Locksmiths often spend part of their working day opening locks for people who have lost or misplaced their keys. They may do this by picking the lock or by making a duplicate key. Sometimes locksmiths use the scratches that the lock leaves on a blank key as a guide for filing the blank key into the proper shape. At other times they get the key code number and make a duplicate key on a key cutting machine. Locksmiths open combination locks by turning the dial on the lock until the tumblers click into place. Or they may drill through the lock with an electric drill.

Locksmiths use screwdrivers, pliers, tweezers, lock picks, and a variety of other hand and power tools in their trade. They repair locks by taking the mechanism apart and replacing worn and broken parts, such as springs and tumblers. They sometimes make new parts by hand. To protect homes and businesses, locksmiths often adjust and change locks. They also create new master key systems for businesses.