Views: 1000 Author: Site Editor Publish Time: 2025-09-19 Origin: Site
A set screw is a type of headless fastener designed to secure an object within or against another object, typically by applying compressive force. Threaded along its entire length or partially, it is primarily used to prevent relative motion between two components, such as fixing a gear or pulley to a shaft. Its core function is to act as a mechanical stop, transmitting torque and locking parts in place securely.
Set screws are categorized by the shape of their working end (point), which determines their grip, marring effect, and application.
Flat Point (Flat End): Features a flat tip that applies pressure without digging into the mating surface. It is used when the shaft must not be marred and is often paired with a pre-drilled dimple to prevent the screw from walking under vibration.
Cone Point (Taper Point): Has a sharp, conical tip that exerts high pressure on a small area, providing excellent resistance to rotation. It is best used with a pre-drilled center dimple to ensure precise location and prevent slipping.
Cup Point (Concave End): The most common type. Its concave end creates a sharp circular edge that bites into the mating surface, offering a very strong grip. Ideal for permanent or high-torque applications but will leave a permanent indentation.
Cylindrical Point (Half-Dog Point): Features a short, cylindrical tip designed to fit into a pre-drilled hole on the shaft. This provides positive locking, preventing both rotation and axial movement, and is highly resistant to vibration loosening.
Spherical Point (Ball End): Has a rounded, ball-shaped tip. It is less common and is typically used for applications where minimal marring is acceptable and where the screw may need to be adjusted frequently against a hardened surface.
Material:
Carbon Steel (Grade 2 or 5): The most common and economical material, suitable for general-purpose applications.
Alloy Steel (Grade 8): Heat-treated for high strength and durability. Used in high-stress and heavy-duty applications.
Stainless Steel (18-8 or 316): Offers excellent corrosion resistance. 316 is preferred for marine and highly corrosive environments.
Brass: Used for its corrosion resistance and non-magnetic properties, often in plumbing and electrical applications.
Surface Finish/Plating:
Zinc Plating: A common, low-cost finish that provides moderate corrosion resistance (often with a clear or yellow chromate topcoat).
Black Oxide: Offers a sleek appearance and mild corrosion resistance while reducing light glare.
Nickel Plating: Provides a hard, smooth surface with good corrosion resistance.
Phosphate Coating: Primarily used as a base for holding oil or paint, offering good anti-galling properties.
Strength Grade (Metric/Inch):
Set screws are graded based on their tensile strength. Common metric property classes are 45H (medium carbon steel), A2-70 (stainless steel), and A4-80 (high-strength stainless steel).
In the imperial system, common grades are Grade 2, Grade 5, and Grade 8, with Grade 8 being the strongest.
The drive type is the shape in the head used to turn the screw with a tool.
Hex Socket (Allen): The most popular drive type. It allows for high torque application with minimal risk of slippage and a clean, recessed appearance.
Slotted: A traditional flat-head drive. Less common today as the tool can easily slip and damage the screw.
Square Socket: Provides good torque transmission and is less likely to strip than a hex socket.
Torx® / Star: Becoming increasingly popular due to its superior torque transmission, reduced risk of cam-out (slippage), and higher tool life.
Set screws are available in a vast range of sizes, defined by their thread diameter and length. Common imperial diameters range from #0 (0.060") up to 1" or more. Common metric diameters range from M1.6 to M24 and beyond. Lengths are similarly varied to suit specific application needs.
Proper installation is critical for a set screw to function correctly.
Select the Correct Screw: Choose the appropriate type (point style), size, material, and strength for your application.
Prepare the Hole: The threaded hole in the outer component must be perpendicular to the shaft. For Cone Points and Cylindrical Points, it is essential to drill a matching dimple or hole on the shaft.
Clean Components: Ensure the threads and the contact points are clean and free of debris.
Insert the Screw: Use the correct, undamaged driver bit that fits snugly into the socket.
Tighten to the Proper Torque: Tighten the set screw firmly according to the recommended torque specifications. Overtightening can strip the threads or damage the point. For applications subject to vibration, apply a thread-locking adhesive to the threads.
Set screws are ubiquitous in machinery and precision equipment. Some specific examples include:
Power Transmission: Securing gears, pulleys, sprockets, and collars to rotating shafts in motors, engines, and conveyor systems.
Automotive: Holding door handles, knobs, and various linkages in place.
3D Printers: Attaching stepper motor pulleys to shafts and securing various brackets and components.
Furniture: Assembling frames and securing adjustable components.
Electronics: Mounting components inside enclosures and securing knobs on control shafts.
Jigs and Fixtures: Acting as adjustable stops and leveling feet on manufacturing equipment.
In summary, the set screw is a fundamental and versatile fastener essential for locating and securing components in a wide array of mechanical and industrial applications. Selecting the correct point type is crucial for achieving a secure and reliable assembly.
At RoHsTon Fastener, we don't just supply set screws—we provide engineered fastening solutions. Our comprehensive range includes all point types (Flat, Cone, Cup, Cylindrical, Spherical), in various grades and materials, ensuring you find the perfect fit for your application.
Why Source From Us?
In-Stock Variety: Metric and imperial sizes, from carbon steel to stainless steel, readily available.
Quality Guaranteed: All our screws meet or exceed international standards (ISO, DIN, ANSI).
Technical Expertise: Our engineering team is ready to provide technical support and product recommendations.
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