Rotating a screw advances a spiraled incline into a surface. The head of a screw functions as a lever, while its threading is just a long incline that has been wrapped around a vertical shaft.
To determine wood screw size, measure the thickness and width of the wood that the screw is entering and root diameter of the screw. Ensure that the size of the screw is such that there is enough wood material beyond and around the length and diameter of the screw.
Screw size charts are available at the websites of W. L. Fuller, Inc., Engineers Edge and Jamestown Distributors. All of these websites also offer additional information about choosing the right screws for a particular project.
Diameter, pitch and length in millimeters define the size of a metric screw. Metric screws have pitches of coarse, fine or extra fine. Carriage and stove screws are coarse threaded. Machine screws are either coarse threaded or fine threaded.
Bolt Depot lists nine standard machine screw sizes, the smallest of which is seven-sixty-fourths of an inch with a thread count of 40, while the largest is three-eighths of an inch with a thread count of 16. Some machine screws share the same diameter but feature differ...
The size of the screws needed to attach a license plate varies with the make of the vehicle. A 1/4 x 3/4 screw is most commonly used and is the size of license plate screws marked "universal."
Some of the nominal screw sizes of self-tapping screws are 00, 0, 2, 4 and 6. A screw of size 00 with a round head has six thread starts and a maximum head diameter of 0.099 inches. Size 6 flat head screws have a maximum head diameter of 0.279 inches.