Counterbore / countersink

Illustrated explanation

Recess shapes provide different seating and clearance

1Counterbore / countersink
Recess shapes provide different seating and clearanceCallout 1: Counterbore / countersink. Callout 2: Spot-face. Callout 3: Undercut relief. A counterbore has a cylindrical recess, a countersink has a conical form, a spot-face creates a seating surface and an undercut provides local relief. Current term: Counterbore / countersink, callout 1. 1CylindricalConicalCounterbore / countersink 2Spot-face 3Undercut relief
  1. Counterbore / countersinkThis term

    The two recess profiles are different. Specify the exact form and depth required for the mounting component.

  2. Spot-face

    The local machined land provides a defined seating face. Check its size, flatness and finish for the actual gasket or washer.

  3. Undercut

    The recess provides clearance near a transition or shoulder. Keep it separate from usable full-form thread engagement.

A counterbore has a cylindrical recess, a countersink has a conical form, a spot-face creates a seating surface and an undercut provides local relief.

Conceptual machining sections without depths or angles. Confirm each feature from the actual enclosure and accessory drawings.

ReferencesISO 1101:2017 — Geometrical tolerancingIEC 62444:2010 — Cable glands for electrical installationsISO 5408:2009 — Screw threads — Vocabulary