Two holes are bored, perpendicular to one another, into the door. The "face bore" is the larger hole which is bored into the door face and a smaller "edge bore" hole is bored into the door edge. The edge may require additional preparation to receive the latch assembly, typically by routing or chiseling a shallow mortise.[1] Some commercially-sold doors may come prepared to receive one or more bored cylindrical locks, such as entry doors, which typically require both a door knob and dead bolt.[2]
In the United States, typically, the face bore is sized from Шаблон:Convert in diameter and is centered at Шаблон:Convert from the leading edge of the door. This distance is referred to as the "backset."[3] Other, less popular, backsets are at Шаблон:Convert. Residential doors are normally prepared with a Шаблон:Convert backset and commercial doors have a Шаблон:Convert backset. The edge bore is typically centered on the edge.
History
The cylindrical lock was invented by the German-born engineer Walter Schlage[4] in 1923.[5] The bored cylindrical lock arose from a need for a more cost-effective method of locking doors. The previous norm (still the norm in Europe), the mortise lock, is a more complex device, and its higher manufacturing cost as well as its more labor-intensive installation make the bored cylindrical lock an ideal substitute, both in price and functionality. Because the mortise lock has a larger lock case, a larger and more complex volume must be removed from the door before it can be installed, but the mortise lock may offer additional functions compared to a cylindrical lock; for instance, the mortise lock may include a deadbolt in a single unit, while the cylindrical lock would require separate face bores for a deadbolt and doorknob.[6] The 1923 patent evolved from an earlier Schlage patent filed in 1920[7] for a lock whose installation required a face bore and surface rabbet, which simplified door preparation compared to a mortise lock.
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