Screws - overview of screw types

Screws - overview of screw types

Screws - overview of screw types: overview

A nailed screw holds better than a screwed nail! Even if there is even a grain of truth in this somewhat nonsensical saying, it is better to use the right screw and above all the right screwdriver.

On this page we would like to offer an overview of screw types, show different types of screw types, introduce different types of screw heads and explain what they can be used for.

Screw connections are a great way to create detachable connections. Although many so-called universal screws are available, but only with the choice of the right screws, they also offer the perfect grip and can even be used creatively.

Basic knowledge: Hard screwdriving - soft screwdriving

In the search for the right screwdriver or wrench frequently fall concepts, such as hard screwing and soft screwing. But what is the difference and what must be considered when buying bits?

The difference in the case of screwdriving lies in the terms "hard" and "soft." This refers to the onset of torque when tightening the screw.

    • Onhard screw case occurs when the torque suddenly rises so hard. If the screw head hits a solid surface, the screw stops jerking and the torque increases enormously in a very short time. This is often the case when hard materials are fastened with carriage bolts.
    • Thesoft screw case is more likely to be found in the wood sector. Here, the screw head presses gradually into the material and the torque rises slowly to the maximum

Screws - overview of screw types: screw

Hard bits with torsion zone for hard and soft screwdriving

Decisive is the knowledge about the screwdriving case when buying bits. If, for example, a hard screwdriving case is often to be expected, hard bits must not be used. Hard materials are also often brittle and a hard bit would break with a jerky increase in torque. Here rather soft or tough bits are required, which bend easily resilient when the torque occurs and absorb the torsional forces.

If only wood is screwed and can be counted on many soft screwdriving, hard bits can be used. In soft screwing they are not subject to the risk of breaking, but are due to their hardness but wear-resistant and last longer.

Do-it-yourselfers seldom have an advantage to pay attention to the difference of hard or soft bolting, and to direct the purchase of the bits afterwards. Here, so-called tough-hard bits are used, which are hard enough not to deform even at higher torques, but not so hard that they break in a hard screwing. The combination is often made possible by bits with torsion zone. These are softer zones in the middle area of ​​the bit, which are springy while the tip of the bit can be hard. This way, the properties of hard bits are combined with those of tough ones.

Division of the screws

Screw connections belong to detachable connections. For this they have a thread which makes it possible to tighten and loosen them. Important for the distinction is primarily the shape of the thread.

  • metal screws have a cylindrical shaft (cylinder driver) with a standardized thread. This can be a metric thread but also screws with other types of threads, such as round, trapezoidal or pipe thread. Commonly used in Germany are metric ISO and fine threads. Metal screws always need a counterpart with the same thread in the form of a nut or a threaded hole in the workpiece.
  • wood screws are more or less conical and have a coarse thread. Since they cut the mating thread itself into the material (mainly wood), they do not need a standardized thread.

Screw types metal

Marking machine screws according to DIN

Metal screws will toomachine screws called because they are mainly used in mechanical engineering and metalworking. Due to fixed shapes and strengths, also finds the nameDIN screws often application. Often less interesting for do-it-yourselfers, the strength class is of particular interest in mechanical engineering.

A special code on the screw head provides information on tensile strength and yield strength. It informs you about the torque with which the screw can be tightened to the maximum and for which load it is designed. In the private sector and without special stress the strength class 8.8 is in use.

strength classTensile strength in N / mm²Yield strength in N / mm²
4,6400240
5,6500300
5,8500400
6,8600480
8,8800640
10,91000900
12,9120010,9

Screws - overview of screw types: types

Designation of metal screws

Screws - overview of screw types: thread

1. Carriage bolts, 2.Mass bolts, 3. Hanger bolts, 4. Furniture handle bolts, 5. Eyebolt, 6. Screw plug, 7. Composite screws

From the complete DIN designations of a metal screw, however, much more information can be gathered.

Screw ISO 4017 M8 x 50 - 8.8

  • ISO 4017 (old DIN 933) - Hexagon bolt with continuous thread up to the head
  • M8 - Thread size metric thread M8 (also possible M8 x 1 for fine thread)
  • x 50 - Shaft length of 50 mm (with partial thread: 50/30 - Shaft length 50 mm of which 30 mm thread)
  • 8.8 Tensile strength 800 N / mm² and yield strength 640 N / mm²

The following table for screw types offers a selection of different metal screws. It shows the special features and explains what the screws are used for.

Special threaded screws and designations

###

particularityuse
carriage boltSemicircular head with square
After mounting, only one lens shape can be seen from the carriage bolt. The attachment of a key is not possible on the screw head. As a stop serves only a square below the head, which presses into the wood or is held in a square prefabricated hole.
Without screwdriving, carriage bolts can not be removed from the visible side. Therefore, they are often used for fastening safety-relevant components. Due to the smooth shape, they also look appealing and reduce the risk of injury. Therefore, they are used for chairs and benches.
grub screwThreaded pin without head
Grub screws have no head and can be completely rotated by the mating thread. The screw drive is incorporated in the threaded pin. Therefore, in addition to a slot only internal screw drive, such as Torx, internal serration or hexagon socket possible.
Without protruding head, grub screws are unable to press two workpieces against each other. They are often used to secure by the grub screw is screwed into a threaded hole and presses with the tip into a hole or notch of the second part.
hanger boltThreaded pin without head
Grub screws have no head and can be completely rotated by the mating thread. The screw drive is incorporated in the threaded pin. Therefore, in addition to a slot only internal screw drive, such as Torx, internal serration or hexagon socket possible.
Without protruding head, grub screws are unable to press two workpieces against each other. They are often used to secure by the grub screw is screwed into a threaded hole and presses with the tip into a hole or notch of the second part.
Furniture handle screwBolt with metal thread and wood thread
Hanger bolts have both types of screw threads. A screw drive can be incorporated internally on the side of the metal thread, but also be present in the middle in the form of a hexagon.
The large diameter of the head should prevent it from pressing into the wood while providing a large friction surface. Since furniture handles are often made of plastic, the screws must not be tightened too tight and yet not come loose. This is ensured by a large contact area between the screw head and the wood
eyebolt

Threaded bolt with ring

Eyebolts have no screw drive and instead an attached ring in different designs.

eyebolts are additionally equipped with a collar that rests on the surface.

Eye bolts are not used to connect two or more workpieces. They are used to create mounting options. The "eye" is used for hanging knitting, chains or carabiners. Also versions as a mother are possible.
thumbscrew

Threaded bolt with manual screw drive

Thumbscrews have no typical screw drive. There are two wings on your head that allow the screw to be turned by hand.

The suit by hand excludes a large power transmission. Thumbscrews are therefore used there, where a tool without tools

Screw

Similar to the grub screw with or without collar

Locking screws have a very short thread, in many cases a fine thread and can be designed with or without collar.

Closing screws are used to seal pipes, openings or filling holes. Their shape can be very special and is often adapted to the requirements. They are used in mechanical engineering, for example as an oil drain plug.
composite screws

Screw with counterpart

Composite screws bring their "mother" in the form of a matching counterpart.

Instead of a nut or a threaded hole, composite screws have special counterparts, which make it possible to pull together two furniture boards without damaging them. Their field of application is therefore furniture construction

Types of screws wood

Screws - overview of screw types: screw

1. Chipboard screws, 2. Viennese screws, 3. Drywall screws, 4. Plunger screws, 5. Self-tapping screws, 6. Furniture screws

The thread of wood screws is not standardized and so a uniform designation of wood screws is difficult. Here different manufacturers try to develop the optimal thread pitch and best screw shape for different materials.

Especially the screw manufacturer Spax has a pioneering position, because not only different fields of application are covered, but also a continuously very good quality is offered.

In the following table on screw types we would like to explain some designations of special screws. However, many terms only define usage and specific properties. Nevertheless, screws with the same name can be very different. Differences are particularly evident in the thread form or the screw cut. Sometimes you have to try a little until the optimal screws are found. Then it is advisable to stay with a manufacturer in order to always achieve a consistent tightening result.

Special wood screws and labels

chipboard screw

The chipboard screw is a fairly simple slim wood screw without any special features. It can have a partial or full thread and has a countersunk head. As a screwdriver except all hexagon almost all variants in question.

Chipboard screws can be used in many areas and thus form a universal screw. Special additional details can also be specified for special applications

Viennese screw

Viennese screws are characterized by a partial thread, especially in their hexagonal screw head. Since this can be used a jaw or ring spanner, Viennese screws are often referred to as key screws.

Since a large torque can be transmitted with a key, Wiener screws are mainly used for connections with special stress. Their partial thread ensures that the parts to be joined can be pressed firmly together.

Drilling screwsIf the material is very hard or bursts quickly, the screw hole must be pre-drilled. For this purpose, self-drilling screws have a small drill at the tip, which makes additional drilling unnecessary. Self-drilling screws are used for wood and thin sheets.
board screws
However, planks can be screwed, as drill screws have a drill bit, but are also designed without running smoothly into the material. An additional small screw head, which often runs very pointed, prevents the wood surface from bursting when the screw is lowered.
Window Frame Screws
Very slim, long and mostly equipped with a small head are window frame screws (Frame screws, window screws). Their special difference, however, lies in their thread, which can be screwed directly into the concrete and brick without dowels.
adjusting screwsAdjustment screws have rings in tooth form on the upper shaft. If a board is fastened with such screws, the adjustment screw can then be adjusted by turning it to the left. Through the toothed rings, the screw rotates only from the ground, the board is raised or lowered with the screw.
furniture boltFurniture screws are very individually made, but have a commonality. The screw head is always designed as a countersunk or flat lens head and can have a conspicuously large diameter. This ensures that furniture screw gets a good grip, is sunk and primarily does not present a risk of injury.
Drywall screwsDrywall screws are mainly used in drywall. They have a very sharp point and a double thread. This allows a quick operation, since the thread has a very large slope, but by two threads total not gears than a conventional wood screw. It offers the same hold, with a much larger slope.
Wood screwsThe screw shape, screw size or thread is not decisive for a Spengler screw. Decisive is their sealing function by a rubber seal. This can be directly under a very large screw head or an additional disc. Their use is mainly found in the flat roofing by means of metal sheets
terrace screwsAs the name suggests, patio screws are designed for fixing decking. In addition to a self-cutting tip, which makes a pre-drilling unnecessary, they have a split thread. The lower part fits securely into the wooden structures, the middle without thread provides working space and the upper threaded part holds the deck board firmly. Terrace screws are additionally characterized by non-rusting materials, such as stainless steel, whileinstallation screws Provide only a conditional rust protection through a zinc layer.

Full thread or partial thread - which is better?

Less relevant in the case of metal screws, since the upper workpiece always has a hole that fits the screw, the question of partial threads or full threads in wood screws can be of great importance.

Advantages and disadvantages of fully threaded screws

Screws - overview of screw types: screws

Full-thread screws and partial thread screws

As the name implies, the thread runs from tip to head in full thread screws. This property is advantageous if angles, sheets or the like are attached. Here, the full thread engages over the entire screw length in the wood or the dowel and provides the maximum grip.

If the part to be fastened has a bore which is larger in diameter than the screw, this part is pressed firmly onto the substrate by screwing in the screw. However, if the upper material does not have a bore and the workpieces to be screwed are not pressed firmly together, there remains a gap between the two parts, which can not be removed even by tightening the screw more tightly. If both parts are to be firmly connected, the upper part must be drilled large enough.

When fixing planks, however, it can be advantageous that the full thread engages in the substructure (beam ceiling) and in the floorboard. Even if the planks dry and the material thickness shrinks, it is securely held by the thread and no creaking noises are generated under load.

Advantages and disadvantages of partial thread screws

Partial screws have a thread only in the lower part (about 2/3) of the screw. The upper shaft is smooth and slightly narrower than the thread itself (lock and Viennese screws have a thicker shaft). This has the advantage that the upper workpiece does not have to be pre-drilled. After the threaded part has drilled through it, the shaft without thread is movable in this area and can pull it firmly against the lower workpiece. For simple wooden structures, this way of working is faster and more effective than full-threaded screws.

A disadvantage, however, is that partial thread screws react negatively to movements or material shrinkage. If the material under the screw head shrinks due to dehydration or regular loading and unloading, as is the case with planks, a play arises and the upper piece of wood can move. The result is the typical creaking noise in old floorboards.

Screws - overview of screw types: screw

With full thread there is a risk that both parts will not be pressed together.

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