steelrule

A steel rule, or steel rule, is a rigid measuring instrument used in drafting, metalworking, woodworking, and related trades. It consists of a flat, straight blade made from hardened steel with graduation marks etched or stamped along its length. The tool functions as both a ruler and a straightedge, allowing users to measure distances, lay out lines, verify straightness, and serve as a reference edge for cutting or machining.

Construction and markings commonly include scales in metric (millimeters, often with 0.5 mm subdivisions) and imperial (inches, typically 1/16 or 1/32 inch subdivisions). Many steel rules provide one scale on each side or have dual graduations to accommodate different measurement systems. Popular lengths range from 6 inches (150 mm) to 24 inches (600 mm), with thinner, stiffer blades preferred for precision work.

Uses and applications vary by field. In drafting and engineering, steel rules are used to draw precise lines and check dimensions. In metalworking and woodworking, they help verify stock dimensions, transfer measurements, and serve as a straightedge for layout and cutting. Some rules include features such as beveled edges or anti-glare finishes to suit specific tasks.

Care and maintenance are straightforward. Wipe the blade clean after use, keep it dry to prevent rust, and store it flat or in a protective case. For longer life, lightly oil the blade and avoid bending or dropping the rule, which can affect accuracy. Steel rules remain a common, inexpensive tool for quick, dependable measurement and layout work.