Gauge blocks are the longest‑standing and best established dimensional standards in industry. They have form of parallelepipeds whose opposite (measuring) faces materialize a length equal to the face spacing. Typical materials are steel and ceramic, as well as tungsten carbide. Gauge blocks are categorised as “short” (up to 100 mm in length) or “long” (longer than 100 mm), based on the provisions of the international standard ISO 3650. Short gauge blocks are usually used in workshops to set bench instruments such as internal micrometers and height instruments (height gauges). Long gauge blocks are mostly used in acceptance and reverification tests of CMMs (Coordinate Measuring Machines) as per ISO 10360‑2.
The laboratory is able to calibrate both types of gauge blocks, by means of separate equipment. The uncertainty of measurement for the short gauges is