The invention is a snap locking angle adjustable device, particularly applicable to carpenter's squares. Carpenter's squares, being used in rough environment, must be simple to adjust while providing robust snap locking at
high angle precision. Prior art attains this by protruding steel balls, attached around the pivot axis of the square's
handle, pressed strongly against a hole punched area around the pivot axis of the square's blade-balls aligns to holes gives the snap locking. The problem is to simplify manufacturing. The invention comprises components with moulded alignment structures. These components are the complete pivot members (
handle or blade) themselves, or are separately attached to the pivot members. The components, and optionally, are sandwiched, alignment structures against each other, and axially pressed together strongly by a spring held in compression by a press frame that also may constitute a pivot shaft for the pivot members.