We are confronted with the problem of sharpening knives, especially kitchen knives, almost every day. It's not for nothing that the market has a huge assortment of various devices( the demand for them is large), which can be electric and mechanical, expensive and cheap, for every taste and purse - from 850 to 86 000 rubles( "sharpeners", machine tools, musates).
Still, experts recommend that you sharpen knives manually, with the help of bars. Professionals use them up to 4 - 5, because this process has its own nuances. But just such a blade treatment provides not only its sharpness, but also a long operating time without additional grinding. In addition, it is not a fact that the acquisition of the most expensive, "heaped" product guarantees a high quality of work. After all, the experience together with the "sharpener", as you know, can not be bought in the store.
As most of us do not belong to the category "pros" in this business, it is advisable to make the simplest( identical) devices for 2 bars( sharpening + grinding).Time will take a bit, and the benefit from them will be great, since the technique used in everyday life by "iron on stone", which adheres to the hand, rarely gives the desired effect. Especially since it is often short-lived, and again all over again.
manufacturing technology Who has been working on the self-sharpening of blades on an electric / hotplate( motor + circle), knows how difficult it is to withstand the right angle, especially if the abrasive, in addition to rotating it, also "drives" from side to side. And such beats can be even for equipment manufactured in an industrial way( as the resource is developed).not to mention a machine made by own hands. In addition, the metal itself, constantly exposed to thermal effects( and sometimes banal overheating), with time becomes softer, which reduces the life of the knife.
It is much easier to work if the grindstone( bar) is fixed in a certain position. It only remains to "drive" the blade up and down, maintaining the required angle. On the Internet there are various homemade products that have both advantages and disadvantages, but the proposed design is the simplest and does not require much time for manufacturing, much less financial investments. It looks like this.
As can be seen from the drawings, it is only necessary to pick up wooden blocks, glue( or fix them with hardware) a pair of girders and drill holes for screws with clamping nuts. Such a device is universal, as the angle of sharpening is set by any. It is enough to weaken the "ties" and change the slope of the abrasive bar, and then fix it again.
The main question remains - how to calculate it, this very corner? This is easy to do if you recall the basics of trigonometry( in the figure).What is the tangent, everyone knows. A calculator for engineering calculations is in any OS of your computer.
Although it is possible to use an ordinary school protractor, which is only enough to attach to the horizontal "leg" of the device.
Features of sharpening ceramic knives are described in detail here.
What to take into account
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Each knife, depending on the purpose and material of the blade, requires its own grinding angle. The smaller it is, the cutting edge is sharper, but at the same time its strength decreases, especially if the knife is used to cut solid products or materials. Therefore, it will be necessary to sharpen it more often. For most kitchen knives, the optimum angle is 15 to 250. - The grinders available for sale are not the same, therefore, you need at least 2 to 3 different ones in stock, since each type of knife needs a certain type. And how to choose the right abrasive - a topic for another conversation.
