Flatness refers to single plane surface and is usually a function of volumetric shrinkage.

Tolerances for axial straightness: ±.005 in. per inch (±.127 mm per 25 mm) as cast.

1. Concentricity of diameters in a shaft is also a function of straightness. Centers will be concentric within .005 in. per inch (±.127 mm per 25 mm) of maximum separation.
2. Centers of I.D. to O.D. will be concentric within .003 in. per 1/2 in. (.076 mm per 13 mm) of wall thickness. This disregards out-of-roundness, and assumes measurements in the same plane If the concentricity is being measured in separate planes, the requirements of paragraph 1 above must be added.

Roundness is a function of normal shrinkage variations in the metal. Shrinkage variation increases with diameter and the tolerance required increases proportionately. A general rule of ±.005 in. per inch (.127 mm per 25 mm) may be applied.

As-cast tolerances of angles depend on their location in casting. They range from ± 1/2° for well supported positions to ± 2° where inherent distortion could be expected. Inclusion of gussets and ribs often minimizes distortion and many sections can be mechanically straightened.

±.005 in. per inch (.127 mm per 25 mm) from any single reference point.

Blind holes can be cast if length does not exceed the diameter. In nonferrous materials, blind holes under 2 in. (6.5 mm) may be cast if length does not exceed twice the diameter.

Controlling relationship is between length and width of the elements being checked. To establish a specific tolerance range for all combinations would be impossible, but a general tolerance of .010 in. TIR per inch (.254 mm per 25 mm) may be used.

As-cast tolerances are ± .005" per inch (± .127 mm per 25 mm). Tubular section out-of-roundness may be altered mechanically according to wall thickness and ductility. Tolerances are as follows: