Cam out
Encyclopedia
To 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.
Frequently, camming out damages the screw, and possibly also the screwdriver, and should normally be avoided. 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, that is, the screw does not slip off the screwdriver, unlike a normal slotted-head (flat-head) screws, 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.
In recent years, automated manufacturing insertion tools can now precisely sense fastener torque. Consequently, it is typical for computer parts, automobiles, and other highly-engineered products, to be assembled with Torx
or Pozidriv head screws, which have been specifically designed not to cam out.
Screwdriver
A screwdriver is a tool for driving screws and often rotating other machine elements with the mating drive system. The screwdriver is made up of a head or tip, which engages with a screw, a mechanism to apply torque by rotating the tip, and some way to position and support the screwdriver...
slips out of the head of a screw
Screw
A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
being driven once the torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
required to turn the screw exceeds a certain amount.
Frequently, camming out damages the screw, and possibly also the screwdriver, and should normally be avoided. The Phillips head
Henry F. Phillips
Henry F. Phillips was a U.S. businessman from Portland, Oregon. The Phillips-head screw and screwdriver are named after him....
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, that is, the screw does not slip off the screwdriver, unlike a normal slotted-head (flat-head) screws, 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.
In recent years, automated manufacturing insertion tools can now precisely sense fastener torque. Consequently, it is typical for computer parts, automobiles, and other highly-engineered products, to be assembled with Torx
Torx
Torx developed by Camcar Textron, is the trademark for a type of screw head characterized by a 6-point star-shaped pattern. People who are unfamiliar with the trademark generally use the term star, as in star screwdriver or star bits...
or Pozidriv head screws, which have been specifically designed not to cam out.
External links
- When a Phillips is not a Phillips! at Instructables.com