Runout

Controls how much a surface varies as the part rotates through 360 degrees around a datum axis.

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0.03

Runout is the total indicator variation of a surface as the part rotates about a datum axis.

It combines effects from axis offset and out-of-round surface form at each measured cross-section.

Use runout on shafts, gears, drills, axles, spindles, and other rotating features where wobble or vibration matters.

It is a practical replacement for many concentricity requirements because it can be measured on the actual surface.

Rotating Shaft Surface Checked With An Indicator

Runout captures wobble by holding the datum axis fixed and reading surface variation during rotation.

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0.03

A circular tolerance zone at each cross-section, referenced to the datum axis during rotation.

Constrain the datum axis in V-blocks, centers, or a spindle, then rotate the part while an indicator contacts the controlled surface.

Circular runout is checked at individual cross-sections. Total runout sweeps along the length as the part rotates.

A shaft journal has circular runout 0.03 mm to datum A. The indicator ranges from -0.006 mm to +0.018 mm during one rotation.

Indicator spread

0.018 - (-0.006) = 0.024 mm

Runout is total indicator movement during rotation.

Compare

0.024 <= 0.03

The surface variation is inside the allowed runout.

Section check

Repeat

Other cross-sections along the feature should be checked separately.

The journal passes circular runout at the checked cross-section.

Control	Measured By	Coverage	Datum
Circular runout	Indicator per section	2D cross-section	Axis
Total runout	Indicator swept along length	Full surface	Axis
Circularity	Roundness per section	2D cross-section	No

Runout is always regardless of feature size; MMC and bonus tolerance are not used.

Circular runout can be thought of as concentricity effects plus circularity effects at a section.