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rate as the parts, and therefore no temperature compensation is required.

•If the gage blocks are made of the same material as the parts temperture compensation is less significant.

•For high accuracy measurements we want to allow temperatures of gages and parts to stabilize.

•The ISO 1 and ANSI Y14.5 standards speify a typical dimensional ambient temperature as 20°C.

•Materials may vary widely from the listed coefficient of thermal expansion. As a result it is best to take them to 20±0.1°C for high precision measurements, and 20± 0.01°C for critical measurements.

35.6.3.1 - References

Doiron, T., NIST, Personal Correspondence.

35.6.4 Odd Topics

• There are also a number of angular gauge blocks for the measurement of angles. The two common sets are,

16 piece set
degrees	45°, 30°, 15°, 5°, 3°, 1°
minutes	30’, 20’, 5’, 3’, 1’
second	30”, 20”, 5”, 3”, 1”
13 piece set	1°, 3°, 9°, 27°, 41°, 90°
degrees
minutes	1’, 3’, 9’, 27’, 0.1’, 0.3’, 0.5’
tool room accuracy ±1 second
laboratory accuracy ± 0.25 seconds

• The selection of angular gauge blocks is similar to the selection of linear gauge blocks, except that subtration may also be required. (When the blocks are stacked, then angles are simply reversed.