Overview
ISO 9960-1:1992 specifies the main requirements, accuracy and graduations for professional draughting scale rules (in SI units). It covers two types of scale rules: hand-held rules and rules for manually operated draughting machines. School scale rules are explicitly excluded. The standard defines shapes, nominal lengths, graduation systems, dimensional and geometrical tolerances, materials and surface requirements, inspection methods and marking/designation rules.
Key topics and requirements
- Scope & application: Professional draughting scale rules only; graduations in SI units; two usage types - hand use and manually operated machines.
- Cross-section and shapes: Multiple cross-section profiles are allowed (flat, bevels, oval, triangular, semi-oval, etc.), with recommended shapes shown in the standard.
- Nominal lengths: Standard nominal lengths include 150, 200, 250, 300, 350, 400, 450, 500, 600, 800 and 1000 mm (inspection rules typically 300 mm or 500 mm).
- Graduation details: Three-length division-line system for major/subdivisions; smallest subdivision not less than 0.4 mm; division-line lengths, widths and tolerances specified (e.g., mean width ranges and maximum variation). Characters shall follow ISO 3098-1 vertical character type.
- Dimensional & geometrical tolerances: Specified straightness, flatness and parallelism limits; accuracy grades (e.g., Grade 0 / Grade 00) with different tolerances for working edges and underside flatness. Concavity is not permitted for machine rules.
- Materials & surface: Materials must be dimensionally stable between 10 °C and 30 °C and 25–100% RH; underside must be smooth and non-damaging to drawing media.
- Inspection & test methods: Prescribed tests under standard atmosphere (ISO 554: 23/50); use of surface plate, feeler gauge, dial gauge and micrometer microscope for measuring flatness, straightness, division widths and distances.
- Designation & marking: Required designation format includes type, ISO reference, cross-section shape number, nominal length and tolerance grade (examples provided in the standard).
Practical applications and users
- Architects, mechanical and technical drafters and CAD studios that maintain traditional draughting equipment.
- Manufacturers of professional draughting scale rules and suppliers of draughting machines seeking to certify products to international tolerances.
- Quality and inspection technicians responsible for acceptance testing of scale rules and draughting machine accessories.
Related standards
- ISO 9960 (Parts 2 & 3): Protractors; Set squares.
- ISO 9962 series: Manually operated draughting machines (Parts 1–3).
- ISO 5455: Technical drawing scales.
- ISO 3098-1: Technical drawings - lettering.
- ISO 554: Standard atmospheres for testing.
- ISO 9175-1, ISO 10209-1 (referenced for related definitions and drawing terminology).
Keywords: ISO 9960-1, draughting scale rules, scale rules, graduations, draughting instruments, manually operated draughting machines, tolerances, inspection, SI units.