When performing construction work, furniture repair, as well as for fixing various kinds of home furnishings (paintings, shelves, etc.), it is impossible to do without such a necessary thing as a self-tapping screw. There are several types of this mounting tool, but wood screws are perhaps the most commonly used type. It provides reliable fastening of parts made of wood or wood materials (fiberboard, chipboard, plywood), as well as for fixing sheets of drywall to a wooden base.
In appearance, such self-tapping screws resemble screws. But they differ from these types of fasteners, which have a thread for 2/3 of the length, in that they have a thread along the entire length of the product.
The main feature that distinguishes wood screws from the same for metal is a rarer thread pitch (the angle of inclination is 45 ° relative to the top of the profile), respectively, and a smaller number of turns. This is due to the fact that the structure of the tree is not as solid and dense as iron.
What are wood screws
In their appearance, which depends on the specifics of the manufacture, they are:
- golden (yellow-passivated);
- white (galvanized);
- black (phosphated).
Regardless of color, the material used for the production of self-tapping screws is high-strength carbon steel. It is subjected to a special treatment that increases resistance to moisture. After that, the steel is coated either with a thin layer of zinc, or treated with a special substance that gives it a yellow color, or phosphated to improve sliding on the material and ensure a high level of adhesion of the bonnet surface to the finishing material. It should be noted that black wood screws are used much more often.
Structurally, they consist of the following parts:
- The core . The basis of the screw, on which there is a thread.
- Head a. In appearance there are conical, carob, loop.
- Schlitz . Depending on the tool used for twisting, there are cruciform, straight and hexagonal.
- Tip . May have a pointed or drill shape.
Depending on the fastening of which parts, wood screws are used, their sizes can be very different - from 11 to 300 mm in length. Most often, self-tapping screws with a length of 35 and a width of 3.5 mm are used.
Features of using self-tapping screws
- In order for the connection to be reliable enough, it is important to choose the desired length of the self-tapping screw, which should exceed the thickness of the attached part by at least one and a half times.
- Most self-tapping screws used to fasten parts do not require pre- drilling holes. However, sometimes you have to deal with hardwood. In order to avoid violation of the integrity of the slot at the junction in this case, it is necessary to drill a hole. If wood screws having a diameter of more than 4 mm are used, it should also be made to prevent cracking of the wooden workpiece. The hole is drilled to a length of 2/3 of the screw, and the diameter of the drill should be 1-1.5 mm thinner than the width of the screw. Since it is very difficult to choose a special drill for wood of the desired diameter, you can use the same, but for metal.
- When using furniture screws (confirmates), drilling a hole is necessary. In this case, it is necessary to use a special drill having a variable diameter along its length, since such self-tapping screws closer to the head have a thickening.