The GO / NO GO plug gauges for British BSW threads are inspection tools designed to verify the conformity of internal British Standard Whitworth threads according to BS 84. They are used for fast and repeatable checking of threaded holes on mechanical components, industrial spare parts, British-standard machinery, equipment, vintage vehicles, inch-based fastening systems and technical parts requiring compatibility with Whitworth threads.

The GO / NO GO configuration provides a simple method for checking the functional suitability of internal threads. The GO side must screw correctly into the threaded hole, confirming that the thread meets the minimum acceptance requirements and is compatible with the corresponding male component. The NO GO side, on the other hand, must not screw in beyond the specified limit, helping identify oversized, deformed, worn, out-of-tolerance or non-conforming threads. This method is especially useful in quality control, production, maintenance and inspection departments because it allows rapid verification without complex measurements on every single part.

British Standard Whitworth threads use a 55° profile and remain present in many industrial applications, especially on machinery, spare parts, equipment and components with inch-based threads. It is important to correctly distinguish gauges for British BSW threads from UNC, UNF, BSP, NPT or metric gauges, because profile, pitch, thread angle and mating compatibility are not interchangeable. Using the wrong gauge may lead to accepting non-conforming threads or rejecting correct components.

The correct gauge must be selected according to the nominal British thread size, the corresponding pitch according to BS 84 and the required inspection function. These tools are particularly suitable when correct mating, functional accuracy and repeatability of internal Whitworth threads must be ensured.

For reliable inspection, the gauge must be used on clean threads, free from chips, burrs, oxides, dirt or machining residues. During checking, proper coaxial alignment with the threaded hole must be maintained and the gauge must not be forced, because misaligned or excessive use may damage both the gauge and the inspected component. These plug gauges are suitable for mechanical workshops, quality departments, maintenance technicians, toolrooms, technical restoration, vintage automotive work, mechanical engineering and industrial repairs where British internal threads must be checked with accuracy, speed and reliability.

Accredia certification or a calibration report can be supplied on request: this documentation increases delivery time because the gauge has to be sent to the inspection or certification body.