There are many ways to sharpen knives. Modern industry, promptly responding to the demands of professionals and just private masters who want to use a quality tool, has developed and introduces special grinding equipment into production.
Using a homemade knife sharpener, you can sharpen a knife at any angle, since the angle of sharpening can be adjusted independently.
But it happens that the factory device for one reason or another does not suit the customer. In this case, you can make a device for sharpening knives with your own hands. It, most likely, will be much cheaper and, not excluded, much more convenient for its creator.
Necessary condition for proper knife sharpening
The goal of any sharpening blunted tool at first glance is simple and clear. But making a knife sharp is only part of the solution to the whole task. The most important factor for long and efficient operation of the product is the angle of sharpening.
Figure 1. The cross section of the blade: 1 - cutting edge (RK), 2 - supply, 3 - angle of grinding, 4 - lowering, 5 - butt.
The value of this factor can be estimated in practice. It would seem that the less we make the angle between the edges of the blade, the sharper the knife becomes. But such an action leads to the fact that our subject will be able to demonstrate their improved cutting qualities for a long time. Moreover, the sharper the knife turns out, the faster it becomes blunt, since a direct pattern is manifested here - the smaller the angle of sharpening, the lower the strength of the cutting edge of the blade.
Thus, the task of high-quality knife sharpening comes down to restoring the sharpness of the blade while maintaining the correct angle of sharpening. In a sense, sharpening is the process of restoring a previously defined angle. And it can be considered correct in the case when it fully complies with certain technological standards and most effectively, freely and quickly cuts the material for which the knife is intended.
Therefore, each blade is sharpened at its own, optimal for him, angle.
However, to do this without having a special device is generally difficult. The fact is that, holding the knife with your hands, it is difficult to ensure uniform sharpening with given angles of inclination of the cutting edges.
To eliminate this problem, there are special tools for sharpening knives, which can be made by yourself. It is worth noting that usually their designs, despite the great diversity, do not differ in any increased complexity, and it takes relatively little time to manufacture such devices.Back to table of contents
Materials and tools needed to sharpen knives
Mechanisms for sharpening planing knives.
The following blanks and tools will help to make simple and fully sturdy tools:
- wooden bars;
- set of abrasive bars (musat);
- hacksaws (for metal and wood);
- electric drill;
- set of various emery paper;
- marking devices;
- screws, nuts.
What are the devices for sharpening: a few examples
It is rather difficult to describe in detail all the current grinding equipment. Let us dwell on some of the most characteristic and common devices for sharpening knives.
The first fixture is made of two wooden and two abrasive bars of the same size. All wooden burrs should be carefully removed from wooden blanks using sandpaper. Then, depending on the required angle of sharpening of knives, a preliminary marking of wooden bars is performed. For this, the corresponding line is drawn on the bar.
Methods of sharpening knife saws: a - scoring of saw teeth (1 - file, 2 - block, 3 - saw blade), b - the sinuses sawed with a hacksaw to a shallow depth, c - saw teeth set up, g - saw teeth sharpened , 2 - rubber safety case, 3 - wooden clamp, 4 - vice).
Further, a grinder is applied to the intended line in order to fix its width on the wood. On the opposite side of the wooden bar according to the principle of mirror reflection are applied to the corresponding lines.
The cuts from 1 cm to 1.5 cm in depth are made along the marked lines on both wooden bars. The bars made of abrasive material are inserted into the cavities thus obtained. Making these operations, you need to make sure that all the grooves coincided with the grinding stones. After this, the abrasive elements are bolted. In order that the obtained device for sharpening is stable and does not slide on the worktable, a piece of rubber can be attached to its lower surface.
The second device is based on the principle of the vertical positioning of the knife blade. In this case, the blade to be sharpened will move along the abrasive bar, which is fixed at a certain angle to the horizontal and vertical surfaces. As practical experience shows, keeping the blade in an upright position is much easier and more functional than driving with a blade on the horizontal plane of an abrasive bar, while at the same time trying to withstand a given angle of sharpening.
Device for sharpening knives.
The specified device is made very simply. To do this, take a pair of ready-made, identical in size wooden squares. It is also possible to independently make such blanks-gons, providing in them strictly right angles. In several places of both squares, holes are drilled symmetrically into which the clamp screws are inserted.
Then it is necessary to mark horizontal and vertical bars with a centimeter scale. The angle of inclination of the abrasive beam will subsequently be set on it. After setting the required angle, it was rigidly fixed in the device by means of the clamping screws.
Using in his practice the device of this type, the grinder will have to make friends with trigonometry. With the help of its formulas, it will be possible to accurately determine at which points of the horizontal and vertical bases of the square should the edges of the abrasive bar be fixed. So, for example, when the angle of sharpening is x = 30 °, the extension of the bar horizontally should be 4 cm, and 15 cm along the vertical.
The third variant of the device for sharpening knives considered here is somewhat similar to the previous one. In this case, a wooden base is made, on which two side and one central lining are then placed. They are also made of wood so that it is easier to cut their side edges at an angle that will be needed for high-quality grinding.
Shapes of a knife blade after sharpening.
This option assumes a rigid fastening of the two side plates on the base and the removable (with a screw) of the central plate. This pad will play the role of clamp for bars. The mating inclined faces of the lateral and central elements should have the same angles of cut.
Thanks to this, it will be possible to clamp the bars at the angle required for sharpening. But, in contrast to the previous version with angle clamps, this method does not imply a smooth adjustment of the angle of inclination of the grinding stone. Therefore, the knife blade can be sharpened here only in two rigidly fixed positions.
The following adaptation is based on the principle opposite to the two previous options. In this case, it is not the abrasive bar that is rigidly fixed, but the product to be sharpened. Grinding element is mounted on a fairly long rod.
With its supporting side, the bar is hinged to the vertical stand through hinges. At the same time, the connection of the bar with the bar should ensure free horizontal movement of the bar with the bar in different directions. A certain angle of sharpening knives is set by the height at which the movable rod is fixed on a vertical stand.Back to table of contents
Determination of sharpening angles depending on the purpose of knives
Mechanisms for sharpening circular saws and mounted mills.
As already noted earlier, the most important parameter of any knife is its angle of sharpening (Fig. 1). It is formed (3) as a result of sharpening under the given inclinations of two supply planes (2), which intersect along the line of the cutting edge of the blade (1).
Its use in practice depends on the angle at which a particular knife is sharpened. This ratio is as follows:
- sharpening angle 10 ° -15 ° - scalpels, razors;
- sharpening angle 15 ° -20 ° - knives for cutting bread, vegetables and fruits, meat and fish fillets;
- angle of sharpening 20 ° -25 ° - multifunction knives for cooking food;
- sharpening angle 25 ° -30 ° - universal hiking and tourist and hunting knives;
- sharpening angle 30 ° -40 ° - knives for cutting hard materials.
Some tips to remember when sharpening blades
Ways to sharpen knives.
When choosing a quality abrasive bar, you should focus on a stone with not very small and not very large grain.
Kitchen knives with special coatings for the cutting edges are not sharpened. These coatings are made of very hard alloys, which provide a high degree of protection of the blade against wear.
You should not try at home, without the appropriate tools and accessories, to sharpen a kitchen knife, equipped with a special cutting edge in the form of teeth. The fact is that such blades are usually sharpened with the use of laser control, which can hardly be found in an ordinary apartment.
Do not wash the knives often with hot water. From heat, they dull faster.
If you urgently need to sharpen the knife, but you don’t have a suitable fixture - factory or homemade - you can try to sharpen the blade with a regular ceramic mug. The mug is turned upside down, which usually has a rough, non-glazed rim.
It is necessary to put the blade on it and move it towards yourself (from the handle to the tip) several times on one side and on the other side to lead the supply planes on it. But we must bear in mind that in this way it is very difficult to sharpen a knife in a qualitative manner - this method is suitable for an auxiliary point.
These recommendations should help those people who not only like to use sharply-cut knives, but also want to learn how to make them so.