ISO/TC/ 1 Business Plan, 2007-03-05, Version 1.3. Table 3: The market share of each screw thread, p. 7. Austria, Azores, Czech Republic, Denmark, Finland, Greece, Italy, Madeira, Poland, Portugal, Spain, Sweden In addition to coarse and fine threads, there is another division of extra fine, or superfine threads, with a very fine pitch thread. Superfine pitch metric threads are occasionally used in automotive components, such as suspension struts, and are commonly used in the aviation manufacturing industry. This is because extra fine threads are more resistant to coming loose from vibrations. [8] Fine and superfine threads also have a greater minor diameter than coarse threads, which means the bolt or stud has a greater cross-sectional area (and therefore greater load-carrying capability) for the same nominal diameter. Tables of the derived dimensions for screw diameters and pitches defined in ISO 261 are given in ISO 724.

Screw sizes are a mystery to most people so we have tried to make life a little easier with the metric imperial screw conversion chart below.

Metric and Imperial Screw Sizes

Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (2000), Machinery's Handbook (26thed.), New York: Industrial Press Inc., ISBN 0-8311-2635-3. Bulgarian, Croatia, Cyprus, Estonia, Hungary, Latvia, Lithuania, Malta, Romania, Slovakia, Slovenia A wood screw is sized by two different numbers. First is the Gauge of the screw which refers to the diameter – the larger the number, the larger the diameter. A number 4 screw is much smaller than a number 12 screw.

A concrete screw is what you need for fastening concrete. Some require you to pre-drill, while others are self-tapping. It allows you to drill directly into the surface without pre-drilling. Drive Types These are the most commonly used screws nowadays, but there are great deal more so if you are not sure about which types of screws to use, see also our projects on different types of screw, We also have a great project on how to countersink. ISO 68-1:1998 ISO general purpose screw threads – Basic profile – Part 1: Metric screw threads. International Organization for Standardization. Lastly, you need to measure the distance from one thread to another. It’s also referred to as the pitch. In the metric system, we use pitch instead of thread spacing. To get this final measurement, use a ruler or measuring tape. In most cases, the pitch would only measure less than 1 mm. It is recorded in a decimal point of an mm. Hex bolts – have a hexagonal shaped head and can have a full or partially threaded length, used with a tapped hole or interior nut thread.The standard system is otherwise known as the imperial system. It was introduced in the British Weights and Measures Act of 1824. It evolved through a series of amendments in the said act. For some time, the imperial system had been the standard measurement system. By the late 20th century, several countries have adopted the metric system. Presently, Canada and the United Kingdom are countries still using the imperial unit system. The design principles of ISO general-purpose metric screw threads ("M" series threads) are defined in international standard ISO 68-1. [2] Each thread is characterized by its major diameter, D ( D maj in the diagram), and its pitch, P. ISO metric threads consist of a symmetric V-shaped thread. In the plane of the thread axis, the flanks of the V have an angle of 60° to each other. The thread depth is 0.54125 × pitch. The outermost 1⁄ 8 and the innermost 1⁄ 4 of the height H of the V-shape are cut off from the profile. The gauge (imperial) is approximately the head’s size in millimeters (metric). However, there is no correlation or scientific explanation here. Metric System You can use a multi-material one in several materials, such as drywall or sheet metal. Wood and plastic ones are also good options. Concrete ST – Self Tapping; These screws have a tip that will allow them to be screwed into (typically wood) without a pilot hole being drilled. This saves a lot of time!