If in construction it is necessary to fasten wooden structures bearing heavy loads directly to each other, then special bolts and screws, the so-called cap screws, with a hex or square head are used. Capercaillie - a fastener having an external thread. Such self-tapping screws are made of galvanized carbon or stainless steel.
When screwing in, use a wrench or wrench. Its specially made external thread forms an internal thread in the hole of the tree, due to which the connection is very strong and reliable. Therefore, it is used to connect large and massive parts. The screw-capercaillie has different sizes. Section - from 6 to 12 mm, length - from 30 to 300 mm.
Structure
This screw has many names - capercaillie, plumbing bolt with a hex head, screw DIN 571, hexagon. The names are associated with its structure. The self-tapping screw on the hex head has a mark on which the manufacturer and product strength class are indicated.
The rod consists of two parts: a smooth cylindrical and a part with an external thread. The wood grouse ends with a sharp sharpened end, which, when screwed, cuts into the wood of the lags or laths.
The main parameters of such fasteners are the length, diameter and size of the wrench. Its length is measured from the base of the hex head to the pointed end. Diameter is measured by rod or thread. And the size of the turnkey head is measured by the distance between the opposite faces of the nut located parallel to each other.
Types of Bolts
Such products are distinguished not only by the size and diameter of the hex head, but also by the material of manufacture. For woodwork, structural carbon steel is used, which is treated with a layer of zinc protective coating. This is quality steel 08 kp, 10 kp, 1022.
Also, good products are bolts made of stainless steel, A2 and A4. These are high strength austenic steels. You can replace them with similar materials - AISI 304 and AISI316. They are also used for plumbing work.
Application
A screw bolt is used in cases where a strong connection is needed. Use it to connect two wooden parts that carry a heavy load. You can take them for attaching wooden structures (timber, logs, slats, boards) to a brick or concrete wall. The brick can be either solid or hollow.
Also use such fasteners when installing sanitary products to a concrete floor or walls. The use of capercaillie screws was found not only in construction, but also in mechanical engineering. On railway tracks with their help, the rails are mounted on sleepers. And the wires are fixed on concrete poles.
Features of use for wooden products
If the work is carried out with wooden structures and the wood of the products is not too hard, and the self-tapping screw has a small diameter, then it can be screwed in without drilling holes.
If the wood is solid and the bolt is large in diameter, then a hole must be drilled before starting the screwing process. To do this, a drill of a smaller diameter, about 70% of the diameter of the bolt, is taken, and a hole is drilled to a depth slightly greater than the capercaillie, by about 10 mm. This is done so that the thread does not break off at high pressure during screwing.
After that, you need to take a small brush and clean the hole, taking out the rest of the wood. Sawdust can clog the passage, and the screw does not screw in until the end. In the absence of a brush, you can take a thin long screw and draw it back and forth several times in the hole.
In order for the self-tapping screw-grouse to hold firmly, you need to use washers with it, corresponding in diameter. Their outer diameter should be equal to three internal. Washers DIN 9021 are suitable. Before screwing in, it is necessary to string the washer onto the shank and then begin work.
Using dowels
When using a self-tapping screw “plumbing capercaillie”, fixing through a dowel is necessary. They are inserted into a drilled hole in concrete or brick walls, and screws are screwed into them already. This is necessary to increase the strength of fastening parts to surfaces. Dowels are nylon, nylon and polyamide.
For this kind of attachment, you need to take not a conventional capercaillie with a pointed end on the thread, but a special one in which the thread is blunt and closer to the base there is a reduction in the diameter of the rod. When screwing the capercaillie into the dowel, cutting does not occur, due to the blunt end. The dowel expands under the pressure of the wrench in the hole. Further advancement takes place without much effort.
There are on sale such special products that are already complete with the right size dowels. There are frame and facade products. The formation of a plastic gasket due to the presence of a dowel skirt located between the capercaillie head and the part is considered a great advantage. It serves as compensation for temperature differences, causing different expansion of materials.
Step-by-step instructions for use
Wood gadgets or screws with a gap must be screwed in correctly so that the fastening of the parts is as strong as possible. Before starting work, it is necessary to completely align the two bonded surfaces so that the grip is clear, without gaps. If possible, it is better to fix the parts with a clamp so that there is no material shift.
Then you need to take a drill, smaller in diameter, and drill a hole in the wood through all the materials. Since the capercaillie has a hex head, the worker will not be able to use a screwdriver to pull together the fastened parts.
You will need a wrench or an electric wrench. Insert the nut head evenly, so that the pressure distribution is over the entire surface of the product, then screw it in carefully. This is an important point, because otherwise the bolt will go crooked or break.
Causes of breakdowns
If too much pressure is exerted on the self-tapping screw with a hexagonal head, then you can break the head of the capercaillie. This happens for several reasons. Firstly, the poor quality of the bolt itself. Process disruption may occur during head disembarkation. In this case, the shake experiences a strong stress, being at the boundary between the heating and deformation lines. If in the process there was no equalization of the structure of quenching and tempering, then when performing fastening work, the head has the ability to break.
Secondly, a hole was made in the material for the capercaillie. If the hole is not deep, the chips are not cleaned properly, then it will be difficult to prevent the bolt from breaking. When tightening with a wrench, there may be a high torsion speed or strong pressure. Capercaillie from acceleration rests against a wooden beam and breaks.
Thirdly, the reason may be an incorrectly selected drill for creating a preliminary hole. When performing twisting movements, the metal temperature rises from strong friction, the bolt is jammed. To save the situation, you can add a little grease to the bolt.
Fourth, an inappropriate dowel was taken.
There is another reason for folding the head, but it is extremely rare. This is a great speed, namely the sharp start of twisting a wood screw.
Price
The cost of such products depends on their size and quantity. The smallest in size is estimated at 70 kopecks apiece. The biggest wood screws will have a much higher price, as much as 22 rubles per piece. Wholesale deliveries will, of course, be much cheaper.