Cylindricity constrains the form of a cylinder. In ASME Y14.5 the tolerance zone is the space between two coaxial cylinders, and the surface must lie between them. Cylindricity covers roundness, straightness, and taper together. It has no datum. A hole can be a true cylinder and still be in the wrong place; that place is Position. It can be a true cylinder and still lean; that lean is Perpendicularity or Parallelism.
The Cylindricity Tool in 3D Auto-Dimensioning evaluates one cylinder from the feature set — a hole or a pin — whether it was extracted or authored. A fillet is its own feature, not a cylinder.
What the number means
The reported cylindricity is the radial width of the zone that contains the surface: the difference in radius between the outer and inner cylinders of the zone. The Viewport draws the deviation as a heatmap on the cylinder. The callout carries the value and a pass or fail state against the tolerance.
Cylindricity does not use the erosion control that Flatness uses.
Workflow
Select Cylindricity
Choose Cylindricity from the Toolbar in Dimensioning Mode, or right-click a cylinder and choose Add cylindricity control…. Choose a cylinder
Click the cylinder. Eligible cylinders highlight on hover.
Set the tolerance
Enter the tolerance in millimeters.
Submit
Submit to add the control to the feature set. The heatmap and the callout appear on the cylinder.
The tolerance can be edited after the control exists. The heatmap and the pass or fail state update without a new extraction.
Reading the result
The heatmap shows where the surface leaves a perfect cylinder. A band at one end is taper. A stripe along the length is a flat or a lobe. Use the callout controls to move the leader. The cylindricity value does not change.
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