How to properly sharpen a drill for metal: methods and rules for sharpening a tool with video

1. When should you sharpen drills?
2. Drill geometry and parts
3. Parameters to be restored
4. Dependence of sharpening angle on material
5. What to use for sharpening
6. Tools to check for proper sharpening
7. How to sharpen a drill for metal
8. Methods for sharpening a drill for metal to obtain the correct back plane
9. Processing options based on the number of bevels on the edge
10. Instructions for operating the machine
11. Processing on special equipment
12. How to sharpen metal drills correctly: video instructions
13. Important points
14. How to extend the life of a cutter

A dull instrument can and should be restored to sharpness. Therefore, we will tell you how to properly sharpen a drill for metal: processing methods, what geometry to achieve, and so on. As a result, you will know what to do to restore its full characteristics and use it again. Agree, this is much more practical than buying a new one right away.

Attention, as soon as you notice that the cutting edge has lost its original profile, you must immediately stop performing the technological operation. Because its edge, under the influence of friction forces, has heated up and become soft, and continued work will cause even greater deformation, already critical, after which recovery will become impossible.

When should you sharpen drills?

You can understand that it is necessary based on the following fairly obvious signs:

• when the tool is immersed into the thickness of the workpiece, a sharp creaking sound is heard;
• the chips come out in the form of small crumbs, and not a long spiral;
• the edge quickly overheats - if you try it with your finger, you might get burned.

So, if you notice any of these warning signs, stop immediately, otherwise you will not avoid damage. If a usual operation begins to take longer - for example, before you made a hole in 3 seconds, but now in 5 - this also indicates wear.

If in doubt, you should simply check the edge by touch: if it is round or smooth and, conversely, with unevenness, chips, or burrs, this indicates that the tool is unsuitable for further use and it is time to worry about restoration.

When should you sharpen a drill?

The need for sharpening can be determined by the following signs:

• significant heating of the cutting tool;
• excessively small chip size;
• Uncharacteristically loud noise during operation.

If the tool begins to make a lot of noise, you should stop working. The noise appears due to a significant increase in friction force. To avoid damaging the equipment, you need to stop drilling. If this is not done, the drill will overheat, after which it will no longer be possible to restore its cutting characteristics.

Drill geometry and parts

The design of the instrument in question is quite simple and consists of the following elements:

1. cutting edge, directly removes chips;
2. neck, which acts as a kind of jumper;
3. working part with cut grooves that remove waste;
4. shank fixed in the machine (hand drill);
5. a pair of rear (back of the head) and front surfaces forming a profile;
6. two backs with ribbons creating the outside.

When technological operations are performed repeatedly, it becomes dull, which means that it is the sharpness that needs to be restored.

Parameters to be restored

Proper sharpening of a drill for metal allows you to normalize the following characteristics:

The apex angle that the edges make with the bridge. Initially, it depends on the quality characteristics of the processing material (hardness is as important as viscosity) and can be 60-150 degrees, and sometimes reach 180. In our case, it is necessary for it to become 116-118 0, accordingly, it needs lead to this indicator.

The angle of the axis and the cutting part - it must be half as narrow as the previous one, that is, 58-59 0, and symmetrical with respect to each side of the tool. Otherwise, uneven wear will be observed, which results in faster tool failure, as well as uneven edges of the finished holes.

Relief angle - should be fixed in the range 7-17 0 (depending on what the workpiece is made of); any deviation of the actual value from the nominal value must be corrected, otherwise the performance will decrease significantly, and a breakdown will not be long in coming.

The shape and length of the edges - it is important that they are equal, otherwise runout will inevitably occur, as a result of which it will not be possible to make holes of a strictly specified diameter. Dimensions (to determine symmetry) should be determined from the edge (top) to the central point of the jumper.

Forming an entry point

As you may have noticed, there is a zone between the edges in which the metal is not cut, but rather moves apart. This significantly limits the deepening process. And also, due to this form of impact, the edges are quickly rounded and, as a result, significant efforts have to be made. This problem is solved by reducing the width of the jumper. The point is made with a narrow stone (or edge) in the area opposite to the touch on both sides, with an offset from the axis of 15-20 degrees. It is important to try not to disturb the receiving surface. The effect of this manipulation during manual drilling is noticeable immediately, but the service life will be slightly reduced.

Dependence of sharpening angle on material

We already mentioned above that the number of degrees changes in one direction or another, based on what kind of part is being processed. The smaller it is, the longer the edge, better heat dissipation, and longer service life. The more, the more difficult it is to center the tool at the initial stage of the technological operation.

There is a universal value - 118 0 (with a tolerance of 2 0) and 7-12 0, respectively. It is chosen when no details are specified. If you know what the workpiece is made of, you should give preference to the recommended values, which we have summarized in a table for clarity.

What to use for sharpening

Sufficient accuracy in aligning the angle can only be achieved if the tool is securely fixed, and the feed of the device processing it can be adjusted during the process. This approach will make it possible to restore the geometry of spiral rods ranging in size from 3 to 19 mm.

All work can be performed with minimal errors and maximum productivity on machines. And you will find several versions of suitable equipment, reliable, easy to use, economical and at the same time mobile, in the Izhevsk catalog - choose in favor of quality.

Now we will tell you how to properly sharpen drills for metal not in production, but in the garage or even at home, when there is simply no specialized equipment (the purchase of which for one-time needs is impractical). To do this, you can use the following machines, tools, and devices:

• grinder - will allow you to remove signs of wear and bring the desired edge to 120 0, but for this you will have to remove chips repeatedly for 1-2 seconds, holding the drill vertically in a vice;
• sharpener - you should first remove all the notches from the rod (if any), and then secure it in the clamp and carefully straighten it, lightly pressing (at the required angle) to the rotating circle;
• a special attachment for the drill - just install it, secure the drill in it and turn it on, and then rotate the tool 1800 to debug the second face; but this option is effective for small bluntness, medium diameter (3.5-10 mm);
• needle file or file - here editing is done manually; this is a choice only for cutters made of relatively soft materials; It is not advisable to use an abrasive or diamond stone, since it will be problematic to maintain the desired geometry.

The devices and technologies for their use may be different, but after using each of them, in any case, you should make sure that the desired result is achieved.

Sharpening using reverse mode

You can make a very simple homemade device for sharpening drills with your own hands from sandpaper. This is a convenient option if you don’t have a grinding wheel at hand.

In this case, you should wrap an even round piece of wood or a pipe (even a plumbing plastic pipe will do) with several layers of sandpaper.

It is advisable to make quite a lot of layers (about 2 cm) so that the drill can be sharpened faster and with high quality. You can fix the paper with glue.

To sharpen the drill, place it in a drill or screwdriver. It is extremely important to enable reverse rotation mode. In standard mode, tool sharpening cannot be done in this way.

Next, simply drill through the sandpaper several times along the entire length of the drill. In general, you can even do without a pipe by simply rolling up a long enough piece of sandpaper.

During the drilling process, the edges of the equipment are sharpened with sandpaper. The method allows you to restore even heavily worn drills. But the quality of sharpening will not be as good as when using emery.

Tools to check for proper sharpening

It can be:

• calipers;
• protractor;
• ruler;
• goniometer.

and others - all together or separately. But for maximum accuracy and convenience, it is better to use a universal template - with length scales and angles already applied. The easiest way is to buy a ready-made one, but since it is not always found on sale, it makes sense to make it yourself, it’s not difficult.

You can implement one of two configurations:

• a thin plate made of sheet stainless steel, steel or even tin with markings applied with a diamond pencil;
• 2-3 nuts, welded together or fastened with hot glue - the angle at the junction of their faces will definitely be equal to 120 0, so the tip of the cutter can easily be checked by it.

How to sharpen a drill for metal

With the correct choice of angle, fine-tuning, checking and adjustment (if necessary). But before considering each stage, we note that when working on a modern high-performance machine, using a familiar grinder or a classic abrasive wheel, for your own safety it is better to use an additional locking device.

This could be a simple clamping base or a bushing of suitable diameter. Another option is a template with a whole set of tubes with sections of different widths, suitable for rods of all common sizes. The main thing is that two conditions are met:

• this auxiliary element successfully plays the role of a stop and makes the back movement of the cutter impossible;
• it also ensures accurate centering throughout the entire work period.

Now let's look at each step in order.

Maintain angle

Answering questions from beginners about how to learn how to sharpen drills for metal, the craftsmen note that first of all, you need to get the hang of understanding how sharp the edge should be. This directly depends on the steel, plastic, solid oak or other material for which the tool is intended: the softer the workpiece, the blunter (wider) the angle must be, and vice versa. We provided a correspondence table above, use it as a guide, but here are a few more interesting relationships for:

• silumin – 90-100 0;
• wood – 135 0;
• magnesium and its alloys – 85 0;
• textolite and plastic – 90-100 0;
• granite and ceramics – 135 0;
• aluminum – 135 0.

By analogy, you can select the degree for other cases.

Perform debugging

If you watch any truly complete and well-thought-out video on the topic “how to properly sharpen a drill for metal,” the video will probably contain a stage in which the master arms himself with an angle grinder or a hammer drill with an attachment in the form of an abrasive wheel and begins grinding the edge.

Why is he doing this? To remove minor defects such as burrs or scratches. The geometry of the cutting part does not change, which means the angle remains the same as it was already maintained. But for the most accurate result at this stage, you need to clamp the rod in a vice (or in another such reliable clamp) so that it does not move around.

Finishing is a unique operation in its own way, since it combines two types of surface treatment at once - both rough and finishing - so it is simply necessary to carry out it.

Run check

Those who know from their own experience how to properly thread a metal drill and sharpen it understand perfectly how important it is to ensure the quality of the result. Therefore, after editing the tool, they take a template (we described above how to make it) and make sure that the following indicators meet all standards:

• edge lengths;
• angles - at the vertices, longitudinal edges, inclination of helical grooves.

If any parameter does not meet the norm, this must be corrected. Otherwise, runout will occur and the size of the hole made will be larger than necessary.

Make a point

It is relevant for rods whose diameter exceeds 10 mm. Its implementation makes it possible to reduce the inclination of the leading edge and at the same time increase the angle of the cutting edge.

This will increase the service life of the tool and ensure its resistance to crumbling, as well as narrow it, and therefore make it easier to enter the workpiece (a scraping effect will appear) and reduce the negative impact of friction.

Special opinion on sharpening edges on an angle grinder

On the YouTube channel, many video bloggers show this method as the most accessible. I won’t give examples, you can find them yourself using search queries.

Special sharpening devices are even being developed for this technique.

It is possible that in some critical situation this technology can help out, but I do not recommend using it as a basis, especially when training, for the following reasons:

• cutting wheels are created for metal cuts directed perpendicular to their axis of rotation. They are not designed for lateral loads and may fly apart;
• The speed of the grinder's disc is high;
• machining of the cutting tip is carried out on a flat surface and only allows you to straighten the rear cutting angle without fine-tuning the other two necessary conditions.

A drill treated in this way will work more or less normally in wood and plastics, but problems will quickly arise with hard metal.

My conclusion: the technology for straightening cutting edges on an angle grinder is dangerous and unreliable.

Methods for sharpening a drill for metal to obtain the correct back plane

Methods are classified according to how the back of the head is treated. Today the following variations are distinguished:

• Single-plane – relevant for small rods (up to 3 mm in diameter); you need to make 1 surface, at an angle similar to the back one and selected within 15-25 0.
• Dihedral - in the back of the head, 2 planes are sharpened with varying degrees of intensity; the first, generally adjacent, is at 7-17 0, the second is at 25-40 0. Then the intersection edge as a result of this execution passes at 0-40 0; Ideally, it should be 25-30 0 for materials of high hardness and 35-40 0 for medium and soft ones. Remember, if you increase it, you will reduce the axial force, weaken the wedge on sharp slopes, and worsen heat dissipation and strength.
• Conical - as it is performed, the back of the head becomes curved, since the rear angle gradually increases, and immediately from the blade. It is narrowest on the cutting part, where it ranges from 7-17 0 (the specific value depends on the workpiece itself). To achieve success in the process, it is worth twisting the shank of the rod from top to bottom.

There are other methods, for example, screw factory sharpening of a drill for metal, and this is carried out mainly on machine tools; There is also a cylindrical one, although it is much less common. There is also a manual method - elliptical: for it, just like for the shaped one, you will need abrasive wheels of a specific (indirect) profile.

Processing options based on the number of bevels on the edge

There are two of them, and with each the angle does not remain constant, but changes, gradually narrowing from the central peak to the side ones. This allows for uniform heat dissipation and, in principle, reduces the heating of the tool.

So, 2 technologies:

Normal - the edge geometry is smooth, along its entire length. Very popular, including due to its ease of implementation.

Double-headed - carried out at a couple of angles near the top; Please note, at the first stage and on 4/5 of the cutting part it is necessary to adhere to the indicator of 116-140 0, while on the remaining, final 1/5 of the diameter (if we take the outer edge as the starting point) - already 66-100 0. This approach will allow create a main zone with a transition zone, thereby extending the useful area, which will help improve chip ejection, and therefore increase the service life of the rod.

Drill selection criteria

There are many types of cutting equipment available for sale. When choosing, you should pay attention to the color of the metal:

• Black. A product with an anti-corrosion oxide film, which additionally prevents overheating. Wear-resistant, suitable for high loads.
• Grey. Low quality models for light loads.
• Golden. This color is due to the presence of titanium in the alloy, which increases strength.
• Dark golden. Also an alloy with titanium, but without internal stress in the rod. The highest quality drills for heavy loads.

According to the type of design, the following types of drills are distinguished:

• Traditional spiral. Suitable for most household tasks.
• Left-handed. For drilling out broken fasteners.
• Highly accurate. For delicate work where deviation from the design is unacceptable.

Instructions for operating the machine

Naturally, sharpening twist drills for metal should be carried out in compliance with safety precautions, according to which:

• a mask or goggles for eye protection and gloves with hand guards are required;
• while the equipment is turned on, you must not touch its working parts;
• Even after switching off, it is forbidden to touch the abrasive wheel until it stops rotating and stops.

Now let's move on to the nuances of the procedure:

• Level the back surfaces - this will make it easier for you to maintain the desired degree; You can adjust the corners using a drawn line.
• Place the tool on the index finger of your right hand, fixing it with your thumb and holding it by the shank with your left hand, and then controlling it - this is most convenient.
• Keep the rod strictly horizontal during the process, otherwise you risk removing the jumper and edges; lower only the back part and then smoothly, without rushing.
• Control the pressure and remember that all movements should be short and quick to avoid overheating; Cool the cutter regularly in salted water.
• Continue until you have removed even the smallest defects - it is important to achieve a perfectly smooth surface.

Sharpening at home

When sharpening drills with your own hands, the user is advised to adhere to safety rules. When working on sanding wheels, safety glasses must be worn. This will protect your eyes from abrasives and pieces of scale. Glasses must be used even if there is a protective screen on the sandpaper.

It is strictly forbidden to carry out work wearing gloves. The drill may get caught in the thread, causing hand injury. It is recommended to carry out work in tight-fitting clothing, the buttons of which are pre-fastened. It is recommended to adjust the support so that the gap between it and the stone is small.

Sharpening drills can be carried out in various ways, which allows a person to choose the most suitable option for himself. To avoid injury, you must adhere to safety precautions during work.

Processing on special equipment

We described in detail how to sharpen a broken drill on a machine, but there are other options. For example, the use of devices specially created for sharpening, which are fundamentally divided into 2 types.

Grinding attachments - each of them is a cylindrical device. On the one hand, it has clamps, thanks to which it is fixed to the drill, on the other, there is a cover with holes of different sizes. Insert the rod into a suitable rod, make sure that it is positioned strictly horizontally, and turn on the power tool for 10 seconds, and then turn the shank 180 0 and repeat the procedure. The downside here is the diameter limitation (3-10 mm) and the need to control the feeding direction. Plus – the affordable price of such an assistant.

Stationary devices - with a fixed platform and a rotating part, on which the cutter is fixed. Bring the latter to the abrasive and remove all defects. The advantage is convenience and safety of use: you can easily and accurately set the angle and do not bring your hand closer to the disc. The disadvantage is the lack of mobility: to prevent vibrations, the base must be rigidly fixed.

Tools for facilitating sharpening

Here we will no longer talk about machines, but about useful and convenient devices that simplify work and help maintain the correct angle.

These can be purchased products, for example, this conductor comes from AliExpress. The sharpening disk is very small; rotation is transmitted to it from a drill chuck connected using a special adapter. The user only needs to insert the drill into the groove and turn on the drill. An overview of the use of such a conductor is described in this video.

For those who do not respect Chinese products, there are these racks.

There are also a number of homemade conductor devices designed for convenient sharpening. For example, here are two of them.

There is also an original door hinge fixture.

Important points

When resolving the issue, strictly adhere to the following requirements:

• Keep the rod motionless, under no circumstances allowing it to rotate around its axis; a change in position even by a degree will entail a re-alignment.
• Use only those disks and circles whose surface is perfectly flat; restore it regularly using CBN nozzles.
• Allow the tool to cool after completing the sharpening operations, and only when it has cooled naturally, place it in the template and check.

These rules for sharpening metal drills help to achieve maximum quality of processing and are dictated by practice, so apply them.

How to extend the life of a cutter

To avoid having to edit it for as long as possible, you should:

• avoid overheating, which leads to rapid softening of the metal, and therefore dulling of the edge;
• lubricate with machine oil - this will help reduce such a dangerous friction force and prevent a sharp increase in temperature in the contact zone;
• control the rotation speed - limit it, focusing on the hardness of the material and the desired hole diameter, but do not chase speed, remember that operating conditions should be gentle;
• remove chips in a timely manner so that they do not clog the recess, otherwise the tool may get stuck and even break;
• also process the jumper with a ribbon - this way you will improve the durability and quality of the plunge, which will allow you to weaken the feed while maintaining proper performance;
• make several passes, giving pauses between each of them - so that the device has time to cool down.

We told you how to properly sharpen a drill for metal, we also provided a video of this process, now you can safely start processing damaged rods. And if you need to purchase a machine for this, you will find it in the plant’s catalogue, contact us and order high-quality and modern equipment.

How to understand that a gadget is dull

Initially, you need to understand that a faulty tool will not only fail you in performing a complex task, but may also break because it overheats during operation. Often the remaining part in the hole cannot be removed, and this, in turn, leads to product damage. In addition, during high speeds of the electric drill, fragments can fly apart and cause harm to the health of the master.

Signs of decreased cutting quality:

1. The part itself gets very hot, which is visible to the naked eye.
2. A squeal is heard.
3. The same procedure takes an order of magnitude longer.
4. The accuracy class is reduced.
5. When you touch the tip, you feel a smooth and rounded edge.

6. The workpiece is left with large burrs at the exit and a border at the entrance.
7. A characteristic shine of the head appears, the color of which is very different from the tail and the main cylinder. The cutting surface becomes spherical and the reflection from this line becomes noticeable to the eye.

8. The greatly changed temperature during processing contributes to the appearance of a tarnished color, for example, dark blue.
9. The specialist’s efforts increase when using equipment.

If for some reason you did not recognize the first signs of wear, then you can arm yourself with a high-resolution magnifying glass. You should pay attention not only to the end part, but also to the side surfaces. When they wear out, similar symptoms are also observed.