What is "set screw"

Set \Set\ (s[e^]t), a.

1. Fixed in position; immovable; rigid; as, a set line; a set countenance.

2. Firm; unchanging; obstinate; as, set opinions or prejudices.

3. Regular; uniform; formal; as, a set discourse; a set battle. ``The set phrase of peace.''
   --Shak.

4. Established; prescribed; as, set forms of prayer.

5. Adjusted; arranged; formed; adapted. Set hammer.

   1. A hammer the head of which is not tightly fastened upon the handle, but may be reversed.
      --Knight.

   2. A hammer with a concave face which forms a die for shaping anything, as the end of a bolt, rivet, etc.

      Set line, a line to which a number of baited hooks are attached, and which, supported by floats and properly secured, may be left unguarded during the absence of the fisherman.

      Set nut, a jam nut or lock nut. See under Nut.

      Set screw (Mach.), a screw, sometimes cupped or printed at one end, and screwed through one part, as of a machine, tightly upon another part, to prevent the one from slipping upon the other.

      Set speech, a speech carefully prepared before it is delivered in public; a formal or methodical speech.

alt. 1 A screw with threads the entire length and no head. Typically, setscrews have a hex or slot drive recessed in the threaded length. 2 Any screw used to hold or adjust a setting. Frequently a setscrew (1), but may also refer to any other machine screw or thumb screw used for the purpose of setting. n. 1 A screw with threads the entire length and no head. Typically, setscrews have a hex or slot drive recessed in the threaded length. 2 Any screw used to hold or adjust a setting. Frequently a setscrew (1), but may also refer to any other machine screw or thumb screw used for the purpose of setting.

A set screw is a type of screw generally used to secure an object within or against another object, normally not using a nut (see bolts compared with screws). The most common examples are securing a pulley or gear to a shaft. Set screws are usually headless (also called blind), meaning that the screw is fully threaded and has no head projecting past the major diameter of the screw thread. If a set screw has a head, the thread will extend all the way to the head (whereas a bolt might have an unthreaded shank between the head and thread). A blind set screw (known in the UK as a grub screw, quite possibly from its figurative resemblance to a soil-dwelling grub) is almost always driven with an internal-wrenching drive, such as a hex socket (Allen), star (Torx), square socket (Robertson), or slot. The set screw passes through a threaded hole in the outer object and is tightened against the inner object to prevent it from moving relative to the outer object. It exerts compressional or clamping force through the bottom tip that projects through the hole.

An example application is when a set screw is screwed into a pulley hub so that its end-point bears firmly against the shaft. The fastening action is by friction between the screw and the shaft, often (but not always) with some amount of elastic or plastic deformation of one or both.