A screw sizes chart is an excellent tool to help you figure out what size screws to use for various jobs. The chart will show you a number of things such as the screw gauge, screw pitch, and screw length. There are also columns for different types of heads such as hex and oval countersunk. These charts are used by builders, tradesmen, and home owners to ensure that they are using the correct fasteners for their projects. It is important to know how to read a screw sizes chart so you can understand the numbers listed.
The first number listed on a screw sizes chart is called the screw gauge. The screw gauge is the outside diameter of the threads and is also known as the major diameter. The screw gauge is followed by the number of threads per inch. The threads are what make the screw go into a surface such as wood or metal. The threads can be coarse or fine depending on the job. If you need to drill a hole for the screw, then you will need to know what type of drill bit to use.
In the United States, there are five standard tolerance classes of screws. The next number on the screw sizes chart is the tolerance class, which shows which holes or nuts the screw will fit into. You may see a letter A or B following the tolerance class, which indicates whether the screw is right-handed or left-handed. This is important because right-handed screws will fit into holes and nuts that are left-handed, while left-handed screws will fit into holes and nuts in the opposite direction.
Screws are measured in both imperial and metric systems. The majority of screws sold in the United States are imperial, while most of the rest of the world uses metric measurements. The metric system is based on the ISO screw thread standard. Metric screw size callouts are much easier to read and understand than the imperial system.
The last two numbers on a screw sizes chart are the length of the screw from the head to the tip of the threads. If the screw has a flat head, then the length will be from the base of the head to the top of the threads. If the screw has an oval or hex head, then the length will be from the center of the head to the edge of the head. You should also consider the fact that the head diameter on a screw is roughly double the shank diameter. This means that if the shank is 1?4 inches wide, then the head will be about 1?2 inches wide. The head diameter can vary slightly from screw to screw, but it will be close to this value. This is why it is important to measure the head of your screws before you screw them into a surface, to ensure that you are not over- or under-drilling the screw. screw sizes chart