With the help of a knife we ​​cook food, cut food and do other housework. Therefore, it is very important that the knife blade always remains sharp. Theoretically, there is nothing difficult in sharpening knives, but in practice it turns out that not everyone can sharpen a blade well. To have an idea of ​​what to sharpen knives with and how to do it correctly, we recommend reading our article.

Before you start sharpening a knife, you need to find out what material it is made of. There are several types of knives:

• Carbon steel knives are the most affordable, made from an alloy of iron and carbon, easy to sharpen and remain sharp for a long time. Among the disadvantages, it can be noted that the knife blade oxidizes from interaction with food or an acidic environment, due to this, rust and stains appear on the knife, and food acquires a metallic taste. Over time, after plaque forms on the blade, oxidation stops.



• Low carbon knives of stainless steel- made from an alloy of iron, chromium, carbon and in some cases nickel or molybdenum. Stainless steel knives are inferior in hardness to carbon steel, so they quickly become dull and require regular sharpening. The advantages include corrosion resistance.



• High carbon stainless steel knives – more high class knives with a high carbon content and additions of cobalt or vanadium. Due to the higher quality alloy, this type of knives does not require frequent sharpening and is not subject to corrosion.



• Damascus steel knives are mainly made as edged weapons, but there are also kitchen options. A Damascus steel knife is a multi-layer blade made from different high-quality alloys. The disadvantages include the high cost of knives.



• Ceramic knives have gained popularity due to their sharpness and ability to long time don't be dumb. But besides the advantages, Ceramic knives have a significant disadvantage, which lies in their fragility when falling from a height and poor resistance to fracture.

Sharpening tools

Touchstone (sharpening stone)


Sharpening stones are available with different amounts of abrasive grains per square millimeter. Therefore, for rough sharpening and final grinding you need to use bars with a minimum and maximum abrasive content. In foreign-made whetstones, information about the number of abrasive grains is on their labeling. You have to choose domestically produced sharpening stones “by eye” or ask the seller which whetstone to use for initial sharpening and which for final sharpening.

Mechanical sharpener


Mechanical sharpeners are mainly used for sharpening kitchen knives. Although the sharpening process is quick, the quality leaves much to be desired. For this reason, for hunting and sporting knives, it is recommended to use other sharpening methods.

Electric sharpener


Modern models electric sharpeners allow you to achieve high quality sharpening due to the built-in function of automatically determining the angle of the blade. The electric sharpener is perfect for both household use and for sharpening knives in catering establishments. The lineup There is a wide range of electric sharpeners, so the price may vary, but if you want your knives to always remain sharp, then buy more “advanced” and expensive models.

Musat


Musat - designed to maintain the sharpness of the knife edge. In shape, the musat resembles a round file with a handle. Musats are included in knife sets, and many owners often confuse them with a tool for fully sharpening a blade. Please note that with the help of musat you can maintain the sharpness of a sharpened knife, but if the knife has become completely dull, you will not be able to sharpen it with musat.

Sharpener "Lansky"


This sharpener is used for sharpening small and medium-sized knives. The design of the sharpener allows you to sharpen the blade at the angle you choose. The Lansky sharpener consists of a rod with a removable touchstone and two corners connected to each other. The corners simultaneously serve as a vice for the knife and a scale for selecting the sharpening angle. The sharpener kit also includes sharpening stones of different grits with ANSI markings.

Sharpening and grinding machines


Sharpening machines are used mainly in production for high-precision sharpening of rotating shaft blades. In addition to high-precision machines, there are electrically driven abrasive wheels and rotating discs for grinding. Sharpening knives on such machines should only be done by an experienced craftsman, because due to the speed of rotation of the circle or disk and high temperature heating, with any unsuccessful movement, the knife blade will become unusable.

Do-it-yourself blade sharpening

Sharpening a knife using a whetstone

Sharpening a blade made with a sharpening stone is considered to be of the highest quality, provided, of course, that it was carried out by an experienced craftsman. To sharpen a knife on a whetstone, do the following:




How to sharpen a knife using a sharpening stone, see also in the video:


Sharpening a hunting knife on a Lansky sharpener

Hunting knives are made of hard steel, so their initial sharpening requires sharpening stones with a low content of abrasive grains.




How to sharpen knives in a Lansky sharpener, watch the video:


Sharpening scissors

Sharpening of scissors must be done on a special sharpening machine. Sharpening blades using improvised materials (sandpaper, the edge of a glass, etc.) can temporarily improve the sharpness of scissors, but not for long. If you do not have the opportunity to have your scissors sharpened by a professional, you can try to sharpen them yourself on an abrasive stone. When sharpening you need to follow a few simple rules:




When sharpening scissors, do not rush; patience will be your ally in this matter.

You can also watch the video on how to quickly sharpen scissors:


Sharpening plane and chisel blades

Sharpening the blade of a plane and a chisel are practically no different from each other. Therefore, the sharpening process described below applies to both tools:




Besides manual sharpening, the chisel can be sharpened on a machine with a rotating abrasive disk:




Do not forget that when sharpening products on a machine, a lot of sparks and small particles are generated that can get into your eyes, so be sure to wear safety glasses. To avoid damaging your hands on the rotating disk, wear gloves.

You can also learn how to sharpen tools from the video:


Tips for quickly sharpening a blade using improvised tools

Stone

You can quickly sharpen a knife on a hike or on a picnic using an ordinary cobblestone. Use any stone lying on the ground instead of a whetstone and run the blade of a knife along its surface. You won't achieve razor sharpness, but you will return the knife to working condition.

Second knife

It is quite possible to sharpen two knives at once, without sharpening stones and accessories. To do this, you need to take a knife in both hands and start sharpening the blade of one knife on the blade of another. After 5-10 minutes of this work, the knives will become sharper than before.

Glass objects

The knife blade can be slightly sharpened on the rough edge of glass or ceramic objects. For example, about the bottom of a glass or the edge tiles. The main thing is that the surface is rough.

Leather belt

A leather belt is more suitable for finishing and shaping a knife blade razor sharp than for coarse sharpening. But if there is nothing at hand except for the belt, then you can try to sharpen the knife on it. To do this, you need to give the belt a stretch and start moving the blade along it, strong sharpness You may not achieve it, but you will polish the knife to a shine.


By learning how to sharpen knives and tools yourself, you will acquire a skill that will be useful to you throughout your life!

During operation, the cutting tool ( cutting edge) is blunted.

The tool does not cut the wood fibers, but crushes and tears them.

As a result, the quality of the machined surface decreases and the effort required to machine the workpiece increases.

The final result of your work with wood depends on the quality of sharpening the tool.

Cutting tools must be sharpened regularly.

This can be done manually on a whetstone, manually on sandpaper, or using sharpening machine(electric grinder).

electric grinder

Sharpening a tool consists of three operations:

1.Giving correct form and sharpening angle(rough operation).

Removing a large layer of metal using sandpaper to obtain angles close to the desired ones.

Required for self-made tools or with a damaged cutting edge.

Not required for store-bought tools.

The chisel needs some fine-tuning
(blade damaged)

2.fine-tuning- obtaining an even plane of grinding (chamfer) without collapsing on the edge and without overheating the steel (need cool tool).

During this operation, the metal is ground off on one side of the cutting part of the tool (like a chisel) or on both sides (like a knife) to form the blade shape required for this tool.

Another task is to set the bevel at a certain angle with respect to the second plane (face or bevel) of the blade tip, which is required for this particular tool.

This angle, called the sharpening angle, can be different: 7-8° for a knife, 15-25° for chisels, 37-42° for planes.

The sharpening angle of the tool is strictly dependent on the angle of inclination of the cutting edge (plane) of the blade relative to the surface of the wood, which determines cutting conditions(force applied, cutting surface quality).

For a knife, chisel, or axe, the angle of inclination of the cutting edge and the sharpening angle can vary during the work process depending on the need (cutting wood by hand or by hitting it with a hammer or mallet); for a plane, these angles must be maintained more strictly.

As a result of sharpening, the blade and chamfer of the knife of a plane, chisel, chisel should be straight, have the right angle And located at right angles to the side edges.

This is checked using square And special templates.

When sharpening on an electric sharpener, you need to periodically cool the tool(blade) in water, because with strong heating (overheating), the internal structure of the metal changes(hardness decreases).

Sharpen the tool on a sharpener until a thin and even strip of burrs (1) is formed along the entire blade (on the edge).

Chisel needs editing
(a smooth edge of burrs has formed)

3.Edit– obtaining the required sharpness of the blade (at high magnification you can see that the blade is cut with notches from grains of abrasive sand and looks like a file with very small teeth).

Such a blade will cut wood, but the cut mark will be uneven and not shiny.

After sharpening and finishing, the tool is ground on a block with a very fine grain (the tool is pressed tightly against the block and moved in straight and circular movements, while ensuring that the entire plane of the chamfer is adjacent to the block) or polished on a machine with a special polishing wheel.

During editing, you must periodically turn the tool from one side to the other, until both edges of the blade are polished to a shine and the burr is completely gone.

Sharpening by hand
1 - chisel; 2 – device; 3 – whetstone (touchstone).

Checking the blade angle after sharpening
(using a template)

Checking the straightness of the blade with a square

For hacksaw sharpening First, the teeth are aligned in height (planed).

This is done for old saws whose teeth have become different heights.

The hacksaw is secured in a vice and fugue teeth with a triangular or flat file fixed in a wooden block.

After this they carry out saw teeth setting(If you want to).

After setting, the teeth are sharpened.

The saw blade must be firmly clamped in a vice between wooden blocks, as close to the teeth as possible.

First, the teeth bent “away from themselves” are sharpened with a triangular or rhombic file.

After completing the work on one side, the blade is turned 180° and the second side is sharpened.

Each tooth is sharpened until a cutting edge is formed - smooth, straight, sharp, without burrs.

Saws for rip sawing sharpened at right angles to the blade (straight sharpening).

For transverse– at an angle of 60°-80° (oblique sharpening).

Tooth planing:
1 – whetstone for a file; 2 – file; 3 – saw blade;
4 – block for securing the saw.

Sharpening saw teeth and checking
uniformity of teeth set:
1 – template; 2 - teeth; 3 – saw blade; 4 – file;
A – for longitudinal sawing; B – for cross cutting.

Sharpening a two-handed saw

Safety precautions when sharpening tools

1. Operate the machine only with glasses or a protective screen.
2.When sharpening, do not lean close to the grinding wheel.
3.Do not run your fingers along the blade of the tool.
4.Do not overheat the tool blade.
5. Monitor the correctness of sharpening.
6.Use blocks to secure the saw and file.
7. Make sure that the chamfer is in contact with the surface of the block with its entire plane, so as not to spoil the sharpening angle.

The optimal characteristics of water stones for sharpening have been worked out carpentry tools using several unusual components. High performance sharpening, second only to diamond, is ensured by the use of silicon carbide abrasive grains, which are sharp and brittle. The high hardness of silicon carbide grinding materials allows you to confidently process not only carbon steels, but also hard alloys, which is impossible with stones made from electrocorundum powders. In addition to performance, it is worth noting the extraordinary tactile sensations when sharpening the tool. The stones quickly suspend and produce a very pleasant sound.

Making whetstones is a very delicate and lengthy process. The use of a number of natural components requires qualification at the level of skill - you need to feel the material, since some parameters cannot be determined using instruments. In the four weeks required to create stone, materials and semi-finished products undergo eleven technological transitions. Even minor deviations of the modes, in almost every operation, entail the appearance of irreparable defects. Therefore, if you hold our stone in your hands, you are holding not only a wonderful instrument, but also, without exaggeration, a work of art.

We produce sharpening stones measuring 70x20x200 mm from silicon carbide with a grain size from 150 to 2000 grit on a ceramic bond. The characteristics of water stone indicate: the first letter is hardness (I, J - soft, K - medium); grain size according to the Japanese standard JIS R6001-1987 - 150 (80 microns), 360 (34 microns), 500 (24 microns), 1000 (12 microns), 2000 (6 microns) and material - C silicon carbide. A comparison of FEPA, JIS and GOST standards is given in the Technical literature section.

Since 2017, stones have been produced under the TM "PETROGRAD".

For editing work surface For water stones, you can purchase dressing stones measuring 77x24x203 from us.

for sharpening blades

The line of tools for sharpening blades was developed and continues to expand with the active participation of Andrey Petrov (GRINDERMAN). A wide range of characteristics of abrasive stones for sharpening knives on hand tools, water stones for manual sharpening, grinding stones for straightening water guides and whetstones, as well as wheels for tabletop sharpening machines will satisfy the most demanding craftsman.

Bars GRINDERMAN Analogs "Dressing Stone"

Whetstones for Apex sharpeners

Whetstones for Edge Pro Apex sharpeners are commercially available in sizes 25x6x152 mm and 12x5x152 mm. Bars for Apex sharpener analogues measuring 20x6x150 mm. Abrasive stones are produced in grit sizes from 120 to 1000 according to FEPA-Standard 42-2:2006. The average grain size is from 110 to 6 microns, the binder is ceramic. Discussion of the properties of the stones on forum.guns.ru and a beautiful report on the stones on survivalpandas. Video demonstrating the durability of the bars:

HARDENING AND SHARPENING OF JOINERY TOOLS

1. Hardening of the tool

Not every steel can be heat treated at home. The most common carbon steel, from which many tools are made, including files, can be easily hardened. Old files are convenient blanks for making, for example, straight and semicircular chisels, especially semicircular cutters. Hardening includes two operations.
During the first operation, the instrument is heated to a cherry-red glow on a gas burner or in another way. Well cleaned kitchen gas-burner It is quite suitable for heating small instruments. The heated tool is quickly lowered into water, the vessel with which is located as close as possible to the burner, and it is moved sharply to get rid of the steam shell that forms around it, which interferes with the contact of the metal with the water.
The second operation (tempering) consists in softening the steel hardened to brittleness. Now the cutter is heated slightly, controlling the color of the tarnish. Therefore, the scale formed on the tool during the first operation must be removed by light polishing to a shine on a fine sandpaper (at least the chamfer of sharpening), trying not to spoil the blade. A section at a distance of 1-2 cm from the end of the cutter is heated on a flame. Do not heat the cutting tip itself, which can quickly overheat. The tip should get hot internal heat, coming from the rod. It is necessary to monitor the color of the tint on the polished surface, catch the moment when the cutting tip starts to turn from blue to cherry, and sharply lower it into the water (preferably with a layer of oil on the surface).
Then the tool, such as a chisel, is tried on a tree and sharpened clean again. If the cutting edge is chipped during carving, it is necessary to increase the temperature of the second heating to a straw-coloured tint.
A wrinkling tool blade indicates a discrepancy between the hardening mode and the steel grade or an unsuccessful operation: the first heating temperature is not high enough, slowing down when lowered into water, not abrupt cooling due to a layer of steam formed in the grooves and sinuses of the tools, too high tempering temperature.
In other cases, when the tool is not made of carbon steel, it is better to seek the help of a specialist, since at home it will not be possible to obtain a high enough temperature to harden high-quality steels.
For a carpenter who has the ability to heat the tool, for example, in muffle furnace or blacksmith's forge, here are some basic recommendations.
The grade of steel can be approximately determined by a spark on a grinding wheel in a dark place. Thus, a white beam of sparks with individual stars indicates that the steel is carbon, requires slight heating during hardening (up to a temperature of 780 ° C - cherry-red glow) and tempering when the color of tarnish changes from violet (for cutting tool) to straw (for working with a mallet). Heat treatment of such steel can be carried out at home using a gas burner.
If there is a short beam of dark red sparks with almost no stars, the high-speed steel is R18. It requires a high quenching temperature - about 1270°C, which corresponds to a bright white glow. This can only be achieved in a large muffle furnace or in a forge.
The hardening temperature is slightly lower (about 1230°C) for P9 high-speed steel. It hardens with a light yellow glow and produces reddish-orange sparkles with a small number of stars on the grinding wheel.
Other alloy steels (chrome produces subtle yellow sparks, tungsten produces well-defined red sparks) are hardened with a light red glow (temperature 820-900°C). Alloy steels are best quenched in oil or in water heated to a temperature of 70°C.
Approximately the same temperature is required for annealing steel before processing: alloy steels are heated to 1000°C, high-speed steels to 1200°C. After heating, they should cool slowly along with the oven.
It should be noted that with high and prolonged heating, carbon burns out. Therefore, it is better not to harden a tool with a very thin section, or after hardening, remove the sharp decarburized tip on a whetstone or sharpener while cooling. For the same reason, you should not be afraid to sharpen the tool, especially the first one, until a burr forms along the entire length of the blade. Also, if the first trial work with a hardened and sharpened tool does not give the desired result, sharpening must be repeated.

2.Tool sharpening

The whole secret of making good carpentry tools consists of two factors: correct sharpening and the right type of steel, which retains this sharpening for a long time, does not wrinkle and does not crumble from any wood. If the grade of steel does not always depend on the master, then sharpening depends only on him. But to do it correctly you need to have some knowledge. Sharpening a tool consists of two operations.
The task of the first operation is to achieve an even plane of grinding (it is called a chamfer) without rounding it at the very edge and without burning the steel. During this operation, metal is ground off on one side of the cutting part of the tool (like a chisel) or on both sides (like a knife) to form the blade shape required for a given tool. Another task of the first operation is to place a chamfer at a certain angle relative to the second plane (face or chamfer) with the blade tip required specifically for a given tool. This angle, called the sharpening angle, can be different: 7-8° for a knife, 15-25° for chisels, 37-42° for planes and 50-53° for a special plane - a grinder.
The sharpening angle of the tool is strictly dependent on the angle of inclination of the cutting edge (plane) of the blade relative to the surface of the wood, which is determined by a complex formula. If in tools such as a knife, chisels, axes, we can adapt to the angle of inclination of the cutting edge during work, and therefore the sharpening angle of the blade can vary depending on the need (cutting wood by hand or by hitting it with a hammer or mallet), then in other tools, such as planes, this sharpening angle must be maintained more strictly.
The task of the second operation - editing - is not to spoil the sharpening angle and to achieve a sharp tip of the blade, which is associated with removing irregularities, small notches, burrs from it, and polishing both surfaces of the blade to a shine.
The first operation is usually performed on a mechanical sharpener - a rotating abrasive wheel. It is finished by hand on a large flat block. It is dangerous to sharpen the blade on a sharpener to a sharp point, since in this case it is difficult to control the overheating of the steel when high speed circle, when unexpectedly a tarnished color appears on the thin edge of the blade during sharpening - a sign that the strength of the steel is compromised and the sharpening is damaged. Such a place will have to be completely cut off on the same sharpener and sharpened again.
In order to reduce subsequent handmade on a block, they try to remove the metal as much as possible along the entire chamfer, except for its edge, which is not difficult to do on a sharpener cylindrical: it allows a notch on the chamfer to remove excess metal from its entire middle.
To prevent the steel from overheating, the tool is periodically dipped in water and the sharpener itself is also soaked in water. The disappearance of water droplets on the tip of the blade or their boiling is a sign that it is time to put it in water.
It is advisable for a novice sharpener to sharpen the tool on a sharpener so that the circle does not rotate towards the blade, but vice versa or at a certain angle to it (in different directions). So there is less danger, if the wrong movement is made, that the sharpener will crash into the blade and spoil all the work. However, throughout the literature, it is recommended that any tool be sharpened on a sharpener only when it rotates towards the blade. But this rule is only suitable for a specialist or a craftsman with extensive sharpening experience. Undoubtedly, when the surface of the circle moves towards the blade, its sharpening is better: there is less chipping of metal particles on the very edge of the blade - they seem to be pressed during rotation, and do not tear away from it when the movement of the sharpener occurs from the blade. Also, this does not produce such large burrs as when sharpening "on the edge", where there are more opportunities for bending the edge, which gives a burr. In addition, with strict observance of the rules for sharpening the tool towards the blade, if it is accurately fixed (with the help of a special stop or with trained hands), a clearly defined edge of the blade is also obtained. These are the positive aspects of sharpening using the method towards the blade. But it also has negative sides, the weight of which is more significant, especially for a novice grinder. The main drawback is that we cannot bring the sharpening to a sharp sting of the blade, since the danger of burning it is too great. The blade of the tool can be brought to the desired sharpness only on a water grinder, the rotation speed of which is very small (as the speed increases, water floods the hands). On all other mechanical sharpeners, sharpening is carried out without water. But even after a water sharpener, the blade becomes sharp only due to good angle sharpening and clearly defined edges. In fact, it is excised with notches from abrasive grains and is like a file with very small teeth. Such a blade will cut wood, but the cut mark will be uneven and not shiny. The blade will need a thorough editing - the complete removal of the sting and the formation of a new one.
In order to complete the sharpening of a tool on a hard bar, it is better to clamp the bar in a vise or fix it on a workbench. Then the work can be carried out with a clamp, with two hands. The block must first and then periodically be washed with soap and water using a brush, since it becomes greasy and clogged with small metal filings and abrasive dust; it is good to soak it in water. During operation, it is more convenient to wipe the surface of the bar with a wet cloth. It is under such conditions that the surface of the bar grinds off the metal well.
When sharpening a tool, it is especially necessary to ensure that the chamfer is in contact with the surface of the bar with the entire plane, so as not to spoil the sharpening angle. You can drive the tool along the bar in any direction, but as the blade sharpens and a burr appears on it - a thin shiny strip of bent metal on the blade sting - you should be more careful with the direction of movement during sharpening. In order to avoid the risk of cutting into the abrasive by the tool blade, it is better to completely stop its movement towards and along the blade. It is preferable to make movements at an angle of 45 ° both in one direction and in the other direction with respect to the edge of the blade, in the direction away from it. This is how we reduce the force that bends the sting of the blade into a burr. This sharpening method is confirmed by practice experienced craftsmen. Hairdressers have been known to shave straight razors in a similar manner.
The second sharpening operation - dressing - is performed first on a fine-grained bar or a special filling board, then on a whetstone or on a smooth place of the filling board worn during sharpening, sometimes on a whetstone or filling board covered with leather, using a special paste.
The filling board is covered with fine sandpaper (preferably sandpaper on a cloth). Its edges are glued end-to-end on one of the narrow sides of the board. One side of the filling board should be pre-rounded, and with different curvature along the edge. On it we will edit the concave face of semicircular chisels.
When dressing on a whetstone, you can first make circular movements with a tool (for example, a chisel), emphasizing efforts when moving away from the blade, but on the filling board, you must immediately beware of making movements towards the blade: soft fabric or paper of the skin from pressure, even slightly, but bends and the blade "attacks" the emery surface at a large angle, which will lead to chamfering, i.e. to change the sharpening angle. Also, for the reasons described above, the blade can be damaged from grazing over irregularities on the sharpening surface. For example, when sharpening a knife on a cutting board towards the blade, it even happens that it cuts off part of the glued skin.
During editing, you must periodically turn the tool from one side to the other until both edges of the blade are polished to a shine and the burr disappears completely. As the editing is completed, hand movements should become more frequent and easier, and the sharpened edges should be replaced more often.
After straightening, you need to make a test thread, testing the tool in cutting techniques along and across wood, especially hard wood. It is likely that the bladeIn this case, the instrument will “sit down” and will not give the desired result. This is not always a sign of bad steel, but is most likely the result of carbon burning out of the edge of the blade during hardening, as discussed above. True, this also happens with tools that have not been subjected to heat treatment. In any case, it needs to be adjusted again and checked until the cutting edge is stable.
A well-sharpened tool lasts a long time and does not require frequent refilling. It is corrected only after many hours of work. To achieve results faster, if the tool has been in use for a long time, when refilling, you can slightly increase the contact of the edge of the blade being sharpened with the block, taking into account that during initial sharpening its sharpening angle was quite sharp. In this case, the sharpening angle increases slightly and a secondary chamfer is formed. Naturally, after some time you will have to again straighten the angle of sharpening the blade on a block, or even on a wheel hand drill. Practice has shown that it is not necessary to use polishing paste or chromium oxide oil paint for final straightening of the instrument. As you work, smoother (worked) and harder places will appear on the dressing board, which will allow you to use the same sandpaper on the board for consistent sharpening: from rough to clean.

3.Sharpening wheel

Abrasive wheel, driven into rotation by a mechanical or electric drive, is usually called a sharpener, grinding wheel or grinding wheel. Abrasive discs sold in hardware and tool stores, like other grinding wheels, are made from artificial minerals: electrocorundum, silicon carbide (carborundum), boron carbide, etc., sometimes from emery (emery is a natural mineral and is currently used in mainly for the production of abrasive cloths). It is better to buy abrasive disc made of white electrocorundum (its marking on the wheel begins with EB) or monocorundum (marking M). In terms of grain hardness, they are more suitable for finishing processing, and in our case, for sharpening hardened tools; they have proven themselves well in grinding very hard metal surfaces with a shallow grinding depth.
The hardness marking on abrasive wheels is indicated by the initial letters of the words: soft (M), medium-soft (CM) and then similarly - medium, medium-hard, hard, very hard, extremely hard and adding the numbers 1 and 2 (sometimes 3), specifying the degree of hardness .
Modern grinding wheels are formed on a strong binder, have a high resistance to tearing, providing them with two to three times the speed of rotation than that reported by an electric drill. Nevertheless, after buying a grinding disc, especially if it is unmarked, you should definitely check it at a high speed, taking safety measures (not being in the plane of rotation of the disc) in case of a break. And in the future, it is advisable not to keep your head in the plane of its rotation at idle (ie, maximum) revolutions of the circle. These measures are needed in case of a defective or defective disc.
And to make sure that it is safe to rotate a new grinding wheel in a drill, it is useful to know the following information. Usually, the disc marking does not indicate the rotational speed (in rpm), but the circumferential speed (in m / s). This is due to the fact that the centrifugal force (and hence the discontinuous force) depends not only on the frequency of rotation, but also on the diameter of the circle. For example, we calculate the peripheral speed of the grains on the rim of a grinding wheel with a diameter of 175 mm, inserted into an electric drill, giving 2000 rpm. With a rim circumference of 0.175? 3.14 = 0.55 m, the rotational speed will be approximately 33 rpm (2000:60), and the peripheral speed of the grains on it is 0.55? 33 = 18.15 m/s. And the permissible rotation speed of modern grinding wheels ranges from 35 to 40 m/s, which is more than twice our calculated value.
It should be noted that it is more expedient to take circles with a diameter of less than 175 mm for sharpening to an electric drill. This is more convenient for many reasons. Often, in the process of work, you have to sharpen the tool, holding the drill with a sharpener in your left hand and turning it on with short impulses - so there is more confidence not to spoil the sharpening and not burn the steel. In this case, the mass of the circle, affecting its inertia, will interfere with the inclusion of the drill every time. For the same reasons, the excessive circumferential speed of the grinding surface, which is associated with the diameter of the circle, is also undesirable. It is clear that with a decrease in the diameter of the circle, our calculated circumferential speed will also decrease, i.e. the degree of work safety will increase.
It is in this sense that abrasive fingers with a length of 25 mm and a diameter of 10 mm on a metal axis of rotation, manufactured specifically for an electric drill and sometimes available for sale, are very convenient for sharpening tools.
Grinding wheels have the ability to self-sharpen, i.e. worn out and dull abrasive grains gradually fly off, giving way to new ones. But they also require certain operating conditions: you must try to sharpen the tool in such a way that the wheel is ground evenly over the entire surface, without the formation of grooves. Therefore, it cannot be used for sharpening a tool manually, as a whetstone - this will lead to local damage to its surface and to eccentricity during rotation.
Industrial discs are made in such a way that the hole of each of them is coordinated with the center of gravity and with the geometric center of the rim circumference. Also, when mounting a circle on the axis of rotation, these conditions must be met. Such an axis, with a diameter of up to 9 mm, can be made from a bolt from which the head is sawed off. At the threaded end, a disc is clamped between washers, plate spacers and nuts. First, a hardwood insert is driven into the hole of the disk, its center is precisely found relative to the outer cylindrical surface of the disk, and a hole is drilled for the selected axis. The diameter of the washers and spacers for them must exceed the diameter of the liner, and the liner must be cut flush with the disk. Then, at low speeds of the drill, you need to check the alignment of the disk by touching its cylindrical surface with the tip of a pencil or chalk.

Selecting the hardness of the grinding tool.

Table 1.

Grinding wheels for rough hand grinding.

Table 2.

Grinding wheels for cutting and finishing grinding.

Table3.

Table4.

Grinding wheels.

Table 5

For carpentry work that requires a plane or chisel that can extra effort remove thin curly shavings from wood. Here you can use a system that allows you to get perfectly flat, extremely sharp and mirror-like cutting edges.

The main link of the system, how to sharpen a tool, is a set of four Japanese water stones. These artificial sharpening stones contain the finest abrasive particles such as natural clay and silicon carbide bonded into blocks with a ceramic bond.

Rough 700 grit Bester stone for removing coarse grinding marks on a new tool or after major regrinding.

Bester brand stone, 1200 grit, for intermediate dressing and removing marks from the previous rough stone.

2000 grit Shapton stone for fine finishing of the cutting edge.

8000 grit Takenoko stone for final polishing to a mirror finish.

Each stone is equally important to the sharpening process. If you skip one of the intermediate stones, you will encounter the same problems as when sanding wood with sandpaper: it will take longer to remove the marks and scratches left by a coarse abrasive than with successive transitions from coarse to finer grains.

Before you begin working with water stones, have the following supplies ready: a container of water for soaking the stones, a clean cloth, napkins or towels for wiping the blades and wiping up puddles and drips, and a corrosion preventative. Sharpening devices that fix the blade under the right angle, water ditches, angle checking templates and other accessories will help you make the process easy sharpening and neat.

Prepare the stones

Before starting work, immerse the stones in clean water for two to five minutes until small air bubbles stop coming out of them. After soaking, sand the working side of each stone to create a smooth surface for sharpening. You can use a completely flat Shapton diamond stone for this, it is no less effective and more cheap way: A sheet of 150 grit waterproof sandpaper on top of a square of thick glass about 300mm on a side.

Wet waterproof sandpaper well and place it on the glass. Water holds the paper on the glass, preventing it from moving. To avoid clogging fine-grained stones with coarse abrasive particles, first level the 8000-grit water stone, then successively coarser stones, ending with a 700-grit stone. Move the stone back and forth across the paper, making circular movements from time to time (photo A), until the marks of the previous sharpening are completely gone. The leveled surface of the stone should be completely covered with a thin layer of water, and not just in the center or at the edges.

A. Minor scratches on the working side, such as on the left stone, mean that its surface needs to be sanded using wet abrasive paper.

Rinse the abrasive paper thoroughly before smoothing the next stone. Wash all the stones running water before you start sharpening the blades.

Start sharpening

Let's look at the working techniques using a chisel as an example, but the principles of sharpening do not change for other cutting tools, such as a plane blade. Your goal is to get a completely flat bevel and back of the blade, the intersection of which creates a straight and sharp cutting edge. While you have no experience, focus on developing coordinated movements and even pressure. Speed ​​will come with time.

Place the soaked and leveled stones on flat surface so that they do not move or sway during operation. It is convenient to use a small anti-friction mat for this, but it can be replaced with several old newspapers.

B. Start by leveling the back of the chisel blade. With one hand, press the tool against the surface, and with the other, hold it perpendicular to the long side of the stone.

Start sharpening your chisel or plane blade by leveling the back. When starting to work on a 700 grit waterstone, hold the tool blade perpendicular to the long side of the stone, pressing the flat side of it against the abrasive 12-15mm wide (photo B). Do not straighten the entire plane of the blade at once; you only need to remove rough marks near the cutting edge.

Using light pressure, move the tool back and forth along the entire length of the stone. Develop coordination of movements and constant hand position so that the tilt of the blade and the pressure on it do not change when working on the other three stones. You will have to sand the back and bevel before moving on to the next water stones and finishing the job by polishing the blade on an 8000 grit stone.

Now finish the chamfer.

Use one hand to hold the tool at the desired angle. Using the fingertips of your other hand, press the bevel of the blade firmly and with constant force onto the surface of the water stone (Photo C).

C. When sharpening any chisels (except the narrowest ones), use two fingers to press the bevel of the blade evenly and firmly against the stone. With your other hand, hold the tool at the desired angle.

Use the entire surface of the working side of the stone to avoid uneven wear of the abrasive in the middle or at one edge. With practice, the sharpening technique will certainly improve, so do not start sharpening with the best chisels. Sharpen planer blades and narrow chisels last when you have acquired the necessary skill. With wide chisels, it is easier to maintain the desired sharpening angle, since the fingers feel better that the blade is adjacent to the stone with the entire chamfer.

If you are not sure about the strength of your hands and need help to hold the blade at the right angle, use simple devices for sharpening like the one shown in photo D. Use it sharpening device, until you learn how to press the bevel of the blade of a planer or chisel to the surface of the stone with the entire plane and keep the tool at a constant tilt.

From many existing models choose a jig with a sufficient width to reduce wear on the stone surface. First, check the quality of work by inspecting the bevel after three or four movements in order to notice in time possible mistakes. The table below will help you spot your technique flaws before they become a bad habit.

Once the back of the blade and bevel are evenly finished, move on to the next waterstone up to 8000 grit. You can change the stone as soon as all traces of previous polishing have been removed. But before doing this, be sure to rinse the tool with water and wipe it thoroughly to remove all remaining abrasive and not clog the finer-grained stone with it.

During the sharpening process on the first two rough stones, you will feel, and perhaps even see, a very fine burr forming on the cutting edge. It should disappear by the end of sharpening.

When finished grinding the blade on an 8000 grit stone, the cutting edge will shine like a mirror. Rinse the blade clean water, wipe it dry and apply a thin layer of light lubricant to protect it from rust. (Do not let the lubricant get on the stones!) Check the quality of sharpening of the blade at the end of the cutting board (photo E). E. The flat bevel and flat back create a sharp cutting edge capable of cutting fine chips even on the end of wood.

Before storing stones, wash and dry them. Cover sharpened chisel blades with plastic protective caps.

Caring for water stones

Water sharpening stones will last you for many years, requiring only minimal maintenance.

■ Some craftsmen constantly keep stones in water, but this sometimes leads to damage to certain types of stones, and corrosion of metal flakes embedded in the pores of the stone causes a change in its color.

■ Avoid contact with oil or silicone grease on water stones. This leads to a decrease in abrasive properties and irreversible loss of performance.

■ Protect wet stones from frost. Freezing water can cause cracks.

■ Store stones away from falls and impacts. A plastic container with a lid is an excellent container for storing stones and for soaking them.

It is suggested to delete wooden coasters on the stones, carefully cutting them down band saw. This is not necessary, but without stands it is easier to store and soak the stones. If you want to separate the stand from the stone, do not try to tear it off with a chisel or hammer blows - rough chips will appear on the stone before the glue gives in to your efforts.

1. The sharpening marks are shifted to one edge of the chamfer.

Solution. Narrow chisels (6-12 mm) have a small contact area between the chamfer and the stone, making it difficult to press with the entire plane. Use a sharpener or gain skill by sharpening wide blades.

1. The sharpening marks are wider at the front end of the chamfer or are visible only on one end.

Solution. Stop working often to monitor the results. Concentrate on maintaining a consistent blade angle, even if this means releasing pressure.

1. Sharpening marks do not reach the center of the chamfer.

Solution. The abrasive wheel of the sharpener makes the chamfer slightly concave, so rough marks in its center will be the last to disappear when finishing on a flat stone. Continue sharpening until you obtain a uniform shine, indicating a smooth and flat bevel.

1. Numerous edges on the chamfer.

Solution. If the chisel looks like this after sharpening on the sharpener, resharpen the bevel. If edges appear when sharpening on water stones, focus on keeping the tool at the same angle as you move back and forth across the surface of the stone.

1. Problem. Don't know when to stop?

Solution. The chamfer is almost complete (notice a few marks at the top left). A few more strokes on the 8000 grit stone are required to achieve a sharp cutting edge and final polish. A perfectly sharpened bevel reflects a ray of light just like a mirror.