In woodworking, getting the right size screws is crucial. There are many factors to consider including screw diameter, length and threading. Knowing the proper screw dimensions can make or break a project. There are several standards for screw sizing that all manufacturers follow. These include the gauge, threads per inch and shaft length. This information is usually indicated on the packaging of each screw. Screws are also sold in metric sizes and most manufacturers will display both imperial and metric sizes on the packaging of each product. Metric screw diameters are measured in millimeters while imperial sizes are measured in fractions.
Screws are generally classified by their gauge number, with the larger numbers corresponding to thicker screws. These screw sizes are then further broken down by their threads and shank diameters. These dimensions are typically listed on the package in a three-part format, with the first number representing the screw gauge, the second number specifying the threads per inch and the third number representing the shaft length. For example, a wood screw with a threaded head may be labeled as: #6-32 x 1 1/2″. This would mean that the screw is a #6 gauge, has 32 threads per inch and is 1 1/2 inches long.
Most screw charts will only list the three aforementioned measurements but some may provide other important specifications as well. For example, some charts will also provide the lead angle of the screw. This is a factor that helps determine how easy or difficult it is to drive the screw into the material. Other measurements that are sometimes provided include the major diameter and the minor diameter. The major diameter is the diameter of the unthreaded portion of the screw and can vary slightly from the minor diameter.
For example, a screw with a major diameter of 0.1495 inches will have a minor diameter of about 0.1320 inches. Screws can be made with either coarse or fine threads. Fine threads are generally used in hardwoods while coarse threads are often used in softwoods and plywood. Screws can also be manufactured with a rounded or oval countersunk head. This type of screw is commonly used in decorative applications and is sometimes referred to as a mushroom head screw.
Screws can be purchased with different types of heads as well, including flatheads and drywall screws. Each type of screw has a specific purpose and is best used in specific materials. Drywall screws, for instance, are mainly used to secure full and partial sheets of drywall in home construction and do-it-yourself projects. They are also used to repair nail pops, which are circular bumps in drywall caused by nails and screws pushing against one another. The most common small imperial screw is the drywall screw, which has a major diameter of 0.1138 inches, 32 threads per inch and is 1 1/2 inch long. These are often found in new homes and can be easily purchased at hardware stores. #6 screw diameter