Types of screws and their use
After the appearance on the construction market of artificial wood materials, various building materials made of plastic, the range of fasteners expanded, new ones appeared types of screwsthreads on them and the shape of the heads.
Content
- General information
- Screw thread
- Screw heads
- Slotted and cross head screws
- Screw dimensions
- Washers, sockets and caps
- Unhardened screws
- Hardened wood screws
- Particleboard screws
- Frame screws
- Drywall Screws
- Screwless screws
- Square head screws
- Self-tapping screws (self-tapping screws) video
- Masonry screws
- Hooks and eyelets with screw
General information
Under various works, the production of self-tapping screws with various types of heads has been established, they are usually produced from non-hardened steel, but there is a small assortment of red-hot.
Corrosion-proof screws are made of brass and stainless steel, to increase the anti-corrosion properties, steel screws are sometimes coated with zinc, chrome or brass.
On the market for fasteners, there are sherardised screws coated with bronze or varnish.
Modern builders use screws and self-tapping screws instead of nails for joining all wooden plastic parts, since screws provide powerful compression of parts, they can be unscrewed, they can be used to correct building structures, and when used with glue, they can replace clamps. Recently, polycarbonate canopies for automobiles have gained wide popularity, during the installation of which self-tapping screws with thermowells are widely used.
Screw thread
The design of a traditional screw assumes that under the head there is a smooth, whole body of the screw, it acts as a screw or tenon and is about 1/3 of the length of the screw, the rest has a thread that has a sharp tip at the end.
Modern screws are available with a modified thread, it can be one - or two-way. To facilitate the start of screwing, there is a sharp tip at the end of the screw, a smooth body with a diameter smaller than the thread, which eliminates the need for preliminary drilling for small screws.
There are screws with a thread along the entire length, they can be quickly screwed in with an electric drill or screwdriver, this allows not to split the wood.
Screw heads
The assortment of heads is great, but we will describe the most common ones:
- countersunk head - for work where the head must be recessed either flush or below the surface;
- a semicircular head - more often used with sheet materials, the thickness of which is too small for a countersunk head;
- semi-countersunk head - a hybrid of countersunk and semicircular heads, used to fasten metal parts to wood;
- mirror screws - this is a screw with a countersunk head, a hole with a thread is made in the end of the screw to secure the decorative cap, it is often used to install wall mirrors;
- a flat cylindrical head;
- a head with a press washer - both heads are similar to a semicircular, but are on self-tapping screws, used to connect metal sheets.
Splined and cross heads
All of the above heads are divided into slotted, having a straight slot and cross, having a cross slot.
Phillips heads provide better engagement of a screwdriver (Phillips), great for an electric screwdriver.
Screw Dimensions
The length of the screws and their diameter is indicated in millimeters or inches, or by a number. The ratio of diameter to length varies for different standards, but these differences do not have significant practical value, the number is indicated by a number from 1 to 20.
The higher the number, the thicker the screw, the most running diameters: 2, 3, 4, 6 mm.
The length of the screw includes the distance between its tip and the plane under the head, the length varies from 6 to 150 mm.
Washers, sockets and caps
To enhance the clamping action, as well as for a decorative effect, countersunk and semi-countersunk head screws can be used with metal washers. Plastic sockets with caps, after screwing in, allow screw heads to be closed.
Unhardened screws
Widely used, traditional screws with single-thread helical threads have a variety of sizes, heads are made of different materials.
These screws are used for most types of wood, as well as for fixing metal parts to wood (hinges, locks and locks).
Before using screws, it is necessary to drill a guide and a technological hole.
The length of such screws is from 9 to 150 mm., The diameter is from 2 to 8 mm.
Hardened wood screws
For fast screwing in, screws with a countersunk or semicircular head with two-thread and large pitch are produced.
Such screws are used when working with any kind of wood, as well as artificial wood materials.
The hardening of these screws allows them to be screwed into relatively soft materials without a guide hole.
The length of such screws is from 12 to 100 mm., The diameter is from 2.4 to 5.6 mm.
Particleboard screws
Such hardened steel screws can be used not only for chipboard, but also as universal fasteners, they are made only with countersunk heads and single-thread.
Basically, a guiding hole is required for them, but small-diameter screws can be screwed without guides into coniferous wood or soft artificial wood materials.
The length of such screws is from 12 to 100 mm., The diameter is from 3 to 6 mm.
Frame screws
For screwing into the edge of the chipboard, in order not to split the material, hardened steel screws with single thread and large pitch are used. To facilitate screwing, it is advisable to drill a guide hole.
The diameter of the screw is 4.2 mm., The length of the screw is 45 mm.
Drywall Screws
Special two-way screws made of hardened steel, used for attaching drywall or fiberboard to racks or to a wooden (metal) crate.
These screws have a pointed tip, he makes a hole for himself, as well as a head, it allows it to be fixed in the material.
The screw length is 25-70 mm., The diameter is 3.5 and 4.2 mm.
Screwless screws
Such screws, at present, are relevant for fastening car numbers, since special slots are made in the heads, they allow you to screw in the screw, but push out the tip of the screwdriver when you try to unscrew the screw.
The screw length is from 18 to 50 mm., The diameter is from 3.5 to 5.6 mm.
Square head screws
Such screws are used for products that, during operation, have a high load. They are made of non-hardened steel, large washers are placed under the square head, they do not allow the head to crash into wood.
The length of the screw is from 25 to 150 mm., The diameter of the screw is from 6 to 12 mm.
Self-tapping screws (self-tapping screws)
These screws are capable of cutting their own thread in plastic or thin sheet metal. Made of cemented steel i.e. surface hardening, have a variety of heads, straight or crosswise slots.
Screw length from 6 to 63 mm., Screw diameter from 2.7 to 6.3 mm
Masonry screws
Very hard screws, have a special double-thread. They can be screwed into any masonry without plugs and dowels.
The length of the screw is from 57 to 100 mm., The diameter of the screw is 4.8 mm. and 6.4 mm.
Hooks and eyelets with screw
Steel hooks and eyes, have the usual screw thread. Used for mounting to a wall or panel, have different sizes, different configurations, are used to attach a cord, chain, etc.
