Often when replanning, overhauling, changing the interior decoration, the question arises, how to create a hole in a concrete or brick wall for a switch, an electrical outlet or conduits? Ordinary drills for wood or metal in such situations, of course, are not suitable: they will instantly lose their properties. Specialized fixtures are needed, including crowns for concrete structures of various sizes.
What is a concrete crown?
Today, the use of concrete is practiced at all stages of installation and construction works: from the construction of foundations and walling to pouring ceilings and screeds of various types.
As a result, the presence of drilling tools, ready to drill holes in concrete structures, is extremely important for any type of construction (residential, public, industrial). A crown for concrete is one of the types of drilling equipment through which holes are drilled in the supporting and enclosing structures of buildings and structures made of concrete. This procedure is necessary when performing the following work:
- laying of engineering and technical support networks in every possible direction: sewerage and water supply, electric networks and communication lines, automation and fire fighting systems;
- installation of technological and electrical equipment;
- installation of anchors and other mounting components;
- installation of components for supporting and enclosing structures for various purposes.
Types of concrete drill bits
Crowns are made only of hard alloys of metal materials, which make the product strong, durable and efficient. Often, newcomers are interested in about what purpose the crown has a center drill. Through this drill, you can make precise holes. Its absence can lead to vibrations during drilling - the hole will be deformed, distorted and uneven. Crowns are classified according to shank design. They are available in the following types.
- SDS-plus - models that are placed in household drills.
- SDS-max - are used exclusively in professional rotary hammers. The diameter of the shank is 20 millimeters.
- Hex Shank Drills - A similar type of drill bit is practiced for drilling large holes with an electric drill.
Crowns differ among themselves in the material of which the cutting area (teeth) is made. There are 3 product options.
- Pobeditovye - for the manufacture of teeth for the crown, an alloy of cobalt and tungsten is used in a proportion of 8% and 92%. The characteristic properties of these nozzles are resistance to high temperatures and long-term loads. They are used in reinforced concrete or brick.
- Carbide - this type of product is considered budgetary and is intended solely for making holes in concrete substrates. Collision with iron leads to damage to the teeth of carbide crowns.
Diamonds are one of the most expensive, but along with this effective. Diamond drilling tools have a number of positive qualities: they are not afraid of meeting with metal. That is why in reinforced concrete it is possible to make a hole exclusively with instruments of this kind. On sale there are many modifications with a variety of diameters. In addition to the particularly popular concrete crown for 68 millimeters, concrete devices for 100 mm, 110 mm, 120 mm, 130 mm and 150 millimeters are also in demand. Equipment with a similar large diameter is practiced for drilling holes in reinforced concrete or brick walls for pipes. The quality of the resulting hole is very high: virtually no chips, cracks and other surface flaws.
It should also be noted that crowns differ in cooling methods. They are wet and dry.
Nozzles having openings on the side walls of the bowl are dry. Closed bowls are considered to be wet, which must be wetted with water during drilling. Both samples of nozzles can be wetted with water, since this will not only increase the service life of the devices, but also reduce the accumulation of dust generated during drilling operations.
Based on the drilling technology, the nozzles are additionally divided into shockless and shock. The first option is suitable only for functioning in the drilling mode and is often used for electric drills. Percussion devices can be operated by using the function of a jackhammer on a puncher.
For the right choice of a suitable size crown, you need to know the diameter of the hole to be created for an electrical outlet or another component - for example, for the diameter of the pipes or the coverage of the wiring line when installing electrical communications. When buying a crown at a point of sale, you need to find out from the sales assistant its technical parameters, which are available in the attached documents or on the marking. Crowns can be realized both by individual products and by special sets of several units of different sizes.
The main component of switches or installation boxes for sockets is located with a standard outer diameter of 68 millimeters (with an inner diameter of 60 millimeters), in connection with this, concrete crowns for boxes for sockets for 68 millimeters are the most popular devices. 70 mm and 75 mm nozzles are used less. For laying communication lines, nozzles with a diameter of 300 millimeters are especially common.
The choice of the tool is also affected by its length and the number of elements in the cutting area: 5, 6 or 8 - the higher this indicator, the greater the productivity of the nozzle.
A center drill is also included in the set of nozzles for concrete for boxes for sockets, the function of which is to center the crown in the center of the hole being created, not allowing vibrations in the working material. The center drill often needs to be replaced as it is rapidly dulling. The crown is designed to penetrate into the depth of the material up to 1.5 meters.
Features of the use of concrete nozzles
If the shank of the selected crown corresponds to the clamping device of the punch, it simply needs to be put and fixed in the working position, no adapters are needed. You can start drilling concrete on the mark.
Carbide core drilling
The nozzle can be equipped with a centering drill or not. If it is, then the point is placed at right angles to the plane of concrete in the area where the middle of the hole will be located. If the cup structure does not provide for such a drill, then the circle of the cutting edge is pressed against the concrete. They begin drilling without effort - the cutting edge should select a shallow tunnel and straighten its direction. When it will be seen that the nozzle has laid down as it should, the device moves forward with pressure.
It is not necessary to remove the drill until it has drilled concrete to the required depth or the bottom of the crown rests against the wall. From holes not made through and through, the roll of cut concrete is picked out by a lance. For gear nozzles with carbide solders, the main thing is to correctly determine the functioning of the hammer drill. Excessive heating of the edge should not be allowed; therefore, after one or two holes, the device must be allowed to cool.
Diamond core drilling
If it is necessary to prolong the duration of operation of the nozzle on reinforced concrete, it is required to apply water spraying to cool the cutting part. This is especially important for devices with soldered edges, since with excessive heating they will fall off. Such crowns are practiced for more sophisticated equipment than a manual punch. It is fixed on reinforced concrete, and the operator can only feed the drill, making the hole deeper.
However, in a home environment, you can use tools that can operate in the electric drill mode, since diamond nozzles cut hard materials in an unstressed manner.
When choosing a nozzle for concrete, it is necessary to take into account 2 important conditions: what is the concrete structure made of (concrete grade for strength and reinforced concrete reinforcement parameters), and with what equipment the crown will be used. Despite the fact that the lion's share of nozzles is compatible with various types of electric drills and perforators, it is impossible to say that any crown will fit every instrument.
This comes primarily from the model of the cartridge drill - SDS-plus (they are equipped with lightweight punchers weighing up to 5 kilograms) or SDS-max (it is placed on more powerful and heavy devices). The nozzle must be with the appropriate shank. There are adapters that allow you to put a crown of one type on a perforator with a cartridge of another type, it is only advisable to choose a nozzle that exactly matches the tool.
More about crowns for concrete, see the video below.