When performing construction work, repairing furniture, as well as for fixing various kinds of home interior items (pictures, shelves, etc.), it is impossible to do without such a necessary thing as a self-tapping screw. There are several types of this fastening tool, but wood screws are perhaps the most commonly used type. It provides secure fastening of wood or wood materials (hardboard, chipboard, plywood), as well as for fastening drywall sheets to a wooden base.
In appearance, these self-tapping screws resemble screws. But they differ from these types of fasteners, which are threaded for 2/3 of the length, in that they are threaded along the entire length of the product.
The main feature that distinguishes self-tapping screws for wood from the same for metal is a rarer thread pitch (the angle of inclination is 45o relative to the top of the profile), respectively, and a smaller number of turns. This is due to the fact that, in its structure, wood is not as hard and dense as iron.
What are wood screws
Potheir appearance, which depends on the specifics of manufacturing, they are:
- golden (yellow-passed);
- white (galvanized);
- black (phosphated).
Regardless of color, the material used for the production of self-tapping screws is high-strength carbon steel. It undergoes 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 over the material and provide a high level of adhesion of the cap 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:
- Rod. The base of the self-tapping screw, on which there is a thread.
- Head a. In appearance, there are conical, carob, loop.
- Slot. Depending on the tool used for twisting, there are cruciform, straight and hex.
- Tip. May be pointed or drilled.
Depending on what parts are used for fixing wood screws, their sizes can be very different - from 11 to 300 mm in length. The most commonly used self-tapping screws are 35 mm long and 3.5 mm wide.
Features of using self-tapping screws
- In order for the connection to be sufficiently reliable, it is important to choosethe desired length of the screw, which should exceed the thickness of the attached part by at least one and a half times.
- Most of the self-tapping screws used for fastening parts do not require pre-drilling holes. However, sometimes you have to deal with hardwoods. In this case, it is necessary to drill a hole in order to avoid violating the integrity of the slot at the junction. If wood screws with 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 self-tapping screw, and the diameter of the drill should be 1-1.5 mm thinner than the width of the self-tapping screw. Since it is very difficult to find a special drill for wood of the desired diameter, you can use the same one, but for metal.
- When using furniture self-tapping screws (confirmates), drilling a hole is mandatory. In this case, it is necessary to use a special drill with a variable diameter along its length, since such self-tapping screws have a thickening closer to the head.
