Bored cylindrical lock

A bored cylindrical lock is one in which a hole must be drilled into the face of the door, as opposed to the edge of the door (as is the case with a mortise lock). Typically, the hole is sized from 1.5 inches to 2.125 inches and is centered 2.5 inches to 5 inches from the leading edge of the door.

The bored cylindrical lock owes its existence to discovering a more cost effective method of locking doors. The previous norm, the mortise lock, is a more complex device, and its higher manufacturing cost as well as its more labor intensive installation made the bored cylindrical lock an ideal substitute, both in price and functionality. The great majority of locks now in use on residences are of this type.