It is not a secret for anyone that after many hours of work with a drill on metal or concrete, its cutting part loses its sharpness and, in simple terms, becomes dull. But to continue the work further using such a badly worn or dull tool is simply impossible. At such a moment, most people wonder: how to sharpen the drill correctly, so that the tool’s size and geometry can be fully restored.
Spiral drill bit sharpen sandpaper, leading at the right angle to the sharpened disk.
There are special machines and devices with which you can sharpen drills of any size and configuration without any special problems. However, not everyone has access to such special equipment. No need to despair, you can perform high-quality grinding with your own hands at home, using a traditional grinding machine with a stone.
How to sharpen a twist drill
The first thing you need to do to properly sharpen the drill for metal - is to choose the type of sharpening you need. These types of sharpening drills with their own hands differ from each other in the form that you intend to give the back surface of the tool. To date, there are five different types of sharpening, the most popular of them: single-plane and two-plane sharpening, cylindrical, screw and conical.
It should be noted that the sharpening of any drill is always performed on its rear edges. It is very important to ensure that both teeth are ground very exactly, without any visible differences. Doing it yourself is not easy, but possible. It is also quite difficult when performing sharpening manually to manage to give the desired shape of the rear face and maintain the required rear angle.Back to table of contents
Single plane and conic sharpening
Elements of the working part of the drill.
When performing a single-plane sharpening of the back surface of the tooth, the shape of one plane is given. In this case, the value of the rear angle should be from 28 to 30 °.
During work, the blunt drill should be attached to the grinding wheel, so that the cutting part of this tool is located parallel to the surface of the circle. At the same time, in the process of sharpening, it is not necessary to rotate or move the drill in any way, it should always remain in place, then the sharpening will be performed correctly. This type of sharpening is considered the simplest, but it is not suitable for all types of tools. Today, single-plane sharpening is used only when restoring old drills with a diameter of not more than 3 mm.
If you need to sharpen the drill, whose diameter is more than 3 mm, then you should prefer the conical type of sharpening. To do this job by hand, you must have certain skills. However, if you are not an expert in this case, then you need to be especially careful and try to do everything correctly so as not to spoil the drill.
In the process of sharpening the drill, you need to hold the fingers of your right hand for its tail, and your left hand for the working part, while placing your hand in close proximity to the intake cone.
When working, press the cutting edge to the side of the grinding stone, and swaying it with your right hand a little, try to create the necessary conical surface on the back edge of the tooth.
Sharpening spiral drills on conical surfaces.
During sharpening the tool should not break away from the stone, all movements with your hands should be unhurried and smooth. Then, when one tooth is completely sharpened, repeat all the same steps for the second.
During the work, it is necessary to try to keep the original shape of the back part of the screw drills that they received at the factory. This will allow you to not violate the desired parameters and leave the same value of the rear corners. If you have managed by all the rules to grind a blunt drill and if the diameter of your part is less than 10 mm, then you can safely begin to use it. If the diameter exceeds 10 mm, then in this case it is necessary to work over the new sharpening, namely, to sharpen its front surface.Back to table of contents
How to make a point
What is necessary to do underboots? The underpoint allows you to make the rake angle a little smaller, and the cutting edge, on the contrary, is larger, which significantly increases the resistance of the drill to chipping and prolongs its service life. In addition, due to undercuts, you can reduce the size of the transverse edge, which, as is well known, does not drill a metal surface, but scrape it in the very center of the hole. Therefore, the intentional shortening of the transverse edge can significantly facilitate the drilling process.Back to table of contents
How to make fine-tuning
At the factory, after sharpening, a so-called finishing is always carried out, which helps to make the cutting surface of the tool more smooth and remove all small serrations. Any screw drill bit that has been refined when sharpened, wears out much more slowly than just well sharpened. Therefore, if you have the necessary experience and time to do the finishing, be sure to do it, you will not regret it.
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How to sharpen pobedit drill
The position of the hands when sharpening the drill (a) and the location of the drill relative to the axis of the abrasive wheel (b).
Over time, absolutely any drill, including the one, can become dull. To regain his former sharpness, you need a device such as a diamond-coated grinding machine and a liquid for cooling. Do not even try to sharpen a poker drill with an ordinary grindstone, you will still fail. Before you begin the process of sharpening, it is necessary to carefully examine the drill and make sure that it is not too worn out and can still be sharpened. To this end, you need to take a ruler and with its help measure the height of the cutting part. If the height of this part is victorious (its soldering) is 10 mm or more, it is still possible to do this.
It is very important to remember that the speed of sharpening directly depends on the hardness of the material from which the grinder is made - the higher it is, the slower the speed should be. Therefore, when sharpening pobedit drill it is necessary to reduce the angular speed, that is, to reduce the number of revolutions of the stone.
Correct sharpening should be done with very short time touches of the cutting part to the surface of the grinding stone.
It is important to remember that it takes quite a bit of time to sharpen the drill bit, it is usually necessary to only slightly correct the dull edges. Therefore, during work, try to follow the process of this process in the most attentive manner so as not to accidentally remove excess part from the working surface of the tool.Back to table of contents
How to sharpen drill bit
Sharpening jumper drill.
For sharpening drills with taps, you should use the same sharpening methods that are used to restore the former sharpness to the usual small diameter. This means that in order to sharpen such a drill, you simply need to give its back surface a flat shape. It is important to note that in such a situation it is necessary to grind down the back surface right up to the soldering.
The front surface should also be slightly sharpened. This is especially important when the soldering of the tool is already steeped almost to the drill itself and the softer metallic material begins to reach the cutting part from the front surface. Therefore, experts recommend sharpening the front surface slightly, which will reduce the width of the center of soldering.Back to table of contents
Options sharpening drills and their characteristics.
During the sharpening of the drill, it is very important to be attentive and make sure that both of its cutting teeth are exactly the same.
In addition, regardless of the type of device that you use to process the drill you sharpen, you must always control the ratio of the front corners of the cutting edge to the rear.
Another very important point that should be remembered during sharpening drills is in no case to prevent strong heating, since as a result of this, cracks may form on it, as well as delamination of solid metal plates.
To avoid this, during the work it is necessary to regularly cool the drill with a liquid, for example, using ordinary water.