Cylindricity

Controls how closely the full length of a cylindrical feature conforms to a perfect cylinder.

⌭

0.04

Cylindricity is a 3D form control that requires every point on a cylindrical surface to fit between two coaxial cylinders.

It controls both roundness at each cross-section and straightness along the axis without referencing a datum.

Use it for shafts, pins, bushings, bores, and sliding cylindrical features where the full surface form matters.

It can control the shape more directly than tightening the entire size tolerance.

Cylinder Controlled For Roundness And Straightness

Cylindricity is the full-length form control for round features, independent of any datum.

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0.04

Two coaxial cylinders separated by the cylindricity tolerance and covering the full feature length.

Measure multiple cross-sections along the full cylinder length with a CMM, roundness machine, or rotating indicator setup.

The evaluated surface must fit inside the coaxial cylindrical tolerance band.

A bore has cylindricity 0.04 mm. The evaluated full-length cylinder requires a 0.033 mm separation between enclosing cylinders.

Form spread

0.033 mm

This is the minimum coaxial cylinder separation enclosing the surface.

Compare

0.033 <= 0.04

The full bore surface fits inside the allowed zone.

Datum

None

The control checks form only, not alignment to another feature.

The bore passes cylindricity.

Control	Datum	Zone	Scope
Circularity	No	Two concentric circles	One section
Cylindricity	No	Two coaxial cylinders	Full cylinder
Total runout	Yes	Rotating surface zone	Full related surface

Cylindricity is the 3D counterpart of circularity.

Because it is a form control, it does not use datum references or material condition modifiers.