UNC Bolts, Nuts and Washers

Commonly referred to as a setscrew and longer versions are referred to in the United States as a tap bolt. A standard spanner or ratchet is typically used to fit this product. Used for decades on all types of assembly throughout the world. The hex drive allows a higher torque to be applied. Produced to ASME B18.2.1.

The most common type of fastener, a hex head bolt is designed to be tightened with a standard spanner or ratchet and socket. Popularly used in all assemblies, a standard hex bolt is a staple across the world. Manufactured to ASME B18.2.1, and includes an unthreaded section of the shaft. A hex drive permits a greater torque load to be applied to the joint over most other drive types.

Hexagon headed bolt with a flange. Also known as a washer bolt. The wider surface area beneath the head spreads the clamping pressure and negates the need for a washer. These UNC hex head flange bolts are serrated. The serrations are anti-rotational and bite into the material which they are connecting to secure the fixing.

Also known as an Allen screw or Allen bolt, or simply a cap screw, socket head cap screws are a more modern alternative standard machine fastener to the standard hexagon headed bolt or setscrew, as found on much modern machinery. A hex key (otherwise known as an Allen key) is required to fit these fasteners. Conforming to ASME/ANSI B18.3, the contact surfaces of this screw or bolt are protected from external damage. Generally manufactured with a partial thread beyond a certain length and nominal diameter combination, but occasionally some stock may include a fully threaded shank.

Also known as an allen screw or allen bolt, or simply a cap screw. Socket head cap screws are a modern machine threaded fastener, an alternative to the standard hexagon headed bolt. The geometry of the hex drive mechanism means that these internal contact surfaces are protected from external damage. A hex or allen key is therefore required to fit these fasteners. Conforming to ASME B18.3 and material to ASTM A574, UNBRAKO® socket head caps are manufactured to be stronger than other size for size high tensile versions. Please note that due to the nature of the surface finish on Unbrako products, some surface corrosion may be evident. This does not affect the performance of the product. Minimum tensile strength of UNBRAKO® socket head caps is minimum 180,000psi which is similar to metric property class 12.9.

UNC low socket cap screws have a low head height and shallower hex drive. These are designed to be used where there is restricted clearance for the head height of the screws. The lower head height means that they are unable to withstand the same tightening torque as a full height socket head cap screw. This range is generally manufactured with a partial thread beyond a certain length and nominal diameter combination, but occasionally some stock may include a fully threaded shank. The socket head generally has a flat chamfered top surface with smooth or knurled cylindrical sides and a flat bearing surface.

Socket shoulder screw with a UNC imperial coarse thread. They are also known as shoulder bolts, precision shoulder screw and in the US, stripper bolts. The main dimensions are for the diameter and total length required under the head. Shoulder screws have an undercut portion between the thread and shoulder, allowing a close fit. They are used in a wide range of punch and die operations and as shafts, pivots, guides, pins, linkages and trunnion mountings. Please note that the nominal diameter here refers to the shoulder diameter, except where shown otherwise.

A countersunk headed screw conforming with ASME/ANSI B18.3, requiring a hex key (otherwise known as an Allen key) to fit. The countersunk head is typically used in conjunction with a countersunk hole providing a flush, snag free fit. Generally manufactured with a full thread, though occasionally some stock may include a partially threaded shank.

A popular and attractive socket head screw, typically used where aesthetics are important, or where a lower profile domed finish is required. The hex drive is generally smaller than other hex driven ranges and thus the ultimate tightening torque is reduced. Manufactured to ASME/ANSI B18.3, and always fully threaded.

A Machine screw with a phillips drive, designed to be tightened with a screwdriver. Typically found on consumer electronics and other small machinery where high torque fasteners are not necessary. Conforms with ASME B18.6.3.

A popular machine screw with a phillips drive. The countersunk head is typically used in conjunction with a countersunk hole providing a flush, snag free fit. These items are always fully threaded. Conforms to ASME B18.6.3. Typically found on consumer electronics and other small machinery where high torque fasteners are not necessary.

Philips Truss Head Machine Screws (UNC) have a wide and shallow domed shape, which can negate the use of a washer. The head shape also gives a larger contact area with the surface, which means a snag free fitment and helps guard against tampering. For use either in a pre-tapped hole or nut assembly. Ideal for sheet metal projects and applications where there is minimal clearance, such as sliding supports in draws and cabinets. Imperial Unified Coarse thread version. Phillips drive is x-shaped for installation with a Phillips screw driver.

A countersunk headed screw incorporating a slightly raised head which gives it an attractive finish when fitted. Includes a phillips cross recess for driving in. Manufactured to ANSI/ASME B18.6.3.

UNC Phillips Fillister machine screws have a large cylindrical head, with a slightly convex top surface. Fillister head screws are the preferred head type for counterbored holes and can also be used for protecting a surface by raising the level by which the tool is used to tighten the fixing. They are similar to a Pan head machine screw, but with a greater head height. Height to diameter ratio is also larger than a cheese head. Imperial Unified Coarse thread version.

A machine screw with a hexalobular or torx drive, designed to be tightened with a 6 lobed torx screwdriver. Typically found on consumer electronics and other small machinery where high torque fasteners are not necessary.

A popular machine screw with a 6 lobed torx drive. The countersunk head is typically used in conjunction with a countersunk hole providing a flush, snag free fit. These items are always fully threaded. Typically found on consumer electronics and other small machinery where high torque fasteners are not necessary.

Torx Truss Head Machine Screws (UNC) have a wide and shallow domed profile, which can be employed without the need for a washer. The head shape also gives a larger contact area with the surface, which means a snag free fitment and helps guard against tampering. For use either in a pre-tapped hole or with a nut assembly. Ideal for sheet metal projects and applications where there is minimal clearance, such as sliding supports in draws and cabinets. Imperial Unified Coarse thread version. Torx drive is a 6 lobed drive installed with a Torx screw driver.

Slotted pan machine screws with a UNC (Unified Coarse) Thread. A machine screw with a relatively large diameter head and a straightforward slot drive.

A slot drive, countersunk headed screw, to be used with a flat head screwdriver. These are typically used in conjunction with a countersunk hole which provides a flush, snag free fit. This UNC threaded version is produced to ANSI/ASME B18.6.3.

A UNC slotted round machine screw has a rounded, domed head with a slot drive. The height of the rounded head and the depth of the slot offers a more secure engagement with a flat screwdriver.

UNC slotted fillister machine screws have a large cylindrical head, with a slightly convex top surface. These are similar to a Pan head machine screw, but offer a larger side height. These fillister head machine screws have a height to diameter ratio larger than a pan head machine screw. Fillister head screws are the preferred head type for counterbored holes and can also be used for protecting a surface by raising the level which the screw diver is used to tighten the fixing.

Also known as a set screw, these headless types of screws have many uses. This particular type has a hex socket drive, and a depression called a 'cup' on the opposite end, and conforms to ASME/ANSI B18.3.

Flexible usage threaded bar or threaded rod to ASME B18.31.3.

Hexagon full nut to ASME B18.2.2. Typically fitted with a spanner or ratchet with socket. The most popular nut type, and used for decades on all types of assembly throughout the world.

Hexagon Machine Screw Nuts (UNC - Unified Coarse Pitch) imported from the USA. These nuts generally have smaller internal diameters than the range available in standard hexagon nuts, so fit the smaller gauge sizes for Imperial screws. They also tend to be thinner or lower in height but have a larger outer diameter. These are specifically designed to be used in conjunction with other UNC screws or bolts. Often used in small electrical goods manufacturing, such as computers and hifi systems.

Prevailing torque type nut manufactured to IFI-100/107. Popularly employed Hexagon nut incorporating a nylon insert to help prevent loosening when fitted. Typically fitted with a spanner or ratchet with socket.

Prevailing torque nut, thin type. Popularly employed Hexagon nut incorporating a nylon insert to help prevent loosening when fitted. Typically fitted with a spanner or ratchet with socket.

Nut conforming to ASME B18.2.2. Also known as a half nut, thin nut, or jam nut. Typically fitted with a spanner or ratchet with socket, often used in pairs in a nut locking arrangement. A popular nut type, and used for decades on all types of assembly throughout the world.

A popular nut used in applications where aesthetics are important. Also known as an Acorn nut, these nuts are manufactured to ASME B18.2.2, in this instance they have a standard Unified Coarse Thread Pitch (UNC). To be used in conjunction with same sized UNC screws and bolts.

An hexagon nut with incorporated flange. The flange offers protection for the bolted component where the driving tool may otherwise scratch it's surface. The flange also lessens the need to use a washer. This particular version has serrations on the base.

Larger and thicker variant of a standard hexagon full nut. Generally used with large diameter and high strength bolts, and manufactured to ASME B18.2.2. These nuts are manufacured with a double chamfer (chamfered both sides), but sizes larger than 7/16 will likely include a flat or washer face on one side. Please bear this in mind when ordering.

Popularly employed where frequent hand tightening and untightening of joints is required. To ASME B18.6.9.

Also known as a long nut, these coupling or connector nuts are typically employed in joining sections of threaded bar/studding together where required.

Slotted or split beam type hexagon all metal locking nut with UNC Thread form . Manufactured in the UK with the Aerotight trademark. On assembly, when tightened into position, the inwardly deflected locking arms are forced outwards creating the locking element. A locking nut useful in high temperature applications where a locking nylon ring nut would be unsuitable.

Thin gauge standard sized flat washer manufactured to British Standard 3410 Table 3 Light Specification.

Thicker gauge standard sized flat washer manufactured to British Standard 3410 Table 3 Heavy Specification.

Thick gauge flat washer manufactured to British Standard 3410 Table 4 Heavy Specification. Features a larger external diameter than the popular table 3 spec.

Also known as a penny or repair washer, this very popular type offers a large external diameter; it is therefore able to spread the load of the joint over a wider area. This is a useful feature when working with softer materials. Dimensions shown are approximate. Please note that hole clearances can be generous on these washers.

Flat washer to American SAE specifications, now part of the Unified Thread Standard. Washers with a smaller external diameter than that of an equivalent USS washer. Conforms to ASME B18.21.1-1999.

Flat washer to American USS specifications, now part of the Unified Thread Standard. Washers with an external diameter larger than that of an equivalent SAE washer, but smaller than a penny/fender washer. Conforms to ASME B18.21.1-1999.

Imperial Commercial Series washers imported from the USA. Similar thickness to the imperial Table 3 washers, also available on this site, but with a larger outer diameter. Available in 316 (A4) grade stainless steel, so ideal for marine use.

Flat washer with reduced outside diameter. Manufactured to NAS620, a standard specified by the Aerospace Industries Association of America.

Spring washer designed to help prevent loosening of bolted joints under vibration. Also know as a Split Lock Washer and a Split Ring Washer. This type has a rectangular section and is manufactured to ASME B18.21.1-1999. Where even distribution of load on the mating surface is the primary requirement an alternative spring washer or a flat washer would be a more suitable solution. In addition Spring Washers do not offer protection for the material being fastened.

A toothed or perforated washer usually employed in electrical connections such as battery terminals, but can also be used in assemblies to help prevent loosening. This variant includes teeth on the external diameter. Produced to ASME B18.21.1.

Military specification general purpose imperial sized round washers. Available in corrosion resistant A2 stainless steel and manufactured to US standard MS15795. Please note that these items can have large clearances to the bolt or stud: please refer to the data sheet for further information.

Nord-Lock washers, also known as wedge-locking washers, secure bolts with tension instead of friction. Working as a pair, these washers create a wedge-effect underneath the bolt head or nut so that the joint is prevented from loosening unintentionally. Nord-Lock washers are quick and easy to install and remove, and they are reusable. Supplied as a glued pair, they are appropriate for use in vehicles, for DIY and for watersport equipment. Most sizes are available in two external diameters: the smaller standard type listed here, and the larger SP type. Here you will find the specific imperial sizes; please refer to the data sheet and the metric section for other appropriate sizes.

Nord-Lock washers, also known as wedge-locking washers, secure bolts with tension instead of friction. Working as a pair, these washers create a wedge-effect underneath the bolt head or nut so that the joint is prevented from loosening unintentionally. Nord-Lock washers are quick and easy to install and remove, and they are reusable. Supplied as a glued pair, they are appropriate for use in vehicles, for DIY and for watersport equipment. Most sizes are available in two external diameters: the smaller standard type, and the larger SP type listed here. Here you will find the specific imperial sizes; please refer to the data sheet and the metric section for other appropriate sizes.