The Swiss-designed Thury screw thread (alternatively called the Filière Suisse (FS) screw thread) is a metric thread standard that was developed in the late nineteenth century for screws used in scientific and horological instruments. The thread is named after Marc Thury, an engineer and professor at the University of Geneva who contributed heavily to the standard's development.
Development of the Thury thread began in 1876, when the Horological Section of Geneva Society of Arts appointed a committee to look into the requirements for a uniform thread standard for use in Horological arts in Switzerland.Professor Thury began his studies by collecting and measuring samples of screws made by nine independent screw and screw tackle manufacturers in Switzerland. The Thury thread form was developed in 1878, thirty-seven years after the British Standard Whitworth thread form was designed in England and fourteen years after the United States Standard thread was presented in the United States. However, unlike these two predecessors, the Thury thread was designed for small-diameter screws which were then produced with screw plates. This production technique mandated that the Thury thread form have rounded crests and roots. Thread forms with rounded or "radiused" crests and roots like the Thury and Whitworth thread generate smaller stress risers than those forms like the American National or ISO metric which have truncated roots and crests; in modern engineering this is particularly important factor when tapping holes in acrylic plastic, where a larger stress riser can lead to an earlier onset of crack formation. The Thury thread is unusual in having a comparatively small 47.5° thread flank angle, which was chosen to make fabrication easier and to achieve greater holding capacity than screws with larger flank angles. Screws in the Thury thread system are given nominal sizes, with the base size "0" being six millimeters in diameter and having a thread pitch of one millimeter. Sizes are proportional, so a size "1" is ten percent smaller in diameter that a size "0", while a size -1 is ten percent larger than a size "0". The Thury thread was believed to be the first thread form to solve the problem of creating a single system of screw dimensions applicable to all sizes. The relationship between the pitch P of a Thury screw and its diameter D is expressed by the equation D=6P5/6. Another variable Thury standardized is the thread depth, which had until then been variable when cutting threads in different materials. The proliferation of the Thury standard was hindered when in 1882, the British Science Association produced a committee report on the consideration of a standard screw gauge, where they declined to accept the Thury thread but instead chose to use the Whitworth thread standard previously designed by committee member Joseph Whitworth, in part because the Whitworth form was historically successful and because the committee did not believe England was prepared to use a metric thread as its standard. However, the committee recognized the validity of many of the design aspects of the Thury thread, and a mere two years later published their specifications for the British Association (BA) thread. The BA committee made only slight modifications to the rounding radii of Thury thread and gave specifications rounded to the nearest thousandth of an inch.
Despite being a popular screw standards for nearly a century,both the Thury thread and the BA thread have largely been replaced by the ISO Metric thread form. Today the Thury thread is rare outside out antiques due to the relative abundance of other standard sized fasteners. For example, the British Association 0BA, the Löwenherz 6mm and ISO M6x1.0 fasteners have identical pitch and diameter to the Thury size 0 (however, they are not interchangeable because they differ in thread geometry).
Standardization or standardisation is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organizations and governments. Standardization can help maximize compatibility, interoperability, safety, repeatability, or quality. It can also facilitate commoditization of formerly custom processes. In social sciences, including economics, the idea of standardization is close to the solution for a coordination problem, a situation in which all parties can realize mutual gains, but only by making mutually consistent decisions. This view includes the case of "spontaneous standardization processes", to produce de facto standards.
A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of components in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers. Micrometers are usually, but not always, in the form of calipers. The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil.
Sir Joseph Whitworth, 1st Baronet was an English engineer, entrepreneur, inventor and philanthropist. In 1841, he devised the British Standard Whitworth system, which created an accepted standard for screw threads. Whitworth also created the Whitworth rifle, often called the "sharpshooter" because of its accuracy and considered one of the earliest examples of a sniper rifle.
The Unified Thread Standard (UTS) defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada. It is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in these countries. It has the same 60° profile as the ISO metric screw thread, but the characteristic dimensions of each UTS thread were chosen as an inch fraction rather than a millimeter value. The UTS is currently controlled by ASME/ANSI in the United States.
A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. A screw thread is the essential feature of the screw as a simple machine and also as a threaded fastener.
A thread gauge, also known as a screw gauge or pitch gauge, is used to measure the pitch or lead of a screw thread.
A go/no-go gauge refers to an inspection tool used to check a workpiece against its allowed tolerances via a go/no-go test. Its name is derived from two tests: the check involves the workpiece having to pass one test (go) and fail the other (no-go).
British Standard Whitworth (BSW) is an imperial-unit-based screw thread standard.
British Association screw threads, or BA screw threads, are a largely obsolete set of small screw threads, the largest being 0BA at 6 mm diameter. They were, and to some extent still are, used for miniature instruments and modelling.
Trapezoidal thread forms are screw thread profiles with trapezoidal outlines. They are the most common forms used for leadscrews. They offer high strength and ease of manufacture. They are typically found where large loads are required, as in a vise or the leadscrew of a lathe. Standardized variations include multiple-start threads, left-hand threads, and self-centering threads.
British Standard Pipe (BSP) technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external (male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting, except in North America, where NPT and related threads are used.
British Standard Brass or British Brass Thread is an imperial unit based screw thread. It adopts the Whitworth thread form with a pitch of 26 threads per inch and a thread angle of 55 degrees for all diameters. It is often wrongly called British Standard Brass but is not actually covered by a British Standard.
The ISO metric screw threads are the most commonly used type of general-purpose screw thread worldwide. They were one of the first international standards agreed when the International Organization for Standardization (ISO) was set up in 1947.
British Standard Fine (BSF) is a screw thread form, as a fine-pitch alternative to British Standard Whitworth (BSW) thread. It was used for steel bolts and nuts on much British machinery, including cars, prior to adoption of Unified, and later Metric, standards. For highly stressed conditions, especially in motorcycles, a finer thread, British Standard Cycle (BSC), was used as well.
The distinction between real value and nominal value occurs in many fields. From a philosophical viewpoint, nominal value represents an accepted condition, which is a goal or an approximation, as opposed to the real value, which is always present.
A screw and a bolt are similar types of fastener typically made of metal, and characterized by a helical ridge, known as a male thread. Screws and bolts are used to fasten materials by the engagement of the screw thread with a similar female thread in the matching part.
United States Standard thread, also known as Sellers Standard thread, Franklin Institute thread and American Standard thread, is a standard for inch based threaded fasteners and washers.
ISO 898 is an international standard that defines mechanical and physical properties for metric fasteners. This standard is the origin for other standards that define properties for similar metric fasteners, such as SAE J1199 and ASTM F568M. It is divided into five (nonconsecutive) parts:
The Löwenherz thread is a largely obsolete metric thread form designed in the late nineteenth century and frequently applied in precision instruments. It is named after Dr. Leopold Löwenherz, who was the director of the metrology institute Physikalisch-Technische Bundesanstalt in Berlin.