Precise measurement of large bore surfaces using dial indicating and digital instruments in the past was difficult and not economical. But that scenario is about to change with the introduction of #7 standard style and #8 standard style bore gages. These gages feature modular design, that can be easily assembled to measure a variety of large bore diameter. These instruments reachability can be easily extended to evaluate conditions of a deep bore.

The primary goal for Dorsey was to develop an ergonomic instrument to measure a wide range of large bore diameter. These bore gages include a retractable centralizer to ease placement of the large bore gage into the bore. Additionally, a single horizontal adapter is readily assembled to the large bore gage to extend its use for measuring a second wide range of larger bore diameters. A vertical adapter is provided to extend reachability of the bore gage to measure deep bore diameters.