Which statement best defines total runout?

Which statement best defines total runout?

• A. A type of runout that considers the entire surface around full rotation.
• B. A variation of runout that considers only a single feature.
• C. A measurement of straightness along a line.
• D. A tolerance that applies to a narrow seam.

Answer: (A)

Total runout checks the complete surface as the part is rotated all the way around the datum axis. It enforces that every point on the surface stays within the tolerance throughout a full 360-degree rotation, so the deviation is considered for the entire surface around the circle, not just at one line or location. This is different from circular runout, which examines a single line or cross-section as the part rotates and doesn’t average or constrain the whole surface around the axis. It’s also not about straightness along a line or about a seam tolerance; those describe different geometric concepts.

Total runout checks the complete surface as the part is rotated all the way around the datum axis. It enforces that every point on the surface stays within the tolerance throughout a full 360-degree rotation, so the deviation is considered for the entire surface around the circle, not just at one line or location.

This is different from circular runout, which examines a single line or cross-section as the part rotates and doesn’t average or constrain the whole surface around the axis. It’s also not about straightness along a line or about a seam tolerance; those describe different geometric concepts.