Primary-level calibration of master gears requires quantifying the measurement uncertainty on the artifact being
calibrated by a method that does not rely on a transfer comparison. The measurement decomposition method, developed
jointly by National Institute of Standards and Technology (NIST) and Oak Ridge Metrology Center (ORMC) personnel,
is used to determine the uncertainty of each component of the measurement task. Once quantified, these components are
added in quadrature according to NIST Technical Note 1297, 1994 Edition. Verification of this method can be
accomplished by inter-comparisons with other methods and laboratories. The techniques developed at NIST and ORMC
utilize a CMM with a rotary table, a FORTRAN program for involute data generation, and a ProEngineer solid model for
gear visualization.