Control of roll in fiducialization of quadrupole magnets for the MIT-Bates South Hall Ring

The South Hall Ring (SHR) requires for all 94 quadrupoles in the lattice a roll tolerance of less than 2 mr. An important step in achieving this tolerance is the fiducialization: the relating of the magnetic axes to the position of the survey targets fixed to the magnet. The fiducialization procedure which we developed involved a harmonic analyzer system and the SLAC Industrial Measurement System. After fiducialization and database generation had been completed for over 1/3 of the elements, and after the precision installation had begun, we noticed a random roll well outside the tolerances. The roll had been overlooked partially because the harmonic analyser system is insensitive to rotations about the coil axis. We were able to overcome the problem through software by developing an extensive algorithm and regenerating the database without a need for refiducialization. This correction process for both the roll and the pitch will be presented