Crowns for concrete sockets: device, main types, sizes

One of the key points when installing hidden wiring is drilling holes for socket boxes. If, as a rule, no problems are expected with brick walls and foam concrete, then difficulties can arise with concrete walls. Significantly simplify the solution to such a problem will help special crowns for concrete, with which holes are drilled for the socket. Let us consider in detail the device of this tool, its types, characteristics and sizes.

How is the crown arranged?

This type of drilling tool is a nozzle for a hammer drill or percussion drill. The appearance of such an assembled and ready for drilling structure is presented below.

Now we will consider how the drill nozzle is arranged, its main elements are shown in Figure 2.

Designations:

• A - a cartridge, this is a nozzle on which the remaining structural elements are attached.
• In - a centering drill on concrete, provides the correct hole shape. This element, like conventional drills, “dulls” over time, and therefore needs to be replaced regularly.
• C - the crown itself, as can be seen in the photo, is a pipe segment, on the edge of which the cutting segments are installed (marked with red circles). They are made of special carbide materials capable of cutting stone, brick and concrete. Crowns can be of various sizes, they are selected depending on the required width of the hole. Dry drill bits are sold in sets or individually. The assembly of the tool is quite simple and not difficult.

Both electric and pneumatic tools of appropriate power can be used as a drive, in some cases special drilling rigs are used.

The last two types when installing household hidden wiring at an amateur level, as a rule, are not used.

Overview and description of the main types of crowns

To effectively cut holes in, it is important to choose the correct crown, taking into account the material in which the drilling will be carried out. Depending on this, the type of crown is selected, which is determined by the type of cutting nozzle. For concrete, stone and brick partitions, the following edges are used:

• Diamond
• Tungsten carbide.
• Pobeditovye.

We will tell in detail about each type.

Diamond

A feature of such a tool is the technology of shockless drilling. With this method, a more correct hole geometry is obtained than when cutting with carbide tipped tools.

There are two technologies for drilling concrete: “wet” and “dry”. Accordingly, for each of them different types of crowns are used.

Wet cutting tool.

In such crowns, the cutting part is diamond nozzles soldered to the base by refractory solder. If during the cutting process no water will be supplied to the edge for cooling, the nozzle will quickly heat up to a threshold temperature (about 600 ° C), after which the tool will fail.

A crown of this type that has become unusable can be restored, despite the fact that it is an expensive process, its cost will be lower than the price of a new tool.

Dry cutting tool.

In the manufacture of crowns that do not require forced cooling, the cutting nozzles are welded to the base using a laser. Such a tool may be subject to a higher thermal load, but, unfortunately, if it fails, it cannot be restored.

Advantages and disadvantages of diamond-coated crown mills

Let's start with the undoubted advantages:

• Such a tool can even cope with reinforced concrete, that is, it is able to cut steel reinforcement.
• Low noise and lack of dust (with wet cutting).
• The structure of the structure is not violated, since the shockless method is used.
• It is possible to restore the cutting surface (for wet cutting tools).

The main disadvantage of diamond nozzles is the high cost, which can be offset by the possibility of restoration of the tool. But this is only available for wet-cut castellated mills. To work with such crowns, a special drilling tool is required, which does not make sense to buy for the sake of drilling a dozen or two holes. This is a professional-level technique.

“Dry” crowns can be used with a conventional hammer drill, with an unstressed mode of operation. But this requires a certain skill, the tool is quite fragile, if vibration occurs (for example, when the support drill rotates), cutting nozzles may break off. Such a crown cannot be restored.

Tungsten Carbide

This type of cutting coating allows you to work with brick, concrete and ceramic material (for example, tiles). If such a cutter encounters metal fragments, it almost always fails, that is, such a tool is not suitable for cutting reinforced concrete.

Pobeditovye

This is the most common type of crown milling cutter. Its main feature is that the teeth of Pobedite or another hard alloy are used as cutting material.

For a tool of this type, a shock method of drilling is provided, that is, it is intended for use with perforators. Accordingly, the shank of such crowns is made under the SDS cartridge (SDS + and SDS are possible_MAX).

The main advantage of such a drill is its low cost. As for the shortcomings, then they include:

• Quick tool wear.
• The inability to restore cutting nozzles.
• Failure in contact with metal fragments (fittings).

Despite the large number of shortcomings, the tool with carbide tips remains in demand due to its low cost.

Sockets

A diameter of 68 mm was adopted as a standard for a “glass” for an internal outlet or switch. Naturally, for cutting, it is better to choose a larger core crown cutter, for example, Ø 70 mm, 72 mm and even 75 mm. Accordingly, a crown with a diameter of 65 mm is not suitable for this purpose (if you use standard socket boxes).

Standard diameters.

Conventionally, core milling cutters are usually divided into four size groups:

1. Small diameter tool. These include mills Ø4.0 - 12.0 mm. In everyday life, such nozzles are practically not used. Their scope is electrical switching work of increased complexity.
2. Medium-sized milling cutters (Ø35.0 - 82.0 mm). This is the most popular group, which is used in construction and repair work.
3. Large crowns (Ø150.0 - 400.0 mm). This group refers to professional tools designed for working with concrete structures.
4. Extra large diameter (Ø400.0 - 1400.0 mm). This type of core milling cutter belongs to industrial tools.

Note that to use the milling cutters of the third and fourth groups, special drilling rigs will be required.

Selection recommendations

To begin with, only a high-quality diamond crown can be better than a diamond crown. But given the cost of such a tool, the question arises of its profitability, especially if it is necessary to drill 10 = 20 holes. In such a situation, it is economically feasible to purchase 3-4 Chinese drills. On the other hand, the acquisition of a set of diamond milling cutters of various diameters can be considered as investment in private ownership of the means of production.

Having opted for quality, adhere to the principle to the end. Well, good diamond I crowns for concrete mortars cannot cost less than Polish average quality milling cutters.