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Joinery

Sharpening and adjustment of planing tools

Tool sharpening. Irons with a straight or oval cutting edge are sharpened on a wet sharpener, on a fine-grained bar; the final aiming (editing) is carried out on the touchstone. These sharpening tools are natural or artificial stones containing abrasive grains. Abrasives are called materials of high hardness, which, when finely crushed, form grains with sharp edges. Abrasive grains with their sharp edges sharpen other less hard materials, in particular metals. Grinding tools contain abrasive grains of different sizes. The most coarse-grained is the wet grindstone grinding wheel. Therefore, this sharpener is used for sharpening new, chipped pieces of iron - in those cases when it is necessary to grind off a significant layer of metal.

Sharpening a piece of iron on a sharpener is considered complete when there are no traces of cracks or other flaws on the blade, and a continuous line of burrs forms along the cutting edge on the back of the piece of iron, i.e., a thin roller of loosened metal. Burrs are detected by touch with the thumb right hand when it slides from the back side of the piece of iron behind the cutting edge, as well as when looking at the light of the back side of the piece of iron towards the cutting edge. In this case, the rays of light should be directed along the piece of iron to the cutting edge, and the piece of iron should be slowly turned around the cutting edge.

A wet grindstone leaves traces of large grains on the blade. Therefore, a piece of iron ground on it is additionally sharpened on a bar. The pieces of iron, blunted during work, begin to sharpen immediately on the bar, bypassing the wet grindstone.

When sharpening: on a wet sharpener, the piece of iron is held motionless with the right hand or slightly moved along the width of the working surface of the grinding wheel. Closer to the cutting edge, the piece of iron is pressed against the circle with the fingers of the left hand. On a bar, a piece of iron is sharpened with straight and circular movements. For convenience, the bar is placed on a wooden stand in a nest specially hollowed out for it. When sharpening, you need to keep the piece of iron at the same angle to the working surface of the grinding tool all the time; it must be adjacent to this surface with the entire plane of the chamfer. The chamfer must be even and have the same width. To do this, when sharpening on a round sharpener, devices are often used, for example, a clamp with a roller and a screw clamp, a lever template (Fig. 1),

Rice. 1. Devices for sharpening pieces of iron on a wet sharpener: a - a clamp with a roller and a screw clamp: b - a lever template

When sharpening, do not press very hard with a piece of iron on sharpening tool: This results in coarse, large burrs. Large burrs are removed by pressing a piece of iron with a blade into a smoothly planed end of dense wood. However, even after that, you have to sharpen the piece of iron on a bar and edit on a whetstone. With proper and good sharpening of the piece of iron, the burrs should be very small and appear in the form of a thin, even hair.

When sharpening pieces of iron, water is poured into the trough of the grindstone, and the bar is often moistened. During dry sharpening, the piece of iron heats up and as a result of this, its hardening is released. In addition, water washes away the smallest particles of metal that would otherwise fill the pores on the working surface of the grinding wheel or bar.

Editing of the piece of iron is carried out in a circular motion of the chamfer along the donkey; for final fine-tuning, the piece of iron is turned either back or front side. You can edit the piece of iron and circular movements of the touchstone along the chamfer; the piece of iron at the same time should be motionless. When dressing, the touchstone is moistened with water or lightly oiled with oil. It is even better to moisten the touchstone with a mixture of glycerin (1 tsp) with denatured alcohol (2 tsp).

The sharpness of the sharpening can be checked by running across the blade across to it, now in one place, then in another place with the thumb of the right hand; the finger must first be moistened with water. You can check in another way: by viewing the blade in the light with some rotation of the piece of iron around the transverse axis. When rotated, the bevel moves from lighting to darkening. If this transition occurs immediately along the entire bevel, then the blade has sufficient sharpness. If, during the transition of the chamfer from the illuminated position to the darkened one, glare (light strokes) or a thin light strip are observed on the cutting edge, then this indicates a blunt blade.

At the end of sharpening and straightening, it is necessary to press the piece of iron with the tip of the blade on hard wood or on a knot. After that, they again do fine-tuning on the touchstone. This prevents the formation of a so-called “false sting” in a sharpened piece of iron, which causes the blade to become dull at the very beginning of the work with the tool.

The straightness of the blade is checked by applying a ruler to it with an edge; the right angle between the blade and the edge of the piece of iron is checked with a square. Having firmly attached the piece of iron with an edge to the block of the square, move it along the pen of the square until the blade coincides with the edge of the pen. With absence right angle or if the blade is not straight, it will not protrude the entire length of the nib edge. The ends of a straight blade should be somewhat oval so that when planing they do not pick up the wood and do not leave marks on its surface.

The angle of sharpening (pointing) is checked with a template (Fig. 2).

Rice. 2. Template for checking the sharpening angle

The working edge of the cycle is sharpened on a grinder and a bar at a right angle to the blade; it is allowed to sharpen the cycles with a file with a fine notch. When sharpening with a file, the cycle is clamped in a workbench, and the file is held by the ends perpendicular to the cycle and the edge of the cycle is turned along. The sharpened edge should be perpendicular to the cheeks (sides) of the scraper. Even a slight collapse of the ribs will make it impossible to induce a sting at the cycle. If burrs form on the ribs of the scraper during sharpening, then they are removed on the whetstone, running the scraper flat on the whetstone so that the burrs are ground on lateral side cycles. The working edge of the scraper should be made somewhat convex (humpback): scrapers with such an edge are more convenient to work with.

The sting (burr) is pointed at the cicle with a chisel edge with strong and uniform pressure. The chisel is held with a slight inclination to the machined edge of the cycle; with a large slope, the sting turns out to be littered and the cycle does not work.

Before sharpening, the old tip of the cycle is removed with a file with a fine notch. The following technique is also used: with a blow of a mallet, the cycle is pressed with a working edge into the end of hardwood (beech, hornbeam).

Joiners usually prefer to sharpen the irons of hand planer tools by hand on a whetstone and whetstone to ensure high quality sharpening. Sometimes in production, especially where centralized tool sharpening is organized in a pilot workshop, pieces of iron are sharpened on a corundum grinding wheel powered by an electric motor. The grinding wheel makes a significant number of revolutions per minute, grinds metal very quickly, and the tool being sharpened is very hot. The blades of the glands can heat up red-hot and completely lose their hardening, as they say, "burn out."

In order not to burn the piece of iron, it is sharpened wet, that is, it is periodically torn off from the grinding wheel and immersed in water. It should be borne in mind that the wetted piece of iron must be kept when sharpening with the blade down. With this position of the piece of iron, water from it will drain to the blade and linger on it, since the circle rotating towards the blade will throw it back. On the blade, a foaming roller will be visible, as if boiling water. When such a roller disappears, the piece of iron must be dipped into the water again. If the wet piece of iron is held up with the blade, water will drain from it, dry sharpening will occur and the piece of iron will “burn out”. When sharpening pieces of iron on a grinding wheel, wear safety goggles.

Setting up cutting tools. Before planing, all the tools selected for work are adjusted, i.e., the pieces of iron are set to the required chip thickness. Only at a sherhebel can the blade of a piece of iron be released beyond the plane of the sole by up to 3 mm. Some freedom in the installation of a piece of iron is allowed in a single planer, depending on the depth of the hollows left by the sherhebel. In all other planing tools, you need to release the blade a very small amount so that the thinnest chips are removed. This is especially important in the double planer and sander.

Rice. 3. Techniques for setting up and disassembling a planer: a - correct position planer in the left hand during adjustment; b - reception of disassembly of the planer; c - the first way to feed the piece of iron forward; d - the second way to feed the piece of iron forward; d - fixing the blade; e - checking the adjustment of the planer for chip thickness

The correctness of the installation of the piece of iron is checked by looking at the eye. In this case, the blade is observed as a thin, even thread protruding from the sole by 0.2 - 0.3 mm. The skew of the piece of iron must be eliminated when it is installed. If this fails, then the blade is not sharpened correctly.

When assembling, disassembling and setting up a planing tool, in particular a planer, it must be held in the left hand, supporting the piece of iron with the thumb through the blade (Fig. 3). The piece of iron is knocked out with light blows of the mallet on the back end of the block. They release the piece of iron with the same hammer blows on it from above. Fix the piece of iron with light blows of the hammer on the end of the blade.

The jointer piece of iron is knocked out with light blows of a hammer on the shock button in front of the block.

Each of us has experienced life situation when blunt tools, be it a regular knife or carpentry tools, interfere with normal work. Dull tools require a lot of effort and therefore the hands get tired faster and dangerous situations can arise. Pre-sharpening of the tool will provide you with a quick and easy work process without any extra effort.

Each type of tool has a cutting edge with its own individual sharpening angle. Tools with sharpening angles up to 25° have sharper edges, but are not suitable for jobs where significant forces are required, in this case tools with a sharper sharpening angle are used. This fact must be taken into account, and therefore, before starting the sharpening process, we advise you to familiarize yourself with the optimal sharpening angles various tools. By the way, good sharpeners are equipped with an angular scale for setting the support surface for a particular tool, which greatly facilitates the process of sharpening the tool.

Sharpening angles of some tools

• scissors - 60 °;
• carpenter's ax - 40 °;
• kitchen knife - 20-40 °;
• vegetable and fish knives - 25 °;
• chisel - 35-40 °;
• chisel - 18-20 °;
• plow - 20°;
• turning tool - 15-25 °;

For sharpening you will need an electric sharpener (recommended for beginners), whetstones various shapes and grit and water container. The process of sharpening a tool requires some skill and experience, so it can take quite a while. long time before you learn how to sharpen tools to the highest quality.

Sharpening chisels and chisels

These popular tools are in the kit of every carpenter. Commonly used chisels with a width of 3 to 16 mm and various angles of sharpening, as well as flat and semicircular chisels. The process of sharpening these tools begins with a grinding wheel, and then edits are made on a whetstone. An important point is the position of the blade relative to the abrasive wheel, the sharpened plane at the point of contact must be located strictly perpendicular to the radius of the circle. After sharpening, you need to pay attention to the resulting chamfer. The length of the chamfer to obtain the desired angle of 20° must be 2.5 times greater than the thickness of the tool.

Tool sharpening with cooling

Sharpeners with a cooling function allow even beginners to perform quality work, as the circles in them rotate more slowly and are constantly cooled, preventing the tool from overheating. Also sharpeners can be equipped with special templates for setting sharpening parameters.

1. The necessary parameters are set on the template, and then the tool is installed in it and its position relative to the circle is adjusted.
2. The cutting surface of the tool must fit into the groove of the template until it stops - this allows you to control the correct sharpening.
3. Fine finishing of the cutting edge is made on a leather circle.

Sharpening semicircular chisels

Sharpening large tools

In these posts, I will only consider sharpening blades: ordinary knives, planer blades and chisels. About sharpening cycles, drills and saw blades - another time.

A lot has been written about sharpening on the Internet. And not only on the Internet. There are quite thick books devoted exclusively to this process.

How much have I mastered such works? No one. It doesn't stop me from regularly sharpening up to razor sharp all my tools, and quickly and with a minimum number of inexpensive devices.

Looking through domestic texts on sharpening (primarily those dedicated to knives), I regularly stumble upon an extremely serious attitude towards it. One gets the impression that without magical Japanese stones (necessarily natural ones!) With a grain size of 8000, you don’t even have to start putting your chisels in order. So, get those thoughts out of your mind.

My secret is, I don't sacralize sharpening. And so I am now, at the beginning of this series of posts, I ask all the maniacs to leave here, or at least not to appear in the comments with their offended feelings.

I sharpen the tool so that it can be used effectively. Not for the process. Not for peace of mind. I I'm distracted for sharpening, and I would like to reduce the time that I devote to it. If someone is interested in spending half an hour and twenty magic stones sharpening one knife, I do not blame him. But I will sharpen my knife ten times faster and without any shamanism in exchange for minimal edge degradation. Of course, there is a certain ratio of effort and end result. But the trick is that after some practice you will have to try to sharpen the tool poorly even in the shortest time.

Now it is important to understand the two basic principles of sharpening blades. In the following, I will show how to apply them in practice.

Based on these principles, you can immediately say without which it will be difficult to sharpen the tool. First, you need an abrasive plane on which you can grind the edges of the tool to reduce the radius of their intersection. Secondly, some kind of device for holding the blade at a certain angle to the plane will be useful. There are a great many such devices, and I will talk about them already in the practical part, where you need to show photos of the process. But on the abrasive plane should dwell in more detail.

So. What are the qualities of an IDEAL abrasive plane?

1. It grinds even the hardest steels very quickly, but leaves behind a mirror-like surface.


2. It is flawlessly even, without the slightest deviation from the plane;


3. It does not deteriorate over time;


4. It is extremely cheap to maintain.

The first point, I will say right away, does not happen. Or aggressive metal removal, or a neat surface at the end of sharpening. We'll have to change planes along the way ...
The second point is not as important as it might seem - we are engaged in woodworking, not the construction of Swiss watches. We do not need accuracy up to the third decimal place. But it's good to strive for it.
The third and fourth points go hand in hand and in real life usually exclude each other. Any of them will suffice. If a whetstone is enough for one sharpening, but it costs one penny, then this is an excellent stone. If a grindstone lasts forever and costs like an airplane, then I like it too.

You can go to the store and buy a suitable stone there. And you can not go far and get by with junk in the workshop. What is certainly in bulk for any novice master is sandpaper. It's an excellent abrasive—inexpensive, accurate, available in every grit imaginable—but it definitely needs some sort of Smooth surface as a basis. Wood is no good, it's too soft for the task and tends to bend back and forth with moisture.

The sole of your largest planer will work well. Or a table of some solid machine, for example, a circular. The sandpaper is attached to the table or thin double-sided tape (watch out for bubbles!) Or simply on a few magnets at the corners of the sheet. That's it, it's the simplest and surprisingly effective option abrasive plane from improvised means. Those who wish can also get a stove made of thick glass, aluminum or artificial stone specifically for these purposes.

Now - about grindstones.

All stones are divided into three groups: oil, water and diamond. The latter, as a rule, do not look like stones, but metal tiles with diamond chips on the top face.

oil stones distributed everywhere. This option is typical for the Western school of carpentry. Such a stone, even with a large amount of oil, removes material relatively slowly (especially when sharpening the hardest steels), but it deteriorates very slowly - the plane is preserved very well. Christopher Schwartz wrote that many of the professional carpenters he knew had never ground their oilstones at all and never complained. As far as I understand, if such stones are rubbed, then mainly in order to remove the clogged with dust upper layer abrasive and let the stone work faster.

They are made in many places, if you are interested, you can google according to the words "Arkansas stone", this is the most popular oil stone in America.

water stones, unlike oil ones, are produced in the widest range of grain sizes - from about 150 to 10,000 according to the European system.

They are traditional for the East, you can even find natural Japanese ones on sale (whose graininess, for obvious reasons, is indicated only approximately).

Their surface is moistened not with oil, but with water, which requires a more careful attitude to the cutting tool - it must be wiped dry after sharpening. In addition, some stones need not only to be moistened, but soak in water for a long time, which creates additional inconvenience. Traditional Japanese stones sharpen tools very quickly, but, unfortunately, they themselves wear out just as quickly. We can say that the water stone is constantly destroyed, substituting for sharpening more and more fresh layers of abrasive. If you fork out for a solid set of water stones, add the roughest diamond tile to it, and grind the stones with it if necessary. This practice is well known, and many serious manufacturers of water stones provide such tiles as part of their kits - there it is, with holes for dust removal:

Diamond tiles- a relatively new and rather expensive version of grindstones (although the same high-class Japanese stones will cost no less). Their big plus is that they do not spoil the plane from sharpening the tool at all - there is NO WHERE to dig in there ... classic stones, diamond bars have an abrasive only on the edge, and not throughout the entire thickness. But, considering that diamond is the hardest known material, and that even on cheap Chinese bars, diamond chips are held very firmly in a metal base, you will kill such a bar for a long time. The main thing is not to forget about the liquid (usually it is recommended to use water) and not to put excessive pressure on the tool. However, it hasn't helped anyone yet.

The generally recognized leader in this area is the American company DMT.

Which system to choose? I do not know. You can, in the end, not start stones at all and calmly sharpen tools on sandpaper (especially if you use an electric sharpener for rough removal of material). This is a perfectly normal option.

In my experience, it's pretty simple. I started with oil stones and I can say that this is a really super slow option. Meditative, so to speak. Back and forth, back and forth ... And I, as mentioned above, do not want to be distracted by sharpening; I want to quickly sharpen the edge and then go on cutting the piece of wood. Therefore, I will never go back to oil.

I don’t like grinding on sandpaper only because it needs to be changed, this is a very painful process. Only one piece of skin is placed on an inverted planer at a time. I just don't have some quiet flat place where I can stick sheets of sandpaper of several grains next to each other so that it is convenient to switch from one to another. I thought about getting myself a piece of granite countertop for this case, but met with diamonds.

Diamonds are the theme. Just right for a slob like me. I do not need to follow the plane of the stone, it does not change with a diamond. I don't have to worry about what I cut on a diamond - it grinds bone, any metal and even other stones with equal success (sometimes I grind worn corundum dremel bits). I do not have to think about what liquid to use - if you really want, you can even do without liquid at all. To clean a diamond tile, I can safely rub it with soap and scrub it with a toothbrush over the sink without thinking about how this will affect the abrasive properties.

So I'm mostly on diamonds. But I have the cheapest Chinese set of tiles so far, in which there is simply nothing fine-grained. The smallest is about 500-600 according to the European system. Therefore, I finish the edges on P1500 grit sandpaper, glued to the sole of an old planer and moistened with kerosene. And, fortunately, it does not need to be changed to any other.

But I have not tried water stones. And it looks like I never will.

In the following parts, I will show you how I sharpen edges on this simple equipment, and at the same time I will talk about microbevels and razor sharpening.

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HARDENING AND SHARPENING OF WORKING TOOLS

1. Tool hardening

Not every steel can be subjected heat treatment at home. The most common, carbon steel, from which many tools are made, including files, can be hardened easily. Old files are convenient blanks for making, for example, straight and semi-circular chisels, especially semi-circular 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 Suitable for heating small tools. The heated tool is quickly lowered into water, the vessel with which is located as close as possible to the burner, and it is sharply moved to get rid of the vapor shell that forms around it, which interferes with the contact of the metal with water.
The second operation (tempering) consists in softening the steel hardened to brittleness. Now the cutter is heated slightly, controlling the color of the tint. Therefore, the scale formed on the tool during the first operation must be removed by light polishing to a shine on fine skin(at least the chamfer of sharpening), trying not to spoil the blade. On the flame, the area is heated at a distance of 1-2 cm from the end of the cutter. Do not heat the cutting tip itself, which can quickly overheat. The tip should get hot. internal warmth 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 help from a specialist, since at home it will not be possible to obtain a sufficiently high temperature to harden high-quality steels.
For a carpenter who has the ability to heat a tool, for example in a muffle furnace or forge, here are some basic recommendations.
The grade of steel can be tentatively determined by a spark on a grinding wheel in a dark place. So, a white beam of sparks with separate stars indicates that the steel is carbonaceous, requires slight heating during hardening (up to a temperature of 780 ° C - a cherry-red glow) and tempering when the tint color changes from purple (for cutting tools) to straw (for mallet work). Heat treatment of such steel can be carried out at home on a gas burner.
If a short beam of dark red sparks is almost without stars, high-speed steel P18. It requires a high tempering 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 is hardened with a light yellow glow, and on the grinding wheel it gives reddish-orange sparks with a small number of stars.
Other alloyed steels (chromium gives subtle yellow sparks, tungsten - well-defined red) are hardened with a light red glow (temperature 820-900 ° C). Alloy steels are best quenched in oil or in water heated to 70°C.
Approximately the same temperature is required for steel annealing before its processing: alloyed steels are heated up to 1000°C, high-speed ones up to 1200°C. After heating, they must slowly cool down with the oven.
It should be noted that with high and prolonged heating, carbon burnout occurs. Therefore, it is better not to harden a tool with a very thin section, or after hardening, remove a sharp decarburized tip on a bar or sharpener with cooling. For the same reason, one 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 test work with a hardened and sharpened tool does not give the desired result, it is necessary to repeat the sharpening.

2.Tool sharpening

The whole secret of making a good carpentry tool consists of two factors: proper sharpening and the right grade 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 for her correct execution you need to have some knowledge. Tool sharpening consists of two operations.
The task of the first operation is to achieve a flat grinding plane (it is called a chamfer) without sagging it at the very edge and without burning the steel. 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 of the first operation is to place the chamfer at a certain angle with respect to the second plane (face or chamfer) with the blade sting required for this particular tool. This angle, called the sharpening angle, is different: 7-8 ° for a knife, 15-25 ° for chisels, 37-42 ° for planers and 50-53 ° for a special planer - a grinder.
The sharpening angle of the tool is strictly dependent on the angle of inclination of the cutting edge (plane) of the blade with respect to the surface of the wood, which is determined by complex formula. If in such tools as a knife, chisels, axes, we can adapt to the angle of inclination of the cutting edge in the process of work, which means that the sharpening angle with the blade can vary depending on the need (cutting wood manually or by hitting with a hammer, mallet), then in other tools, such as planers, this sharpening angle must be maintained more strictly.
The task of the second operation - editing - is not to spoil the sharpening angle and achieve a sharp blade sting, which is associated with the removal of irregularities, small notches, burrs from it, with both surfaces of the blade polished to a shine.
The first operation is performed, as a rule, on a mechanical grinder - a rotating abrasive wheel. Finish it by hand on a large flat bar. It is dangerous to sharpen the blade on the grinder to sharpness, since in this case it is difficult to control the overheating of the steel at high speeds of the circle, when suddenly a tint color appears on the thin edge of the blade during turning - a sign that the strength of the steel is broken and the sharpening is spoiled. Such a place will have to be completely cut off on the same grinder and sharpened again.
In order to reduce the subsequent manual work on a bar, they try to remove metal as much as possible on the grinder along the entire chamfer, except for its edge, which is not difficult to do on a cylindrical grinder: it allows you to remove excess metal from its entire middle with a notch on the chamfer.
To prevent the steel from overheating, the tool is periodically dipped in water and the sharpener itself is also saturated with water. The disappearance of water droplets on the tip of the blade or their boiling is a sign that it is time to lower it into the water.
It is advisable for a beginner grinder to sharpen a tool on a grinder so that the circle does not rotate towards the blade, but vice versa or at some 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 sharpener moves away 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 obtained. These are positive sides sharpening 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 is sharp only due to a good sharpening angle and well-defined edges. In fact, it is notched 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, 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 bar must first, and then periodically, be washed with soap and water using a brush, as it is salted and clogged with small metal filings and abrasive dust, it is good to soak it with water. In the process of work, 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 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 the practice of experienced craftsmen. Barbers have been known to cut straight razors in a similar fashion.
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 pasted over with small sandpaper(preferably sandpaper on fabric). 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 do the editing of 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 a filling board, you must immediately beware of making movements towards the blade: soft fabric or paper of the skin from pressure is at least slightly, but bends and the blade "attacks" the emery surface at a large angle, which will lead to chamfering, i.e. to change the angle of sharpening. 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 dressing board towards the blade, it even happens that it cuts off part of the glued skin.
During dressing, 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, the movements of the hand should become more and more frequent and light, and the sharpened edges are also interchanged more often.
After straightening, it is necessary to make a trial thread, having tested the tool in cutting techniques along and across wood, especially hard wood. It is likely that the bladethe tool 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 blade edge during hardening, as we discussed above. True, this also happens with a tool that has not been heat treated. In any case, it is necessary to correct it again and check until the cutting edge is settled.
A well-sharpened tool lasts a long time and does not require frequent refueling. It is corrected only after many hours of work. For a faster result, if the tool has been used for a long time, it is possible to slightly increase the contact of the edge of the blade being sharpened with the bar when refueling, given that during the initial sharpening, its sharpening angle was quite sharp. In this case, the sharpening angle slightly increases and a secondary chamfer is formed. Naturally, after a while, you will again have to straighten the angle of sharpening the blade on the bar, or even on the circle of a hand drill. Practice has shown that the use of polishing paste or oil paint"Chromium oxide" for the final dressing of the tool is optional. In the process of work, smoother (worked) and harder places will appear on the filling board, which will allow you to use the same skin on the board for sequential sharpening: from rough to clean.

3. Grinding wheel

An abrasive wheel driven by a mechanical or electric drive, it is customary to call a sharpener, grinding 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 grinding skins). It is better to buy an abrasive disc made of white electrocorundum (its marking on the circle starts with EB) or monocorundum (marking M). They are more suitable in terms of grain hardness for finishing, and in our case - for sharpening hardened tools - they have proven themselves in grinding very hard metal surfaces with a small depth of grinding.
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 marriage or defective disk.
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 speed of rotation of modern grinding wheels ranges from 35 to 40 m/s, which exceeds our calculated more than twice.
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. increase the level of safety at work.
Just in this sense, abrasive fingers with a length of 25 mm and a diameter of 10 mm on a metal axis of rotation, made specifically for an electric drill and sometimes sold, are very convenient for sharpening a tool.
Grinding wheels have the ability to self-sharpen, i.e. worn and blunt abrasive grains gradually fly off, giving way to new ones. But they also require certain operating conditions: one must try to sharpen the tool in such a way that the circle grinds evenly over the entire surface, without the formation of grooves. Therefore, it cannot be used for sharpening a tool by hand, as a bar - this will lead to local damage to its surface and to eccentricity during rotation.
Industrial disks 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 circle. Also, when fitting a circle onto an axis of rotation, these conditions must be met. Such an axis, up to 9 mm in diameter, can be made from a bolt, from which the head is sawn off. At the threaded end, a disk is clamped between washers, lamellar gaskets and nuts. Previously, a hardwood insert is driven into the disc hole, its center is precisely found relative to the outer cylindrical surface of the disc, and a hole is drilled for the selected axis. The diameter of the washers and spacers under them must exceed the diameter of the liner, and the liner must be cut flush with the disc. Then, at low speeds of the drill, you need to check the centering of the disk by touching its cylindrical surface with the tip of a pencil or chalk.

Choice of hardness of the grinding tool.

Table 1.

Grinding wheels for rough manual grinding.

Table 2.

Grinding wheels for cutting and fine grinding.

Table3.

Table4.

Cutting tool	Sharpening area	Grinding wheel brand
Turning cutters from high speed steel	Back and front edges	25A 30-20-N SM2
Turning cutters with plates of hard alloy	The back and front edges of the chipbreaker.	64S 40-16N CM2 64S 16-5-N SM2
saw blades	Large teeth fine teeth	25A 25-N ST1 18A 16-N CM2
saw blades from high speed steel		25A 10-8-N-ST1
Saw segments made of high speed steel		25A 25-N ST1
Twist drills made of high speed steel: not large diameter large diameter	cone part	25A 25-N ST1 25A 30-25-N ST1
Twist drills with carbide inserts		64S 16-5-N CM2-ST1

Grinding wheels.

Table 5

Circle brand	Purpose of grinding wheels
55S 100-25-N SM2-T2 K 65S 30-16-N SM2-ST1 B 64S 40-5-N SM2-ST1 K 64S 40-6-N SM2-ST1 K	Grinding materials with low tensile strength: gray cast iron, brass, hard alloys, glass, stone, ceramics and plastics
25A 30-5-N SM2-ST2K 94A 40-16-N SM2-ST1 K	quality steel all brands
25A 25-N SM2 K	Grinding at peripheral speeds up to 50 m/s
18A 100-16-N-ST1-T1 K 55S 100-40-N T1 B 18A 100-60-N ST2-T1 B	Grinding by hand and machine structural steel, circles with bakelite (B) bundle - for circumferential speeds up to 50 m/s
94A 40-13-N SM2-ST1 K	Grinding of extra strong steel
55S 25-N M1 V 64C 6-N M1 V 18A 30-16-N M1 V 25A 16-H M1 V	Polishing
64S 25-13-N ST1 K 25A 10-5-N ST2 K

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

The tool does not cut the wood fibers, but crushes and breaks 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 need to be sharpened regularly.

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

electric grinder

Tool sharpening consists of three operations:

1.Giving the correct shape and angle of sharpening(roughing operation).

Removing a large layer of metal on emery to get angles close to the desired ones.

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

Not required for store-bought tools.

Chisel needs fine-tuning
(blade damaged)

2.fine-tuning- obtaining an even plane of grinding (chamfer) without filling it up on the edge and without overheating of 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, is different: 7-8° at the knife, 15-25° at the chisels, 37-42° at the planers.

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

For a knife, chisel, ax, the angle of inclination of the cutting edge and the angle of sharpening can vary in the process of work, depending on the need (cutting wood manually or by hammering, mallet), for a planer, these angles must be kept stricter.

As a result of sharpening, the blade and chamfer of the planer knife, chisels, chisels should be straightforward, have the right angle And located at right angles to the sides.

This is checked using square And special templates.

When sharpening on an electric grinder, you need to periodically cool the tool(blade) in the 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 formed)

3.Edit- Obtaining the desired sharpness of the blade (at high magnification, it can be seen that the blade is notched 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, not shiny.

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

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

Sharpening by hand
1 - chisel; 2 - fixture; 3 - bar (touchstone).

Checking the angle of the blade after sharpening
(using a template)

Checking the straightness of the blade with a square

For sharpening a hacksaw first, the teeth are aligned in height (jointed).

This is done for old saws, in which the teeth have become of different heights.

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

After that, they carry out saw tooth alignment(If you want to).

After divorce, the teeth are sharpened.

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

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

After completing work on one side, the blade is rotated 180 ° and the other side is sharpened.

Each tooth is sharpened until the cutting edge is formed - even, straight, sharp, without burrs.

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

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

Jointing of teeth:
1 - a bar for a file; 2 - file; 3 - saw blade;
4 - a bar for fixing the saw.

Sharpening saw teeth and checking
uniform tooth setting:
1 - template; 2 - teeth; 3 - saw blade; 4 - file;
A - for longitudinal sawing; B - for cross cutting.

Sharpening a two-handed saw

Tool sharpening safety

1. Operate the machine only with goggles 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. Control the correctness of sharpening.
6. Use small blocks to secure the saw and file.
7. Make sure that the chamfer is in contact with the surface of the bar with the entire plane, so as not to spoil the sharpening angle.