BS 959:2008

Foreword
1 Scope
2 Normative references
Section 1: Internal micrometers
3 Material of measuring head
4 Measuring face of measuring head
5 Micrometer screw
6 Thimble and barrel
7 Extension rods
8 Spacing collars
9 Adjustment
10 Accuracy
11 Rigidity
12 Handle
13 Marking
14 Case
15 Packing
Section 2: Stick micrometers
16 Terminal and abutment faces
17 Screwed joints
18 Extension rods
19 Accuracy of micrometer unit
20 Accuracy of extension rods
21 Rigidity
22 Marking
23 Gap setting gauges
24 Case
25 Packing
Annex
Annex A (normative) - Method of test for accuracy of internal
                      micrometer readings
Bibliography

Describes requirements for internal micrometers comprising a measuring head, extension rods with or without spacing collars, and, in the smaller sizes, a handle.

This standard specifies requirements for internal micrometers comprising a measuring head, extension rods with or without spacing collars, and, in the smaller sizes, a handle. Provision is made for three sizes of measuring heads, in both metric and inch units, as shown in Table1 and Table2. NOTE Attention is drawn to the fact that metric dimensions are not necessarily direct conversions of the imperial dimensions. Table1 Measuring heads— metric measurements Size of head Length of graduated scale on barrel Usual ranges of the instrument when used with extension rods mm mm Size 1 5 or 6.5 25-50 Size 2 10 or 13 50-150 50-200 50-300 Size 3 25 200+ Table2 Measuring heads— inch measurements Size of head Length of graduated scale on barrel Usual ranges of the instrument when used with extension rods in in Size 1 ¼ 1-2 Size 2 ½ or 1 2-6 2-8 2-12 Size 3 1 8+ This standard also covers stick micrometers, which are designed for the measurement of longer internal lengths, and comprise the following parts: a 150mm or 300mm or 6 in or 12 in micrometer unit, fitted with a micrometer of 25mm or 1 in range, and having rounded terminal faces; a series of extension rods which, together with the micrometer unit, permit a continuous range of measurement up to the maximum length required. Annex A gives a method of test for the accuracy of internal micrometer readings.