BS 870:2008

• 17.040.30 Measuring instruments

This British Standard applies to the following types of external micrometers.

1. External micrometers having a frame holding a micrometer spindle and nut on one side opposite a fixed anvil on the other, with individual measuring ranges of: 0-13 mm; 25 mm (e.g. 0-25 mm, 25-50 mm, etc., up to 575-600 mm) and 0-½ in; 1 in (e.g., 0-1 in, 1-2 in, etc., up to 23-24 in).
2. External micrometers having a frame holding a micrometer spindle and nut on one side opposite an anvil on the other, and providing for two or more alternative ranges of measurement effected by means of interchangeable or sliding anvils, with individual measuring ranges of:
   • 0-50 mm, 0-100 mm, 100-200 mm, 200-300 mm, 300-400 mm, 400-500 mm and 500-600 mm; or
   • 0-2 in, 0-4 in, 4-8 in, 8-12 in, 12-16 in, 16-20 in and 20-24 in.
3. Setting gauges for micrometers above 25 mm or 1 in.

NOTE Attention is drawn to the fact that metric dimensions are not necessarily direct conversions of the imperial dimensions.