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socket set screws in a row

What Is A Set Screw?

Set screws are headless fasteners with recessed drives. Set screws are designed to hold objects securely in place without the need for a nut, offering an unobtrusive solution that maintains a clean, flush surface. 

This guide covers everything you need to know about set screws, including how they work, their common uses, and the different types of set screws.

What Are Set Screws?

Set screws are small, fully-threaded fasteners without heads used to secure objects to a shaft prohibiting motion between the pieces they join. Set screws may also be referred to as socket set screws or grub screws (skip ahead to our discussion on grub screws vs set screws to learn more). As set screws don't have heads, they don't protrude from the surface they're driven into.

Socket set screws feature a recessed drive that enables them to be driven into a material, securely embedding their threads into the shaft. This frictional engagement effectively prevents axial movement, ensuring the connected pieces remain locked and aligned during operation. They also create compression when their tips dig into the material's surface.

How Do Set Screws Work?

Set screws work by providing an effective hold between two components. When driven into a pre-drilled hole, a set screw creates friction and generates compressive force as its tip applies pressure directly onto another part, such as a shaft. 

What Are Set Screws Used For?

Set screws are used for applications within high-vibrational environments, such as within machinery with motors or pulleys. Additionally, a set screw's design allows for easy insertion and removal, making them ideal for applications that require periodic adjustments. 

Here's a breakdown of the most common uses for set screws.

  • Securing Gears and Pulleys: Set screws affix these parts to rotating shafts to prevent slipping and maintain alignment during operation.

  • Adjusting Collars on Shafts: Holds collars in place, allowing for precise positioning and easy adjustments on rotating shafts.

  • Locking Knobs and Handles: Secures knobs or handles onto control shafts to prevent unwanted rotation or loosening during use.

  • Positioning Components in Electronics: Secures sensitive electronic components, ensuring stability without damaging the area.

  • Aligning Components in Optical Devices: Holds lenses or mirrors in place for fine adjustments and precise alignment within optical assemblies.

  • Joining Mechanical Assemblies: Integrates moving parts within machinery, providing a firm hold while remaining recessed.

  • Fixing Jigs and Fixtures: Secures components within manufacturing setups, offering repeatable positioning and easy adjustments.

What's The Difference Between A Grub Screw VS. Set Screw?

The difference between set screws and grub screws comes down to regional terminology, as they are both terms used to refer to the same type of fastener. In North America, especially the US, these headless screws are typically referred to as set screws, while in British English and other Commonwealth countries, they are called grub screws. 

Set Screw Types

Set screws include a variety of head types, such as cup point set screws and cone point set screws. Each head type is designed to engage the surface of the component they come into contact with. However, some points may dig into the material and create micro indentations.

The set screw type list below covers the most common set screw point types, including their appearance, use, and typical applications.

  • Cup Point Set Screw: Features a concave tip for increased grip, making it ideal for fixtures where material penetration is acceptable. Commonly used in machine parts and for securing pulleys or levers.

  • Knurled Cup Point Set Screw: Similar to the cup point but with knurled edges for enhanced grip, providing strong friction. Utilized in high-vibration environments where extra holding power is needed.

  • Cone Point Set Screw: Tapered point designed to embed into surfaces, suitable for fixtures in softer materials that require a secure fit. Ideal for assemblies needing frequent adjustments, like collars or stops.

  • Oval Point Set Screw: Features a rounded tip for smooth contact, used where minimal surface damage is desired. Typically applied in precision equipment adjustments where repeated loosening is expected.

  • Dog & Half Dog Point Set Screw: Extends beyond the end with a flat point, engaging into slots for precise alignment. Used in machining applications where exact positioning is critical, such as shaft positioning.

  • Flat Point Set Screw: Flat-ended and fully threaded, it provides lateral force without deep penetration and is easy to adjust or remove. Often used in electronics or applications where marking is unacceptable.

  • Soft-Tipped Point Set Screw: Has a soft material tip like nylon to prevent damage to softer surfaces while maintaining secure hold. Common in electronics and delicate assemblies like securing plastics or soft metals.

  • Ball-Point Set Screws: Includes a rounded metal ball end, allowing for slight movement or tilt of the secured object for precision alignments. Utilized in flexible or pivoting connections, such as alignment devices or camera mounts.

black oxide set screw

Set Screw Drive Types

Set screws are headless and utilize a recessed drive to facilitate installation and removal. While hex sockets are the most common drive types, set screws may feature a variety of drives, from common Phillips drives to square drives. Here’s a look at the most common set screw by drive type and their use cases:

  • Hex Socket Set Screws (Allen): Features a hexagonal recess compatible with an Allen wrench. Offers excellent torque application and ease of use, making it ideal for most mechanical and electronic applications.

  • Slotted Set Screw: Has a single horizontal slot for a flathead screwdriver. Simple and common but prone to slipping, used when less torque is needed.

  • Phillips Socket Set Screw: Includes a cross-shaped recess for use with a Phillips screwdriver. Provides more grip than a slotted drive but is less common for set screws due to potential cam-out at high torque levels.

  • Torx Socket Set Screw: Boasts a star-shaped pattern with six points, known for high torque tolerance and reduced cam-out risk. Suitable for applications requiring precise torque settings and additional security.

  • Square Socket Set Screw (Robertson): Features a square recess for a robust connection with the driver tool. Offers good resistance to cam-out, used in applications where heavy torque is needed, though less common than hex socket.

How To Use A Set Screw

To use a set screw, align the components and insert the screw into the pre-threaded hole of the fixture. Then, use an Allen wrench or screwdriver to tighten the set screw until it's secure, taking care not to overtighten and strip the threads. Here’s a step-by-step explanation on how to install set screws properly:

Set Screw Installation

1. Gather Your Tools

  • Allen wrench or driver that matches the screw's head type
  • Caliper or ruler to measure placement depth and alignment

2. Prepare the Components

Clean the surfaces of the components you are joining to remove any debris or oil. Align the component (e.g., gear or pulley) with the shaft or area where the set screw will be installed.

3. Locate the Threaded Hole

Identify the pre-drilled and threaded hole in one of the components where the set screw will be inserted. Ensure the hole is clear of any obstructions or burrs that might impede the screw.

4. Insert the Set Screw

Begin threading the set screw into the hole by hand to ensure proper alignment and prevent cross-threading.

Turn the screw clockwise to start threading it into the hole.

5. Tighten the Set Screw

Use the appropriate tool (e.g., Allen key or screwdriver) to continue tightening the screw. Apply firm, even pressure while turning to ensure the tip of the screw presses securely against the shaft or component.

6. Check Alignment and Security

Verify that the secured component is properly aligned with no wobbling and doesn’t protrude.

7. Final Adjustments

Make any necessary adjustments to the component placement if needed. Re-tighten the screw slightly to ensure a secure fit.

How To Remove Stripped Set Screws

If you need to remove a stripped set screw, first try applying a penetrating lubricant to loosen any rust or debris that might be hindering the process, and let it sit for a few minutes. 

Use a set of locking pliers to grip firmly around the screw and turn it counterclockwise, applying steady pressure. If the pliers don't work, consider using a screw extractor, which is designed to bite into the stripped head and provide the necessary torque for removal. 

As a last resort, drilling a small pilot hole into the screw and using a reverse drill bit can help back the screw out without further damaging the surrounding material.

Choose Quality Set Screws From The Fastener Depot

Choosing the correct set screws is crucial for project success, and we hope our guide helps in that process. At The Fastener Depot, we pride ourselves on being a family-run business that delivers not only superior fasteners but also personalized advice to ensure your selections are spot on.

Take advantage of our free shipping on orders above $50 and enjoy peace of mind with our hassle-free 30-day return policy. We are dedicated to making your fastening purchase simple and satisfactory.

Let The Fastener Depot help you find exactly what you need. Contact us today to explore our high-quality product range and expert support.

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