What is straightness?

What is straightness?

• A. A form tolerance controlling the straightness of a line or axis.
• B. A geometric tolerance controlling the location of holes.
• C. A size tolerance for diameter variation.
• D. A surface finish specification.

Answer: (B)

Straightness is a form tolerance that constrains how straight a feature’s line element or its axis must be. It governs the geometry of the part itself—how much a line or axis can deviate from a perfect straight line—independent of where features are located. If you need to control the location of holes, you’d use a positional (true position) tolerance, not straightness. The other options describe different aspects: a size tolerance would concern diameter variation, and a surface finish specification concerns roughness. So straightness best describes the requirement as a form tolerance on the straightness of a line or axis.

Straightness is a form tolerance that constrains how straight a feature’s line element or its axis must be. It governs the geometry of the part itself—how much a line or axis can deviate from a perfect straight line—independent of where features are located. If you need to control the location of holes, you’d use a positional (true position) tolerance, not straightness. The other options describe different aspects: a size tolerance would concern diameter variation, and a surface finish specification concerns roughness. So straightness best describes the requirement as a form tolerance on the straightness of a line or axis.