Chapter 4 Angular Measurements
Angular Position Measurements
Measurements Reference Guide 4-25
Principles of operation
The system described here measures the angular error of an angular
position, not total angular rotation. Basic operation during an angular
position measurement is simple and straightforward, and is diagrammed
in Figure 4-16A and Figure 4-16B.
1. The precision index table has a Hirth coupling consisting of
360 precision-ground teeth. Its position resolution is one degree,
within a ± 0.5 arc-second tolerance. The top of the precision index
table, which carries the fixture holding the “moveable” optic, is
disengaged from its base.
2. The machine part to be calibrated is rotated, turning the precision
index table’s base with it. The table’s top, along with its “moveable”
measurement optic is kept from turning by the friction clutch in the
fixture.
3. The precision index table’s top is re-engaged with its base, and the
fixture’s clutch is disengaged, allowing best engagement of the two
parts of the table. The error measured is the combined error of the
table under test and the precision index table.
4. The Agilent 5530 calibrator is instructed to record a measurement.
These four steps are repeated until all required data has been collected.
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