How To Sharpen A Drill Bit For Metal Angle Grinder
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 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 fall, may break, and its individual fragments flying in different directions at high speed can cause serious injury.
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.
An emery machine equipped with a grinding wheel is a versatile 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 plates), 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;
- Versatile, 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.
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 with which grinding machines are equipped.
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
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 the 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 done with fine-grain grinding wheels. 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.
Correct sharpening of a drill for metal is desirable to be done with the help of special devices and machines. Unfortunately, in a home workshop, such equipment is not always available, and usually do-it-yourself sharpening of drills for metal is performed on an electric grinder with abrasive materials, for example, on stone wheels. Sharpening is carried out along the back edges, while all teeth should be sharpened absolutely identically. At the same time, it is difficult to manually maintain a given angle and the desired shape, and it is easiest to sharpen at home only spiral and crown tools.
Finishing the material after sharpening
Lapping is carried out on special lapping circles. Their difference from conventional grinding wheels is that aggressive material processing is combined to obtain a good finishing surface.
Due to the softness of the material and high-quality abrasive, such circles are ideal for removing scratches and other surface defects; they can be removed without changing the geometry of the working part of the material. As a rule, such wheels are installed on an angle grinder or a drill, which makes it possible to more conveniently and accurately process a drill clamped, for example, in a vice.
In addition to the lapping discs, you can refill the work surface using emery on the disc of the same angle grinder.
The works described below are traumatic, therefore, a certain set of rules must be observed:
- The machine must have a protective cover and screen to protect the master from flying sparks and dust.
- Before turning on the machine, you need to make sure that the emery wheel is securely fixed.
- Sharpening cannot be carried out on weight, you need to support the tool on a handguard.
- If the drill breaks, it can fly into small fragments, in addition to this, a lot of abrasive dust is produced during the work and sheaves of sparks are cut out. With this in mind, all work should be carried out in goggles and a mask.
One of the compact devices for sharpening a drill is a cylindrical nozzle machine, which is fixed on the working shaft of a conventional drill, from which the grinding wheel of the nozzle is driven into rotation. On the other side of the cylinder there is a special cover with holes of different diameters, into which the cutting part of the drill needed for sharpening is installed.
This nozzle is easy to use, handling it does not require special skills, and drills that have been sharpened on it retain all their geometric parameters.
Work surface corners
In order to know how to sharpen a drill for metal on a sharpener, you should remember a number of important parameters applied to the cutting part, the implementation of which guarantees a high-quality result:
- Angle of the rear of the tool in relation to the drilling plane = 10 °,
- Front surface sharpening angle = 20 °
- Nose angle of cutting tool = 118 °
In this case, the angle at the vertex can change, depending on the material with which you have to work:
- For stainless steel, cast iron and hard bronze. 115−118 °;
- For aluminum. 130-140 °;
- For copper. 125 °;
- For soft bronze. 130 °.
There are several types of sharpening used for different purposes. The most common are:
- One-plane. With this type of processing, the back surface of the feather is made in the form of one plane. The back angle is in the range of 28-30 °. The drill is placed with the cutting part parallel to the grinding wheel and does not change its position. It is considered the simplest type of sharpening of drills with a diameter of up to 3 mm, but the disadvantage is that the cutting edges can crumble during the drilling process.
- Conical sharpening. Typically used for drills with relatively large diameters. It is difficult to carry out it without special equipment and without the appropriate skills. The drill should be taken with the left hand by the working part closer to the cone, and the tail should be held with the right hand. Then the tool is pressed against the end of the grindstone with the rear surface and the cutting edge. In the process of sharpening, the drill slightly sways by the tail with the right hand, this allows you to create a tapered surface on the feather edge.
Improper storage of the tool leads to beating of the blades against each other, adhesion of particles of the processed surfaces and general contamination of the spiral. This factor negatively affects the service life of drilling tools, therefore it is recommended to store them in special cases and stands.
In addition to storage conditions, the wear period depends on the purpose of the tool and the surface to be treated. For example, drills designed for working with wood retain their working surface for several years due to the fact that wood is a relatively soft material.
Due to the fact that metal is a harder and more durable material, drills for working with it wear out much faster. Working with a blunt tool is unacceptable, since the holes will take longer, more difficult, and will not turn out even. The drill itself will be very hot, and therefore further wear occurs even faster and will certainly lead to the fact that the tool breaks. In addition, breaking off is often accompanied by the scattering of small fragments at high speed, which can lead to various injuries. Signs that the drilling tool is dull include:
- Creaks and other non-standard sounds made during work;
- Strong heating of the tool;
- Poor hole quality.
Working with a blunt drill is difficult, often impossible. In addition to the fact that it does not drill the workpiece, the operation of a worn-out drilling tool threatens its fracture, which often leads to damage to the workpiece and to difficulties in removing the broken part of the tool stuck inside the surface.
How to sharpen a metal drill at home
High-quality processing of materials such as metal and stone is impossible without the use of drills made of good materials, the geometry of the cutting part of which is suitable for the required values. During operation, any, even the most durable drill, sooner or later wears out, losing the sharpness of the working surface. In such a situation, you need to decide whether to purchase a new material, or look for information on how to sharpen a drill for metal.
A correctly sharpened metal drill with your own hands on a tool with a diameter of up to 10 mm is quite enough for work, for wider it is recommended to additionally sharpen the front surface.
The meaning of this treatment is that by increasing the angle of the cutting edge and decreasing the rake angle, the resistance to crumbling increases, this leads to an increase in the resource of the drill. In addition, the width of the transverse edge is reduced, so that the material in the central part of the hole is not drilled, but scraped, which facilitates the process of drilling metal. For a drill with a small clearance angle, you can sharpen the flank to reduce friction inside the hole.
Application of special devices
The sharpening process according to the above method is suitable for tools with a diameter of no more than 10 mm. In order to sharpen larger drills with high quality, especially if they have a complex shape or are supplemented with special carbide taps, it is better to use a machine with a special device.
The use of this equipment allows you to control the sharpening angle, and the work will be carried out as safely as possible for the master. The use of such grinding machines is recommended for sharpening tools that:
- Used for drilling blind holes, they are characterized by a decrease in the cutting force along the axis.
- They are characterized by increased strength and alloy quality.
- Used for making very deep holes.
- Differ in insignificant amount of undercut.
These devices differ from a conventional machine in the correct orientation of the cutting part of the drill in relation to the grinding wheel. To accomplish this task, the device has a special base plate on which a machine with a circle and a rotary column that fixes the tool are installed. The use of this column allows you to position the cutting part of the drill in any position at any angle to the surface of the abrasive wheel.
The movement of the tool being processed is carried out by a drive connected to the motor. After fixing the drill in the column, it itself is brought to the circle and all the corners that need to be formed will be maintained automatically. The disadvantage of such a machine is that it has large dimensions and high cost, so its purchase is impractical for home use.
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.
How to sharpen a metal drill at home?
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 sharpens 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.
When to sharpen?
Drill sharpening for metal is needed in the following cases.
- Jumps off the core point.
- When you try to drill without marking the future hole, the drill does not catch the tip of the point 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 purchased 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 angle grinder is distinguished by its speed of use, mobility, but the master pays for turning with its help 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 is applied, which is applied to the surface to be grinded before starting 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.
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 of the drill 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 proof 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 that is not sharpened in time generates 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 regular 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.
Single-plane sharpening of the drill is characterized by the fact that the back surface of the feather 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 that can be used for thin drills up to 3 mm in diameter.
Drills with a diameter of more than 3 mm should preferably be sharpened conically. It is difficult to perform such a sharpening manually without skills, but it is 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 angles. 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
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. Cm.
In production conditions, after sharpening, as a rule, finishing is done, which smoothes the surface, removing small jags. 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 watching which you can definitely sharpen your drills.