Bolt, Screw, Nut and Washer Identification Chart
At one time or another, all of us (even the pros) misidentify a fastener. Not that the guys at the hardware store don't need a chuckle every now and them. Use this handy chart, courtesy BoltDepot.com, to get the name right the first time!
Fastener Categories |
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Wood Screws Screws with a smooth shank and tapered point for use in wood. Abbreviated WS |
Machine
Screws Screws with threads for use with a nut or tapped hole. Abbreviated MS |
Thread Cutting Machine
Screws Machine screws with a thread cutting (self tapping) point. |
Sheet
Metal Screws Fully threaded screws with a point for use in sheet metal. Abbreviated SMS |
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Self
Drilling SMS A Sheet metal screw with a self drilling point. |
Hex
Bolts Bolts with a hexagonal head with threads for use with a nut or tapped hole. Abbreviated HHMB or HXBT |
Carriage Bolts Bolts with a smooth rounded head that has a small square section underneath. |
Lag
Bolts Bolts with a wood thread and pointed tip. Abbreviated Lag |
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Flange Bolts Flange bolts have a flange on the bottom of the head that distributes the load like a washer. |
Socket Screws
Socket screws, also known as Allen head, are fastened with a hex Allen wrench. |
Eye Bolts A bolt with a circular ring on the head end. Used for attaching rope or chain. |
Eye Lags Similar to an eye bolt but with wood threads instead of machine thread. |
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U-Bolts Bolts in U shape for attaching to pipe or other round surfaces. Also available with a square bend. |
J-Bolts J shaped bolts are used for tie-downs or as an open eye bolt. |
Shoulder Bolts Shoulder bolts (also known as stripper bolts) are used to create a pivot point. |
Elevator Bolts Elevator bolts are often used in conveyor systems. They have a large, flat head. |
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Sex Bolts Sex bolts (a.k.a. barrel nuts or Chicago bolts) have a female thread and are used for through bolting applications where a head is desired on both sides of the joint. |
Mating Screws Mating screws have a shoulder that matches the diameter of the sex bolts they are used with. |
Hanger Bolts Hanger bolts have wood thread on one end and machine thread on the other end. |
Set
Screws
Machine screws with no head for screwing all the way into threaded holes. |
Head Styles |
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Flat
A countersunk head with a flat top. Abbreviated FH |
Oval
A countersunk head with a rounded top. Abbreviated OH or OV |
Pan
A slightly rounded head with short vertical sides. Abbreviated PN |
Truss
An extra wide head with a rounded top. |
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Round
A domed head. Abbreviated RH |
Hex
A hexagonal Head. Abbreviated HH or HX |
Hex Washer
A hex head with built in washer. |
Slotted Hex Washer
A hex head with built in washer and a slot. |
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Socket Cap A small cylindrical head using a socket drive. |
Button A low profile rounded head using a socket drive. |
Drive Types |
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Phillips The standard drive type for most screws. Abbreviated PH |
Frearson Similar to Phillips. Requires a Frearson driver for installation. |
Slotted
A slot in the head. Abbreviated SL |
Combination
A combination of slotted and Phillips drives. Abbreviated Combo |
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Socket, Hex or Allen
A hexagonal hole for use with an Allen wrench. |
One Way
Installs with a normal slotted driver but can not be removed without special tools. |
Square Also known as Robertson drive. Abbreviated SQ or SD. |
Star Also known as Torx®. A six-pointed star pattern, specifically designed to prevent cam-out and stripped heads. |
Nut Types |
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Hex
A six sided nut. Also referred to as a finished hex nut. |
Nylon
Insert Lock
A nut with a nylon insert to prevent backing off. Also referred to as a Nylock |
Jam
A hex nut with a reduced height. |
Nylon
Insert Jam Lock
A nylock nut with a reduced height. |
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Wing
A nut with 'wings' for hand tightening. |
Cap
A nut with a domed top over the end of the fastener. |
Acorn Acorn nuts are a high crown type of cap nut, used for appearance. |
Flange
A nut with a built in washer like flange. |
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Tee
A nut designed to be driven into wood to create a threaded hole. |
Square
A four sided nut. |
Prevailing
torque lock
A non-reversible lock nut used for high temperature applications |
K-Lock or Kep
A nut with an attached free-spinning external tooth lockwasher. |
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2-Way Reversible Lock A lock nut that can be installed either side up. Often used in high temperature applications. |
Coupling Coupling nuts are long nuts used to connect pieces of threaded rod or other male threaded fasteners. |
Slotted Slotted nuts are used in conjunction with a cotter pin on drilled shank fasteners to prevent loosening. |
Castle Castle nuts are similar to slotted nuts but with the slots in a rounded section above the main nut. |
Washer Types |
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Flat
A flat washer used to distribute load. Available in SAE, USS, and other patterns. |
Fender
An oversize flat washer used to further distribute load especially on soft materials. |
Finishing
A washer used to obtain a 'finished' look. Usually used with oval head screws. |
Split
Lock
The most common style of washer used to prevent nuts and bolts from backing out. |
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External
Tooth Lock
A washer with external 'teeth' Used to prevent nuts and bolts from backing out. |
Internal
Tooth Lock
A washer with internal 'teeth' Used to prevent nuts and bolts from backing out. |
Square
A square shaped washer. |
Dock Dock washers have a larger outside diameter and are thicker than standard. |
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Ogee Thick, large diameter, cast iron washers with a curved or sculpted appearance. Typically used in dock and wood construction |
Sealing A neoprene washer bonded to a metal backing. Used to seal out air/water or dampen noise and vibration. |
About the author: BoltDepot is an internet fastener retailer in the tradition of the old hardware store, maintaining its family-owned atmosphere and commitment to service while offering our complete catalog of fasteners online!