To cam out (or cam-out) is a process by which a screwdriver slips out of the head of a screw being driven once the torque required to turn the screw exceeds a certain amount. A basic screwdriver (slotted tip shown) A screwdriver is a device specifically designed to insert and tighten, or to loosen and remove, screws. ... Screws come in a variety of shapes and sizes for different purposes. ... It has been suggested that this article or section be merged with Moment (physics). ...

Frequently, camming out damages the screw, and possibly also the screwdriver, and is usually attempted to be avoided. However, the Phillips head screw and screwdriver combination was designed specifically to cam-out, as at the time of its invention torque sensing automatic screwdrivers did not exist. The Phillips design is auto-centering i.e. the screw does not slip off the screwdriver, unlike a normal slotted-head screw/flat-head screw, but cams out once the screw has been driven home. These properties were used to speed up automobile production in the USA in the early years of the industry. Phillips Head refers to the shape of the head of the screw as a plus sign. ...