A Basic Overview of the Different Types of Screws

Do you know all the different types of screws and screwheads available in Seattle, WA? Unless you’re a contractor or handyman, probably not—most home DIY-ers only know the types that are applicable to their current, specific projects. Understanding the difference between these types ensures you can get the right screws and tools for the job at hand. Here’s a basic overview to get you started.

Types of screwheads

Screwheads come in three broad categories: countersunk, non-countersunk and combination:

  • Countersunk: Countersinking helps avoid splitting the wood when you drill. If you use countersunk screw types, you’ll need to use countersinking to get the appropriate angle and finish. This includes flat, raised and bugle screwheads.
  • Non-countersunk: Non-countersunk screwheads are designed to sit on top of your project, so you don’t need to use countersinking before drilling the holes to house the head. Binding screws have a male and female component that screw into each other, while domed screwheads are one of the most common types available. They can be decorative or utilitarian. Flange or frame screws eliminate the need for a washer, and truss heads have a wide screwhead that’s suitable for large holes and sheet metal projects.
  • Combination: Combination heads are also available, although slightly less common than the previous two categories. If you’re thinking about using a combination head, consider whether you need the screw to sit flush with the surface of the project or if it can sit on top. If the underside of the head is angular, it requires countersinking; if it is flat, it does not.

Drive types

A drive type refers to the type of tool you’ll need to drive the screw. Different drive types can help avoid stripping the screw (which makes them useless), but the more unusual the drive type, the harder it is to find tools to install them. Here are some of the more common types:

  • Hex external: This screwhead requires a wrench or a socket to install and remove. The screwhead sits above the surface.
  • Hex internal: Similarly, hex internal screwheads require an Allen wrench to install or remove. They’re common in assembled furniture.
  • Phillips: Phillips screws have a cross shape in the screwhead that’s designed to drill a straight hole. You can use a Phillips screwdriver or a drill with these screws.
  • Pozidrive: These have a star shape in the screwhead, and can be used with a Phillips screwdriver (although not always). They offer more stability.
  • Quadrex: This is similar to a Phillips screw, but has a squared shape in the middle of the cross to prevent stripping.
  • Slotted: Slotted screws are also known as “flathead” screws, and are good for manual installation with a flat screwdriver.
  • Square recess: These are also known as Robertson screws, and have a square recess to prevent cam outs.

Of course, there are plenty more types of screws available. Call or stop by Stewart Lumber & Hardware Co. for advice on choosing the right type of screws and tools for your project in Seattle, WA.

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