Although “nugget” also means “nail” in German, this is a slightly different type of fastener. Unlike screws, self-tapping screws and screws in the joints, it weakly resists external pressure, working more on shear and preventing bending of structures. It is usually used in the construction of wooden structures from logs, beams or boards.
What is a
Nagels differ from most types of fasteners: they have no hats, no threads. Outwardly, these are straight wooden or metal pins 12-15 cm long and 10 to 30 mm in diameter. They are intended for working with wood, although there are pins for concrete structures. The rods placed in the drilled holes prevent horizontal displacements of the fragments.
Timber tends to change in volume with fluctuations in temperature or humidity.. This is especially true for fresh materials. Depending on the structure, timber or logs can increase and decrease in size. As soon as the fragments of the tree begin to diverge, the surface of their contact with the pins increases: the pins under pressure slightly bend, the resistance to further movements increases. When the tree dries up, the pin ceases to experience high pressure and returns to its initial position.
In order for the fasteners not to be destroyed during operation, it is necessary to correctly select the pins, combining the diameter with the holes in the wood. As a result, the walls remain flat, and no deformation occurs. Nipple connections are more flexible than nails. Mounts prevent loosening and displacement of buildings.
Kinds
Since pins are used primarily for working with wood, they are made more often from wood. Metal rods are also used. One or more types of fasteners made of various materials are allowed.
Wooden pins
Wooden pins or dowels are whips with a smooth cylindrical surface. The diameter of their cross section is from 10 to 35 mm. Length can be any: up to 1.5 m or more. When driving into logs, segments of 10–15 cm are usually used. Less often, fasteners made of thin edged square or rectangular bars are used. The best raw materials for the production of daggers are hard rocks: oak or beech. Due to the relative high cost of these materials, birch or ash are more often used. Coniferous species are not suitable for these purposes because of their flexibility. They make the nails only from dry material with a moisture content not exceeding 12%. They are used for work with both soft and hard woods.
The advantages of wooden pins:
- resistance to bending loads;
- uniform change together with the main material: pins made of wood swell and change the temperature at the same time as the logs, without causing condensation to form;
- provide tightness of finished structures;
- do not interfere with the natural vertical shift of fragments, which eliminates the formation of gaps between the crowns.
Wooden dowels are suitable for the construction of boats, rafts, outbuildings, baths, one-story houses made of log houses, outdoor furniture and other wooden structures.
Disadvantages of wooden pins:
- low biostability;
- susceptibility to destruction;
- inability to withstand high pressure.
This type of fastener not only pulls together fragments of structures, but serves as a mortgage element, providing stability relative to each other. Working with wooden pins takes a lot of time, requires certain skills, and is quite difficult to perform.
Round dowels create better adhesion to the surface, it is recommended to use it when building load-bearing walls. Square fasteners are less durable, as it rests on the material only with corners. It is used in the assembly of light parts or walls that do not experience massive loads.
Metal pins
To provide a stiffer connection that can withstand high loads, a stronger material is required than wooden pins. When constructing the walls of large structures, metal rods are used for bonding logs. The production of a similar dowel from steel is almost impossible because of the high cost - a screw fastener with a diameter of 25-30 mm for the construction of a house would cost several hundred thousand rubles. Iron rods of this volume serve, as it were, powerful bridges of cold at lower temperatures.
Greater than that of beech or birch dowels, the strength allows the use of metal rods when working not only with wood, but also with concrete structures.
Metal dowels have more options in size and configuration, depending on the purpose:
- hollow inside rods of circular cross section resemble wooden dowels in shape, but have a smaller diameter;
- lamellae are intended for fastening at once several logs;
- hexagonal or star section rods - special-purpose fasteners, rarely used;
- spring-loaded grouse: type of galvanized self-tapping screws with a diameter of 10 mm, length from 20 to 28 cm, the design of the fasteners involves the use of springs clamped by washers, which allows the elements to withstand the load at the joints more than 150 kg per 1 cm²;
- U-shaped red-hot staples and studs are used to tighten and fix the logs from the end sides;
- pins for concrete work have the form of screws with a variable thread, a diameter of 7.5 mm, a length of 70 to 200 mm. They are screwed into the canvas with impact screwdrivers, preliminary drilling of the material when working with them is not required.
Often during construction, the usual segments of reinforcement or pipes with a diameter of 10-12 mm are used as pins.
Metal fasteners are more durable and durable, stable, prevents warpage of wood, does not fall out of drilled holes. The variety of shapes of manufactured nagles allows you to choose them for any type of screed. The disadvantage of metal products is too rigid fastening. Because of this, for some time, the bars and logs can hang, cracks appear between them. Iron corrugated pins often split and spoil the surface of the tree, the difference in thermal conductivity leads to the accumulation of condensate.
Manufacture
An industrial wooden dowel is produced from dry material of the highest or first grades, which does not contain felts or knots. The structure of the finished fasteners should be completely homogeneous. The parameters of industrial pins are regulated conditionally.
Common sizes:
- diameter 20, 25, 30 mm;
- length 120, 150 mm.
According to GOST during the work, the diameter of the dowels should be ⅙ of the diameter of the log. Pins of standard length are used to connect two logs; for fastening several, longer pins are required.
At the end of manufacture, the pins are treated with antiseptics.
If there is suitable wood, dowels can be machined independently at home on a woodworking machine. The fastener made in this way can have any parameters. It is recommended to make a long one, and later cut as necessary. Better use a well-dried non-hygroscopic material..
Nagels of square section are made simple: the board is cut along the fibers into long bars of 20-30 mm in diameter, the edges of the segments are ground.
To obtain rounded pins, square bars slightly larger than the required size are fixed in a lathe and grinded with a cutter. In the process, the specified diameter is checked several times with a caliper, otherwise there is a risk of over-thinning the material. Sharpened bars are cut and chamfered at the ends of the pins.
Mounting Features
It must be remembered that the pins must be stronger than the material to be joined. For example, pins made of larch are suitable for fastening pine logs, and birch wood must be fastened with no less heavy material: birch or oak. Logs and fasteners must be of the same degree of dryness, otherwise the mechanism for changing pressure and bending will be broken, the fasteners will crack.
To build a bathhouse or a log house under a house alone is problematic. To work with pins, you need to attract several workers.
The main requirements that must be observed during installation:
- The holes in the central parts of the crowns are drilled strictly vertically - along the axis of the walls. The upper log is usually pierced through, the subject - ½ of its thickness. In cases of using long nail joints, 3 logs are drilled at once. The diameter of the holes should be such that the pins do not enter freely, but also do not get stuck, penetrate with little resistance.
- For the first hole, they retreat from the corners of the building by approximately 40–50 cm, further holes are made every 1.5–2 meters. At the next level, they should be staggered.
- In the depth of the hole should exceed the length of the pins by 2-3 cm. This feature will protect the bars from hanging during seasonal swelling, and pins - from deformation and destruction.
- When driving fasteners, it is advisable to use not a hammer, but a wooden mallet, carefully driving the pins with it.
The greatest difficulty in assembling wood structures is the correct direction or size of the holes produced. Inexperienced builders, they often turn out to be curved or not corresponding to the diameter of the pins. Making the right connections in such cases is problematic.