If only a CAD model is supplied the following tolerances apply to machined surfaces:
- For features of size (Length, width, height, diameter) and location (position, concentricity, symmetry) +/- 0.005”
- For features of orientation (parallelism and perpendicularity) and form (cylindrical, flatness, circularity, and straightness) apply tolerances as shown in the table below.
If a blueprint is provided, all tolerances of the print supersede the CAD model tolerancing above. Any supporting dimensioning on blueprints such as GD&T callouts, tap sizes, inserts, specific surface roughness must be followed. Parts that do not require plating or surface treatment must be supplied “as machined” and at most be polished with scotch brite unless there are requirements for sandblasting, bead blast, shot peen, tumble, etc. The surface roughness requirement for “as machined” surfaces is Ra 125 micro-inches maximum. If no Class of Threads is called out on the drawing, Class 2 is assumed.
