Engineering toolkit · PrototypeRUNOUT CONTROL / GD&T SYMBOL GUIDE
Total runout controls the complete surface as a part rotates about a datum axis. For a cylindrical surface, the zone is the space between two coaxial cylinders centred on that axis. It is the full-surface, 3D counterpart of circular runout: variation around the circumference and along the length is assessed together.
INTERACTIVE APPLICATION
Use total runout when contact and alignment matter across the full shaft length. It limits combined circularity, straightness, taper and cylindricity-like form effects, plus orientation and coaxial location relative to the datum axis. Size still needs its own tolerance.
High-speed shafts, pump and transmission shafts, gears, rotating assemblies and bearing or seal surfaces with significant contact.
Identify a cylindrical datum feature A to establish the rotation axis. Attach the runout frame to the surface being controlled, and keep the diameter size tolerance separate.
Datum A is attached to the size-dimension line for the cylindrical reference feature. The frame leader identifies the controlled surface.
The double-arrow total runout symbol identifies the control. 0.05 is the maximum permitted indicator variation in drawing units. A identifies the datum axis.
The illustrated value limits indicator variation during rotation about the datum axis; it is not a universal process grade.
Scroll the table sideways to see every column.
| Application | Illustrative starting value | Example feature | Notes / caution |
|---|---|---|---|
| Full Bearing Journal | 0.05 mm (example only) | full bearing journal | Illustrative only; confirm full-surface coverage. |
These are planning examples, not universal rules or guaranteed process capabilities. Set the actual tolerance from function, size, length, process capability, inspection method and the standard specified on the drawing.
Use circular runout for individual circular cross-sections: each has a 2D tolerance zone checked separately. Use total runout when the full surface matters: its 3D zone covers the whole cylindrical surface.
Total runout is generally more restrictive because it also limits taper and form variation along the surface. Both reference a datum axis; neither replaces the size tolerance.
Circular runout · Total runoutRotate the part about the datum axis and translate the dial indicator along the full controlled surface. The highest minus lowest reading across the complete scan must not exceed the total runout tolerance.
ASME Y14.5 total runout relates the full surface to the datum axis, unlike independent circular sections.
ASME Y14.5 edition reference. Examples are learning schematics; use the complete requirements on the drawing.
LEARN BY DOING
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