Ø40

Ø40 is a technical notation used to indicate a circular feature with a diameter of 40 units. In metric engineering drawings, this is typically read as 40 millimeters in diameter. The symbol Ø denotes diameter and is widely used for holes, bores, shafts, pipe ends, and other round features.

On drawings, Ø40 is a dimension that controls the size of the feature. When applied to a hole or bore, it specifies the bore diameter. For tubing or pipe fittings, Ø40 can denote the outer diameter. The actual length, location, and geometric tolerances are specified elsewhere on the drawing.

Common applications include machining a 40 mm hole, selecting a component with a 40 mm outer diameter, or specifying a cylindrical boss, spacer, or dowel of this diameter. In assembly, the diameter is often paired with a tolerance and a fit class to ensure proper clearance or interference.

Tolerance and standards: Tolerances for a Ø40 feature follow ISO 286, with separate tolerance zones for holes and shafts. The exact values depend on the chosen fit and production method. Clear dimensioning ensures interchangeability of parts across vendors.