special bolt,Fasteners with a non-tapered shaft
Description：special bolt--There is no universally accepted definition of the word bolt. It generally refers to a larger threaded fastener with a non-tapered shaft. See the section Differentiation between bolt and screw above for a more detailed discussion.
Fasteners with a non-tapered shaft
There is no universally accepted definition of the word bolt. It generally refers to a larger threaded fastener with a non-tapered shaft. See the section Differentiation between bolt and screw above for a more detailed discussion.
In places the term is used interchangeably with bolt. In the past the term cap screw was restricted to threaded fasteners with a shaft that is threaded all the way to the head, but this is now a non-standard usage.
Hex cap screw
Cap screw with a hexagonal head, designed to be driven by a wrench (spanner). An ASME B18.2.1 compliant cap screw has somewhat tighter tolerances than a hex bolt for the head height and the shaft length. The nature of the tolerance difference allows an ASME B18.2.1 hex cap screw to always fit where a hex bolt is installed but a hex bolt could be slightly too large to be used where a hex cap screw is designed in.
At times the term is used interchangeably with hex cap screw. An ASME B18.2.1 compliant hex bolt is built to different tolerances than a hex cap screw.
Socket cap screw
Also known as a socket head cap screw, socket screw or Allen bolt, this is a type of cap screw with a hexagonal recessed drive. The most common types in use have a cylindrical head whose diameter is nominally 1.5 times (1960 series design) that of the screw shank (major) diameter. Counterbored holes in parts allow the screw head to be flush with the surface or recessed. Other head designs include button head and flat head, the latter designed to be seated into countersunk holes. A hex key (sometimes referred to as an Allen wrench or Allen key) or hex driver is required to tighten or loosen a socket screw. Socket screws are commonly used in assemblies that do not provide sufficient clearance for a conventional wrench or socket.
Generally a smaller fastener (less than ¼ inch in diameter) threaded the entire length of its shaft that usually has a recessed drive type (slotted, Phillips, etc.). Machine screws are also made with socket heads (see above), in which case they may be referred to as socket head machine screws.
Self-tapping machine screw
Similar to a machine screw except the lower part of the shaft is designed to cut threads as the screw is driven into an untapped hole. The advantage of this screw type over a self-tapping screw is that, if the screw is reinstalled, new threads are not cut as the screw is driven.
Set screw (grub screw)
Generally a headless screw but can be any screw used to fix a rotating part to a shaft. The set screw is driven through a threaded hole in the rotating part until it is tight against the shaft. The most often used type is the socket set screw, which is tightened or loosened with a hex key or hex driver.
A bolt that is threaded all the way to the head. An ASME B18.2.1 compliant tap bolt has the same tolerances as an ASME B18.2.1 compliant hex cap screw.
similar to a bolt but without the head. Studs are threaded on both ends. In some cases the entire length of the stud is threaded, while in other cases there will be an un-threaded section in the middle. (See also: screw anchor, wedge anchor.)
A bolt with a looped head.
A bolt with a special nut known as a wing. It is designed to be used where there is no access to side of the material where the nut is located. Usually the wing is spring loaded and expands after being inserted into the hole.
Carriage bolt (coach bolt)
Has a domed or countersunk head, and the shaft is topped by a short square section under the head. The square section grips into the part being fixed (typically wood), preventing the bolt from turning when the nut is tightened. A rib neck carriage bolt has several longitudinal ribs instead of the square section, to grip into a metal part being fixed.
A type of machine screw that has a round or flat head and is threaded to the head. They are usually made of low grade steel, have a slot or Philips drive, and are used to join sheet metal parts using a hex or square nut.
Screw used for revolving joints in mechanisms and linkages. A shoulder screw consists of the shaft, which is ground to a precise diameter, and a threaded end, which is smaller in diameter than the shaft. Unlike other threaded fasteners, the size of a shoulder screw is defined by the shaft diameter, not the thread diameter. Shoulder screws are also called stripper bolts, as they are often used as guides for the stripper plate(s) in a die set.
A threaded fastener designed to be twisted into a tapped hole by hand without the use of tools.
Tension control bolt (TC bolt)
Heavy duty bolt used in steel frame construction. The head is usually domed and is not designed to be driven. The end of the shaft has a spline on it which is engaged by a special power wrench which prevents the bolt from turning while the nut is tightened. When the appropriate torque is reached the spline shears off.
A bolt similar to a carriage bolt, except the head is flat or concave. There are many variations, with some not using a square base, but rather a key, a locking slot, or other means. The recess in the mating part must be designed to accept the particular plow bolt.