BS 3730-2:1982

Characteristics of contact (stylus) instruments based on the method of determining departures from roundness by measuring variations in radius. Appendices deal with departure from roundness of the measured profile, use of instrument, calibration, determination of systematic errors, least square centre and circle plotting and reading polar graphs.

This Part of this British Standard specifies the characteristics of contact (stylus) instruments based on the method of determining departures from roundness by measuring variations in radius.

It relates to the assessment of the departures from ideal roundness of a workpiece through the medium of a profile transformation, obtained under reference conditions, expressed with respect to any one of the following centres:

1. centre of the least squares circle;
2. centre of the minimum zone circle;
3. centre of the minimum circumscribed circle;
4. centre of the maximum inscribed circle;

NOTE 1 Each of the foregoing centres may have its field of application. The position of the least squares centre can be calculated from a simple explicit formula given in Appendix E.

Departures of roundness from the measured profile, use of instrument, calibration and determination of systematic errors of rotation are dealt with in Appendix A to Appendix D, respectively. Appendix F gives rules for plotting and reading polar graphs.

NOTE 2 Reference conditions include the stylus, frequency limitations of an electric wave filter (if used), permissible eccentricity of the graphic or digital representation of the profile (generally 1/7 to 1/15 of its mean radius, see Appendix F) and the position of the measured section or sections relative to some feature of the workpiece.

NOTE 3 The titles of the publications referred to in this standard are listed on the inside back cover.