Just a few decades ago, micrometers were considered the ultimate
in precision for length measurements . Even the measuring machines
used at those times in gage laboratories operated on the
principles of micrometers.
More sensitive measuring instruments were developed to satisfy the
requirements for higher accuracy , and they replaced the use of
micrometers in many applications . Most of the higher sensitivity
instruments, however, are of the comparator type, which require
setting masters for referencing , possess only a reduced measuring
range and are, to some extent , generally stationary .These , and
many other characteristics , are definite disadvantages in
comparison to the portable micrometer, with its capability of
measuring actual lengths by direct indication over a substantial
measuring range. In addition to these inherent advantages of the
micrometer system and the relatively low price of the instruments
, many recent improvements in the design and manufacture of
micrometer gages contribute to assuring a continuing important
role to this category of measuring tools in the field of length
measurements.