Applied geometric tolerancing in accelerator component design

This paper discusses how the ANSI Y14.5M 1982 Standard for Dimensioning and Tolerancing applies to the fabrication of components for cryogenic accelerators. It includes information on selecting data and assigning positional tolerances that ensure stress-free mechanical mating conditions as well as interchangeability of parts. In addition, modifiers can be used in the feature-control frames that specify allowable deviations from nominal geometry; their uses reduces the cost of fabrication without compromising ease of mechanical assembly. The physics requirements unique to the design of linear accelerators also call for the prudent application of some seldom-used modifiers that reduce the need for alignment of initial assemblies to optimize accelerator performance