If you only have to drill into wood, then you don’t have to worry about the sharpness of the drill, since the drill can serve well for months and years without sharpening. But when it comes to drilling metal, the sharpness of the drill becomes very important, in other words, you can only drill through metal with a sharp drill bit. You can easily feel the difference when you take a completely new drill. Having started to cut into the metal rather quickly, with every minute the drill will plunge into the metal more and more slowly, and you will have to press on it more and more. The rate of dulling of a drill depends, in particular, on revolutions, feed rate, cooling and other factors, but no matter how hard you try, the time it takes for a drill to become unsatisfactory is measured in minutes. If the amount of work is significant, it will be expensive to constantly buy new drills, so it is better to learn how to sharpen them. Although it is still worth having several drills of the same diameter (3-10, depending on the diameter and, accordingly, the price) in order to return to sharpening only when all the drills have become dull.

At the periphery of the drill, the cutting speed is maximum, and, therefore, the heating of the cutting edges is maximum. At the same time, heat removal from the corner of the cutting edge is very difficult. Therefore, dullness begins at the corner and then spreads to the entire cutting edge. Its curve is clearly visible. Then the back edge wears off. Strokes and marks appear on it, coming from the cutting edge. As they wear, the marks merge into a continuous strip along the cutting edge, wider at the periphery and tapering towards the center of the drill. The transverse cutting edge becomes wrinkled when worn.

At the beginning of dullness, the drill makes a sharp creaking sound. If the drill is not sharpened in time, the amount of heat generated will increase and the wear process will proceed faster.

To make it easier to control the geometry of the drill, the main thing that should be done is the template described below. With its help, even if sharpening is carried out without tools, you can always check where else the metal needs to be removed, and, in the end, get what you should get (it’s impossible that it won’t work out, even if you have to grind off half the length of the drill) . To maintain symmetry, try to keep the sharpening time and pressure constant for each section.

Sharpening twist drills

The drill is sharpened along its rear edges. It is very important that both blades (teeth) of the drill are sharpened exactly the same. Doing this manually is very difficult. It is also not easy to manually create the required shape of the back face and the specified back angle (see below for which angle).

There are special machines or devices for sharpening. If possible, it is better to sharpen drills using specialized equipment. But in a home workshop, such an opportunity, as a rule, does not exist. Drills have to be sharpened by hand using an ordinary sharpener.

Depending on what shape is given back surface, exist different types sharpening: single-plane, double-plane, conical, cylindrical, screw.

With single-plane sharpening, the back surface of the pen is made in the form of a plane. The clearance angle for such sharpening should be 28-30°. With single-plane sharpening, there is a high risk of chipping the cutting edges. This method, which is the easiest to do with manual sharpening, is recommended for drills with a diameter of up to 3 mm.

Universal drills with a diameter greater than 3 mm are usually subjected to conical sharpening. In order to understand the features of such sharpening, let’s consider a diagram of conical sharpening on a drill machine with a 2φ angle of 118°. The figure below shows a grinding wheel and a drill pressed against its end with the cutting edge and back surface.

Let's imagine a cone, the generatrix of which is directed along the cutting edge and the end of the grinding wheel, and the apex is 1.9 times the diameter of the drill. The apex angle is 26°. The drill axis intersects with the axis of an imaginary cone at an angle of 45°. If you rotate the drill around the axis of an imaginary cone (as if rolling a cone along the end of a grinding wheel), then a conical surface is formed on the back edge of the drill. If the axis of the drill and the axis of the imaginary cone are in the same plane, then the clearance angle will be zero. To form a back angle, you need to shift the axis of the drill relative to the axis of the imaginary cone. In practice, this offset will be equal to 1/15 of the drill diameter. Swinging the drill along the axis of an imaginary cone with this mixture will provide a conical back face and a back angle of 12-14°. The larger the offset value, the larger the relief angle will be. It should be remembered that the clearance angle along the cutting edge changes and increases towards the center of the drill.

It is clear that it is very difficult to fulfill all these sharpening conditions manually. The drill intended for sharpening is taken by the working part with the left hand, possibly closer to the intake cone, and by the tail with the right hand.

The cutting edge and rear surface of the drill are pressed against the end of the grinding wheel and, starting from the cutting edge, with smooth movements right hand, without lifting the drill from the stone, rock it, creating a conical surface on the back edge of the pen. Then repeat the same procedure for the second feather.

When sharpening, it is advisable to repeat as accurately as possible the shape of the back surface that was after the factory sharpening, so as not to lose the required back angles.

Another sharpening method widely used by home craftsmen is as follows. As in the previous case, the drill is taken with the left hand by the working part as close as possible to the intake cone, and with the right hand by the tail. The cutting edge of the drill is pressed against the end of the grinding wheel and with a smooth movement of the right hand, without lifting the drill from the stone, rotate it around its axis, sharpening the back surface. It is very important to maintain the desired angle of inclination to the end of the grinding wheel when rotating the drill. For this purpose, special bushings are often used when sharpening.

As a result of this sharpening, a tapered surface will be formed on the back surfaces of both feathers, but a relief angle will not be formed. During operation, the friction of the rear surface against the walls of the hole and, therefore, the heating will be greater.

Due to friction with the grinding wheel, the tool heats up during sharpening. This causes the hardened part of the tool to temper. The metal softens and loses its hardness. Inept sharpening renders the tool blade unusable. Therefore, sharpening should be carried out with repeated cooling of the drill in water or in a water-soda solution. This requirement does not apply to carbide drills. Do not use oil for cooling when sharpening. If for any reason the tool is sharpened dry, then:

• a small layer of metal is removed in one pass;
• rotation speed abrasive wheel should be as low as possible;
• The drill should never become so hot that the hand cannot tolerate it.

Practice shows that tool sharpening should be carried out against the movement of the grinding wheel. Then the cutting edge is more durable, and it is less likely to crumple or break off.

For sharpening, grinding wheels made of electrocorundum (grades 24A, 25A, 91A, 92A) with a grain size of 25-40, hardness M3-CM2, on ceramic bonds are used.

In production, sharpening is usually followed by finishing. Finishing makes the surface smoother and removes small nicks. A polished drill is more resistant to wear than a drill after sharpening. If you have the opportunity to do some fine-tuning, take it.

For finishing, grinding wheels made of green silicon carbide grade 63C, grit 5-6, hardness M3-SM1, on a bakelite bond, or wheels made of CBN LO, grit 6-8, on a bakelite bond, are used.

One of the main conditions for correct drill sharpening a - preservation of its axisymmetricity. Both cutting edges must be straight and have identical lengths and identical apex angles (and point angles) relative to the drill axis.

The correctness of sharpening is checked with a special template.

a - template; b - checking the angle at the apex and the lengths of the cutting edges; c - sharpening angle; g - the angle between the jumper and the cutting edge.

It is made independently from a sheet of copper, aluminum or steel approximately 1 mm thick. The most durable template is, of course, made of steel. The template is used to check the angle at the apex, the length of the cutting edges, and the angle between the jumper and the cutting edge. Instead of the back angle, which is very difficult to measure, the tip angle is measured using a template. It is advisable to make a template before using a new drill in order to transfer the required angles from the last one.

The uneven length of the cutting edges and their inclination to the axis of the drill also lead to unequal load. The drill will fail faster due to intense wear of the overloaded cutting edge.

a - the wedges of the cutting edges are not the same, the middle of the jumper does not coincide with the axis of the drill; b - cutting edges are sharpened to different angles to the axis of the drill, the middle of the jumper coincides with the axis of the drill.

An uneven load on parts of the drill will cause it to run out during the cutting process and, as a result, an increase in the diameter of the resulting hole.

The easiest way to check the correct sharpening is test drilling. If the drill feathers are sharpened unequally, then the less loaded one will have less chips from the corresponding groove. Sometimes chips protrude through only one groove. The hole diameter may be exaggerated compared to the drill diameter.

The device consists of a fixed base and a removable holder with holes for drills different diameters.

1 - rail; 2 - drill; 3 - emery wheel; 4 - base; 5 - holder.

The base is made of a planed board 30-40 mm thick, to which it is sewn (nailed, glued) at an angle of 30-32° (depending on the angle 2φ, see below, 30° for 2φ=120°, 32° for 2φ=116°) ) wooden slats with a side edge beveled at an angle of 25-30° (for single-plane sharpening). This rack orients the holder with the drill being sharpened at the desired angle relative to the grinding wheel. The holder is made from a rectangular wooden block, one of the sides of which is planed at an angle of 60-65° (depending on the angle of the side edge of the rail). With this sidewall, the holder is pressed against the rail on the base board, which ensures sharpening of the front angle of the drill within the required limits (25-30°). On the other sidewall of the holder, mark and drill through holes perpendicular to the plane of this sidewall for each drill of one diameter or another. The length of the holder is chosen so that it is comfortable to hold when sharpening drills.

You cannot install the device on a regular pad (armrest), so you will have to come up with some kind of table or shelf for it; you can move the sharpening machine to a table where there will be room for this device. Place a holder with a drill inserted into it to be sharpened, close to the rail, on the base. Turn the drill in the holder socket so that the sharpened edge is oriented horizontally. With your left hand, hold the drill near the edge to be sharpened, and with your right hand, hold the drill shank. While pressing the holder against the beveled strip, move the drill to the emery wheel and sharpen one edge. Then turn the drill and process the second edge in the same way.

It can be done even simpler:

Sharpening angles and other characteristics of the drill

A twist drill is a rod that has two helical grooves to facilitate the release of chips. Thanks to the grooves on the drill, two screw feathers are formed, or, as they are otherwise called, teeth.

A twist drill consists of a working part, a neck, a shank and a foot.

A - with a conical shank; B - with a cylindrical shank; a - working cutting part; b - neck; in - width of the pen; g - foot; d - leash; e - screw flute; f - feather; z - shank; and - jumper; L - total length; L 0 - length of the “working cutting part”; D - diameter; ω - angle of inclination of the “chip screw groove”; 2φ - apex angle; f - width of the spiral ribbon; ψ is the angle of inclination of the jumper.

The working part is divided into cutting and guiding. All cutting elements of the drill are located on the cutting part - the intake cone. The guide part serves to guide during cutting and is a spare part when resharpening the drill. On the feathers of the guide part along the helical line there are cylindrical chamfers-ribbons. The ribbon serves to guide the drill in the hole, as well as to reduce friction of the drill on the walls of the hole. It shouldn't be wide. Thus, the width of the drill strip with a diameter of 1.5 mm is 0.46 mm, and with a diameter of 50 mm - 3.35 mm. The drill shank and foot are used to secure the drill in the machine spindle or chuck. Drills can be made with or without a neck.

The diameter of the drill, measured by the strips, is not the same along the length of the drill. At the intake cone it is slightly larger than at the shank. This reduces the friction of the ribbons against the walls of the hole.

In order to understand the structure of the cutting part of the drill, consider the basic principles of operation of any cutting tool(including drills). One of the most important requirements for a cutting tool is that the separated chips move freely from the cutting site. The surface of the tool along which the chips run is called the rake face. This face is deflected back at a certain angle from the vertical plane.

1 - wedge; 2 - object being processed; γ (gamma) - front angle; α (alpha) - rear angle; δ (delta) - cutting angle; β (beta) - sharpening angle.

Thanks to this angle, it is easier for the tool to cut into the metal and the chips flow more freely along the front edge. The angle between the front edge of the tool and a plane drawn perpendicular to the cutting surface is called the rake angle and is denoted by the Greek beech γ.

The surface of the tool facing the part is called the back face. It is deflected at a certain angle from the surface of the workpiece to reduce the friction of the tool on the cutting surface. The angle between the rear edge of the tool and the cutting surface is called the clearance angle and is denoted by the Greek letter α.

The angle between the front and back edges of the tool is called the point angle and is denoted by the Greek letter β.

The angle between the front edge of the tool and the cutting surface is called the cutting angle and is denoted by the Greek letter δ. This angle is the sum of the tip angle β and the relief angle α.

The rake and back angles are the angles that must be maintained when sharpening.

Now let’s find the edges and angles described above on a drill, which is not at all similar to the tool shown in the figure above. To do this, we cut the cutting part of the drill with plane AB, perpendicular to its cutting edge.

The cutting edge is the line of intersection of the front and rear edges of the tool. The rake angle γ of the drill is formed by a helical groove. The angle of inclination of the groove to the drill axis determines the size of the rake angle. The magnitude of the angles γ and α along the cutting edge is variable, as will be discussed below.

The drill has two cutting edges connected to each other by a bridge located at an angle ψ to the cutting edges.

Having received general idea about the geometry of the cutting part of the drill, let's talk in more detail about its elements. The front edge of a twist drill is a complex helical surface. Facet is a conditional name, since the word “facet” implies a plane. The helical flute, the surface of which forms the leading edge, intersecting with the chamfer, creates straight cutting edges.

The angle of inclination of the helical groove to the drill axis is denoted by the Greek letter ω. The larger this angle, the larger the rake angle and the easier the chip exit. But the drill weakens as the inclination of the helical flute increases. Therefore, for drills with a small diameter, which have less strength, this angle is made smaller than for drills large diameter. The angle of inclination of the helical flute also depends on the material of the drill. High speed steel drills can operate under more stressful conditions than carbon steel drills. Therefore, for them the angle ω may be larger.

The choice of inclination angle is influenced by the properties of the material being processed. The softer it is, the greater the angle of inclination can be. But this rule applies in production. At home, where one drill is used to process different materials, the angle of inclination is usually related to the diameter of the drill and varies from 19 to 28 ° for drills with a diameter of 0.25 to 10 mm.

The shape of the flute should create enough space to accommodate chips and allow them to be easily removed from the flute, but not weaken the drill too much. The width of the groove should be approximately equal to the width of the pen. The depth of the groove determines the thickness of the drill core. Strength depends on the thickness of the core. If the groove is made deeper, the chips will be better accommodated, but the drill will be weakened. Therefore, the thickness of the core is chosen depending on the diameter of the drill. In small diameter drills, the core thickness is a larger proportion of the drill diameter than in large diameter drills. So, for drills with a diameter of 0.8-1 mm, the core width is 0.21-0.22 mm, and for drills with a diameter of 10 mm, the core width is 1.5 mm. In order to increase the strength of the drill, the thickness of the core is increased towards the shank.

The front edge of the drill is not sharpened.

The design of the helical grooves is such that as they approach from the edge of the drill to the center, their angle of inclination decreases, and therefore the rake angle decreases. The working conditions of the cutting edge near the center of the drill will be more difficult.

The rear angle, like the front angle, varies in size at different points of the cutting edge. At points located closer to the outer surface of the drill, it is smaller, at points located closer to the center, it is larger. The clearance angle is formed when sharpening the intake cone and is approximately 8-12° at the periphery of the drill, and 20-25° at the center.

The bridge (transverse edge) is located in the center of the drill and connects both cutting edges. The angle of inclination of the jumper to the cutting edges ψ can be from 40 to 60°. Most drills have ψ=55°. The bridge is formed by the intersection of two back faces. Its length depends on the thickness of the drill core. As the thickness of the core increases towards the shank, the length of the bridge increases with each sharpening. During the drilling process, the transverse edge only interferes with the penetration of the drill into the metal. It does not cut, but scrapes, or rather crushes, metal. No wonder it was once called a scraping blade. By halving the length of the bridge, the feed force can be reduced by 25%. However, reducing the length of the bridge by reducing the thickness of the core will weaken the drill.

The tip angle of 2φ has a great influence on the operation of the drill. If the apex angle is small, the lower edge of the chip will touch the wall of the hole and there will be no conditions for proper chip formation.

The picture below shows a drill with normal angle fence cone.

In this case, the edge of the chip fits well into the groove. Changing the tip angle changes the length of the cutting edge and therefore the load per unit length. As the tip angle increases, the load per unit length of the cutting edge increases, and the resistance to penetration of the drill into the metal in the feed direction increases. As the tip angle decreases, the force required to rotate the drill increases, as the conditions for chip formation worsen and friction increases. But at the same time, the load per unit length of the cutting edge decreases, the thickness of the cut chips becomes smaller and heat is better removed from the cutting edges.

Typically, the point angle (2φ) of standard universal drills made of carbon, chromium and high speed steel is 116-118° and is considered suitable for many materials. But in order to ensure best conditions work, it is changed as shown in the table.

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For smooth operation, accurate and centered drills are required. We suggest you consider where you can buy a machine for sharpening drills, how to do it homemade unit, as well as how household models differ from industrial ones and what their price is.

Types of drills and basic concepts

There are several types of drills, because... They are divided according to the principle of operation and the relationship of the working surfaces; they also need to be sharpened in different ways; let’s get acquainted with the main ones:

• spiral. Used in almost all types of industry, household work, repairs, etc.;
• flat - these are more narrow-profile tools, they are mainly used when drilling holes of large diameters; they got their name due to the flat working edge, which is very similar in shape to a reamer.

Let's consider the fundamental provisions for sharpening twist drills and countersinks:

During the movement of the cutting surface in the material, chips are formed inside the processed raw material, this process is especially evident in the front surface. It is the large accumulation of chips that plays main role in the deformation of the plastic parts of the drill: during operation it heats up, and under the influence of the sharp ends of the chips, its working edge changes. Of course, there is a huge difference in the speed of this process, the most dangerous and toughest is copper and steel.

Photo - Cleaning the drill from chips

Drilling is carried out according to the following scheme: during operation, a conical surface is described; this shape is also acquired by the working surface of the drill; accordingly, the cutting edge becomes somewhat blunt and changes its center. All angles work surface must be located above the surface of the end, this is the only way to ensure a normal and standard clearance angle.

The simplest and effective way How to sharpen a drill at home is to use an electric sharpener. You can work with a regular sharpening bar made from a mixture of abrasive materials, but such a process will take a lot of time and effort, unlike operating a device with an electric motor. A universal manual grinding apparatus has a motor whose speed is 1500-2000 min -1. Optimal power: up to 300 watts. Such models are available from Doctor, Vollmer, Sturm, Proxxon, Drill and Weinig.

Photo – Sharpened drills

Orientation is carried out along the cutting edges; you must act strictly in the direction of the spiral grooves, because they do not change their shape even from exposure large quantity shavings. We fix the drill so that the edge that will be sharpened is strictly parallel to the axis of the grinding tool. Most important question: when is the working part sharpened? As soon as you see a reflection of light from the working surface, this means the edge has been sharpened. Using the same system, we sharpen the second side.

Photo – Sharpening drills

In this case, it is very important not to miscenter the drill earlier, in which case you will lose its balance, and during operation the tool will deviate by several degrees from the standard parameters. The angle between the lumps is the most important parameter sharpening.

Photo – Cutting angle

Standard sizes have the following form:

Alloy steel, structural, tool - 90 degrees;

Soft metals (copper, aluminum, aluminum alloys) – 90-100 degrees;

Wood, plastic, rubber – 90-100;

Bronze, brass – 110-120.

To achieve high precision processing with your own hands, you need special attention give standard and deformed parameters. To control the sharpening process, you can order a special template for a drill with the desired diameter and angle. The photo shows a diagram of processing a drill with such a device.

Photo – Sharpening template

If you don’t have the money or time to purchase a template, use the “old-fashioned” method: we follow the rule of left-hand mechanics. We bend our hand and place it over the drill in such a way that the cutting surface is closed on several sides, we should get a kind of corridor. We place a lamp opposite the end surface and check the evenness and accuracy of sharpening (this will be clearly visible from a distance of 20 cm from the drill, if you look with one eye).

Photo – Left hand rule
Photo – Glare Check

Using homemade electric machine, it is very important to control the drill sharpening processing process. To completely violate the accuracy, it is enough to make a mistake of 1 mm. Device for automatic sharpening of core drills small diameter also can be used for discs, knives, scissors, chains, etc.

Video: Grinding machine Energomash TS 6010S

Professional ways

The methods listed above are suitable for home narrow-profile use, but if you need to sharpen drills serially, then you will not have enough time or effort for manual centering, checking or sharpening. Let's look at how it's used professional machine for drills

The grinding wheel should be made of fine abrasive material. The sharpening area should be illuminated right angle in relation to the drill. The employee must wear safety glasses and gloves.

Step by step instructions:

Before choosing a machine for sharpening drills, you need to read reviews about it, carefully study the passport and capabilities. One mechanics forum even advised to always carry a drill with you so that you can check the effectiveness on the spot.

Price overview

Buying an inexpensive machine for sharpening drills in Ukraine, Russia or Belarus is possible, the main thing is to choose the right model (for metal, wood or plastic), caliber (dd750хibm, drillgrind, edbs2001 - universal), and power. We suggest considering the average prices for such devices:

Nowadays desktop and universal machines brands such as DrillGrind, Sturm (produced by Energomash), BSG, BSM, ESM, MICRA, V391, Diold, EZS, NKCH. They can be found in a professional store, on the Internet, on forums in the “Selling electrical appliances” section. The main thing is to make sure that the documentation matches the data stated by the seller.

The quality and accuracy of drilling depends on the sharpness of the working tool. In addition, unlike a table knife, the drill must be sharpened correctly. Experienced mechanics can straighten the cutting edge on a regular sharpening machine by simply holding the drill in their hands (at least according to them). But this method requires skill and many years of experience. Even if you have steady hand, and an excellent eye - without understanding the process, you will simply ruin the instrument.

A few basic rules for sharpening (using the example of twist drills for metal):

For a better perception of the material, let’s remember the structure of the drill.

• Do not press the tip against the sandpaper for more than 2-3 seconds at a time. The metal heats up and the so-called “tempering” occurs, that is, deprivation of hardening. Accordingly, the necessary hardness of the metal is lost. The first sign is the presence of temperature discoloration on the edge.
• For drills with a diameter of up to 4 mm: each time the sandpaper plane touches the drill, the drill is held in one position: rotation around its axis is not allowed. For larger diameter, the sharpening geometry is somewhat different.
• On twist drills, only the back surface of the cutting part is sharpened.
• The cutting edge should be directed towards the rotation of the sharpener (for mechanical sharpening).
• The main angle (2φ in the illustration) depends on the type of material being processed.

Which drills should I sharpen and how often?

Feather and other special wood drills cannot be repaired at home, and they do not become dull so quickly. Pobedite tips In principle, they are not sharpened for concrete. The most popular tool remains - twist drills for metal. Of course, they are also used for processing wood (plastic, rubber and even stone), but this is not relevant to the topic.

Twist drill. The cutting edge is small in size, so during operation it quickly heats up due to friction (there is no dissipation area). The main reason for dullness is overheating. At correct use wear does not occur as intensely. Characteristic signs of a blunt drill:

• A creaking sound is heard during operation.
• Instead of curled shavings, sawdust comes out of the hole.
• Instant heating of the tool without moving deeper.

Important: Do not use a dull drill; wear from overheating will only progress.

So, it's time to sharpen the tool. You don't want to ruin the drill and want to mechanize the process.

Mini sharpening machines are at your service:

All devices are divided into two types: attachments or stops for universal tool, And independent devices narrow specialization. Let's look at the most popular of them, from simple to complex:

This is just the device for those who have a steady hand and a diamond eye. In fact, it only allows you to hold the drill in a given position without fear of injuring your fingers. Angle control is visual, according to the position of the “wings” relative to any landmark. There are few advantages: instant readiness for work, compactness and price. The disadvantages are obvious: manual control of the process does not add accuracy.

In fact, this element is not a special device for drills. It simply allows you to fix the tool at a certain angle. The accuracy will be higher than in the previous version. Most stops allow you to set the angle of inclination, and even have a marking scale. And yet you have to rely on firmness of hands.

There are also more advanced stands: with replaceable elements and adjustment of not only the angle, but also the height. The devices are mounted not on the emery body, but on the workbench: which makes them more versatile.

In fact, such a stop can be adapted to any electric sharpener. An additional bonus is that with this stand you can sharpen knives, cutters, screwdrivers, chisels, etc.

Semi-professional guides for all types of drills

This is a fairly advanced tool that allows you to control sharpening characteristics with micron accuracy. All linear parameters are reliably fixed, the values ​​are set according to the markings. The drill is mounted in the groove, accidental displacement or rotation around its axis is excluded.

For sharpening, the possibility of both linear movement and movement of the edge along the arc path is provided (for conical sharpening of large-diameter drills). Linear movement (along the axis) can be controlled by a master, or a limit stop can be installed.

From the point of view of processing quality, the device has practically no shortcomings. But for correct sharpening the operator must know the drill parameters. That is, there is no automation: therefore the tool belongs to the professional category.

As a development of the line - a guide with its own sharpening unit. There is no need to install a stop on the workbench and change discs. In fact - you have a semi-automatic table machine for sharpening.

Important note: All listed devices are designed to work with standard electric sharpeners. Therefore, before starting to process drills, it is advisable to install a special emery disc.

They are specialized power tools for performing a single task: sharpening twist drills.

Even a person who is far from technology can use the machine (although why does he need sharp drills?). The operator only needs to determine the diameter of the drill and immerse it in the appropriate hole. It is convenient to work, errors are practically excluded. However, all drills are sharpened with the same comb. The price to pay for ease of use is the lack of flexibility in settings. For home use – best choice: especially if there is an additional attachment for sharpening knives and scissors.

There are versions for masters. The drill is installed taking into account the sharpening parameters, the process can be controlled by the operator.

The sharpening angle, the method of edge processing (linear or conical), and the depth of metal removal are selected. The drill is not located in a common holder, but in an individual cartridge.

Industrial sharpening equipment for a metalworking shop

During intensive use of drilling machines, a separate station is required to restore the functionality of the tool. Professional stands for sharpening drills of any diameter save time and effort, but the cost of such equipment is too high for home use.

The information obtained will help you choose a sharpening device without extra financial costs. In addition, there are replaceable nozzles for hand power tool(for example, a drill). But this is a topic for another article.

A device for sharpening drills is useful in any household. After all, working with a dull drill is a pain. You can make the mechanism yourself using unnecessary and outdated parts.

Rules for sharpening drills

Drills can be sharpened on special sharpening discs, manually or on machines. Before starting work, carefully examine the drills: if there are serious defects on the surface, you need to start sharpening with a coarser abrasive. If the tool is a little dull, use a finishing disc.

When sharpening manually with your own hands, you need to follow the rules:

• hold the shank with one hand and adjust the working end with the other;
• process the cutting edge with the side of the sharpening disc;
• First, one side is sharpened, after which the drill is carefully turned over and the second is processed.

During processing, it is important to maintain the original shape of the drill and the direction of the cutting edges. It is necessary to ensure that the point of the tip does not move from the center, otherwise the tool will deviate to the side during operation. If after sharpening the angle of the cutting edges is not the same, the work of the drill will be poor. This is determined using a template made by yourself or by eye: the shape of the tip should be a cone. To avoid errors, it is better to edit on specialized devices.

Types of sharpening equipment

The homemade device is designed for sharpening drills made of various metals, cutters, taps, milling cutters, countersinks, cutters.

Equipment can be:

• specialized - processes a single type of tool;
• universal - used for all types of cutters and drills.

Homemade mechanisms are more often classified as universal household type. Industrial machines are powerful and work with large tools. There is no need for such at home; they are noisy, take up a lot of space and are energy-consuming.

Household ones are suitable for sharpening drills of small and medium diameter; they are compact and economical.

Making a sharpening machine

To assemble the machine with your own hands, you need to prepare:

• electric motor;
• grinding disc;
• toggle switch;
• stand;
• electrical cable;
• stub.

All components of the machine are placed inside the body with your own hands. This will make work safe and convenient. Only the motor pulley on which the grinding disc is mounted should be accessible. The machine is permanently attached to the workbench, so the location must be selected in advance.

• place the electric motor in right place, mark the attachment points on the table;
• drill holes for the mounting bolts;
• return the electric motor to its place and screw it to the workbench; clamps made of thin metal strips are suitable for fastening;
• install the protective housing;
• Place a grinding wheel on the engine pulley.

It is advisable to select an engine with an extended pulley, otherwise it will have to be delivered. First, put on the washer, then the circle. If the diameters of the pulley and disk do not match, use adapter sleeve. A threaded hole is made on the side of the bushing, and an additional fastening bolt is screwed into it.

In terms of power for a homemade machine, an engine from washing machine. Do not select a high-speed engine, as sharpening of drills occurs at low speed.

Now you can connect the electrical component: toggle switch, motor and connect them to the outlet.

Additional devices

Do-it-yourself additional devices will make the work of sharpening drills more convenient and accurate.

Template for verification. The template is cut out of a sheet of thin (1 mm) soft metal (aluminum, copper). The template reveals the angles at the tip, the length of the working edges, the angle between the working edge and the bridge. Since it is almost impossible to check the rear sharpening angle of a drill using a template, the sharpening angle is checked. The template is cut out before using the drill for the first time.

Guide. This is a small attachment that is made of a metal strip and is fixed to the body with a bolt. During operation, the drill is placed on a guide and brought to the grindstone.

Goniometer. On the stand, which is described above, divisions of sharpening angles are applied. You can cut off a piece of metal protractor with corner marks and attach it to a stand. You need to cut off a part with angles of more than 30 degrees, since smaller ones are not used when sharpening.

A device that makes drill sharpening easier. It consists of a fixed frame and holder, in which holes are provided for inserting cutters different sizes. The holder can be removed. The bed is made of a 50 mm board, a rail is attached to it at an angle of 32 degrees. The rack positions the holder with the tool at the required angle. The holder is cut out with your own hands from a block, the surface of which is removed at an angle of 65 degrees. The beveled part is laid against the rail. The bevel angles of the holder and the rack depend on the type of sharpening.

Multifunctional mechanism

Sharpening drills will become easier when using this mechanism. The device consists of:

• roller slides;
• guide;
• shaft;
• protractor;
• drill chuck.

The guide should be made wide enough, and a protractor is attached to it. The rotation axis is a bolt inserted into the provided hole. Guides and a movable plate are placed on the rotating part. An axis and tube are fixed on its surface; on one side the axis ends with a drill chuck, on the other - with a handle. The movement of the thrust plate is ensured by a threaded axis.

At the bottom of the thrust plate there is a limiter (also known as a pointer), which simultaneously indicates the required displacement angle and fixes it in the desired position.

The mechanism works as follows:

• the drill is fixed in the chuck;
• the thrust plate is locked at the required angle;
• the tool is rotated along the longitudinal axis using a handle;
• mark the angle;
• turn the cutter 90 degrees and process the second half, reaching the marked angle.

Rules for sharpening on a homemade machine

• When machining drills, both hangers must be identical. This means that the drill will fit smoothly into the hole and perform drilling efficiently.
• Before starting the machine with your own hands, securely attach the grinding wheel to the pulley.
• Carry out initial processing with a disc with a coarse abrasive. When you notice a burr on the drill, the disc should be replaced with a thinner one.
• While sharpening, maintain the required angle at all times.
• The circle should only rotate in one direction, along the blade.
• Do not allow the cutter to overheat; it should be cooled periodically during processing. Do not immerse overheated tools in cold water, this promotes cracking of the metal.

Several options for sharpening drills in the videos.

When drilling holes in parts made of metal, the tool used is subject to active wear, which leads to intense heating of the drills and, as a consequence, to their failure. To avoid this, you need to restore them regularly geometric parameters, and a special device for sharpening drills helps to do this as accurately and efficiently as possible. This simple device, which you can make yourself, allows you to quickly and efficiently sharpen dull drills and not spend money on purchasing new ones.

A device designed for sharpening drills is especially relevant in cases where these tools often have to be used on metal, as a result of which they quickly wear out and require regular restoration. When processing wood, the drill used for these purposes practically does not wear out and, accordingly, requires minimal attention to the parameters of its sharpening. For drills, the cutting part of which is equipped with carbide inserts, such a device is also not particularly significant, since they are practically not subject to regrinding and are used by craftsmen until they are completely worn out or broken.

Many experienced specialists do not use sharpening devices at all, completely relying on their experience and eye. However, as practice shows, in such cases it is better to use devices that allow you to mechanize this process. This will ensure maximum accuracy and the required quality of the result.

On modern market There are many devices for sharpening drills that allow you to quickly, efficiently and accurately restore the geometry of the cutting tool, even if you have no experience in performing such procedures. Meanwhile, you can not spend money on purchasing such devices, but make the simplest machine for sharpening drills with your own hands.

Manufacturing options

No matter what device or machine the metal drill is sharpened on, its quality must be controlled. For this, a special template is used, which can also be serial or made by hand. This template is necessary primarily to control the accuracy of the angles of the cutting part, which are formed during the process of sharpening the drill. Tools used for working with various materials, differ from each other, including the values ​​of such angles. You can find out the exact values ​​of the latter from the reference table.

Working with different materials and knowing the angles of the cutting part of drills for such materials, you can make several templates at once and use them to control the correct sharpening of the same drill protruding into in this case as a universal tool.

As the simplest device for sharpening drills, you can use a sleeve with an internal diameter corresponding to the transverse size of the drill, rigidly fixed to reliable basis at a certain angle. When selecting a bushing for such a device, you must ensure that its diameter internal hole strictly corresponded to the transverse size of the drill being sharpened. The tool being processed should not be allowed to dangle in such a hole, since even a 1–2° deviation of its axis from the required value can seriously reduce the quality and accuracy of the sharpening performed.

It is better to immediately equip a homemade device for sharpening drills with a holder made of copper or aluminum tubes, the internal diameters of which correspond to standard sizes the drills you use most often. You can do it simpler and supplement such a device used for sharpening drills, wooden block. Holes must be drilled in the block corresponding to the size of the tools. various diameters. The most important element The design of such a device is a handy tool that simultaneously solves several important problems:

• ensures correct fixation of the drill and its precise movement in relation to the surface of the grinding wheel;
• acts as a reliable support for the tool being processed.

A similar device based on an oak block with holes of different diameters was used by our grandfathers, who used it to sharpen drills with high quality and precision. The main problem that must be solved homemade machine or a device used for sharpening drills - correctly orient the cutting part of the drill being processed in relation to the working surface of the grinding wheel.

To make a homemade machine for sharpening drills, you can use various designs of such devices. The corresponding drawings are easy to find on the Internet. Moreover, if you understand the operating principle of such a device, then you can make your own sharpening machine according to your own design.

Drawings of fixture parts

Promopore Promopore platform Movable platform
Drill bit mount and stop screw Turntable Bolts, nuts, pins and washers

Exists important rule which must be observed when working with such a device: during its use, the drill being sharpened should not rotate around its axis. If the tool rotates even at a small angle, sharpening will have to be done again.

After sharpening the drill, it should be allowed to cool. Then you need to check its restored geometric parameters using a template. It must be borne in mind that the cutting edges of the tool may differ from each other in length by no more than tenths of a millimeter. It is especially important to comply with this requirement for drills with a small diameter.

Among the mistakes made when sharpening drills using such a device, two of the most typical ones stand out.

1. The length of the cutting edges, even with their symmetry and correctly selected angles, is not the same; accordingly, the drilling center is shifted relative to the tool axis. A drill that was sharpened with such an error will create a strong runout during the drilling process, and it will be quite difficult to get it into the center of the future hole on the surface of the workpiece. A tool sharpened in this way is highly likely to break during further use.
2. When the drill is accurately centered, the angles at which its cutting edges are located are asymmetrical. Since this causes only one cutting edge to work, drilling will occur slowly, while the tip of the tool will actively heat up. This will lead to the tempering of the metal from which the drill is made, and the hole created will be broken (will have a diameter greater than the transverse size of the tool itself).

How to make a machine for sharpening twist drills

As a basis for making sharpening machine For twist drills, you can use any commercially available sharpening unit that can operate without runout and withstand significant loads. When equipping such a machine with additional devices, the following requirements must be met.

• The axis of the tool rest must coincide with the axis of rotation of the grinding wheel, and it can be located with it in the same horizontal plane or be higher than it.
• All elements of the structure being created must be securely fixed to ensure the safety of sharpening work.
• The design of the device must allow sharpening of drills both manually and semi-automatically.
• The device of the tool rest should allow the drill shank to be positioned at any angle.

During production of this device sharpening drills does not require complex technical devices and scarce materials that will have to be purchased additionally. All components can be found in almost any home workshop or garage. As equipment and tools with which such components will be modified before assembling the device, you can use a regular grinder and a welding machine.

Since the stop of such a device must be oscillating, which is necessary for sharpening drills in a semi-automatic mode, you should use loop connection. When selecting a tube, bracket and bolt for the fastening unit, you should keep in mind that there should be no play in the device. The homemade product of the proposed design has two degrees of freedom.

The platform of such a device, on which the drill being processed is fixed, has the ability to rotate along a vertical axis, making it possible to change the sharpening angle of the tool. In addition, the tool rest, resting on a horizontal axis, can make oscillatory movements, which ensures correct articulation during sharpening.

For making structural elements such a device is used sheet metal various thicknesses, namely:

• support plate – 4 mm;
• drill guide plate – 5 mm;
• other structural elements - 3 mm.

The tool rest, on the top of which the support plate is installed, must be securely fixed to the body grinding machine. For this, an additional metal “cheek” is used, connected to the device bracket.

The guide plate, on the surface of which it is necessary to make a triangular groove designed to accommodate the tool being processed, is fixed on the support plate using a screw connection.

Device and design features The drill sharpening device in question allows it to rotate up to 90°. Thanks to this ability, you can sharpen drills using this device using almost any of the methods used today.

The drill, sharpened using such a device, fits into the guide groove and can move freely in it in the longitudinal direction. In this case, the sharpening angle of the tool does not change.

Since the upper surface of the support plate is located slightly above the axis of rotation of the grinding wheel, when using such a device, the optimal sharpening shape of the back surface of the drill is achieved.

The process of sharpening drills using such a device is as follows.

• The tool is positioned in the guide groove of the fixture so that its cutting edge is parallel to the edge of the guide plate.
• After adjusting the position, the drill is slowly fed to the working surface of the rotating grinding wheel.

The process of working with such a device is well demonstrated in a video that is easy to find on the Internet.

Despite the simplicity of the design, this device provides high accuracy sharpening being performed, for quality control of which you don’t even need to use a template. If you fix the swing plate of this device at a fixed angle, it can also be used for sharpening drills equipped with carbide inserts.

In order to successfully sharpen metal drills, most of which are made of high-speed steel, it is necessary to use a sufficiently hard sharpening wheel. For this purpose, you can use an abrasive tool made of silicon carbide. Such wheels, which can be identified by their green color and 64C marking, should have a grain size in the range of 8H - 16H. When using discs made of this material, you must keep in mind that they become very hot during operation, so you should not allow the drill to be sharpened to be in prolonged contact with the abrasive tool. To prevent overheating of the drill when sharpening it on such a disk, the tool must be regularly cooled using an aqueous solution of soda.