All screws and not the same and knowing which screw to use is important to ensure that it’s doing its job right. For instance, the screw that holds your furniture together will not work if you decided to hammer it into your wall to hang your pictures. The right screw for the right job makes all the difference whether it is for carpentry or for building a ship.
There are many kind of screws and there are many ways of classifying them. One of these is to classify them according to the job requirement. For instance, brass machine screws, that are used for motor casing. You can also classify screws according to the driving method and head shapes. Here are the classifications in detail:
By Driving Method
This classification is based on the shape of the slot at the screw head. This will also determine the shape of the screwdriver or drill head. These are:
Slotted: This is the oldest and most common shape. The slot at the head is just a linear diameter and can be used with a standard screwdriver.
Philips: The head has a cross-shaped slot that does not reach the edges. It requires a Philips-head screwdriver. This shape offers a more compact grip to the screwdriver head.
Combination: This is a combination of the slotted and Philips. It has a cross-shaped slot like a Philips head with one of the linear slots running to the edges like a slotted head.
Allen/Hex: It has a hexagonal slot that is tightened with an Allen wrench. This type of screw can only be loosened by a socket wrench.
Square: It has a square-shaped slot.
Star: The star-shaped indentation is extremely efficient in preventing stripped heads.
By Head Shapes
This classification is according to the shape of the screw head. Some of these may not even have a slot at the top. These head cannot be fastened by a screwdriver and need a wrench. The different shapes we find in screws are Flat, Oval, Socket cap, Pan, Round, Button, Hex, Flange, Truss, Full bearing, Washer-faced, slotted-hexagon, Flat hexagon socket, Countersunk hexagon slotted, Countersunk, Raised countersunk, Philps round pan, Philips round and so on.
By Job Requirement
The shape of the screw head does not matter here. The material and the shank shape are more important, like brass machine screws. Both these factors determine where the screw can be used. The different type of screws here are:
Wood screw: These are screws used with woodwork. The screws are unthreaded at top with coarse threads at the bottom for better grip on penetration. This ensures that the screw will go in smoothly without excessive splintering. There are various sizes and types here. These can be wood or metal like brass, bronze and steel. Since these are used in making furniture, the type should also be picked for aesthetic purposes, such as round-headed screws.
Machine screw: Made from machining, these screws have the advantage of customization. A typical screw will have very clean threading and a much better grip. Machine screws like brass machine screws are used in pre-drilled holes. These are used in motor casings, electrical terminals etc. However, these cannot be used with wood.
Sheet metal screw: These screws have full thread, but a wide variety in head type. The screws have the advantage of customization and are used in a wide array of applications, such as with plastics, rubber, plywood and metal. However, these cannot replace the wood screw. There are many types of screws that come under this category and the right screw depends on the material you will be using.
Drywell screws: There are two types of drywall screws — finely threaded (S-type) and coarsely threaded (W-type). Finely threaded screws are used to attach metal studs, while coarsely threaded screws are used to attach wood to drywall. Both types have sharp points that makes drilling fast and easy. In addition, the finely threaded do not need any pre-drilling because of their pointed ends.
These are the different types of screws that you have to look for. When buying a screw, you will notice that it will fall into different categories. For instance, a brass machine screw is a machine screw which can have different types of head.