When working with screws, a good way to distinguish them is by their diameter and thread count. For example, a 3/8″-16 screw means that it has a diameter of 3/8 inches and a thread count of 16 per inch. However, this system is not the only way to discern one screw from another. The other method, used with imperial screws (as well as some metric ones) is by their gauge number. This can be a little trickier to understand.
A gauge number refers to a fraction of an inch in size, so you need to use a table or a calculator to figure out what the numbers actually mean. For instance, a #6 screw has a diameter of 7/64ths of an inch. This makes it a pretty small screw and is typically only used in light-duty projects like crafts.
There are many different types of wood screws. Some are designed for construction, while others are meant to be decorative. The best kind of screw for any project will depend on the type of wood, the thickness of the boards and how long the screws will be in place. When selecting a screw length, it is important to remember that the tip of the screw should be buried in the wood. This will prevent the head from securing too loosely or falling off.
Some screws have different heads that are also useful for certain projects. For example, a finish screw has a smaller head than a standard wood screw to allow the tip to reach just beneath the surface of the wood and create a tiny hole that can then be filled with wood putty.
Drywall screws are another type of screw that is often used for a variety of projects. They have a curved head that is specifically designed to crease the top paper layer of drywall, rather than sinking into the studs. This can be a useful feature when trying to repair nail pops in older homes.
A standard rack screw is called M6 x 1. This identifies it as being metric, and the 6 identifies the diameter of the thread in millimeters. If you are working with imperial screws, the naming convention is slightly different: a gauge number corresponds to a specific thread pitch, and the length of the screw is given as a decimal and fraction of an inch. You can find a chart online to help you match up imperial screws and metric threads for an easy conversion. For the most accurate results, you should use a calibrated screw pitch gauge. This will give you the most precise measurement possible, allowing you to make sure your screw sizing is consistent across projects. #6 screw diameter