BS 7172:1989

Foreword
Committees responsible
Guide
1. Scope
2. Definitions
3. Symbols and abbreviations
4. Outline of guide
5. Parametrization of geometric elements
6. Measurement procedure
7. Data pre-processing
8. Establishing a reference
9. Departure from nominal form
10. Information to be provided by an assessment
11. Numerical considerations
Appendix
A. Formulae for distance of a point to a geometric
    element
Table
1. Minimum numbers of points
Figures
1. A distribution of points on a line
2. A distribution of points in a plane
3. A 'chess board' distribution of points in a plane
4. A distribution of points on a lobed circle
5. A distribution of points on a sphere
6. A distribution of points on a cylinder
7. A distribution of points on a cone
8. Example of a profile with two equal maximum
    inscribed circles, centred at A and B
9. Example of a profile with a locally maximum
    inscribed circle, centred at A

For manufacturers of coordinate measuring machines (CMM\'s) and software writers within the CMM industry. To promote better use of CMM\'s for assessment of geometric form.

This British Standard provides information and guidance to manufacturers of coordinate measuring machines (CMMs), and particularly software writers within the CMM industry. It contains recommendations for determining the position, size and departure from nominal form of geometric features, given measurements of coordinates of points on a workpiece. The features covered correspond to the following geometric elements: lines, planes, circles, spheres, cylinders and cones.

This standard is concerned with software implementations of algorithms based on sound mathematical and computational principles, rather than automated versions of manual or graphical assessment procedures.

This standard does not provide detailed guidance on methods for treating data gathered in an unstable environment.

This standard does not cover secondary attributes, i.e. measures derived from departures from form of the above geometric elements, such as parallelism, concentricity or orthogonality.

This standard primarily relates to CMMs that operate with a right-handed Cartesian coordinate system. It also relates to other measurement systems that provide such coordinates. Some of the guidance provided also applies to other coordinate systems.