Last Updated on June 22, 2022 by Kimberly Crawford
There are many different types of screws and screw heads, and it can be confusing to know which one to use for a specific project. In this comprehensive guide, we will discuss the most common types of screws and screw heads, as well as when each type should be used. We’ll also provide some helpful tips on choosing the right screwdriver for the job!
What Is A Screw?
A screw is a type of fastener, typically made of metal, that is used to hold two or more pieces of material together. Screws are inserted into pre-drilled holes and tightened with a wrench or screwdriver. The head of the screw sits on the surface of the material, while the shaft extends through the hole.
Anatomy of a Scew.
Head.
This is the part of the screw that goes into the surface you’re attaching the screw to. The head can be flat, Phillips, hex, or have any number of other shapes. Depending on the type of head, you’ll need a different tool to drive it in (a drill bit, for example).
Drive.
A drive is a type of fastener, often made of metal, used to secure two or more pieces of wood or other material together. A screw is inserted into a predrilled hole in one piece and rotated, which causes it to penetrate the second piece. As the screw is turned, it pulls the two pieces together, creating a strong joint.
Shank.
The shank is the cylindrical portion of a screw that extends from the bottom of the head to the tip. The threads (or grooves) of the screw are cut into the shank. The diameter of the shank is usually smaller than the root diameter, and it may be tapered slightly to facilitate assembly.
The purpose of the shank is to provide a smooth, flat surface for the head of the screw to bear against, and to transmit torque from the head to the threads. In some cases, the shank also serves as a dowel pin, locating one component in relation to another.
Threads.
They’re everywhere. In your clothes, in the pipes under your sink, in the screws holding together your furniture. But what are they, really?
Threads are essentially spirals of thread that interlock with each other to create a stronger connection. They can be either internal or external; meaning, the thread can be on the inside or the outside of the object.
The most common type of thread is the screw thread, which is used to fasten two objects together. A good example of this is a lightbulb; the metal spiral screw thread on the outside of the bulb screws into the threaded socket in the lamp, holding it in place.
Major Diameter.
The major diameter of a screw is the distance between two opposite sides of the head. The majority of screws will have a hexagonal head, which means that the major diameter will be the distance across flats.
However, there are also Phillips and slotted head screws, which have different measurements for their major diameter. To measure the major diameter of these types of screws, you will need to use a caliper.
Once you have located the major diameter of the screw, you can then proceed to measuring the minor diameter.
Thread length.
The first thing to consider when determining thread length is the screw’s diameter and pitch. The diameter is the width of the shaft, and the pitch is how far apart the threads are. To measure these, you will need a ruler or caliper. Once you have these measurements, you can consult a thread chart to determine the correct thread length.
Another thing to consider is the head of the screw. The head is the part of the screw that protrudes from the surface of the material you are fastening. There are many different types of heads, and each one has a different purpose. For example, pan heads are typically used for drywall, while hex heads are used for wood.
When choosing a screw, it is important to consider both the length and the head. The wrong combination can cause the screw to strip or break, which can damage the material you are working with. With a little bit of research, you can find the perfect screw for your project.
Crest.
The top of the screw, where it meets the head. The crest is usually rounded, but can be flat or even knurled.
Pitch.
The pitch is the most important part of a screw. It is the part that determines how well the screw will hold things together. The pitch is determined by the angle of the threads on the screw. A good rule of thumb is that the pitch should be about half the diameter of the screw.
Thread Angle.
The thread angle of a screw is the included angle between the two sides of the thread. It is measured in degrees and typically ranges from 30 to 60 degrees. The most common thread angles are 45 and 60 degrees.
The angle of the thread affects several factors including:
- The amount of friction generated between the threads
- The amount of force required to turn the screw
- The holding power of the screw
The thread angle also affects the amount of space that is required for the screw. A smaller thread angle requires less space than a larger thread angle. This can be important when choosing a screw for a particular application.
Minor Diameter.
The term is used to describe the smaller of two diameters in an object, such as a pipe or screw. The minor diameter is also known as the root diameter. It’s important to know the minor diameter when measuring screws, because this measurement will determine the size of the hole that needs to be drilled. To measure the minor diameter, you’ll need to use a micrometer.
First, you’ll need to find the Thread Pitch. This is the distance between threads and is measured in Threads Per Inch (TPI). To measure the thread pitch, you’ll need to use a caliper. Once you have the measurement for the thread pitch, you can determine the minor diameter.
The minor diameter is determined by subtracting the thread pitch from the major diameter. For example, if a screw has a major diameter of 0.500 inches and a thread pitch of 0.050 inches, the minor diameter would be 0.450 inches.
Tip.
The tip of the screw is the sharp point at the end that pierces into the material being fastened. The threads of the screw are wrapped around the tip.
Types of Screws.
1. Binding Screws.
Binding screws are the most common type of screws. They are used to hold two pieces of wood together and can be either flat head or Phillips head screws.
The most important thing to remember when using binding screws is to drill a pilot hole first. This will prevent the screw from splitting the wood as you drive it in.
2. Carriage Bolts.
Carriage bolt is a type of fastener used to secure metal to wood. The head is round with a square or hexagonal recess and the shank is threaded. Carriage bolts are available in diameters from ¼” to ½” and lengths up to 12”. Carriage bolts are commonly used in construction applications where two pieces of wood need to be joined together.
To install a carriage bolt, first drill a pilot hole through the wood. The pilot hole should be slightly smaller than the diameter of the shank. Next, insert the bolt into the hole and thread it into place with a wrench or socket. Carriage bolts are tightened by turning the head of the bolt with a wrench. The head of the bolt is designed to prevent the bolt from turning once it is tightened.
3. Chipboard Screws.
Chipboard screw is a type of screw used to fasten particle board or fiberboard. It has a sharp point and coarse threads. The head is usually countersunk so that it can sit flush with the surface of the material.
Chipboard screws are available in a variety of lengths, from 12 mm to 100 mm. They are also available in different colors, such as black, brown, and white.
Chipboard screws are made from a variety of materials, such as carbon steel, stainless steel, and brass. They can also be plated with zinc or nickel. Chipboard screws are not meant for use in structural applications.
4. Deck Screws.
Deck screw is a type of screw specifically designed for use in outdoor applications or other environments where rust resistance is important. The head is usually flat or countersunk, and the threads are sharp to bite into the material (usually wood) being fastened.
A deck screw has a large thread diameter in proportion to its shaft diameter, and often has a coarse pitch. It is used to fasten two pieces of wood together, often with the aid of a pilot hole.
Coated deck screws are available which provide even better rust resistance. The most common type has a green vinyl coating, but screws with a brown or tan coating are also available. These colors blend in well with pressure-treated lumber and cedar.
Deck screws are also available in stainless steel, which is the best choice for coastal applications or other situations where the highest level of rust resistance is required.
5. Dowel Screws.
These screws are used to fasten two pieces of wood together. The screw has a pointed end that penetrates the wood and a flat end that rests against the surface of the wood. The screw is then turned until it is tight. This type of screw is not for use in softwoods or plywood.
6. Drywall screws.
Drywall screw is a type of screw used to fasten drywall or sheetrock to wood or metal studs. Drywall screws have a sharp point that penetrates the drywall and a wide, flat head that pulls the two pieces of material together.
Drywall screws come in different lengths, from ½ inch to ⅝ inch, and different gauges, from light-duty to heavy-duty. The length you need depends on the thickness of the drywall and the studs. The gauge is determined by the weight of the drywall.
7. Elevator Bolts.
Elevator bolt is a type of fastener that is used to join two pieces of metal or wood together. It is also known as a lifting bolt because it is often used in the construction of elevators.
The head of the elevator bolt is larger than the shaft, which allows it to be easily gripped by a wrench or pliers. The threads on an elevator bolt are also shallower than those of a standard bolt, which allows it to be tightened or loosened more easily.
8. Eye Bolts.
Eye bolt is a type of screw with a loop on one end and threads on the other. Eye bolts are commonly used to attach cables to surfaces. The loop can also be used for attaching ropes or other fixtures.
Most eye bolts are made from steel or stainless steel. They are available in a variety of sizes and finishes. For projects that require a more finished look, brass or bronze eye bolts are also available.
9. Eye Lags.
Eye lag is a screw with a lag thread on one end and a machine screw thread on the other. It is used to join wood to wood, or metal to wood. The eye is for attaching a cable or rope.
There are two types of eye lags: regular and reverse threaded. The regular eye lag has threads that run in the same direction as the shank of the screw, while the reverse threaded eye lag has threads that run in the opposite direction.
The main advantage of using an eye lag is that it can be installed with a wrench or socket, making it easier to install than a regular screw.
Another advantage of using an eye lag is that it is less likely to loosen over time.
The main disadvantage of using an eye lag is that it is not as strong as a regular screw.
Another disadvantage of using an eye lag is that it is more difficult to remove than a regular screw.
10. Hammer-Drive Screws.
Hammer-drive screw is a type of screw that is driven into place using a hammer. It has a large, flat head that is easy to grip with a hammer and an unthreaded shank. The threads on the screw are designed to grip the material it is being driven into (usually wood).
11. Hanger Bolts.
Hanger bolt is a type of fastener that is generally used to attach a hanging object, such as a sign or a piece of artwork, to a wall. It consists of a lag screw with a wood screw thread on one end and a machine screw thread on the other. Hanger bolts are available in several different sizes and lengths.
12. Hex Bolts.
Hex bolt is a type of fastener with a hexagonal head. screws are used to fasten two or more pieces of material together. A hex bolt is also known as a Hex Cap Screw or Bolts. A typical hex bolt is made from low to medium carbon steel and has a zinc plating to resist corrosion.
13. J-Bolts.
J-bolt is a type of screw or bolt that has a J-shaped head. The J-bolt is threaded and used to hold objects together, or to attach something to a surface.
J-bolts can be made from a variety of materials, including metals such as stainless steel or carbon steel, and plastics such as nylon. J-bolts are used in a wide range of applications, including construction, automotive, and plumbing.
J-bolts are typically installed by first drilling a hole in the surface. The J-bolt is then inserted into the hole and tightened with a nut. J-bolts can also be welded to surfaces.
14. Lag Bolts.
Lag bolt is a type of screw with a large head and a hexagonal drive. The name “lag bolt” comes from the fact that this type of screw is often used to secure lumber (lags) to walls or other structures. Lag bolts are available in a variety of sizes and lengths, and can be either threaded or unthreaded.
15. Machine screws.
Machine screw is a type of screw or bolt that has a thread running its entire length. It is widely available in sizes #0 (smallest) to #14 and lengths up to 24″. Machine screws are generally used with nuts or driven into tapped holes. They might be considered a permanent fastener.
16. Masonry screws.
Masonry screw is a type of screw designed for use in masonry or concrete. It has a sharp point and a tapered body that allows it to penetrate the surface.
The threads on the screw help to grip the material and pull it tight. Masonry screws are available in different lengths and sizes to suit different applications.
17. Mating Screws.
Mating screw is a type of screw used to connect two pieces of material together. The head of the screw is designed to mate with a corresponding recess in the other piece of material. This type of connection is often used where a more permanent connection is desired, such as in woodworking or metalworking.
18. Mirror Screws.
Mirror screw is a type of screw used to fasten mirrors or other reflecting surfaces to a wall, door, ceiling, table or any other flat surface. It is also known as a glass screw. A mirror screw has a head that is flanged or countersunk and often has a Phillips drive.
The fully threaded shank extends through the surface being fastened and is held in place by a nut or an internally threaded hole. Glass screws are usually made of brass, although steel and stainless steel screws may also be used.
19. Security Screws.
Security screw is a type of screw that resists tampering and unauthorized removal. It is used in applications where it is important to prevent casual or intentional tampering, such as in electrical panels, public telephones, computer equipment and vending machines.
Security screws are also used to discourage thieves from gaining access to valuable items that are bolted down.
20. Self-drilling screws (MDF Screws).
Self-drilling screw is a type of screw that can drill its own hole as it is driven into the material.
MDF screws are used in a wide range of applications, from attaching drywall to fastening plywood and MDF boards.
21. Self-tapping screws.
Self-tapping screw is a type of screw that has a threading on the outside and is used to tap its own hole as it is driven into the material. The advantage of this over other types of screws is that it doesn’t require a pilot hole to be drilled first. It can, however, be more difficult to drive in and sometimes requires a power drill.
22. Set Screws.
Set screw is a type of screw generally used to secure an object within or against another object. The most common examples are securing a pulley or gear to a shaft. Set screws are usually headless, meaning that the screw is fully threaded and has no head projecting past the major diameter of the screw thread.
23. Sex Bolts.
Sex bolt is a type of fastener that has a male and female thread. The male thread is on the bolt and the female thread is on the nut. Sex bolts are also known as Chicago screws, binding posts or architecture screws.
Sex bolts can be used in many applications where two pieces of material need to be fastened together such as in woodworking or metalworking.
24. Sheet Metal Screws.
Sheet metal screw is a type of screw that has a large, flat head and a sharp point. It is used to fasten sheet metal to wood or other materials.
The most common type of sheet metal screw is the pan head screw, which has a rounded head with a small diameter. The next most common type is the button head screw, which has a flatter head with a larger diameter. The third type is the oval head screw, which has an oval-shaped head.
25. Shoulder Bolts.
Shoulder bolt is a type of fastener which has a shoulder between the head of the bolt and the threads. These screws are used when there is need for a smooth surface area or to prevent marring.
The most common use for shoulder bolts is in machinery where precise positioning is necessary. For example, they might be used to secure an adjustable handle to a shaft.
26. Socket Screws.
Socket screw is a type of screw or bolt whose head diameter is larger than the shaft diameter, and the head has a hexagon socket drive recess.
This type of screw is driven by a hex wrench or Allen key, which is a six-sided socket wrench with a long handle used to provide leverage.
Socket screws are commonly used in machine parts, where a hexagon socket drive recess is milled into the part.
Another advantage of socket screws over slotted or Phillips head screws is that they are less likely to loosen from vibration.
Socket screws are also used in woodworking, where they are sometimes called cabinet screws, and in metalworking.
27. Tamper-Resistant Screws.
Tamper-resistant screw is a type of screw that is designed to prevent unauthorized removal. The head of the screw is specially designed so that a standard screwdriver will not fit. This makes it difficult to remove the screw without the proper tools.
28. Torx/TORX Plus Screws.
Torx screws are characterized by their six-pointed star-shaped heads. They were originally designed to be used in applications where a high amount of torque is required, such as in automotive and aerospace applications.
One advantage of Torx screws is that they are less likely to strip than Phillips head screws.
Torx screws are available in a variety of sizes, from tiny screws used in electronic devices to large screws used in construction.
29. U-Bolts.
U-bolt is a term most typically used to describe a threaded fastener with a U-shaped cross section. For example, an eye bolt is a type of screw with a loop or eye at one end. The other common type of u-bolt is the square u-bolt, which has squared threads and two bent legs that can be used to attach pipe or other round objects to something else. U-bolts are also used to attach pipes to machinery or vehicles.
U-bolts have a variety of uses, but they are most commonly used to secure pipes and other cylindrical objects. They can also be used to connect two pieces of metal or wood together, or to fasten a metal plate to wood. U-bolts are available in a variety of sizes and materials, so they can be used for a wide range of applications.
30. Wood screws.
Wood screw is a type of screw, typically made from steel, and characterized by a helical ridge, known as a thread. Screws are used to fasten materials by digging in and wedging into a material when turned, while the thread cuts grooves in the fastened material that may help pull fastened materials together and prevent pull-out.
Types of Screw Heads.
Most screws have a head, which is the part of the screw that sticks out from the surface it’s being driven into. The head also provides a way to grip the screw so you can turn it. There are many different types of screw heads, and each has its own advantages and disadvantages. Here are some of the most common types of screw heads.
Countersunk Screw Heads.
These have a cone shaped indentation in the head of the screw. This type of head is used when it needs to be flush with the surface or you want to add a decorative touch. The downside to countersunk heads is that they are more likely to strip.
1. Flat Head.
Flat head is the most common type of screw head. You can identify a flat head by the small, flat surface on top of the head. It is designed to sit flush with the material it is being screwed into.
2. Raised Head.
It has a slightly rounded top with a small flat area beneath it. The raised head is easy to grip and provides a good surface for driving the screw into place.
3. Bugle Head.
Bugle head is a type of screw head characterized by a cone-shaped top and a flat bottom. The Bugle Head is designed to countersink into materials such as wood or drywall, making it ideal for use in applications where a flush or countersunk finish is desired.
Non Countersunk Screw Heads.
These screw heads sit flush with the surface of your material, giving your work a clean and polished appearance. Non countersunk screws are also less likely to catch on clothing or skin, making them ideal for applications where safety is a concern.
4. Binding Head.
Binding head is a type of screw head that is used to bind two materials together. It is also known as a “binding screw.” Binding screws are most commonly used in woodworking and metalworking.
Binding head screws have a wide variety of uses. They can be used to join two pieces of wood together, or to attach a piece of wood to a metal surface. They can also be used to fasten a piece of fabric to a piece of wood.
5. Dome Head.
Dome head is the most common type of screw head. It is rounded with a small depression at the top, and it can be used for almost any purpose.
Dome heads are typically used for wood screws, machine screws, and sheet metal screws. They are also common in plumbing and electrical applications. Dome heads are easy to produce and easy to use, and they are less likely to strip than other types of screw heads.
6. Flange Head.
Flange head is a type of screw head in which the bottom surface is flat and flush with the material. This type of screw is used when a smooth, finished appearance is desired, or when the screw will be subject to stress or wear. The term “countersunk” refers to the angle of the tapered sides of the flange; countersinking creates a seat for the head of the screw that is flush with or below the surface of the surrounding material.
7. Truss Head.
Truss head is a variation of the pan head. The main difference is that the top of the truss head is flat. This makes it ideal for applications where a low profile is needed, such as in electronics.
One disadvantage of the truss head is that it is not as strong as other screw heads, such as the pan head. This is because the truss head relies on the sheet metal for strength, rather than the actual screw head.
Another disadvantage is that it can be difficult to align the truss head when starting the screw, due to its flat top. This can sometimes result in stripped threads or even breakage of the screw.
Combination Head Screws.
A combination head screw has a slotted head and a Phillips head. The screws are used in woodworking and for attaching metal parts. The screws are made of steel and have a black oxide finish.
Tamper Resistant Head Screws.
If you’re looking for a way to secure your belongings, you may want to consider using tamper resistant head screws. These screws are designed to resist tampering and removal, making them ideal for use in high-security applications.
8. Pin Head.
Pin head is the term for a small, thin screw head. It is also known as a flat head or countersunk screw. A pin head is often used in applications where a low profile is needed, such as in electronics.
9. Sentinel Screw Head.
Sentinel screw head is a new type of screw head that is designed to be more resistant to stripping and cam-out. It is available in both Phillips and flathead versions.
The Sentinel screw head has a unique design that makes it more resistant to stripping and cam-out. The head is made from a hardened steel alloy, and the recesses are deeper than traditional screw heads. This allows the driver to bite into the head more securely, preventing it from slipping out and stripping the head.
10. 2 Hole Screws.
These screws have two holes in the head, and are used in a variety of applications. The most common use for these screws is to attach hardware to wood or metal. They can also be used to join two pieces of wood together. Two hole screws are available in a variety of sizes and finishes.
Types of Screw Drives.
There are four main types of screw drives: Phillips, flat head, Robertson, and hex. Each type has its own unique benefits and drawbacks that make it better suited for certain applications than others. Let’s take a closer look at each type of screw drive to see what makes it tick.
1. External Hex Screw.
External hex screw is a six-sided, slotted drive for use with a wrench or drill. It is the most common type of screw drive and can be found in a variety of sizes and lengths.
2. Internal Hex Screw.
Internal hex screw is a type of screw drive that is commonly used in many industries. It is characterized by a hexagonal hole in the head of the screw, which allows it to be driven by a hex wrench or driver.
3. Phillips Head Screw.
Phillips head screw is one of the most common types of screws. It has a cross-shaped head, which is why it is also known as a crosshead screw. The main advantage of Phillips head screws is that they are less likely to slip than other types of screws.
Another advantage of Phillips head screws is that they can be driven in with one hand.
Phillips head screws are most commonly used in woodworking and construction. They can also be used in metal, but they are not as common. Phillips head screws are not recommended for use in plastics or soft metals such as aluminum.
4. Pozidriv Head Screw.
Pozidriv head screw is one of the most common type of screws. It is also known as a slotted head screw. Pozidriv head screws are used in a wide variety of applications, from woodworking to machinery.
5. Quadrex Head Screw.
Quadrex head screw is a type of screw drive that is used in a variety of applications. Quadrex head screws are available in a wide range of sizes and lengths to suit your needs. Quadrex head screws are made from high-quality materials and are designed to withstand the toughest conditions.
6. Square Recess Screw.
Square recess screw is a type of drive used in screws. It is a square-shaped socket that allows the driver to fit into it. The advantage of this type of drive is that it is less likely to slip than other drives.
7. Star Head Screw.
Star head screw is a type of screw drive that has a star-shaped recess in the head. It is also known as Torx screws. The advantage of this type of screw is that it is less likely to slip or strip than other types of screws.
8. Torx Plus Screws.
Torx plus screw is a type of screw drive.
It is an improvement on the Torx screw drive.
The Torx Plus screw drive was developed to provide more torque than a Torx screw and to be more resistant to cam out.
Torx Plus screws are available in sizes from TP0 to TP60.
9. Tri Wing Screw Head.
Tri Wing screw head is a type of screw drive with three radial slots in the head and is designed for use with a screwdriver with a matching tip. The three slots are arranged so that when the driver is turned, the torque is evenly distributed around the circumference of the head. This type of drive is often used in aviation and electronics applications where a high degree of precision is required.
Types of Washers for Bolts.
1. Flat.
Flat is the most common type of washer. It is a thin, flat piece of metal with a hole in the center. The purpose of a flat washer is to distribute the load of a threaded fastener, such as a bolt or screw.
2. Fender.
Fender is a type of washer that is used to distribute the load of a threaded fastener, such as a bolt or nut. These washers are usually made of metal and have a large outer diameter with a small inner diameter. The large outer diameter prevents the washer from pulling through the material it is being fastened to, while the small inner diameter helps to keep the bolt or nut from spinning when tightened.
3. Split Lock.
Split Lock is the most common type of washer. It is a metal ring with a split in it. The split allows the washer to be compressed when the bolt is tightened. This creates friction and prevents the nut from coming loose. Split Lock washers are used on all types of bolts, including those that are high strength.
4. External Tooth Lock.
External tooth lock is the most common type of washer. It has serrations that bite into the mating surface to resist loosening from vibration or centrifugal force. The teeth on an external tooth lock are angled so that they engage with the mating surface as the bolt is tightened. External tooth locks are available in a variety of materials, including stainless steel and nylon.
5. Internal Tooth Lock.
Internal Tooth Lock is a type of washer that is used to secure bolts. This type of washer has teeth on the inside that grip the bolt, preventing it from turning. Internal tooth lock washers are available in different sizes and materials.
6. Square.
Square is the most common type of washer. It is used with a wide variety of bolts, including hex head, carriage, and elevator bolts. The square shape helps to keep the nut or bolt from turning when tightened. Square washers are also known as flat washers.
7. Dock.
Dock washers, also called fender washers, have a large outer diameter and a small inner diameter. They are used to distribute the load of a threaded fastener such as a bolt or screw. These washers are often used in marine applications where they are subjected to salt water and other corrosive elements.
8. Ogee.
The ogee washer is a type of washer with a curved, S-shaped profile. It is designed to fit over the head of a bolt or screw and distribute the load evenly around the circumference of the fastener. Ogee washers are often used in applications where a large amount of force will be applied to the fastener, such as in construction or heavy machinery.
Factors to consider when buying a screw.
When purchasing screws, here are some factors you’ll want to keep in mind:
The type of screw you need will be determined by the material you’re working with. For example, if you’re working with wood, you’ll need a different type of screw than if you’re working with metal.
The size of the screw is also important. You’ll need to make sure the screw is long enough to go through the material you’re working with, but not so long that it sticks out on the other side.
The head of the screw is also something to keep in mind. Some screws have a Phillips head, while others have a flat head. The type of head you need will depend on the type of drill bit you’re using.
Finally, you’ll also want to consider the price of the screws. screws can range in price from a few cents to a few dollars each. The price will vary depending on the size, material, and quantity you purchase.
Conclusion
There are a variety of screws and screw heads available, each with its own advantages and disadvantages. It’s important to choose the right type of screw and head for the job at hand, in order to ensure a secure connection. With a little bit of knowledge, you can easily select the best screw for your needs.