Fasteners come in many different forms. To make it easy for you, we’ve compiled the data below as a guide for figuring out what each fastener is called. Scroll down to learn about many different types of nuts, bolts and screws!*
*Note: Bolts are fasteners that require a nut or pre-tapped hole to be installed. Screws use their threads to provide their own holding power. The terms in the industry are commonly mixed so sometimes you will see something that is called a screw or a bolt that is actually the opposite. Example: Lag Bolts and Lag Screws are the same things. We have broken them down according to their true definition.
Types of Bolts
Carriage Bolts
Also known as a “coach” bolt, has a domed or countersunk head. The square section under the head grips into the part being fastened preventing the bolt from turning when the nut is tightened.
Hex Head Bolts
Hex tap bolts, hex cap screws, trim head hex cap screws, and hex serrated flange bolts fall under this category. They share a hexagonal head and are driven with a wrench. Referred to as both bolts and screws.
Machine Screws
A machine screw is a screw or bolt with a flat point. Available in a variety of drive types and heads, they fit a wide variety of applications. Often driven into tapped holes. Used with nuts and washers, also known as “stove bolts” or “stovers”.
Shoulder Bolts
Shoulder bolts (also known as shoulder screws or stripper bolts) are machine screws with a shoulder between the thread of the screw and the head of the part. Once installed, the non-threaded portion extends out of the surface of the application site, allowing the bolts to act as dowels or shafts for moving parts. They can be installed by hand or with a socket (Allen) driver.
Socket Cap Screws
Socket cap screws are available in button socket, button flange socket head, flat socket, and socket cap. Driven with a socket wrench or a hex Allen key. The term socket head cap screw typically refers to a type of threaded fastener whose head diameter is nominally 1.5 times or more than that of the screw shank diameter.
Socket Set “Grub” Screws
Set screws are most often headless (aka blind), meaning that the screw is fully threaded and has no head. A blind set screw, known in the UK as a grub screw, is almost always driven with an internal wrenching drive, such as a hex Allen key. Socket set screws are installed in threaded holes or inserts.
Square Head Bolts
Square Head Bolts are similar to hex cap screws but with a 4-sided head. This head style allows for a wrench to grip more easily onto the head of the bolt. The head also provides a larger gripping area as compared to a standard 6-sided hexagonal head.
Types of Screws
Deck Screws
Our deck screws feature a type 17 point (notched point at the tip) to aid in chip removal during thread cutting which allows for easy installation in wood and composite deck materials. A bugle head and square drive help to eliminate the stripping effect sometimes experienced with other types of drives.
Hex Lag Screws
Lag screws, also called lag bolts, are large wood screws. The head is external hex and is driven with a wrench. Used for lag together lumber for framing, machinery to wood floors, and other heavy-duty applications.
Self-Drilling Screws
Self-drilling screws have a sheet metal thread with a self-driller cutting (TEK) point to pierce through 20 to 14 gauge metals. The higher the TEK number, the larger the drill point to pierce heavier gauge metals.
Sheet Metal Screws
Sheet metal screws (SMS) have sharp cutting threads that cut into sheet metal, plastic or wood. They have a fully threaded shank and sometimes have a notched point at the tip to aid in chip removal during thread cutting.
Wood Screws
Wood screws are partially threaded with large cutting threads and a smooth shank. They are designed to slide through the top piece of wood and tightly pull all boards together.
Types of Nuts
Cap Nuts
The cap nut, also known as the acorn nut, gets its name from its shape. The nut has a domed top to prevent contact with the external thread.
Castle Nuts
Used with cotter pins to prevent loosening, a castellated nut, also called a castle or slotted nut is a nut with slots cut into the top. Used in low-torque applications such as holding a wheel bearing in place.
Coupling Nuts
A coupling nut is a threaded fastener used for joining two male threads, most commonly threaded rod. The outside of the fastener is a hex so it can be driven with a wrench.
Flange Serrated Nuts
A flange nut is a nut that has a wide flange at one end which acts as an integrated washer that does not move or spin. The serrated flange distributes the pressure of the nut over the part being secured and creates a locking action to prevent loosening.
Flange Serrated Nuts
A flange nut is a nut that has a wide flange at one end which acts as an integrated washer that does not move or spin. The serrated flange distributes the pressure of the nut over the part being secured and creates a locking action to prevent loosening.
Hex Finish Nuts
Hex finish nuts are used for fastening to a hex cap screw, socket cap screw or bolt. The most common nuts, hex finish nuts are hex-shaped with internal threads and driven with a wrench.
Hex Jam Nuts
A jam nut is often used when a nut needs to be locked in place without clamping to another object. Hex jam nuts are hex-shaped with internal threads, but they are thinner than hex finish nuts.
Heavy Hex Nuts
Larger, heavier, and thicker than a standard hex nut. Heavy hex nuts are hex-shaped, internally threaded, and driven with a wrench. Often used with hex cap screws and carriage bolts.
Hex Machine Nuts
A machine nut is hex-shaped with internal threads. Smaller than a hex jam or hex finish nut, they are used with machine screws under 1/4″ diameter.
Hex Machine Nuts Small Pattern
A machine nut is hex-shaped with internal threads. Smaller than a hex jam or hex finish nut, they are used with machine screws under 1/4″ diameter.
