Runout tolerances control how much a feature deviates when the part is rotated around a datum axis. They are essential for rotating components to ensure smooth motion and minimal vibration.
1. Circular Runout
Controls variation at a single cross-section during rotation.
- Measured using a dial indicator while the part rotates
- Applies to each circular element independently
- Tolerance zone: variation in radius at one section
Detects local issues like out-of-roundness or slight misalignment.
2. Total Runout
Controls variation across the entire surface during rotation.
- Measured along the full length while rotating
- Combines effects of form, orientation, and straightness
- Tolerance zone: full surface envelope during rotation
Ensures the whole feature runs smoothly without wobble.
Key Difference
- Circular Runout → checks one slice at a time
- Total Runout → checks the entire surface at once
Circular Runout is easier to measure but less strict
- Total Runout is more comprehensive and often used for high-precision shafts, spindles, and bearing surfaces
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