficiency Source prom.st
Types of knife sharpeners
There are 3 types:
- mechanical;
- electrical;
- completely manual.
Each type differs in a number of parameters: material properties, degree of abrasiveness, functionality (adjustment of the tip angle, speed of work).
In addition, kitchen knife sharpeners vary in size. You need to determine in advance the location of such a tool in the kitchen. Manual products can be stored in a cabinet, while automatic sharpeners that are larger in size require more space.
Hand whetstones
This is the simplest option. Such sharpeners are a rectangular block made of durable material. They are characterized by varying degrees of abrasiveness, which is determined by the type of sharpening stone. They are made from natural or artificial stones.
CBN bars and Belgian slates are often used for sharpening. The last option is made from a combination of materials: slate and sandstone. Abrasive properties are provided due to the content of garnet.
Hand sharpening stones have different hardness and surface grain.
Natural stones work well on different types of steel: chromium-containing, high-alloy, carbon. They can be used for rough and fine sharpening. The result is a sharp blade. CBN bars are best used for finishing grinding. They provide softness during processing.
Hand sharpening stones come in different sizes. Most of them are small. They produce products with a handle and an anti-slip coating on one side (made of rubber). This ensures ease of use. At the same time, the speed of work increases, because the block is firmly fixed in the hand, rests on the surface and does not move. The tabletop sharpener can be put away in the closet at any time. This saves space on the kitchen countertop.
Diamond sharpeners
An example of a diamond sharpener in a compact folding case.
Products of this type last longer, due to their design. Diamond chips are applied to the metal bar. This ensures a sufficient degree of abrasiveness and, as a result, wear resistance of the products.
This type of sharpener can even be used to work with cutting tools made of hard alloys.
Sharpening takes a long time, while ensuring high quality sharpening of the blade. Externally, a diamond stone differs little from a standard product.
Water stones
Unlike other types of sharpeners, which are used to work on a dry surface, water stones provide better results after treating the material with water. Oil is not used for this.
When sharpening is performed, a substance with abrasive properties is formed. Thanks to it, roughing and finishing processing is performed. To obtain a blade that matches the sharpness of a razor, alternate cutting edges with varying degrees of abrasiveness.
Mechanical sharpeners
You can use a more complex tool than hand blocks. With their help, the desired degree of blade sharpness is achieved faster. Design features: emphasis for stability, different shapes and sizes of abrasive stone.
A common model includes 2 parallel wheels with a pre-set blade sharpening angle - ranging from 25 to 30°. The mechanical sharpener does not connect to a power source. The sharpening angle of the blade is determined using guides.
Inside a mechanical sharpener there are two parallel abrasive wheels pressed tightly against each other.
There are professional mechanical sharpeners. They are sold with a set of abrasive bars, changing which allows you to adjust the degree of sharpness of the blade, as well as with blade locks and other auxiliary elements. Mechanical sharpeners can remove imperfections and polish surfaces.
Knife with vacuum fastening
The device is distinguished by the presence of suction cups in the lower part of the body. Thanks to this fastening method, stability is ensured when installing the sharpening tool. Another advantage is the blade angle adjustment. There are several sharpening zones, which allows you to sharpen knives and scissors, blades of various sizes.
Brass knuckles
The brass knuckle-shaped sharpener is inconvenient to use and is only suitable as a temporary option.
This is the least suitable option due to the ill-conceived design of the device. The product, reminiscent of brass knuckles, is put on the fingers; in its upper part there are 2 sharpening zones.
The disadvantage of the device is a high degree of danger. The knife is in constant motion, and the sharpening zones are of small length and depth. As a result, the blade may slip and cut your hand. The tool is sharpened in 2 stages.
In addition, the processing quality is not high enough. The blade edge may become uneven with frequent use. This is due to uneven sharpening. However, this option is suitable for home use: the sharpener is small in size and can be easily stored in a drawer.
Sharpening system
Such devices are used in everyday life and for professional purposes. The design is a stable machine, equipped with a knife lock, an abrasive bar mounted on a rotating rod, which makes it possible to sharpen the blade at the desired angle. The sharpening system is also suitable for scissors.
This is the most effective type of mechanical tool. Its advantage is its ability to maintain the same sharpening angle. However, it is necessary to provide storage space, since the device is large.
Electric cutters
The electric knife is convenient and practical to use.
This group includes functional devices that are simple in design, but at the same time provide high quality sharpening. They are used to work with knives made of different materials, including ceramics.
The structure of the electric knife is quite simple: it has a plastic body, inside there are diamond discs, partially covered on top with a protective material.
There are 2 to 4 grooves on the surface of the housing. A cutting tool is installed in them. Moreover, some of the grooves are intended for primary sharpening - removing rough defects, and some are used for grinding the surface. A power tool can sharpen even the dullest knife much faster. The product is connected to a 220 V power source.
Musaty
Knife sharpening musat is used only as a tool for straightening the edge of the blade.
Musat is a rod that is made from different materials: metal, ceramics, diamonds. The length of the working part reaches 25 cm. The main purpose of the musat is to correct the edge of the blade. It is not used for rough sharpening.
Using musat you can only eliminate defects on the cutting edge. For this purpose, notches are provided on the surface. They allow you to straighten the blade. For ease of use there is a handle.
Sharpening devices, practical at home
The list of sharpening devices used in everyday life includes hand-held devices. A popular option is musat. Professional chefs use it to quickly sharpen (sharpen) a knife that has become slightly dull. Musat looks like a long rod with a round cross-section and a handle. It is convenient for beginners to use, but only if a minor correction is needed. If the blade is completely dull, more radical action will be required.
A mechanical sharpener is designed to improve the blades of kitchen knives; it sets the optimal sharpening angle. The design consists of a plastic case in which the sharpening discs are hidden. The device can be equipped with several holes, and they are used for both sharpening and straightening.
There are models designed for sharpening scissors and bread knives with a saw-tooth edge (serrated). Mechanical devices are easy to use, affordable in price, and the result is achieved without much effort. A significant disadvantage is the low quality; the blade quickly becomes dull and the process has to be repeated.
Musat is a professional editing tool Source stockfood.com
Electric sharpeners (machines) are found in home kitchens much less frequently than their mechanical counterparts. The devices are designed for household and professional use and do not require special skills. They are a universal and effective tool for owners who prefer simplicity and speed of the process (it only takes a couple of minutes).
The best manual sharpeners
It may seem that the choice of manual tools for sharpening knives is small. However, today many sharpeners are produced, differing in type of material, dimensions, and design.
Nadoba Borga knife
The Nadoba Borga knife sits comfortably on the table and does not slip.
The device resembles the “brass knuckles” model, but the holder is located not from the bottom, but from the side, which increases the safety of the product. This is also facilitated by the significant length and depth of the sharpening zone.
The body is made of black plastic and has a rubberized coating. The sharpening zone is made of metal with an abrasive surface. The sharpener is designed for knives with a straight blade. The design provides 2 sharpening blades.
Smith's Edgeware SM50044
The product is made in a black and gray case. The design has 2 sharpening blades with carbide and ceramic elements, which allows you to sharpen blades made of hard materials. Moreover, the abrasive surfaces are removable. This increases the service life of the product.
The sharpening blades are located on one side of the body, on the other side there is a round-shaped handle with a rubberized coating. This tool is used for rough and finishing sharpening. It is suitable for different types of knives: serrated, with a wavy edge, and double-sided sharpening. The cutting edge angle is 15-20°.
The Smith's Edgeware SM50044 sharpener (left) has a rather bulky body, but the company also offers more compact options.
Three-zone Chef's Choice CC4623
The advantage of this model is the three-stage processing process. For this purpose, 3 sharpening blades are provided. The blade angle is 15-20°. The required quality of sharpening is ensured by diamond coating. The entire process of increasing the sharpness of the blade takes 3 minutes. The sharpener is designed for 1000-1500 sharpening cycles.
Chef's Choice CC4623 three-zone sharpening has 3 sharpening blades with an inclination angle of 15-20°.
Video description
About the classic homemade sharpener in the following video:
Electric machines operate on mains power; special guides allow you to sharpen the blade in compliance with the sharpening angle, so that the knife remains sharp for a long time. Sharpening is carried out using flexible abrasive belts; some devices are supplemented with abrasive discs with preset sharpening angles. All this allows you to sharpen not only straight blades, but also more complex blades: fillet, curved, with a hook.
Many owners do without expensive tools. When the need arises to sharpen a blade, and specialized tools are not available, emery for sharpening knives or a wooden block is used. Owners of a tabletop (grinding) sharpening machine do not have problems with dull knives. The work can also be done by carpentry grinding machines in which the saw blade can be replaced with a grinding wheel.
The simplest device for a certain angle Source mtdata.ru
Homemade devices
Since professional sharpening devices cost a lot of money, many owners make such devices on their own. The designs of homemade knife sharpening machines presented on the Internet are divided into several main types.
Common knife sharpener design Source odstroy.ru
A practical solution is those options that provide the ability to set the desired sharpening angle, depending on the type of knife (kitchen, tourist, universal, hunter or survivalist knife).
Popular devices are those in which the knife is fixed motionless, and the abrasive surface (the same sandpaper) is fixed at the required angle. After adjusting the angle, all that remains is to sharpen the blade, periodically removing waste so that it does not spoil the cutting edge.
Some craftsmen copy the design of the factory model, making a sharpener in which the bars are hidden in a body with a hole, while one abrasive sharpens the edge, the other polishes it. Devices are made in which a block is fixedly fixed, and the performer remains to control the vertical movement of the knife, which is quite simple with a certain skill.
Diagram of a simple sharpener Source bassin.ru
How to properly care
Musat should be stored hanging or on a special stand.
The instrument must be washed manually using a soft sponge. Musates with abrasive coating should not be stored with hard objects.
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Briefly about the main thing
Sharpening a knife is a necessary operation, no matter how expensive and high quality it is. When the blade loses its former sharpness, you have to resort to manual or machine sharpening. To restore the functionality of the knife, it is important to know what the sharpening angle should be. Its value depends on the method of using the blade, the shape of the cutting edge, and the material.
For manual sharpening, sharpening stones are used. In order not to spoil the blade, it is important to choose the right characteristics of the bar: grain size and material. An easier way to sharpen a knife is to use a mechanical or electric sharpener.
At home, alternative solutions are often found: they use sandpaper and construction power tools (for example, a grinder). If desired, you can make a simple sharpener with fixation of the knife or sharpening surface.
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Blade Sharpness Determination
You can check the sharpness of the cutting edge with your finger, but do not run it along the knife. The blade should be moved across the finger. This method requires training and experience.
Checking the quality of blade editing on paper.
There are other reliable and safe methods:
- Paper. Holding the sheet suspended, you need to cut a thin strip from it. A properly sharpened knife carefully cuts through paper without creasing it. The sharper the edge, the thinner the strip you can cut.
- Tomatoes. The sharpened cutting edge easily cuts the tomato under the influence of the weight of the blade and does not crush the skin.
- Hair. This method requires caution. It is necessary to bring the blade to the hair on your arm (against your height). If the edge is not straightened, the hair will bend. A sharp edge will cut it off.
You can also check the sharpness with your fingernail. You need to apply the knife across the growth of the nail plate. With a dull edge, the blade will slide down under its own weight. The sharp blade will leave a small notch and will be held in place. The method requires careful use; sudden movements should not be made.
