PROFILE OF A SURFACE

PROFILE

Controls the form of an entire surface simultaneously

~ DATUM OPTIONALASME Y14.5-2018 §11

Profile of a surface is the most versatile GD&T control — it can simultaneously control form, orientation, and location of any surface (flat, curved, or complex) relative to a true profile defined by basic dimensions. Without datums it controls form. With datums it controls everything.

WHEN TO USE IT

Use profile of a surface for complex curved surfaces, freeform shapes, cast surfaces, or any surface where the complete three-dimensional form must be controlled. It is the preferred control for surfaces that cannot be defined by simple size or form controls. It replaces the need for separate flatness, angularity, or location callouts on complex geometry.

COMMON MISTAKES

Omitting basic dimensions that define the true profile — all geometry must be basic

Not specifying datums when orientation or location must also be controlled

Confusing bilateral and unilateral tolerance application

Using profile of a surface on features of size where position would be more appropriate

IS YOUR CALLOUT CORRECT?

Check these before releasing your drawing.

Are all dimensions defining the true profile basic (boxed)?

Every dimension that defines the nominal shape must be a basic dimension.

If orientation or location must be controlled, are datum references included?

Without datums, profile controls form only. Add datums to also control orientation and location.

Is the tolerance zone bilateral or unilateral, and is it clearly indicated?

A standard profile zone is bilateral (equal on both sides). If unilateral, use phantom lines or the unequal tolerance symbol to indicate which side.

RELATED SYMBOLS

OTHER PROFILE CONTROLS

⌒Profile of a Line

Redprint checks profile of a surface automatically

Redprint verifies that profile of a surface callouts are supported by basic dimensions and flags missing datum references when orientation or location control is clearly intended.

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