How To Sharpen Drills For Metal Angle Grinder
If the task is to automate the process of sharpening drills for concrete, then it is best to use the helical method, which assumes that, in addition to rotation, two translational movements are also communicated to them, coordinated with the rotation of the grinding wheel. One of these movements, which is called oscillating, is directed along the generatrix of the grinding wheel, parallel to the cutting edge of the tool; during its execution, back angles are not created. The occipital movement, during which the back angles of the working part are formed, is performed along the axis of the drill.
Drill screw sharpening
When performing screw sharpening, two sections of the working part of the drill must be especially carefully processed:
- 0-1, located on the diameter of the core of the tool and processed by the edge part of the grinding wheel;
- 1-2 machined by the generatrix of the circle.
For helical sharpening, as well as for conical sharpening, an increase in the back angles of the working part is characteristic as it approaches the center of the drill. This feature of this method allows, by setting even small values of the clearance angles for the peripheral region of the cutting part, to obtain the clearance angles of the required value in its central zone.
The most common way to restore the geometric parameters of drills used for concrete work is conical sharpening. The tool to be sharpened is installed in a special prism that can move (swing) around its axis located at a certain angle to the working surface of the grinding wheel. The rear surface of the cutting part of the drill for concrete takes the form of a cone with the apex located at the intersection of the working surface of the grinding wheel with the swing axis of the prism.
A sharpening device, even a relatively simple homemade one, allows you to sharpen the cutting edges of the drill evenly
To sharpen the drill using this method, it is necessary to adjust the parameters indicated in the table.
- The distance between the axis of the sharpening cone (the swing axis of the tool) and the axis of the drill itself (h);
- Distance from the tip of the sharpening cone (H) to the drill axis;
- The angle with which the drill axis (o) and the sharpening cone axis cross;
- Half the value of the angle located between the sides of the sharpening cone (b).
Conical drill sharpening diagram
There are two methods for conical sharpening of concrete drills:
- The tip of the tool to be sharpened is lower than the tip of the sharpening cone. When sharpening a drill on concrete in this way, use the following settings: a. 45 °, b. 13–15 °, H. 1.9 D, h. (0.05–0.08) D. In this case, the angle "o" located between the axis of the drill and the guide of the taper, less than the angle between the axes of the tool and the circle forming the shape of the grinding wheel (φ0).
- The tip of the drill to be ground is higher than the tip of the sharpening cone. With such sharpening, the following parameters are used: the distance of the tip of the cone from the tip of the drill (H). 1.16 D; half of the angle at the tip of the sharpening cone (b). 30–35 °; the angle at which the axes of the drill and the cone are located (o). 90 °; displacement (h). (0.05–0.08) D; angle φ0 0.
The tool sharpened according to these methods for working on concrete has the parameters indicated in the table.
Table from text
Drill sharpening angles
The value of the clearance angle of the cutting part is changed by adjusting the value of h. the distance between the intersecting axes of the sharpening cone and the drill. To change the angle of inclination of the transverse cutting edge (φ), it is necessary to turn the sharpened drill around its axis, and to change the angle in the plan, change the angles "o" and "b". If you increase the distance between the axis of the sharpening cone (h) and the axis of the drill, the angle "a" will increase, and the angles "φ" and "2φ" will decrease. An increase in the parameters "o", "b" and "H" leads to a decrease in the values of φ, 2φ, as well as the angle "a".
Geometrical parameters of the cutting part of drills with victorious inserts
Tapered sharpening is preferred because it creates a sharper increase in the clearance angle of the drill. When drilling concrete, the tool makes a rotational movement and at the same time moves along its axis, so the trajectory of movement of each of the points of the cutting part is a helical line. The value of the angle "m" at which such a helical line is located to the cutting plane without taking into account the axial movement of the tool is determined by the following formula: tg m = S0 / nD, where S0 is the drill feed, measured in mm / rev. From this formula it becomes clear: the closer the point on the surface of the cutting part is to the axis of the drill, the smaller the clearance angle in the plane in question will be. This property of conical sharpening, which assumes that the clearance angle in the areas of the working surface of the drill approaching its axis increases, contributes to an increase in its durability.
Drill sharpening for concrete: methods, parameters, angles
Drills designed to perform work on such a complex material as concrete are made using carbide inserts, which are soldered onto their cutting part. Like any other, such a tool wears out during use, it is then that the question arises of how to sharpen a drill on concrete. In order to restore the geometric parameters of the working part of the concrete drill and at the same time not damage the tool itself, you can try several methods of sharpening it, each of which is relevant under certain circumstances.
A victorious drill with blunt edges drills for a long time and overheats quickly
The sharpening of the drill bit for concrete can be carried out on a corundum grinding wheel mounted on the appropriate equipment. Such drills are sharpened in the same way as ordinary drills, but there are a number of nuances that should be taken into account.
Carbide inserts, which are equipped with the cutting part of concrete drills, are very critical for severe overheating. The latter can lead to the fact that the insert cracks or even disconnects from the main body of the tool at the point of its soldering. That is why, in the process of sharpening concrete drills, they should be cooled with water as often as possible, without bringing the cutting part to overheating. It should be borne in mind that the very red-hot tip of a drill for concrete, if it nevertheless reached such a state, should in no case be immersed in water: it must cool slowly under natural conditions. Harsh cooling of carbide inserts can cause them to burst.
The cutting edges of the drill must be sharp without roundness
The concrete drill should be sharpened in such a way that its worn cutting edges become straight, and the place of their intersection exactly coincides with the axis of rotation of the tool. In addition, care must be taken to ensure that the machined cutting edges of the carbide insert have the same length. In this case, the load taken by each of these edges will have the same value, respectively, they will wear out evenly.
Differences in the length of the cutting edges of a concrete drill can also cause the tool to be pushed to the side during the drilling process due to the higher load applied to the longer cutting section, eventually causing it to break.
The angle of sharpening of the cutting edges is another important parameter that should be paid attention to. If the uniformity of this parameter for two edges is not maintained, then the edge having a larger sharpening angle will work and, accordingly, actively load. This will also lead to rapid tool breakage.
How to sharpen the drill
In the process of drilling, the tool that performs such an operation must contact the workpiece material only with its cutting edges. That is why the back surface of any drill must be sharpened at a certain angle, which provides a gap between it and the bottom of the hole being formed (cutting surface).
This method of sharpening drills is used mainly in cases where they are planned to be used for drilling materials that are not too hard and not too high. The peculiarities of a tool with such a sharpening are that when processing too hard materials, the bridge on the cutting part, located in the central part of the drill tip, will undergo active wear.
Geometry of double sharpening of a victor drill
When deciding how to sharpen a victorious drill, you should first of all take into account which materials will be processed with its help. over, any sharpening method presupposes strict adherence to the recommendations for performing this procedure.
Drill sharpening for metal: how to properly sharpen a drill at home
It is impossible to perform high-quality metal processing (including drilling a hole in a metal part) without using a tool whose mechanical characteristics and geometric parameters correspond to the required values. That is why the question of how to sharpen a drill for metal correctly is relevant for DIYers who often work with such a tool that wears out (which is natural) during operation.
Sharpening a drill for metal using a special tool greatly simplifies the task
Drills designed for metal work have to be sharpened much more often than those with which woodworking is performed. When processing such a soft material such as wood, the drills are practically not dull and can be successfully operated for a very long time, fully retaining their original characteristics. The situation is completely different with drills, with the help of which holes are made in metal parts. It is necessary to constantly monitor the condition of such drills and immediately take measures if their working part has undergone wear.
The fact that a drill for metal needs to be sharpened is evidenced by a number of signs:
- Squeak and hum from a worn-out instrument;
- Intensive heating of the drill during its use;
- Poor hole quality.
For drills with different cutting edge lengths, only one side works and the chips come out along one spiral flute
Working with a worn drill bit is not only ineffective but also unsafe. At any time, such a drill, on the working part of which significant loads are applied, may break, and its individual fragments, flying in different directions at high speed, can cause serious injury.
Drill sharpening parameters
Basic forms of sharpening twist drills
The most important parameters that should be considered in order to properly sharpen a metal drill with your own hands are:
- The angle at which the back of the tool is to the drilling plane;
- Sharpening angle of the front surface of the cutting part;
- Length of the crosspiece on the cutting part;
- The angle at the tip of the cutting tool;
- Length of cutting edges.
The main parameters of sharpening the drill
To sharpen the drill to be of high quality, it is necessary to ensure that it is fed into the processing zone at the required angle. To solve this problem, various devices are used that are equipped with grinding machines.
It should be borne in mind: if the sharpening of the drill for metal is performed incorrectly, this can lead not only to a poor-quality result, but also to tool breakage.
Influence of nose angle on correct chip formation
An emery machine equipped with a grinding wheel is a universal device that allows you to sharpen a drill for metal with high quality even at home. Using such a device, the technological operation should begin with machining the flank of the tool. The drill to be sharpened is held in relation to the grinding wheel so that its cutting part is parallel to the surface of the wheel. This sharpening technique is ideal for metal drills with a diameter of less than 10 mm.
To sharpen drills with a diameter greater than 16 mm (including those equipped with carbide inserts), it is best to use an emery machine with a special device. The use of the latter allows not only to control the sharpening angle of drills of significant diameter, but also to carry out such a process with maximum safety.
Sharpening precision in a special tool is achieved by precise fit and secure fixation of the drill in the arbor
Grinding machines equipped with accessories are recommended for use in cases where it is necessary to sharpen drills of the following categories:
- Used for drilling blind holes, which is characterized by a decrease in the axial cutting force;
- Universal, characterized by increased durability;
- Used for drilling deep holes and characterized by a small amount of undercut.
The main task solved by devices that allow high-quality sharpening of a drill for metal on a grinding machine is the correct orientation of the cutting part of the tool in relation to the surface of the abrasive wheel. That is why there is a special base plate in the design of such a device. The machine itself, the motor that drives the grinding wheel in rotation, as well as the turntable, on which the tool being processed is fixed, is installed on it. The use of such a column allows you to sharpen drills in almost any spatial position, positioning their cutting part in relation to the surface of the grinding wheel at the required angles.
What is needed for the procedure
To sharpen a drill for metal yourself, you must first determine what tasks it will be used for. In production conditions, for sharpening drills, as a rule, special devices are used to ensure maximum accuracy and productivity of such a process. When sharpening drills at home, you always have to look for ways to make the result of this process of high quality.
The minimum set for sharpening drills for metal should include:
- Sanding machine;
- Grinding wheels of various hardness, selected depending on the material of manufacture of the drill to be sharpened;
- The container for the coolant and the liquid itself, which can be used as ordinary water (or machine oil);
- Tools to maintain correct sharpening angles.
Drill sharpening stand mounts next to the abrasive disc to sharpen the cutting edge at a precise angle
When sharpening drills with your own hands, you need to pay attention to the following parameters:
- The angle between the plane of the front of the drill and the base of its cutting edge (such an angle, measured in the main cutting plane, is called the front);
- The clearance angle, which is measured in the same way as the front angle, but along the back plane of the drill;
- Tool nose angle measured between two cutting edges.
To sharpen metal drills in accordance with all the rules, you must adhere to the following values of the above parameters:
- Rake angle of the cutting part. 20 °;
- Back angle. 10 °;
- Apex angle. 118 °.
Table 1. Angles at the top of the drill depending on the material being processed
Table 2. Rake and rake drill angles
If you need to sharpen a drill for metal in a production or at home, you must strictly follow safety precautions. This process is accompanied by the formation of a large number of sparks, from which it is necessary to protect the organs of vision. In addition, since this procedure is performed with sharpened metal tools, it should be carried out using gloves to protect the hands.
Benefits of using special tools
A big advantage of using grinding machines equipped with special devices is that the movement of the tool being processed on them is provided by a drive connected to an electric motor. The structural diagram of such a drive includes a bearing assembly and a shaft. At the end of the latter, a drill is fixed, which must be sharpened.
Before starting the procedure, the tool is fixed on the device at the required sharpening angles. After the metal drill is fixed on the movable column of the fixture, it itself is brought to the rotating grinding wheel. Thus, all corners that need to be formed on the flank of the cutting part are automatically maintained during the sharpening process. Among the main disadvantages of such a drill sharpening machine, its large dimensions are usually noted.
Drill sharpening machine
If you are looking for an answer to the question of how to properly sharpen a drill for metal without performing complex manipulations with the tool being processed, you can recommend more compact devices. One of these devices is a packing machine. It is installed on the spindle of a conventional electric drill, from which its main working element, the grinding wheel, is driven into rotation. One end of such a device is equipped with a special coupling connecting the device with a rotating spindle of an electric drill, and the other with a cover with holes of different diameters, into which the working parts of the sharpened metal drills are inserted.
Drill bit for sharpening Sparta drills
It is very easy to teach someone to use this tool, which allows you to quickly sharpen a drill at home. At the same time, you may not even show such a process live or live, everything is clear and without demonstration. To sharpen a drill for metal using such a device, it is enough to insert the tool into the hole of the corresponding diameter until it stops and turn on the electric drill, which will rotate the grinding wheel. A tool sharpened with such a simple device has all the required geometric parameters.
It would seem that you can sharpen a drill using any device that can rotate the grinding wheel. Meanwhile, without the use of fixtures for fixing the tool in the sharpening process, such a procedure cannot be performed efficiently. In addition, serious injury can occur. You can turn to this simplest sharpening method only if you need to sharpen small-diameter drills that are easy to hold in your hands during processing.
When sharpening manually, a corner fixed on the support will help to maintain the required parameters
After you have sharpened the drill for metal, it is necessary to perform such a technological operation as debugging. It is needed in order to bring the quality of the cutting part of the reconditioned tool to the required values. Lapping is carried out using grinding wheels with a small grain size. At the same time, all irregularities are eliminated from the cutting part of the drill, it is given smoothness. Drills with no roughness on the working part create less friction during the drilling process, heat up less, which means they can last longer. Grinding wheels made of silicon carbide are used to perform finishing operations both in production and at home.
An important condition for high-quality sharpening is the absence of vibration of the abrasive stone
Drills, the working part of which is equipped with hard alloy solders, can also be sharpened, but a number of nuances should be taken into account. Carbide inserts are very critical of overheating, therefore, such metal drills can be sharpened qualitatively only at low speeds of rotation of the grinding wheel. In addition, when sharpening, care must be taken that the tool does not overheat. Otherwise, the carbide inserts will crack or even break off at the soldering point.
To sharpen carbide inserts, you can follow the processing technology of conventional cutting tools. It must also be borne in mind that diamond grinding wheels are used to sharpen drills with carbide inserts, since only they can effectively cope with the processing of such a hard material.
How to sharpen a metal drill at home?
- When to sharpen?
- Required tools
Whatever the drill turns out to be. even a high quality one. after hundreds of drilling cycles it becomes duller, losing the perfect sharpening given to the product itself at the factory. It will not drill a perfect, not torn hole until the drill is sharpened.
Any of the selected tools, including those equipped with an electric motor, must sharpen steel products (knives, drills, scissors, etc.). The second requirement is to keep the drill to be sharpened in the process. How quickly and efficiently the drill is sharpened depends on the setting of the required grinding angle of the excess steel layer from the edges of the point and the speed of pushing the product towards the grinding wheel. Mechanized sharpening tools allow you to bring a drill with a diameter of 3-19 mm to working condition in a couple of minutes. Twist drills are sharpened on special or conventional machines with an electric motor and a simple feed system. Such a machine can be assembled independently in a garage. there is no need to purchase professional machines; often the alignment of the drilling point is straightened with a file, a sharpening stone or a circle.
The master will need, in addition to the electric drive itself, a vice in which the turned product is clamped.
To turn an angle grinder drill, do the following:
- Clamp the drill in a vice vertically;
- Grind back edge to remove wear marks;
- Grind the cutting edge at a 120 ° angle.
Do not hold the drill continuously for more than two seconds. Short sessions involve removing thin, much less than 1 mm, layers of alloy from the working edge. The drill is ready for work again.
The angle grinder is distinguished by its speed of use, mobility, but the master pays for turning with it with injury risk. Even putting on a protective cover on the grinder, there is a possibility that the wheel will crack, the tool will lead with a short jamming at a speed of thousands of revolutions per second. The sharpener reduces the risk of injury due to the rigid fixation of the machine itself. If it is impossible to determine the sharpening angle, a plastic template will come in handy, which is applied to the surface to be grinded before grinding. So that the holder does not go to the side, it is attached with a bolt. To turn a drill on a sharpener, do the following.
- Fix the drill in the holder and turn on the machine.
- Attach cutting edges to the grinding wheel at an angle of 120 °.
- If there are notches and gouges on the drill, grind them off from all sides. They disrupt the alignment of the product and drill, causing the latter to vibrate unnecessarily.
When to sharpen?
Drill sharpening for metal is needed in the following cases.
- Jumps off the core point.
- When trying to drill without marking the future hole, the drill does not catch the tip of the tip at the selected point, but “walks”, no matter how hard the master makes.
- There is a beating, knocking, noise during drilling, which turns into a high-frequency clang. Knocking and vibration loosen the drill (or hammer drill). On the mechanics broken by blunt drills, you cannot drill with new, just bought drills: a new drill often breaks from this.
- Overheating even after a minute of continuous operation. Overheating of high-speed steel will lead to a loss of its strength properties (toughness, hardness), and the product will be suitable only for woodwork, and not for metal.
- Metal particles become torn, spiral shavings disappear.
The drill bit allows you to grind drills for metal. The scheme of actions here is as follows.
- Install the adapter adapter for conventional drills on the drill. On a simple electric drill, it is unlikely to be required.
- Install a drill into the hole of the desired diameter.
- Run the drill and grind the drill from one side.
- Turn the other side from the same end to turn the second cutting edge.
The drill bit will only sharpen a slightly blunt drill.
But due to the relatively low cost. in comparison with other tools. turning drills on a nozzle is inexpensive.
How to sharpen a drill for metal and concrete with your own hands
It does not require special evidence that the drill loses the sharpness of the cutting part during operation, that is, simply speaking, it becomes blunt. A blunt drill is not a bother until it is needed. Then it suddenly turns out that it is impossible to work with a worn out or blunt drill.
We can only regret that the geometry and size of the drill were not restored in time. This article will show you how to sharpen a twist drill as well as a hard-tipped drill bit for drilling concrete.
How to sharpen a spiral drill correctly
You don’t have to worry about sharpening a drill for wood, you can work with such a drill for many months and even years without any sharpening. Unfortunately, this cannot be said about a drill for metal, which must necessarily be sharp. That is, you can drill metal with an exceptionally sharp, well-sharpened drill.
A sharp squeak at the beginning of drilling is characteristic of the loss of drill sharpness. A drill not sharpened in time produces more heat and thus wears out even faster than a sharp one.
You can sharpen the drill on special machines or using tools. Naturally, if possible, it is preferable to do this on special equipment. But in the home workshop, as a rule, there are no such machines, so you have to use a conventional electric grinder with a stone.
Main components of twist drill.
The type of sharpening depends on the shape that should be given to the back surface of the drill and can be single-plane, two-plane, conical, cylindrical and screw.
The drill is sharpened along the back edges. Both teeth (feathers) of the drill should be sharpened exactly the same. It is not easy to do it manually. It is also not easy to manually maintain the desired flank shape and flank angle.
1. Single-plane sharpening of the drill is characterized by the fact that the back surface of the pen is made in the form of one plane. In this case, the posterior angle ranges from 28-30 °. The drill is simply attached to the circle, so that the cutting part is parallel to the circle and sharpening is performed without rotating, without moving the drill.
With such a sharpening, the cutting edges of the drill can be chipped during drilling, which is a disadvantage of this sharpening method. This is the easiest hand-sharpening method and can be used for thin drills up to 3 mm in diameter.
2. Drills with a diameter of more than 3 mm should preferably be sharpened conically. Manually, without skills, such a sharpening is difficult, but possible. 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 drill is pressed against the end of the grinding stone by the cutting edge and the surface of the rear part, and is slightly swayed with the right hand, while creating a tapered surface on the rear feather edge. The drill does not come off the stone during sharpening, hand movements are slow and smooth. For the second pen, everything is repeated in the same way.
Guide the drill with the cutting edge to the grinding wheel.
We swing the drill down, and then up again.
When sharpening, try to maintain as much as possible the original shape of the factory surface of the rear part in order to maintain the desired rear corners. If sharpening is done correctly, then on drills with a diameter of up to 10 mm it is quite sufficient. For diameters above 10 mm, this sharpening can be improved by sharpening the front surface, as shown in the photo:
Front surface sharpening.
What is the point of undermining? By reducing the rake angle and increasing the angle of the cutting edge, the chipping resistance increases, which increases the drill life. In addition, the width of the transverse edge becomes smaller. The transverse edge does not drill, but scrapes metal in the center of the hole. The second figure clearly shows that here it is shortened, which makes drilling easier.
For drills with a selected small clearance angle, you can additionally sharpen the clearance surface. In this case, the drill rubs less than the back surface in the drilling hole. See photo:
Back surface undercut.
In production conditions, after sharpening, as a rule, finishing is done, which smoothes the surface, removing small notches. The drill, on which the finishing is done, wears out less than just a sharpened drill. If possible, debugging should be done without fail.
For finishing, you need to use grinding round stones from green silicon carbide (grade 63C, grain size 5-6, hardness M3-CM1) on a bakelite bond, as well as circles from Elbor LO (grain size 6-8) on a bakelite bond.
Below we present to your attention an excellent selection of trainings by looking at which you can definitely sharpen your drills.
How to sharpen an "angle grinder"
Such a power tool has long ceased to be a curiosity and is present in the arsenal of almost every master who from time to time deals with the processing of metal surfaces.
However, one "angle grinder" is clearly not enough to restore a dull drill. Additionally, you will need a locksmith vise, in which the sharpened tool will be attached, and a template made of plastic or interconnected nuts to check the sharpening angle.
The tools are ready. It’s time to move on to the process itself:
- Clamp the drill between the "jaws" of the vice;
- Turn on the "angle grinder";
- We carefully grind the worn out part;
- We sharpen the cutting surface at an angle of 115. 140 degrees (the larger the angle, the "softer" the processed metal).
How to sharpen a drill for metal with different tools: angle grinder, sharpener, drill
Modern drills have sufficient strength reserves to make straight holes in a wide variety of materials. However, during operation, the cutting edge of this complex tool can become dull rather quickly, which sharply reduces the efficiency of its use. Therefore, a drill intended for work on metal must be sharpened in a timely manner.
What signs indicate that it is time to sharpen the drill
It is not recommended to start sharpening the cutting edge of this tool without an urgent need. Indeed, during this difficult procedure, you can spoil the product with one wrong movement, and only a professional can fix such a defect. Therefore, you should start sharpening the cutting part of any tool only after it has really become dull.
Experienced craftsmen understand that the time has come to sharpen the cutting surface of the drill, according to the following signs:
- During drilling, small chips fly instead of spiral shavings;
- The workpiece and the drill quickly overheat;
- The process is accompanied by strong noise.
Each of these problems should be the reason for checking the sharpness of the tool, followed by its sharpening.
Employees of specialized centers using expensive equipment will cope with the problem in a couple of minutes. However, even in a home workshop, you can solve this problem if you have sufficient skills and tools in the form of an "angle grinder", sharpener or special attachments for an electric drill.
How to sharpen with a sharpener
This "home" method has its own characteristics. Manual sharpening mode is available only to experienced locksmiths who have extensive experience, allowing "by eye" to restore any blunt tools.
All other home craftsmen will have to purchase or borrow a special holder "from a neighbor". This device must be installed next to the sandpaper (about 1 mm.). In this case, it is necessary to ensure the stability of the bolted connection in order to exclude the displacement of the retainer during work.
Only then can you go directly to sharpening the tool:
- We fix the drill in the holder (the sharpening angle is set in advance);
- Turn on the sharpener;
- We remove damage from the cutting surface;
- We sharpen the cutting surface by short-term. no more than 2 seconds. contacts with emery.
How to sharpen with a drill bit
In this case, you must act in the following order:
- We fix the nozzle;
- We turn on the electric drill;
- Insert the drill into the hole on the device and sharpen the cutting part from one side;
- Then we take out the sharpened tool from the hole, turn it 180 degrees and sharpen the cutting part on the second side.
At home, it is easiest to restore the performance of a blunt drill for metal using a drill with a special nozzle. After all, this device, in contrast to the "angle grinder" and sharpener, will help novice craftsmen to avoid mistakes due to which they will have to throw out the damaged tool.