Which statement differentiates circular runout from total runout?

Which statement differentiates circular runout from total runout?

• A. Circular runout concerns a single datum axis and a cross-section; total runout concerns the entire surface as the part rotates about the datum axis.
• B. Circular runout concerns the entire surface during rotation; total runout concerns a cross-section.
• C. They are defined identically.
• D. Circular runout applies to curved surfaces only.

Answer: (A)

Runout specs measure how far a surface deviates from true rotation about a fixed axis. Circular runout looks at a single cross-section and tracks how that circular trace moves as the part spins around the datum axis. Total runout expands that view to the entire surface as the part completes a rotation, capturing deviations all around the surface, not just in one slice. So the differentiating idea is that circular runout concerns a single datum axis and a cross-section, whereas total runout concerns the entire surface during rotation about the datum axis. The other descriptions mix up the scope—circular runout is not about the whole surface, and total runout is not limited to just a cross-section.

Runout specs measure how far a surface deviates from true rotation about a fixed axis. Circular runout looks at a single cross-section and tracks how that circular trace moves as the part spins around the datum axis. Total runout expands that view to the entire surface as the part completes a rotation, capturing deviations all around the surface, not just in one slice. So the differentiating idea is that circular runout concerns a single datum axis and a cross-section, whereas total runout concerns the entire surface during rotation about the datum axis. The other descriptions mix up the scope—circular runout is not about the whole surface, and total runout is not limited to just a cross-section.