Different Types of Screws and Their Uses
Screws are commonly used fasteners that resemble nails in shape and function, but with the addition of ridges known as threads. These threads help the screw grip the inside of the screw hole as it is driven into the material. There is a wide variety of screws available, each designed for specific applications and materials.
Screw Anatomy
A screw consists of five main parts:
- Drive: The recess in the head where a screwdriver or driver bit is inserted.
- Head: The wide, circular part that sits on top of the material to prevent it from ripping through.
- Shank: The smooth area between the head and the threads.
- Tip: The pointed end of the screw.
- Threads: The ridged part that wraps around the main shaft and grips the material.
Types of Screws
Wood Screws
Wood screws are commonly used to join two or more pieces of wood together. They have a sharp tip that penetrates wood easily and typically do not require a pilot hole. The threads are widely spaced to grip the wood fibers.
Drywall Screws
Drywall screws are designed to fasten drywall panels to wooden studs or beams. They have coarse threads that provide a secure hold in the soft material. The countersunk heads allow the screws to be concealed below the surface of the drywall.
Deck Screws
Deck screws are used to attach deck boards to deck joists. They have a flat head that can be countersunk below the surface of the decking, providing a flush and aesthetically pleasing finish. Deck screws are typically made of stainless steel to resist rusting.
Masonry Screws
Masonry screws are designed for use with masonry materials such as concrete and brick. They require a pilot hole to be drilled before insertion. The threads are designed to grip the dense material securely.
MDF Screws
MDF screws are used with medium-density fiberboard (MDF). They have a special tip and threads that can penetrate the tough material without the need for a pilot hole.
Sheet Metal Screws
Sheet metal screws are used to attach various materials to sheet metal. They have sharp tips that can penetrate the metal surface, and fine threads that provide a secure grip. Sheet metal screws made of stainless steel are suitable for outdoor use.
Self-Tapping Screws
Self-tapping screws create their own threads as they are driven into the material. This eliminates the need for a pilot hole in most cases. They can be used in a variety of applications, including metal, wood, and plastic.
Double-Ended Screws
Double-ended screws have no heads and are inserted into two pre-drilled pilot holes. They are commonly used in furniture assembly.
Mirror Screws
Mirror screws have rubber grommets that prevent the metal screw from pressing directly against the mirror. They are used to mount mirrors securely without damaging the glass.
Security Screws
Security screws have unique heads that make them difficult to remove without special tools. They are used to deter theft and vandalism in public areas.
Hammer-Drive Screws
Hammer-drive screws are driven into materials using a hammer or mallet. They have thick, rounded heads and durable shafts, making them ideal for fastening signs and nameplates.
Machine Screws
Machine screws are used to join various parts of machinery or electronic devices. They have flat or rounded heads and typically do not have pointed tips.
Pocket Hole Screws
Pocket hole screws are designed for use in wooden furniture. They have special heads and shanks that draw pieces of wood together securely.
Choosing the Right Screw
When choosing a screw for a project, consider the following factors:
- Material: The type of material you are working with will determine the type of screw you need.
- Size: Screws come in a variety of lengths and diameters. Choose a screw that is the appropriate size for the material and the desired level of hold.
- Head: The head of the screw should be suitable for the material and the desired finish. Countersunk heads are typically used for a flush finish, while flat heads are used when the screw head will be exposed.
- Threads: The threads of the screw should match the material and the desired level of hold. Coarse threads provide a stronger hold in soft materials, while fine threads are better suited for hard materials.
- Special Features: Some screws have special features such as self-drilling tips, anti-corrosion coatings, or security heads. Choose a screw with the appropriate special features for your project.
Safety Precautions
Always use the correct size and type of screw for your project. Oversized or undersized screws can damage the material or fail to provide a secure hold. Wear safety glasses when using screws, and always drill a pilot hole when necessary.