Devices for sharpening drills for metal. How to sharpen a drill for metal with your own hands - home-made drawings and a tool for sharpening, how to simply and correctly sharpen a tool on a machine. The correct form of sharpening is the key to efficient work

If you only have to drill wood, then you don’t have to think about the sharpness of the drill, since the drill can regularly serve 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. It's easy to feel the difference with a brand new drill. Having started to crash into the metal quite quickly, every minute the drill will plunge into the metal more and more slowly, and you will have to put pressure on it more and more. The rate of drill blunting depends in particular on revolutions, feed rate, cooling and other factors, however, no matter how hard you try, the time it takes for a drill to work to unsatisfactory performance 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, consequently, 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, blunting starts from the corner, then spreads to the entire cutting edge. Its rounding is clearly visible. Then the back edge is abraded. Strokes appear on it, risks coming from the cutting edge. With wear, the risks 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 collapses when worn.

At the beginning of blunting, 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 go faster.

To make it easier to control the geometry of the drill, the main thing to do is the template described below. With its help, even if sharpening is performed without tools, you can always check where else you need to remove the metal, and, in the end, get what you should get (it cannot be that it doesn’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 of each section and the pressing force constant.

Sharpening twist drills

The drill is sharpened along its back edges. It is very important that both feathers (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 clearance angle (see below for which angle).

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

Depending on what shape the back surface is given, there are different types of sharpening: single-plane, two-plane, conical, cylindrical, screw.

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

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

Imagine a cone, the generatrix of which is directed along the cutting edge and the end of the grinding wheel, and the top is 1.9 times its size from the diameter of the drill. The vertex angle is 26°. The axis of the drill 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 the cone along the end of the grinding wheel), then a conical surface is formed on the back face 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 an 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 such a mixture will provide a conical back face and a clearance angle of 12-14 °. The larger the offset value, the larger the relief angle will be. It should be recalled that the relief 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 conditions for sharpening manually. The drill intended for sharpening is taken with the left hand by the working part, possibly closer to the intake cone, and with the right hand by the tail.

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

When sharpening, it is desirable 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. With a cutting edge, the drill is pressed against the end of the grinding wheel and with a smooth movement of the right hand, without taking the drill off the stone, turn it around its axis, sharpening the back surface. It is very important to maintain the desired angle of inclination to the end face of the grinding wheel when rotating the drill. For this, special bushings are often used when sharpening.

As a result of such sharpening, a tapered surface will be obtained 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, consequently, the heating will be greater.

Due to friction on the grinding wheel, the tool heats up during sharpening. This causes tempering of the hardened part of the tool. The metal softens, loses its hardness. Inept sharpening causes the blade of the tool to become 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 whatever reason, the tool is sharpened dry, then:

• a small layer of metal is removed in one pass;
• the speed of rotation of the abrasive wheel should be as low as possible;
• the drill should never be heated to such an extent that it cannot be tolerated by the hand.

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

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

In production, sharpening is usually followed by finishing. Finishing makes the surface smoother, removes small notches. A drill that has been honed is more resistant to wear than a drill that has been sharpened. If you have the opportunity to refine, use it.

For finishing, grinding wheels made of green silicon carbide grade 63C with a grain size of 5-6, hardness M3-CM1 on a bakelite bond or ELBOR LO wheels, a grain size of 6-8 on a bakelite bond are used.

One of the main conditions for the correct sharpening of the drill is to maintain its axisymmetry. Both cutting edges must be straight and have an identical length, identical angles at the top (and taper angles) with respect to the axis of the drill.

The correctness of sharpening is checked with a special template.

a - template; b - checking the angle at the top and the lengths of the cutting edges; in - pointing angle; d - 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, of course, is made of steel. The template checks the angle at the top, the length of the cutting edges, the angle between the jumper and the cutting edge. Instead of the back angle, which is very difficult to measure, the taper angle is measured with a template. It is advisable to make a template before starting to use a new drill in order to transfer the desired angles from the latter.

The uneven length of the cutting edges and their inclination to the axis of the drill also lead to an unequal load. The drill will fail faster due to the 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 - the cutting edges are sharpened at different angles to the drill axis, the middle of the jumper coincides with the drill axis.

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

The easiest way to check the correctness of sharpening is test drilling. If the drill bits are not sharpened equally, then the less loaded one will have less chips from the corresponding groove. Sometimes chips protrude through only one flute. 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 of 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 at an angle of 30-32° (depending on the angle 2φ, see below, 30° for 2φ=120°, 32° for 2φ=116°) is sewn (nailed, glued ) a wooden lath with a side edge beveled at an angle of 25-30 ° (for single-plane sharpening). This rail also orients the holder with the drill being sharpened at the right angle relative to the grinding wheel. The holder is made of a rectangular wooden bar, one of the sidewalls 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 that the front angle of the drill is sharpened within the required limits (25-30 °). On the other sidewall, the holders mark and drill through holes perpendicular to the plane of this sidewall for each drill of one or another diameter. The length of the holder is chosen so that it is convenient to hold it when sharpening drills.

You can’t install a fixture on a regular thrust bearing (armrest), so you have to come up with some kind of table or shelf for it, you can transfer the grinding machine to a table where there will be room for this fixture. On the base, place a holder with a drill inserted into it to be sharpened close to the rail. Rotate the drill in the socket of the holder so that the edge to be sharpened is oriented horizontally. With your left hand, hold the drill at the edge to be sharpened, with your right hand, the drill shank. Pressing the holder against the beveled rail, bring the drill to the emery wheel and sharpen one edge. Then unfold the drill and process the second edge in the same way.

You can do it even easier:

Sharpening angles and other characteristics of the drill

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

The 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; c - pen width; g - foot; d - leash; e - helical chip groove; g - feather; h - shank; and - jumper; L - total length; L 0 - the length of the "working cutting part"; D - diameter; ω - the angle of inclination of the "groove chip screw"; 2φ - angle at the top; f is the width of the spiral ribbon; ψ - 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 as a guide during cutting and is a spare when regrinding the drill. Cylindrical chamfer-ribbons are located on the feathers of the guide part along the helical line. Ribbon serves to guide the drill in the hole, as well as to reduce the friction of the drill against the walls of the hole. It doesn't have to be wide. So, the width of the drill bit with a diameter of 1.5 mm is 0.46 mm, 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 collar.

The diameter of the drill, measured by the ribbons, 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 on the walls of the hole.

In order to understand the device 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 chip to be separated is free to move away from the cutting point. The surface of the tool along which the chips run is called the front face. This face is tilted back at some angle from the vertical plane.

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

Thanks to this angle, it is easier for the tool to plunge into the metal and the chips come off more freely along the front edge. The angle between the front face of the tool and a plane drawn perpendicular to the cutting surface is called the front 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 back face 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 faces of the tool is called the angle of taper and is denoted by the Greek letter β.

The angle between the front face 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 taper angle β and the relief angle α.

The front and back angles are the angles that must be observed when sharpening.

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

The cutting edge is the line where the front and back edges of the tool intersect. The rake angle γ at the drill forms a helical groove. The angle of the groove to the drill axis determines the rake angle. The value of the angles γ and α along the cutting edge is variable, which will be discussed below.

The drill has two cutting edges interconnected by a jumper located at an angle ψ to the cutting edges.

Having received a general idea of ​​the geometry of the cutting part of the drill, let's talk in more detail about its elements. The front face of the twist drill is a complex helical surface. Edge is a conventional name, since the word "edge" suggests a plane. The helical groove, the surface of which forms the front face, intersecting with the intake cone, creates straight cutting edges.

The angle of inclination of the helical groove to the axis of the drill is denoted by the Greek letter ω. The larger this angle, the larger the rake angle and the easier the chip flow. But the drill with an increase in the inclination of the helical groove is weakened. Therefore, for drills with a small diameter, which have less strength, this angle is made smaller than for drills with a large diameter. The helix angle also depends on the material of the drill. HSS drills can work in more stressful conditions than carbon steel drills. Therefore, for them, the angle ω can be larger.

The choice of the angle of inclination is influenced by the properties of the material being processed. The softer it is, the greater the angle of inclination. But this rule applies in production. At home, where the same drill is used for 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 room for the chips to be easily evacuated from the flute without weakening the drill too much. The groove width should be approximately equal to the nib width. The depth of the flute determines the thickness of the core of the drill. Strength depends on the thickness of the core. If the groove is made deeper, the chips will be better placed, but the drill will be loose. 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 fraction 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 re-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, which means that the rake angle also decreases. The working conditions of the cutting edge at the center of the drill will be more difficult.

The rear angle, as well as the front angle, varies in magnitude at different points of the cutting edge. At points closer to the outer surface of the drill, it is smaller, at points closer to the center, more. The back angle is formed when sharpening the intake cone and is approximately 8-12 ° on the periphery of the drill, and 20-25 ° in the center.

The jumper (transverse edge) is located in the center of the drill and connects both cutting edges. The angle of inclination of the bridge to the cutting edges ψ can be from 40 to 60°. Most drills have ψ=55°. The jumper is formed by the intersection of two back faces. Its length depends on the thickness of the core of the drill. Since the thickness of the core increases towards the shank, the length of the web increases with each sharpening. In the process of drilling, the transverse edge only prevents the penetration of the drill into the metal. It does not cut, but scrapes or, rather, crushes the metal. No wonder it was once called the scraping blade. By cutting the web length in half, 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 angle at the top 2φ has a great influence on the operation of the drill. If the angle at the top is small, the chips with their lower edge will touch the wall of the hole and there will be no conditions for proper chip formation.

The figure below shows a drill with a normal taper angle.

The edge of the chip in this case fits well into the groove. Changing the corner angle changes the length of the cutting edge and, consequently, the load per unit of its length. With an increase in the angle at the top, the load per unit length of the cutting edge increases, while the resistance to the penetration of the drill into the metal in the feed direction increases. With a decrease in the angle at the top, the force required to rotate the drill increases, since 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 HSS is 116-118° and is considered suitable for many materials. But in order to provide the best working conditions, it is changed, as shown in the table.

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Drills for metal are always hardened, but products can become dull over time. Naturally, this is not a reason to throw them out. If desired, you can sharpen the drill with your own hands, using professional equipment or home-made devices.

The main types of sharpening

Experienced craftsmen know that sharpening a drill for metal can be different. depending on diameter and application.

• Single plane sharpening is designed for drills with a maximum diameter of 3 mm. In the process of doing the work, it is possible to “chunk” the edge, so you need to be very careful. To properly sharpen the product, it should be applied to the circle and moved parallel to the surface.
• The tapered procedure is for larger metal cutting tools. In this case, the tool must be held with both hands, making consistent sharpening.
• Finishing is performed after the end of sharpening. Thanks to this procedure, it is possible to grind the cutting edge and eliminate even the smallest notches.

To sharpen the drill with your own hands correctly, you must use the appropriate machines. Similar devices are divided into 2 groups.

If you are interested in the question of how to sharpen a drill for metal, then be sure to purchase the appropriate machine. For home use, an inexpensive model with medium power is suitable. It will allow you to sharpen small drills for metal.

Naturally, when buying pay attention to the noise level, as well as the design of the model. The best option would be a simple machine, because it will not be difficult to select the necessary parts for it.

It is necessary to buy such devices only in specialized places, since the kit provides for the presence of a technical passport. Moreover, you will be given a warranty card.

Use of machines at home

As mentioned earlier, at home it is advisable to use household machines. With their help, it is possible to sharpen various types of drills. It is important to remember that for some varieties you will have to buy the appropriate circles.

To sharpen the drill yourself, you should give preference to a machine equipped with a universal chuck. It allows you to clamp elements of various diameters.

The kit often comes with:

• keys;
• collets;
• spare parts;
• lamp for the working area.

The equipment from Drill Doctor and GS is the most popular. Similar products are designed for sharpening drills with a diameter of 2–13 mm and 14–34 mm. Unfortunately, this equipment does not allow you to sharpen drills that are too thin. For this purpose, you will have to purchase a special machine.

All equipment designed for sharpening drills at home, has a number of advantages:

• the ability to work from the mains;
• high performance;
• ease of use;
• functionality;
• sharpening accuracy;
• affordable price;
• compact dimensions;
• light weight;
• convenient control system, thanks to which you can adjust the intensity of sharpening and its speed.

Homemade sharpeners

If you do not have the appropriate machine, then you can sharpen using other devices. We are talking about an electric drill or home-made equipment, created according to the drawing. It is best to give preference to the second option, otherwise you can ruin a lot of drills before you master the correct sharpening.

You can create a suitable fixture with your own hands even from wood. So, a bar with holes corresponding to the diameter of the drills is fixed on a horizontal surface. The mentioned holes are made at a slight inclination to obtain the required sharpening angle.

Some masters prefer an electric drill equipped with the appropriate nozzles. Naturally, a small range of similar items, which complicates the sharpening with your own hands. As a rule, a stone and a leash are included with the nozzles. If you plan to sharpen drills using a specific drill, the leash should be shortened immediately.

If you wish, you can independently make a similar nozzle for a drill, guided by the recommendations given in the corresponding video. Such devices must be equipped with fasteners for fixing the drill.

Features of the sharpening process

If you first decided to sharpen a part with your own hands, do the work in a strict sequence.

1. First of all, the back surface is processed. So, the drill is pressed tightly and constantly monitored so that the sharpening angle remains the same. As a result of processing, the tip of the drill will resemble a regular cone.
2. Next comes the turn of the cutting part.
3. The last stage involves finishing the back surface. In this case, it is necessary to make sure that the size of the jumper is no more than 0.4 mm. Naturally, for a large drill for metal, this parameter should be slightly larger.

If something doesn't work out right the first time, don't despair. It is best to start practicing with tools that are unlikely to be needed. The main thing is to learn how to press and maintain the angle correctly. In this case, it is necessary to take into account the fact that the side parts of the drill, and not the tip, are responsible for drilling. Accordingly, the edges must be sharpened.

It is important to remember that in the process of sharpening small particles are formed. Because of the heat, they scatter in the form of sparks. It is for this reason that safety precautions must be followed. We are talking about the use of goggles and gloves. Also, when sharpening, make sure that the drill is securely fixed. Otherwise, it may accidentally slip out of your hands.

If you decide to use the appropriate machine for sharpening, be sure to prepare your workplace. In particular, we are talking about good lighting. Also need wear protective gloves and goggles.

To properly sharpen the drill with your own hands, you need use a suitable device. It can be a household or industrial machine, as well as an electric drill with a special nozzle. If you have not tried to sharpen a drill before, first check out the corresponding video.

On the Internet you can find a huge number of schemes for the manufacture of devices with which you can sharpen drills. However, most often such schemes are very complex and a simple layman cannot understand them. You can, of course, try to sharpen the drills by hand on a grinder, holding the tool at an angle of 60 degrees. However, even in this case it is very difficult to achieve perfect sharpening so that there is no center shift. However, there is an alternative option - this is a home-made device for sharpening drills made from a door hinge. To make such a device under the power of everyone.

Features and manufacturing process

The mechanism of operation of a homemade sharpener is based on the rotary movement of a conventional door hinge (you will need a hinge with a metal thickness of at least 3 mm). The lower part of the loop will be fixed on the handrest, and the upper part will move the drill. In order to securely fix the lower part of the hinge on the handrest, you will need to weld a 25x25 mm corner, then drill a hole in it and cut the thread for the M6 ​​bolt.

At the next stage of work, you need to set the correct angle for sharpening the drill, using for this a piece of a steel corner that needs to be welded to the loop, and an ordinary school ruler with a protractor. To check the correctness of the set angle, use a drill with factory sharpening - it must be in contact with the entire plane of the pen edge. Next, you need to weld an M8 stud to the structure with a pre-prepared clamping nut made of metal 4 mm thick. The device is ready!

Having picked up the correct drawing of a device for sharpening drills, you can make home-made full-fledged equipment at home. Thanks to this device, the task of providing the desired geometric shape of the tool is greatly simplified.

When using it, there is no need to worry not only about the rotation of potentially dangerous whetstones, but also about the sharpening angles that need to be properly maintained, catching every degree by hand.

Features of the use of sharpening homemade devices

In the process of drilling holes in metal products, the drills wear out quite a lot, which leads to their heating and loss of their properties. In order to avoid such a phenomenon, measures are required to ensure the regular restoration of their geometric parameters. This can be done using special equipment for sharpening drilling tools. The creation of such a simple device can be done independently, which will allow high-quality sharpening without any significant financial costs.

Many experienced professionals almost never use sharpening devices, because they are absolutely confident in their experience and eye, which allows them to correctly sharpen drills. But in practice, the use of such devices is extremely necessary, as this allows mechanization of this process. As a result of such work, maximum accuracy and quality of the performed sharpening will be ensured.

The modern market offers various types of equipment that allows you to qualitatively restore the geometry of cutting tools, even in the absence of experience in this matter. At the same time, there is no urgent need to purchase such products, since they can be made by hand according to the existing drawings of devices for sharpening drills.

Drawings of the simplest fixtures

The simplest devices for sharpening can be bushings, the inner diameter of which corresponds to the transverse dimensions of the drills. The sleeve is rigidly fixed in a reliable base, taking into account a certain angle. When selecting a bushing for such devices, one should pay attention to the correspondence of its inner diameter with the transverse size of the tools being sharpened. It is forbidden for the processed tools to dangle in the sleeve, since even with a deviation of 1-2 degrees along the axis from the required values, the quality and accuracy of sharpening can be significantly reduced.

Such home-made devices for sharpening drills must be equipped with clips. For their manufacture, copper or aluminum tubes are suitable, the inner diameter of which is equal to the typical size of the drilling tool used.

In some cases, the task can be simplified by installing a wooden block on this structure, in which holes are to be drilled, with a diameter corresponding to the tool used. One of the most important elements of such a product is the presence of a handpiece, which is necessary for:

• ensuring the correct fixation of the drilling tool and the possibility of precise movement in relation to the surface of the abrasive stone;
• creating a stop point for the drill being sharpened.

Such products made of oak bars, in which holes of various sizes are provided, are the most reliable. Thanks to them, high-quality and accurate sharpening of tools is performed. The main task that must be solved by a homemade machine or similar device is the correct orientation of the cutting part of the processed tools in order to obtain the accuracy of the required sharpening angle.

For the manufacture of a home-made machine for sharpening drills, a number of different design variations of such equipment can be used. If you have the appropriate drawings and understand the principle of operation of this equipment, you can make grinding equipment yourself at home.

The design consists of the following elements:

Promoport site

Attachment for drill and stop screw

Bolts, nuts, pins, screws

There are important rules that must be observed during the operation of such a device, namely, the tool being sharpened must not rotate around its axis. In the event of even a slight turn, the sharpening must be carried out again.

Sharpened tools should be allowed to cool naturally. After that, you should check its restored geometric parameters. You can use a template for this. It should be borne in mind that each cutting edge of the drill may differ from each other by no more than a tenth of a mm. At the same time, special attention should be paid to this parameter if the drills have a small diameter.

Video "Device for sharpening drills according to the drawing"

Drawing of a complete fixture

A fairly simple way to make homemade grinding equipment, which is practically no different from a factory product. It takes about 1.5-2 hours to assemble it according to ready-made drawings.

To make do-it-yourself devices for sharpening drills, it is necessary to provide for the following consumables, equipment and tools:

• welding machine;
• electric drill;
• grinders;
• standard locksmith tool kit;
• corner, the size of the shelves of which is 30x30, and its length is 100-150 mm;
• metal plates having different thicknesses (3-5 mm);
• hairpins or a piece of steel rods, the diameter of which is 10-12 mm;
• washers, screws, bolts and nuts of various sizes.

First of all, the manufacture of the frame is carried out, which will be the base in the grinding device. For this, a steel plate is used, on which a steel bar (12 mm in diameter) is welded at an angle of 75 degrees. It will be the axis.

After that, a washer should be put on the welded rod, which will be a thrust bearing. The angle, rotation of the bed when sharpening the drill will be insignificant, so there is no reason to use a standard ball bearing.

The bed where the sharpened tool will be placed is made from a prepared corner. One side on the corner profile that faces the side of the grindstone needs to be ground off at a 60 degree angle. On the bed, according to the drawing, a bracket is welded, through which the device's rotary assembly will be fixed. As a result of this, a structure will be made, the corners of which, in the case of a parallel position of the bed and bed, must be located to the surface of the abrasive stone in accordance with the angle of the drill being sharpened.

The grinding machine, which is shown in the drawing, has fixed angles of inclination, but for greater opportunities it is desirable to provide the ability to adjust the angles. In such cases, there will be more chances of using the device if necessary to restore tools with different sharpening angles, for example, if it is necessary to sharpen drills for metal, concrete, etc.

To create a more functional assembly, you can use the drawings of other structures that have the ability to adjust the angles:

Video "Device made according to the drawing"

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 result, to their failure. To avoid this, it is necessary to regularly restore their 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 accurately sharpen dull drills and not spend money on acquiring new ones.

A device designed for sharpening drills is especially relevant in cases where these tools often have to be worked on metal, as a result of which they wear out quickly and require regular restoration. When processing wood, the drill used for these purposes practically does not wear out, therefore, it 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 practically do not undergo regrinding and are used by craftsmen until they are completely worn out or broken.

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

On the modern market, there are many devices for sharpening drills that allow you to quickly, accurately and accurately restore the geometry of the cutting tool, even if you do not have experience in performing such procedures. Meanwhile, you can not spend money on the purchase of such devices, but make the simplest machine for sharpening drills with your own hands.

Manufacturing options

On whatever device or machine the drill is sharpened for metal, its quality must be controlled. For this, a special template is used, which can also be serial or handmade. This template is necessary primarily to control the accuracy of the angles of the cutting part, which are formed during the sharpening of the drill. The tools used to work with different materials differ from each other, including the values ​​of such angles. You can find out the exact values ​​\u200b\u200bof the latter from the reference table.

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

As the simplest tool for sharpening drills, you can use a sleeve with an inner diameter corresponding to the transverse size of the drill, rigidly fixed on a reliable base at a certain angle. When choosing a sleeve for such a device, it is necessary to ensure that the diameter of its inner hole strictly corresponds to the transverse size of the drill being sharpened. The tool being machined 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 home-made device for sharpening drills with a holder made of copper or aluminum tubes, the inner diameters of which correspond to the typical sizes of the drills you most often use. You can do it easier and supplement such a device used for sharpening drills with a wooden block. In the bar, it is necessary to drill holes corresponding to the sizes of tools of various diameters. The most important design element of such a device is a handpiece, which simultaneously solves several important tasks:

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

A similar device based on an oak bar with holes of different diameters was used by our grandfathers, who used it to perform high-quality and accurate sharpening of drills. The main task that a home-made machine or device used for sharpening drills should solve is to correctly orient the cutting part of the drill being processed in relation to the working surface of the grinding wheel.

To make a home-made machine for sharpening drills, you can use various designs of such devices. Corresponding drawings are easy to find on the Internet. Moreover, if you understand the principle of operation of such a device, then you can make your own grinding machine according to your own design.

Fixture details drawings

Promoport Promoport platform Mobile platform
Drill holder and stop screw Turntable Bolts, nuts, pins and washers

There is an important rule that must be observed when working with such a device: during its use, the sharpened drill should not rotate around its axis. If the tool turns 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 stand out.

1. The length of the cutting edges, even with their symmetry and correctly selected angles, is not the same, respectively, the drilling center is offset relative to the tool axis. A drill with such a mistake made during sharpening will create a strong beating during the drilling process, and it will be quite difficult to get into the center of the future hole on the surface of the workpiece. A tool sharpened in this way is more likely to break during further operation.
2. With precise centering of the drill, the angles under which its cutting edges are located are asymmetrical. Since only one cutting edge will work due to this, drilling will be slow, while the tool tip will actively heat up. This will lead to the release of the metal from which the drill is made, and the hole created will be broken (it will have a diameter greater than the transverse dimension of the tool itself).

How to make a twist drill sharpening machine

As a basis for the manufacture of a sharpener for twist drills, you can use any serial grinding unit that can work without runout and withstand significant loads. When equipping such a machine with additional devices, the following requirements must be observed.

• The axis of the handpiece must coincide with the axis of rotation of the grinding wheel, while it can be located with it in the same horizontal plane or be higher than it.
• All elements of the structure to be created must be securely fixed to ensure the safety of grinding work.
• The design of the fixture should allow for the possibility of sharpening drills both in manual and semi-automatic modes.
• The device of the handpiece should provide for the possibility of positioning the drill shank at any angle.

In the manufacture of this device for sharpening drills, complex technical devices and scarce materials are not required, which 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 finalized before assembling the fixture, you can use an ordinary grinder and a welding machine.

Since the stop of such a device must be oscillating, which is necessary for sharpening drills in semi-automatic mode, a loop connection should be used to fix it. When selecting a tube, bracket and bolt for the mounting unit, it should be borne in mind that there must be no backlash in the fixture. Homemade of the proposed design has two degrees of freedom.

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

For the manufacture of structural elements of such a device, sheet metal of various thicknesses is used, namely:

• base plate - 4 mm;
• guide plate for drill - 5 mm;
• other structural elements - 3 mm.

The handpiece of the device, on the upper part of which the base plate is installed, must be securely fixed to the body of the grinding machine. For this, an additional metal “cheek” is used, which is 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 machined tool, is fixed on the base plate with a screw connection.

The device and design features of the considered device for sharpening drills allow it to rotate through an angle of up to 90 °. Thanks to this ability, almost any of the methods used today can be used to sharpen drills with this device.

The drill sharpened with 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 base plate is located slightly above the axis of rotation of the grinding wheel, when using such a device, the optimal shape of sharpening the rear 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.

It well demonstrates the process of working with such a device video, which is easy to find on the Internet.

Despite the simplicity of the design, such a device provides high accuracy of the performed sharpening, for quality control of which you can not even use a template. By fixing the oscillating plate of this jig to a fixed angle, it can also be used to sharpen drills equipped with carbide inserts.

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