2025.3.13
Set screws are widely used in mechanical assemblies to secure components such as gears, pulleys, and collars onto shafts. Unlike standard screws, they do not have a protruding head, allowing them to be used in confined spaces. The purpose of this guide is to provide detailed information on set screw types, size charts, and torque specifications.
What is Set Screw?
A set screw is a fully threaded fastener without a head, designed to secure one object within or against another. It is tightened using an internal drive such as a hex socket (Allen), slotted, or Torx. The tip of the screw presses against the surface of the material it fastens, creating mechanical resistance to movement.Set screws are commonly used in applications where a flush, compact fastening solution is needed, such as in rotating machinery or precision instruments.
As shown in the diagram, when a set screw is screwed into a “threaded hole” in a part, the set screw comes into contact with the shaft. At this point, an axial force is generated in the set screw, which fixes the part in place.
Set Screw Types in Different Terms
Before we look at the sizes of set screws, let’s first take a look at the different types of this fastener. This will make it easier for you to find the most accurate size for your needs. Set screws can be categorized in terms of tip type and fastener head type (drive styles). These two aspects determine how the set screw interacts with the material it secures and the tools required for installation.Below are the most common types:
Types of Set Screws by Tip Type
The tip type refers to the shape of the screw’s end that contacts the material. Each type is designed for specific applications:
- Cup Point Set Screw
- Flat Point Set Screw
- Cone Point Set Screw
- Dog Point Set Screw
- Oval Point Set Screw
- Knurled Cup Point Set Screw
Types of Set Screws by Drive Style
The fastener head type refers to the design of the screw’s drive, which determines the tool required for installation and removal:
- Hex (Allen) Set Screw
- Slotted Set Screw
- Torx Set Screw
- Square Head Set Screw
- Phillips Head Set Screw
More on these different types of Set Screws below, so keep reading!
Set Screw Size Charts (Metric & Inch)
The size of a set screw refers to its dimensions, which include the thread diameter, thread pitch, length, and other relevant features such as the drive type and point style. Set screw sizes are standardized and described using various international systems, including metric (ISO/DIN/JIS) and imperial (ASME/ANSI) standards. The size is essential for ensuring proper fit, holding power, and compatibility with the application.
Key Dimensions of a Set Screw
- Thread Diameter (Nominal Size):The major diameter of the screw thread. For metric screws, this is specified in millimeters (e.g., M3, M8). For imperial screws, this is specified in inches or gauge sizes (e.g., #10, 1/4 inch).
- Thread Pitch:The distance between adjacent threads, measured in millimeters for metric screws (e.g., 1.25 mm). For imperial screws, the pitch is defined as threads per inch (TPI) (e.g., 24 TPI).
- Length:The total length of the threaded portion of the set screw, measured from the tip to the flat end (excluding the drive recess or head). Typically given in millimeters for metric screws and inches for imperial screws.
- Drive Type:The type of recess in the screw for applying torque, such as Hex (Allen), Slotted, Phillips, Torx, or Square Head.
- Point Style:The shape of the tip of the screw, such as Flat Point, Cup Point, Cone Point, Dog Point, or Knurled Cup Point, which determines the holding and load-distribution characteristics.
Below are standard size charts for both metric and inch-based set screws.
Metric Standard Set Screw Size Chart (DIN/ISO/JIS)
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Socket Size (mm) | Common Lengths (mm) | Drive Type |
|---|---|---|---|---|---|
| M1.6 | 0.35 | 1.60 | 0.7 | 2, 2.5, 3, 4, 5, 6, 8 | Hex, Slotted, Phillips |
| M2 | 0.40 | 2.00 | 1.0 | 4, 5, 6, 8, 10 | Hex, Slotted, Phillips |
| M2.5 | 0.45 | 2.50 | 1.3 | 4, 5, 6, 8, 10 | Hex, Slotted, Phillips |
| M3 | 0.50 | 3.00 | 1.5 | 6, 8, 10, 12, 16 | Hex, Slotted, Phillips |
| M4 | 0.70 | 4.00 | 2.0 | 8, 10, 12, 16, 20 | Hex, Slotted, Phillips |
| M5 | 0.80 | 5.00 | 2.5 | 10, 12, 16, 20, 25 | Hex, Slotted, Phillips |
| M6 | 1.00 | 6.00 | 3.0 | 12, 16, 20, 25, 30 | Hex, Slotted, Phillips |
| M8 | 1.25 | 8.00 | 4.0 | 16, 20, 25, 30, 40 | Hex, Slotted, Phillips |
| M10 | 1.50 | 10.00 | 5.0 | 20, 25, 30, 40, 50 | Hex, Slotted, Phillips |
| M12 | 1.75 | 12.00 | 6.0 | 25, 30, 40, 50, 60 | Hex, Slotted, Phillips |
| M16 | 2.00 | 16.00 | 8.0 | 30, 40, 50, 60 | Hex, Slotted, Phillips |
| M20 | 2.50 | 20.00 | 10.0 | 40, 50, 60, 70 | Hex, Slotted, Phillips |
| M24 | 3.00 | 24.00 | 12.0 | 50, 60, 70, 80 | Hex, Slotted, Phillips |
Imperial Standard Set Screw Size Chart (ASME/ANSI Standards)
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Socket Size (in) | Common Lengths (in) | Drive Type |
|---|---|---|---|---|---|
| #4-40 (UNC) | 40 | 0.112 | 0.05 | 1/8, 3/16, 1/4, 5/16 | Hex, Slotted, Phillips |
| #6-32 (UNC) | 32 | 0.138 | 1/16 | 3/16, 1/4, 3/8 | Hex, Slotted, Phillips |
| #8-32 (UNC) | 32 | 0.164 | 5/64 | 1/4, 5/16, 3/8 | Hex, Slotted, Phillips |
| #10-24 (UNC) | 24 | 0.190 | 3/32 | 3/8, 1/2, 5/8 | Hex, Slotted, Phillips |
| #12-24 (UNC) | 24 | 0.216 | 7/64 | 3/8, 1/2, 5/8 | Hex, Square Head |
| 1/4-20 (UNC) | 20 | 0.250 | 1/8 | 1/2, 5/8, 3/4, 1 | Hex, Square Head |
| 5/16-18 (UNC) | 18 | 0.313 | 5/32 | 1/2, 5/8, 3/4, 1, 1-1/4 | Hex, Square Head |
| 3/8-16 (UNC) | 16 | 0.375 | 3/16 | 3/4, 1, 1-1/4, 1-1/2 | Hex, Square Head |
| 7/16-14 (UNC) | 14 | 0.438 | 7/32 | 1, 1-1/4, 1-1/2 | Hex, Square Head |
| 1/2-13 (UNC) | 13 | 0.500 | 1/4 | 1, 1-1/4, 1-1/2, 2 | Hex, Square Head |
Specific Set Screw Size Charts for Different Point/DriveTypes
Each type of set screw can have slightly different size standards based on its point style, drive type, and intended application. Below are specific size charts for different types of set screws, categorized by their point styles (Flat Point, Cone Point, Cup Point, Dog Point, Knurled Cup Point) and drive types (Hex, Slotted, Phillips, etc.). These charts include both metric and imperial sizes.
1. Hex Set Screw
The Hex Socket (Allen) set screw is the most common type, featuring an internal hexagonal drive that requires an Allen wrench for installation. Its compact design allows for high torque application without the risk of stripping the drive. This makes it ideal for industrial and mechanical applications, such as securing pulleys, gears, and other rotating components in assemblies.
Metric Hex Set Screw Sizes
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Hex Socket Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M1.6 | 0.35 | 1.60 | 0.7 | 2, 2.5, 3, 4, 5, 6, 8 |
| M2 | 0.40 | 2.00 | 1.0 | 4, 5, 6, 8, 10 |
| M3 | 0.50 | 3.00 | 1.5 | 6, 8, 10, 12, 16 |
| M4 | 0.70 | 4.00 | 2.0 | 8, 10, 12, 16, 20 |
| M5 | 0.80 | 5.00 | 2.5 | 10, 12, 16, 20, 25 |
| M6 | 1.00 | 6.00 | 3.0 | 12, 16, 20, 25, 30 |
| M8 | 1.25 | 8.00 | 4.0 | 16, 20, 25, 30, 40 |
| M10 | 1.50 | 10.00 | 5.0 | 20, 25, 30, 40, 50 |
| M12 | 1.75 | 12.00 | 6.0 | 25, 30, 40, 50, 60 |
Imperial Sizes
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Hex Socket Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| #4-40 (UNC) | 40 | 0.112 | 0.05 | 1/8, 3/16, 1/4, 5/16 |
| #6-32 (UNC) | 32 | 0.138 | 1/16 | 3/16, 1/4, 3/8 |
| #10-24 (UNC) | 24 | 0.190 | 3/32 | 3/8, 1/2, 5/8 |
| 1/4-20 (UNC) | 20 | 0.250 | 1/8 | 1/2, 5/8, 3/4, 1 |
| 3/8-16 (UNC) | 16 | 0.375 | 3/16 | 3/4, 1, 1-1/4, 1-1/2 |
2. Slot Set Screws
The Slotted set screw has a single straight slot on its head, designed for use with a flathead screwdriver. It is a simple and traditional design, easy to install and remove with standard tools. While it is less resistant to cam-out than other drive styles, it is suitable for applications where precision torque is not critical.
Metric Sizes
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Slot Width (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M2 | 0.40 | 2.00 | 0.4 | 4, 5, 6, 8, 10 |
| M3 | 0.50 | 3.00 | 0.6 | 6, 8, 10, 12, 16 |
| M5 | 0.80 | 5.00 | 1.0 | 10, 12, 16, 20, 25 |
| M8 | 1.25 | 8.00 | 1.6 | 16, 20, 25, 30, 40 |
Imperial Sizes
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Slot Width (in) | Common Lengths (in) |
|---|---|---|---|---|
| #6-32 (UNC) | 32 | 0.138 | 0.04 | 3/16, 1/4, 3/8 |
| 1/4-20 (UNC) | 20 | 0.250 | 0.06 | 1/2, 5/8, 3/4, 1 |
3. Phillips Set Screws
The Phillips Head set screw features a cross-shaped recess in the head, designed for use with a Phillips screwdriver. This design offers a better grip compared to slotted heads, reducing the risk of the tool slipping during installation. Additionally, it is engineered to cam out under excessive torque, which helps prevent over-tightening or damage. Phillips Head set screws are commonly used in furniture assembly, electronic devices, and light-duty machinery.
Metric Sizes
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Phillips Size | Common Lengths (mm) |
|---|---|---|---|---|
| M3 | 0.50 | 3.00 | PH0 | 6, 8, 10, 12, 16 |
| M5 | 0.80 | 5.00 | PH1 | 10, 12, 16, 20, 25 |
| M8 | 1.25 | 8.00 | PH2 | 16, 20, 25, 30, 40 |
Imperial Sizes
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Phillips Size | Common Lengths (in) |
|---|---|---|---|---|
| #6-32 (UNC) | 32 | 0.138 | PH1 | 3/16, 1/4, 3/8 |
| 1/4-20 (UNC) | 20 | 0.250 | PH2 | 1/2, 5/8, 3/4, 1 |
4. Torx Set Screws
The Torx set screw is designed with a star-shaped drive, which provides superior resistance to cam-out compared to slotted or Phillips styles. This design enables high torque application while reducing wear on both the screw and the tool. Torx set screws are commonly used in demanding industries like automotive, aerospace, and electronics.
Metric Sizes
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Torx Size | Common Lengths (mm) |
|---|---|---|---|---|
| M3 | 0.50 | 3.00 | T6 | 6, 8, 10, 12, 16 |
| M4 | 0.70 | 4.00 | T8 | 8, 10, 12, 16, 20 |
| M6 | 1.00 | 6.00 | T15 | 12, 16, 20, 25, 30 |
| M8 | 1.25 | 8.00 | T25 | 16, 20, 25, 30, 40 |
| M10 | 1.50 | 10.00 | T40 | 20, 25, 30, 40, 50 |
Imperial Sizes
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Torx Size | Common Lengths (in) |
|---|---|---|---|---|
| #8-32 (UNC) | 32 | 0.164 | T10 | 1/4, 5/16, 3/8 |
| 3/8-16 (UNC) | 16 | 0.375 | T30 | 3/4, 1, 1-1/4, 1-1/2 |
5. Square Head Set Screws
The Square Head set screw features a square-shaped head that can be easily gripped and turned using an adjustable wrench or pliers. This design is particularly useful in situations where manual turning is needed, especially in tight spaces. It is often found in older machinery and heavy-duty industrial applications due to its durability and ease of use.
Metric Sizes
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Head Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M8 | 1.25 | 8.00 | 6.0 | 16, 20, 25, 30, 40 |
| M12 | 1.75 | 12.00 | 9.0 | 25, 30, 40, 50, 60 |
Imperial Sizes
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Head Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| 1/4-20 (UNC) | 20 | 0.250 | 3/8 | 1/2, 5/8, 3/4, 1 |
| 1/2-13 (UNC) | 13 | 0.500 | 5/8 | 1, 1-1/4, 1-1/2, 2 |
6. Flat Point Set Screw Size Chart
A flat point set screw has a flat tip that makes full contact with the surface it secures. It is ideal for applications where minimal surface damage is required, such as soft materials or where frequent adjustments are needed. This type is commonly used in temporary or adjustable fastening applications.
Metric Sizes (ISO/DIN Standards)
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Socket Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M1.6 | 0.35 | 1.60 | 0.7 | 2, 3, 4, 5, 6, 8 |
| M2 | 0.40 | 2.00 | 1.0 | 4, 5, 6, 8, 10 |
| M3 | 0.50 | 3.00 | 1.5 | 6, 8, 10, 12, 16 |
| M4 | 0.70 | 4.00 | 2.0 | 8, 10, 12, 16, 20 |
| M5 | 0.80 | 5.00 | 2.5 | 10, 12, 16, 20, 25 |
Imperial Sizes (ASME Standards)
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Socket Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| #4-40 (UNC) | 40 | 0.112 | 0.05 | 1/8, 3/16, 1/4 |
| #6-32 (UNC) | 32 | 0.138 | 1/16 | 3/16, 1/4, 3/8 |
| #10-24 (UNC) | 24 | 0.190 | 3/32 | 3/8, 1/2, 5/8 |
| 1/4-20 (UNC) | 20 | 0.250 | 1/8 | 1/2, 5/8, 3/4 |
7. Cone Point Set Screw Size Chart
Cone point set screws have a sharp, pointed tip that digs into the material for a strong grip. This type is excellent for permanent installations or applications requiring precise alignment, such as securing a shaft or locking components in place.
Metric Sizes (ISO/DIN Standards)
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Socket Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M2 | 0.40 | 2.00 | 1.0 | 4, 5, 6, 8, 10 |
| M4 | 0.70 | 4.00 | 2.0 | 8, 10, 12, 16, 20 |
| M8 | 1.25 | 8.00 | 4.0 | 16, 20, 25, 30, 40 |
| M10 | 1.50 | 10.00 | 5.0 | 20, 25, 30, 40, 50 |
Imperial Sizes (ASME Standards)
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Socket Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| #8-32 (UNC) | 32 | 0.164 | 5/64 | 1/4, 5/16, 3/8 |
| 3/8-16 (UNC) | 16 | 0.375 | 3/16 | 3/4, 1, 1-1/4, 1-1/2 |
8. Cup Point Set Screw Size Chart
Cup point set screws are the most common type, with a concave tip that provides maximum holding power. These are ideal for general-purpose applications.
Metric Sizes (ISO/DIN Standards)
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Socket Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M1.6 | 0.35 | 1.60 | 0.7 | 2, 3, 4, 5, 6, 8 |
| M3 | 0.50 | 3.00 | 1.5 | 6, 8, 10, 12, 16 |
| M6 | 1.00 | 6.00 | 3.0 | 12, 16, 20, 25, 30 |
| M12 | 1.75 | 12.00 | 6.0 | 25, 30, 40, 50, 60 |
Imperial Sizes (ASME Standards)
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Socket Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| #6-32 (UNC) | 32 | 0.138 | 1/16 | 3/16, 1/4, 3/8 |
| 1/4-20 (UNC) | 20 | 0.250 | 1/8 | 1/2, 5/8, 3/4, 1 |
| 1/2-13 (UNC) | 13 | 0.500 | 1/4 | 1, 1-1/4, 1-1/2, 2 |
9. Dog Point Set Screw Size Chart
Dog point set screws have a cylindrical tip extending beyond the threaded portion, which fits into a mating hole for precise positioning. They are ideal for indexing, alignment, or use as a pivot in assemblies with pre-drilled holes.
Metric Sizes (ISO/DIN Standards)
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Socket Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M4 | 0.70 | 4.00 | 2.0 | 8, 10, 12, 16, 20 |
| M8 | 1.25 | 8.00 | 4.0 | 16, 20, 25, 30, 40 |
Imperial Sizes (ASME Standards)
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Socket Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| 1/4-20 (UNC) | 20 | 0.250 | 1/8 | 1/2, 5/8, 3/4, 1 |
| 3/8-16 (UNC) | 16 | 0.375 | 3/16 | 3/4, 1, 1-1/4, 1-1/2 |
10. Knurled Cup Point Set Screw Size Chart
Knurled cup point set screws have a serrated edge on their concave tip for enhanced grip and vibration resistance. These screws are particularly useful in high-vibration environments where additional holding power is required.
Metric Sizes (ISO/DIN Standards)
| Nominal Size (mm) | Thread Pitch (mm) | Major Diameter (mm) | Socket Size (mm) | Common Lengths (mm) |
|---|---|---|---|---|
| M5 | 0.80 | 5.00 | 2.5 | 10, 12, 16, 20, 25 |
| M10 | 1.50 | 10.00 | 5.0 | 20, 25, 30, 40, 50 |
Imperial Sizes (ASME Standards)
| Nominal Size | Threads Per Inch (TPI) | Major Diameter (in) | Socket Size (in) | Common Lengths (in) |
|---|---|---|---|---|
| #10-24 (UNC) | 24 | 0.190 | 3/32 | 3/8, 1/2, 5/8 |
| 1/2-13 (UNC) | 13 | 0.500 | 1/4 | 1, 1-1/4, 1-1/2, 2 |
Set Screw Torque Chart
Set screw torque refers to the amount of rotational force applied to a set screw to properly secure it without causing damage to the screw or the mating component. The correct torque ensures:
✔ Proper holding power
✔ Prevention of loosening due to vibration
✔ Avoidance of thread stripping
✔ Prevention of excessive deformation of the mating surface
Torque values are affected by various factors, including:
- Material of the set screw (e.g., steel, stainless steel, titanium, brass)
- Material of the mating part
- Thread size and pitch
- Tip style (cup point, flat point, cone point)
- Lubrication or dry installation
Below, we’ve sorted out the Set Screw torque chart based on our experience, providingrecommended tightening torque values based on thread size, material, and tip style for steel, stainless steel, and brass set screws.
Metric Set Screw Torque Chart (ISO 4026, 4027, 4028, 4029– Nm)
| Thread Size (M) | Torque (Nm) – Steel (Class 12.9) | Torque (Nm) – Stainless Steel (A2-70) | Torque (Nm) – Brass |
|---|---|---|---|
| M1.6 | 0.2 | 0.15 | 0.1 |
| M2 | 0.4 | 0.3 | 0.2 |
| M2.5 | 0.8 | 0.6 | 0.4 |
| M3 | 1.8 | 1.4 | 0.9 |
| M4 | 4.0 | 3.2 | 2.0 |
| M5 | 8.0 | 6.4 | 4.0 |
| M6 | 14.0 | 11.2 | 7.0 |
| M8 | 33.0 | 26.0 | 16.0 |
| M10 | 66.0 | 52.0 | 32.0 |
| M12 | 115.0 | 90.0 | 54.0 |
| M16 | 285.0 | 225.0 | 135.0 |
| M20 | 560.0 | 440.0 | 260.0 |
ImperialSet Screw Torque Chart (ASME – in-lb)
| Thread Size (Inches) | Torque (in-lb) – Steel (Grade 8) | Torque (in-lb) – Stainless Steel (18-8) | Torque (in-lb) – Brass |
|---|---|---|---|
| #0-80 | 1.5 | 1.2 | 0.8 |
| #2-56 | 3.0 | 2.4 | 1.5 |
| #4-40 | 6.0 | 4.8 | 3.0 |
| #6-32 | 10.0 | 8.0 | 5.0 |
| #8-32 | 20.0 | 16.0 | 10.0 |
| #10-24 | 35.0 | 28.0 | 17.0 |
| 1/4″-20 | 75.0 | 60.0 | 37.0 |
| 5/16″-18 | 150.0 | 120.0 | 74.0 |
| 3/8″-16 | 250.0 | 200.0 | 120.0 |
| 1/2″-13 | 500.0 | 400.0 | 240.0 |
| 5/8″-11 | 1000.0 | 800.0 | 480.0 |
Specific Set Screw Torque Chart for Different Tip Styles
The tip style of the set screw affects the torque recommendation.
| Tip Style | Torque Adjustment |
|---|---|
| Cup Point | Standard torque values (default) |
| Flat Point | Slightly lower torque (reduce by ~10%) |
| Cone Point | Higher torque (increase by ~15%) |
| Dog Point | Standard torque values (default) |
| Knurled Cup | Higher torque (increase by ~10%) |
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