All about twist drills

Each professional or amateur craftsman has a different set of tools. Separately, a group can be distinguished - drills, they are necessary to perform a number of works - drilling through or blind holes, and with their help you can increase existing ones.

A drill is a tool element with a cutting edge that is used to drill holes in various materials. Cutters are made of high-strength steels, since the working part must be harder than the surface to be drilled. In accordance with the purpose, each tool has its own characteristics and features; work can be carried out with wood, metal, concrete, glass and tile objects and materials. The most common was the twist drill, or in another way - the twist drill.

The device is presented in the form of a cylinder, consisting of three main parts:

• Working. It looks like two grooves located in a spiral along the cutter cylinder - this is a cutting structure. Thanks to this shape, the chips are removed from the working surface. Also, if the technique provides for the supply of lubricant, it will drain precisely along these grooves. The working part itself consists of two parts - cutting and calibration (the second name is a tape, this is a strip that continues the surface of the notch along the drill). The cutting structure consists of two main blades and two additional blades. The structural elements also include a tapered transverse edge located at the end of the drill.
• Shank. This part is intended for fixing the drill in the mill or hand tool.
• Cutter neck connects the working part and the shank, it is also marked on it.

Depending on the design, cutters are divided into the following types:

• cylindrical - general purpose drills, maximum diameter 80 mm;
• left-handed - the area of ​​application is not so large, used for drilling broken bolts or other fasteners, differs from the standard in the direction of the screw recess;
• increased accuracy - they must have a symbol - A1. Their diameter is made with special precision, down to a fraction of a millimeter.

The legend for cutters of any diameter will always be the same. The angle of the drill tip between the main cutting blades, depending on how hard the work surface is, varies from 90 ° to 120 °. The slope of the helical recess is measured along the outer diameter - this is from 18 ° to 30 °. The slope of the transverse edge at the end of the cutter is from 50 ° to 55 °. The rake angle is measured in the main secant area perpendicular to the main blade, and the clearance angle is measured in a plane parallel to the cutter axis.

The working part of the tool can be used for any materials and surfaces, therefore, the classification according to the processed material is highlighted.

• For metal. The drill type is selected depending on the type of metal.

If during operation the tool works slowly and heats the metal, it is necessary to sharpen it. This is done manually if the diameter is up to 12 millimeters, and large dimensions are already sharpened on a special machine.

• On concrete. Concrete is the most difficult to process; here you will need drills with special additional plates made of superhard alloys - pobeditovye. As a result of the work, the hole will be larger than the diameter of the cutter, this is due to the beating of the structure.

• Wood. The simplest type of twist drill is made of high strength steel. The diameter ranges from 2 to 20 millimeters, the standard length is from 49 to 210 millimeters.

The shank is an indispensable part of the drill, which is mounted in the chuck of a drill, hammer drill or machine tool. All four types are distinguished.

• Conical (or Morse taper) - from the name it becomes clear that the shank has the shape of a cone. Such drills are used mainly on machine tools, its shape allows for quick or automatic replacement of the cutter. Fixed with feet, threads or without threads and feet. This type is also divided into subgroups - instrumental (the most popular, they work on machines), shortened (to form small holes), elongated (for holes of greater depth), metric (the size of the shank in relation to the working part is 1: 20).

• Cylindrical - this form of drive is mainly in demand among non-professional craftsmen, as it is suitable for the simplest models of drills. The shank diameter is usually the same as the cutting edge diameter, but an oversized drill bit can be used for better clamping.

• Faceted - a bar on which there are three, four or six faces. Triangular - resistant to turning, comfortable with a greater transfer of revolutions. Quadrangular - the main advantage is resistance to twisting and ease of manufacture. They began to use them when a special clamping chuck had not yet been invented. The disadvantage of such a drive is the impossibility of centering the drill. Hexagonal - most often this type can be found on thin cutters. It is characterized by high resistance to twisting.

• SDS - for the first time such a shank was developed by Bosch, its main feature is the presence of two recesses of 10 millimeters, due to which the fixation occurs.

Haisser is the most popular German manufacturer. The branches of the company are located all over the world, so the quality can sometimes vary. The main direction is drills for metal. They are produced in two lines - medium TN (from 34 to 150 millimeters) and long TM (from 56 to 205 millimeters). Drills are sold individually and in sets.

Bosch is a world-class manufacturer, whose rating is high. The packaging of the sets is distinguished by its design, where the cutters are securely fixed and remain in place after transportation. Dimensional characteristics: diameter - 1-13 millimeters, length - 34-133 millimeters. In one package, the number of instruments can be from 10 to 156 pieces.

Metabo is also a German companyfounded in 1923. Their first piece of equipment designed and produced was a hand-held metal drill. This brand is distinguished by a wide variety of cutters and other components.

DeWALT is an American company, which began its work in 1922. In Russia, it began to gain popularity since 1997. The assortment includes more than 1400 types of goods. This company is at the top of the list as the best shank manufacturer.

AEG is another firmdeveloping and manufacturing tools in Germany. The high price, but the quality fully justifies its value. We sell both piece goods and sets. AEG drills are some of the best for concrete and stone.

An overview of twist drills in the video below.