Screws may not be much to look at, but they have an important place in wall framing, woodworking, furniture-making, and many other projects. Because they hold materials together, it’s crucial to use the right kind for each project. But there’s a lot of options to choose from on the screw aisle, and it can be difficult to determine the best screw size for the job. This article will give you the information you need to understand the jargon of screw sizing, and how to choose the best screws for each application.
Screw sizes are identified by their major diameter and thread pitch. The major diameter is the largest measurement around the outside of the screw threads, while the thread pitch is the distance between each point where a screw thread’s grooves meet. The screw size you need will depend on the type of material you’re using, and also on whether you’re using an imperial or metric system.
The imperial system is the standard used in the United States, while metric screws are the most common elsewhere. Screws are usually listed in an imperial system, with their lengths measured in inches and the diameter of their threads measured by a gauge. You can convert gauges to diameters using a conversion chart or calculator. Screws are sometimes also labeled in metric measurements, but these are not as common.
Most screws are designed for basic wood construction, and the best screw size for any given job will depend on the kind of material you’re working with. For example, screws for framing walls are generally longer than those for joining boards together. In general, you’ll want to select a screw length that allows the tip to reach into the bottom board by about 2/3 of its thickness.
There are a number of different head types for wood screws, including hex, slotted, square, and Phillips. Each type of head has a different effect on the way a screw is driven into material, and some kinds of heads are intended for specific uses. For example, finish screws have smaller heads than standard wood screws, and they’re designed to be driven just below the surface of the material, leaving a small hole that you can fill with wood putty.
Aside from the type of head, another factor that goes into determining the best screw for a project is whether it needs to be countersunk or not. Some heads, such as hex and slotted, sit flush with the surface of the material, while others, like truss and pan, have a rounded top that can be countersunk to leave a smooth finish on the bottom of a project. To measure a screw’s head shape, you can use a ruler or tape measure to find the width of the head at its widest point. This is often referred to as the head diameter. A countersunk screw has a larger head than a non-countersunk one. #5 screw diameter