How to sharpen drill bits. basic rules and easy ways for beginners
To perform drilling work, special tools are produced, the most common of which is a drill.
Attention! Special drills with different sharpening angles are available for different materials. In addition, the angle of sharpening is influenced by the structure of the material
A drill is a cutting tool that performs the cutting process with a rotary motion during axial feed.
Drills are used not only for making through holes of various diameters, but also for reaming existing holes.Using a drill, you can drill a through hole, make a hole of the desired diameter, perform drilling to the required depth.
Drill bit selection criteria
quite a few types of cutting tools are available on the market. When choosing, you should pay attention to the color of the metal:
- Black. Product with an anti-corrosive oxide film which additionally prevents overheating. Resistant to wear, suitable for high loads.
- Grey. Low-quality models for light-duty applications.
- Golden. This color is due to the presence of titanium in the alloy, which increases the strength.
- Dark gold. Also alloyed with titanium, but without internal stress in the core. The highest quality drill bits for heavy loads.
According to the type of design there are these types of drills:
- Traditional twist drills. Suitable for most domestic tasks.
- Left-handed. For boring out broken fasteners.
- High-precision. For delicate work, where deviations from the design are unacceptable.
Signs that it is time to sharpen the edge
Knowing that it is time to sharpen your metal drill bit is easy. These signs are bound to appear:
How to Hand Sharpen Drill Bits. Quick tip for Angle. Great Cutting
- There is a strong heat, and the metal (especially aluminum or brass) at the place of drilling can begin to melt. This is because the drill does not cut, but rubs the metal. You can tell by the rapid burnout of the grease.
- The sound becomes like a squeak. Even if you add grease, after a second there is a squeak.
- Drilling takes longer.
- The hole turns out to be “flattened”. Instead of clear, sharp edges you get a polished hole.
- If you look at the edge, it will not be sharp, but rounded, does not trim the nail. You can see this with a magnifying glass.
If these signs are observed, it is necessary to sharpen the metal drill. Often the edge gets blunt because of overheating. Lengthening the tool life by using coolant or at least some solidol.
By the way, dull drill bits are more dangerous than sharp ones. Overheating makes them brittle and often breaks off, and that can be very dangerous.
How the drill bit sharpening process works
Metal cutting speed in drilling is maximum on the periphery of the drill. This means that the greatest heating of cutting edges occurs here, and it is rather difficult to remove heat effectively from this area. This is why the blunting process begins in the corner and gradually spreads over the entire cutting edge.
The next step is back-edge abrasion. From this cutting edge, this part of the drill extends the strokes that merge to form a solid band along the cutting edge. Then this band becomes solid and expands, becoming more extensive at the periphery, narrowing towards the center of the drill bit. The cutting edge crumples, the tool becomes dull.
While working on metal drilling it is necessary to follow the sounds. in the initial stage of blunting of drill bit the tool makes sharp squeaking sound. If the drill bit is not sharpened immediately, the wear process is accelerated.
To make it easier to check whether the drill geometry is correct, very simple templates are used. How to make the simplest one will be described below. With such a template, including cases of sharpening drills without resorting to any devices, it is easy and simple to control where you need to remove more metal from the drill. As masters joke, applying such a template, you always get what you are supposed to get, simply because it cannot fail, even if you have to grind half of the drill for it.
In order not to break symmetry, the pressure force when sharpening any part of the drill bit must be identical.
Regardless of which drill bit sharpening machine you want to use with your own hands, it is important to observe all the basic requirements. If there is a sharpening machine in the garage or workshop, it is best to use it
The method of sharpening may vary depending on the configuration of the tool. But, regardless of the configuration of the drill bit, it is always necessary to sharpen only the rear cutting edges.
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It is necessary to achieve the same degree of sharpening of all facets. It is very difficult to do by hand. But, for the smallest drills in this case only manual sharpening is suitable.
The easiest tooling to sharpen is the one-plane tooling. The sharpening of a metal drill bit of a single-plane configuration should be performed with an angle of 28-30°. If the angle is not maintained, it will not be possible to restore the cutting properties of the tool.
At this angle, the drill bit should be slightly pressed against the sharpening stone. Models with two planes are sharpened similarly, but both faces must be sharpened accordingly.
If the drill bit is tapered, it is extremely important to keep its original taper. This is done by oscillating movements on the cones in the process of pressing to the stone
After sharpening the tool, it is desirable to perform finishing. Small nicks caused by contact with the stone must be removed. Due to such resharpening, the product will last much longer. For the finishing you need a tool for finer work (stones with less abrasiveness).
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Sharpening of small drills
Unfortunately, a tool with a diameter of less than 4 mm cannot be sharpened with the use of a nozzle or on a machine tool. Therefore, such drills are turned by hand, using a file or nadfil. As for the latter, it is better to choose a diamond-coated one. Even if a file was used, it is necessary to finish the edges with a file.
All the complexity of the operation lies in the fact that the cutting tool has a small size planes and edge. Therefore, it is recommended to buy glasses with a fourfold magnification, as well as to use a lamp with a good light flux.
The principle of sharpening is exactly the same. But there are some recommendations:
- Grind a layer of more than 1 mm is not recommended;
- Metal drill bit sharpening angle is standard, but is maintained by eye;
- As practice shows, the first drill bit you are sure to spoil, do not despair, the skill comes with experience.
The video shows how to sharpen metal drills by hand:
How to sharpen a metal drill with your own hands: recommendations
Even the strongest drill bit dulls over time. It is irrational to throw out and buy a new one, because when grinding, you do not get rid of the knife or axe, but sharpen it and continue to use. Exactly the same should be done with drills. Of course, their processing is much more complicated, so you need to carefully understand how to sharpen a drill bit on metal.
When to sharpen a drill bit
A sharp squeak when working is a sign of sharpening, because this sound occurs when the drill bit rubs strongly against the workpiece. It is also time to sharpen the tool, if when drilling, the chips look like crumbs, but not like spiral strips. After use, touch the drill bit and if it is too hot, the cutting edges have blunted, excessive friction occurs.
If you notice any symptoms, stop work immediately and sharpen the drill bit. After all, the metal is heated by friction. In doing so, it changes its physical and mechanical properties, becomes soft. over, even after cooling it will not regain its qualities, because the hardening is “released” upon such heating.
This renders the tool unusable. That is why it is better to sharpen the drill bits too often than too seldom. There is no need to fear that a lot of metal is removed from them. Reducing the length of the tool during sharpening will not damage its performance, but the heat from friction will put it out of order very quickly.
Geometry and parts of the drill bit
Before finding out how to sharpen a metal drill bit, it is necessary to understand the design and geometry of the tool. The components of the design are shown in the figure below.
In the picture you should find the following parts that will be useful later on:
When sharpening, the back surfaces and the lintel are machined. The cutting edge is formed by the plane of the groove and the nape. It is the back surface that is machined when the tool is tapered.
The shape of the back of the head, in particular the lower position relative to the cutting edge, is necessary so that the edge is above the back surface when drilling.
This is required to reduce friction during operation and to transmit all pressure to the cutting edge.
The curvature and slope of the cutting edge must be determined by fitting a special template to the center of the drill. The main parameter of the tool is the angle at the apex, which is formed by the cutting edges. It determines what metals can be drilled with the bur.
The degrees for the items to be drilled are as follows:
- For thick plates, 130;
- For cast iron, 2 angles are made: the main one is 118, the additional one is 90;
- Aluminium, bronze and other medium hard metals. 118
- copper and other soft metals. 100.
You should also monitor the work using the angle that is formed by the cutting edge and the tool axis. To measure it, it is necessary to put a template on the side surface of the drill. Here it is obligatory to be half of an angle at the top. This way of measuring gives a guarantee that the drill is symmetrical.
Important! The symmetry of the drill is much more important than the correspondence of the angle at the apex.
Since it is the edge that cuts strips from the metal, it will be necessary to sharpen this part with sufficient sharpness, removing all chips and irregularities. For this purpose, the back part of the drill is machined, which, together with the groove, sets the angle.
Metal drill bits come in different types, all of which are used in certain cases:
The most common type, often worked with in the home. Suitable for making holes in most situations, easy to use and easy to sharpen.
Named so because the working blade has the shape of a paddle. Used for making deep, wide-diameter holes.
Used in those cases where it is necessary to make a hole with a very precise diameter. Cutting edge positioning on one side makes it possible.
Tool with coolant channels inside. Used when drilling hard metals for a long time, when there is a risk of overheating.
Drill bit has the form of a hollow washer or ring. The cutting part is often serrated, which is why it is referred to as a crown. Used when you need to make a wide hole.
Thanks to its shape the drill bit is easy to center when working. One tool can make different sized holes.
Let’s get to the subject of templates. The simplest pattern can be made yourself from soft metal. It is enough to cut triangular hollows in the sheet with an even degree. Usually it is 116-118o (can be rounded up to 120o) and 58-59o (or 60o). The first is needed to check the angle at the apex, the second is to control the angle given by the back surface and the groove.
Scheme of the simplest template is shown below:
Sharpening with a file or file
It is impossible to sharpen a drill properly with a file or file, so it is better to refuse such an idea at once. There are 2 good reasons for this:
- Even the simplest and “softest” drill cannot be taken with a file because it is too hard. You are more likely to wipe out a file than sharpen a tool. A file will also not help in sharpening drills that have let go.
- If you use an abrasive or diamond bar, then there is another problem. you need to keep a perfectly even angle of erasure of the metal. This is difficult to learn, even with a sharpening machine, and almost impossible to learn by hand.
Instructions for operation of the sharpening machine
To begin with, it is advisable to remember the safety rules:
- you must not work without gloves or an underhand;
- Protect your eyes with safety glasses or a face shield
- Do not touch the sharpening wheel;
- once switched off, the wheel must not be touched until it has come to a complete stop.
Now we can proceed directly to how to sharpen a metal drill bit. The important rule for this procedure is that the back surfaces must be made flat and at an identical angle. To make it easier to control the desired degree during processing, you can directly on the undercarriage of the machine with an abrasive wheel to draw a felt-tip line for a trimmer, over which then you should adjust the angle when holding the drill.
Sharpening the metal drill bit
You have probably tried to sharpen a drill bit with your own hands. Did not succeed. Well, let’s take a look at this problem. First, a little bit of theory and terminology. Then we will get acquainted with the tools and the technology. Including the budget drill bit sharpening kit. Let’s begin at.
What drills are available
The geometry of this tool is quite diverse. We will consider only the shapes that are typical in terms of sharpening.
Cylindrical twist drill.
Drill bit material
Consider the materials in order of increasing wear resistance and price:
Regular drill made of cutting steel without any further processing. The cheapest. The color of ordinary steel. Superheated steam cured. It has a black color. Tempered has a faint golden hue. With a titanium nitride coating, they have a bright golden color.
Alloyed with cobalt is characterized by the presence of a golden red glow.
The elements of the drill bit for sharpening
For a better understanding, the elements for sharpening will be considered using the example of a double-channel cylindrical twist drill.
How To Sharpen Drill Bits. Drill Bit Sharpening Jig
The cutting edges cut the metal out of the hole area. Back surfaces. It is these that are processed when sharpening the drill bit, to give the cutting edge sharpness and the desired geometric shape. The jumper will be the first indicator that the drill is properly sharpened.
These are the elements you must concentrate on when sharpening the drill bit.
Tool for sharpening drill bits in the workshop
Here we look at the device for sharpening the drill with tools that are often used at home.
4.1. angle grinder
In order to achieve an acceptable quality of sharpening, the power tool must be clamped.If you have a helper, everything is solved quite easily. Have a helper place the power tool on a hard, level, horizontal surface with the disc down and the shield up. For example on the table. the angle grinder must rest on the disk shield. And, taking hold of the body, in the places shown in the photo, securely locks it.
If you do not have an assistant and suitable holders, you can use a banal locksmith or carpenter’s vise. Clamp the angle grinder in such a way that the jaws of the vise do not cover the ventilation holes. The abrasive disc can be oriented either vertically or horizontally.
You can use a normal saw blade, but it is better to use a sharpening blade. It is much thicker than a cutting disc.
4.2. Hand drill
To fix the drill, all that you have read about fixing the angle grinder in the previous paragraph is true.
IMPORTANT! Only drill with cam chuck is suitable for sharpening.
Not everyone knows, but angle grinder disc holders are commercially available that allow you to use “angle grinder” cutting and sharpening discs with a drill. This allows the high-speed drill to replace the function of the angle grinder.
You can also use a sanding disc with sandpaper glued to it. The harder the base, on which the paper is glued, the better. Now you can find sandpaper, which is not glued to the disk, but sits “on Velcro”. This one is also good. The quality of sharpening will be worse.
Instead of the drill bit in the cam chuck of the drill, the holder of the “grinder” disc or grinding disc is installed.
4.3. Grinding and Sharpening Machine (sharpener, emery machine) 3
Not everyone has such a machine at home. But we’ll take a brief look, though. So how to understand the technology of proper drill sharpening and how to properly adapt a home tool for sharpening, the easiest thing to do on it.
The corundum grinding wheel is designed for steel work, including the sharpening of drills.
Horizontally, at the level of the wheel’s axis of rotation, is the undercarriage. a steel bar. Supports fingers and tool during sharpening.
5.1. Preparing for sharpening
Put a marker on the surface of the trimmer line at an angle of 60 degrees with respect to the working surface of the abrasive disk (the end of the disk, which looks at you).
This helps to correctly orient the drill bit when sharpening. The angle shown in the figure is approximately 120 degrees in most cases. Actually, the harder the metal for drilling, the larger this angle should be.
IMPORTANT! Do not wear gloves when sharpening. Be sure to protect your eyes with goggles or face shield. Beware of hands being knocked off and touching the grinding wheel too hard.
5.3. The movement of the drill bit during sharpening
After placing the drill bit in its original position, slowly feed it forward until it touches the grinding wheel. Immediately after touching, move, simultaneously, in three directions: tip up, shank down, drill forward along axis.
Rotate the drill 180 degrees around its longitudinal axis, and then do Step 5.2, 5.3, 5.4 for the second rear surface.
5.6. What we should get
Put the drill bit upright, with the tip pointing up. In this position, the entire back surface should be below the cutting edge. over, the further away from the cutting edge on the rear surface, the lower. This is what is known in sharpening technology as undercutting.
By undercutting the back surface we undercut. As a result, only the cutting edges and the bridge of the metal that the drill bit cuts touch the surface. Lack of undercutting is the most common mistake of beginner sharpeners.
Technology of sharpening a metal drill with an angle grinder or a hand drill
If you have figured out the sharpening of the drill on the sharpening machine, it’s time to learn that on the grinder (angle grinder) it is done similarly. As an undercut, we simply use the edge of the abrasive disk protector. The pivot of the shield is adjustable.
Before sharpening, turn it so that it is comfortable to rest your finger under the drill bit to be sharpened. Try to follow the same movements as on the sharpening machine. The fact that you can learn how to properly sharpen drill bits without a sharpening machine quite simply and quickly.
That’s why it is recommended to fix the angle grinder. you will get a decent result faster.
It is more complicated with a hand drill. Nothing to use instead of an improvised object. But you can also use an improvised object to do it. Two firm, even surfaces are needed.
How to sharpen a metal drill bit with different tools
Sharpening of metal tools can fully restore their functionality. You can sharpen them using various aids.
How to properly sharpen a metal drill bit and not to spoil the cutting surface of the product will be told in the publication.
Signs of dull metal drills
To sharpening should begin only when obvious signs of blunting of the cutting edge are detected.
Among the main manifestations of the ailment are the following:
When drilling metal with blunted drill bit, a high-frequency sound is produced due to friction of the working edge against the workpiece. Therefore, if the appearance of increased noise, you should postpone the work and start sharpening. If you continue to drill metal, the excessive heat will cause the cutter to become too hot.
Before the signs described above appear, the lack of spiral chips can be an indication of a drop in drill bit sharpness. Such a sign can not always be detected in time. If the drill bit produces too fine chips during operation when correctly fed, it is advisable to immediately begin debugging the tool.
How to sharpen a metal drill bit
The right tool can significantly reduce the time required to complete the job as accurately as possible. Learn below how to sharpen a metal drill bit on the sharpener.
In addition to the main unit with an electric motor and a wheel, you will need to purchase special devices that hold the drill in a stationary state. These supports allow controlled tilt angle and tool feed during turning.
Many tools allow you to make deburring of metal cutters with a diameter of 3 to 19 mm. For sharpening twist drills you can use special machines that have an integrated motor and feed mechanism.
Unlike using an ordinary sharpener and holder, professional equipment can cost tens of thousands. Therefore, if sharpening drills is not a profession, you can get by with the above described tandem of a grinding wheel and a holder or make the tool dressing by hand.
It is also possible to sharpen a drill with a file without any experience. The main thing is to choose the right file. Considering the fact that even cheap drills are made of high quality cutting steel, it is necessary to select a diamond-coated file. In addition to the file, you need to prepare a vise in which the tool should be secured.
To avoid wasting time and energy on the manual method, you can use an angle grinder with an abrasive wheel.
Drill sharpening with an angle grinder
The grinder is available in almost every home workshop, so the method will be one of the most cost-effective.
In addition to the angle grinder with an installed grinding wheel for work necessary to prepare a vise in which to hold the drill during sharpening. the room where the tool is used must be bright, so that you can control the process of metal removal from the cutting surface.
Debugging is carried out in the following sequence:
- the drill is placed in a vice in a vertical position;
- part of the trailing edge is removed with the angle grinder to completely eliminate the traces of wear;
- the cutting edge is sharpened at an angle of 120 degrees.
To avoid overheating during sharpening, the contact of an emery wheel with the metal should not last more than 2 seconds. Repeatedly removing a small amount of metal from the working edge, it is possible to adjust the tool to the desired angle.
For measurements, it is advisable to make a plastic template to help control the size of the sharpening angle.
It is more convenient and safer to perform the work with the use of a sharpening wheel and a special holding device.
Resharpening the drill bit with a sharpener
It is possible to determine the extent of damage to the cutting product and debugging by eye after many years of practice.
In other cases, a special drill bit holder can be installed in close proximity to the emery wheel. The mount must be strong so that the retainer does not shift during operation. If the sharpening machine is fixed on a wooden base, the mounting of the retainer must still be done with a bolted connection.
To perform sharpening: the tool is firmly fixed in the holding device, the motor of the sharpener is switched on and the drill comes into contact for a short time with the grinding wheel at a pre-selected angle.
- If there are nicks on the surface of the cutting tool, you must remove the damage evenly on both sides before deburring it.
- Care must be taken. Products with larger diameters heat up from contact with the abrasive wheel to a high temperature, which reduces the mechanical strength of the metal.
Sharpening with a drill bit
Without a sanding machine, using a special attachment on the drill can perform the operation qualitatively and with less time.
You can purchase the nozzle in any specialized store, but the device can be used only for sharpening medium-diameter products. Most of these bits allow you to effectively sharpen tools with diameters of 4 to 10 mm.
For beginners this is the preferred method. Sharpening drills in the following way.
- Install the nozzle on the drill;
- Drill a hole with a suitable diameter;
- the drill is switched on and the product is sharpened on one side;
- Turning the drill 180 degrees, the opposite edge is sharpened.
To use the device effectively, consider the following features:
- Only slightly blunt tools are sharpened with the drill bit. If there is deep damage to the cutting surface and when the drill has been overheated, this is not the way to restore the product.
- The sharpening angle in such devices is fixed. Therefore, to restore drills for work with non-ferrous metals, you will need to buy the original device, or perform refinishing of products with a file.
How to make a sharpening machine
The stationary device for sharpening, described a little earlier, can be made by a good craftsman. You can even use wooden bars to make some elements (stand and others). The main thing when assembling the construction is to strictly follow the parameters on the drawing, one of the variants of which is presented below.
In addition, you must carefully control all necessary angles
Pay special attention to the part where the drill bit is mounted, remember that it must not turn during sharpening. At first, you can make the device entirely of wood
And then, having made sure that the drawing is correct and you followed it completely, you can make a full-fledged machine tool.
Concrete drill sharpening Before we consider the concrete drill sharpening, it is necessary to study its structure.
- the shank. this part is designed for its reliable fixation in the chuck of the torch or drill. has a diameter of 10-18 mm. Different types of drills differ not only by the diameter of their shank, but also by the grooves and projections on it.
- The body. the spiral-shaped central part of the drill bit, made of durable steel resistant to high stress and temperature. This part is designed to remove concrete particles from the drilled hole, which are crushed by the cutting head.
- Cutter head is the working part of the drill bit, which has a wear-resistant diamond coating or consists of durable carbide plates. One of the most common alloys used in the manufacture of conventional concrete drill heads is tungsten carbide.
Resharpening by yourself
Only the cutting edge (groove) is sharpened. It is forbidden to sharpen step drills, because it leads to change of work surface geometry and burr formation during operation. Incorrect sharpening leads to a decline in tool quality, often resulting in complete uselessness.
Bevel drills have a long service life because they require periodic resharpening. Drills with rectilinear progressive groove are the easiest to sharpen at home. Grinding is carried out by hand with abrasive cores, diamond cutting stones or sandpaper.
How to sharpen a step drill bit for metal with a spiral groove, it is necessary to know any handyman. The process requires the use of sharpening machines, on which the drill is guided so that the abrasive wheel runs exclusively in a spiral. To be able to turn smoothly at the same time special appliances are used, manual feed of the drill bit is not recommended at all.