Category: Form

Circularity

by GD&T Basics on December 21, 2014.

Controls how round a cross-section must be at any given slice. Applied independently at each cut — it doesn't control the overall cylinder.

Cylindricity

by GD&T Basics on December 18, 2014.

Controls the entire cylindrical surface at once — roundness, straightness, and taper combined. Stricter than circularity, and harder to inspect.

Straightness

by Tom Geiss on November 6, 2014.

Controls how straight a line element or axis must be. Can apply to a surface line or to an axis — and the difference matters more than most people realize.

Flatness

by Tom Geiss on November 3, 2014.

Controls how flat a surface must be. No datums needed — it's self-contained, making it one of the simplest form tolerances to apply.