AS B233-1966

Provides a series of standard cylinders used for checking the effective (pitch) diameter of external threads, and covers standard ranges of ISO inch, ISO metric, Whitworth and BA threads. Two grades of measuring cylinder are covered, Grade A (pitch-line) and Grade B (grouped), the latter series being the same as the so-called 'best size' cylinders introduced by the National Physical Laboratory and amended and extended to cover ISO screw threads. Diameters of standard cylinders and P-values are given in inch and metric measures and some theoretical data, including relative merits of grades A and B, are also included.

This British Standard relates to two grades of screw thread measuring cylinders intended for use in checking external screw threads by means of pitch diameter measuring machines.NOTE. For a full description of this well established method of measuring the effective diameter of an external screw thread when using thread measuring cylinders, and also for an explanation of the P value used in this measurement, see 'Notes on Applied Science No. 1' issued by the Department of Scientific and Industrial Research and entitled 'Gauging and Measuring Screw Threads', published by Her Majesty's Stationery Office.The standard comprises two parts:Part 1 gives the bases for the diametral tolerances of Grade A and Grade B screw thread measuring cylinders and the relative merits of the two grades.Part 2 gives the complete specification for both grades of cylinders suitable for the forms and pitches of screw threads shown in Table 1.

Reconfirmed 1987