Grub Screws

Grub screws, also known as set screws, are headless fasteners used to secure components in place within an assembly. Their fully threaded body allows them to sit flush with or below the surface, making them suitable for applications where space is limited or a smooth finish is required.

Grub screws are commonly used to secure pulleys, gears, collars, and couplings to shafts, as well as to attach handles or cams to spindles. They are typically driven using an internal hex (Allen) key, although other drive types are also available.

RS Singapore supplies a wide range of grub screws in different sizes, materials, and drive types to suit a variety of industrial, maintenance, and mechanical fastening applications.

Types of Set Screws

Set screws are produced with several tip, or point, styles, and the point determines how the screw grips and how much it marks the surface it bears against.

Cup Point

Cup point set screws have a concave tip with a circular edge that bites into the mating surface for high holding power, and they are one of the most widely used point styles. Because force is exerted over a relatively small edge, there is a higher chance of marking the part being fastened.

Flat Point

Flat point set screws have a flattened end that spreads compressive force over the area where the tip meets the surface. They cause relatively little surface damage because the tip does not significantly penetrate the mating part, and they are useful where adjustment or reuse is required.

Cone Point

Cone point set screws have a pointed tip designed to penetrate the underlying surface to a degree. This wedging action provides strong axial and torsional holding power, so they are commonly used for more permanent location, or in some cases as a hanger or pivot point.

Dog Point

Dog point set screws, also called extended point screws, have a lengthened, protruding nose that is usually flattened at the end. This extended end is intended to fit into a matching hole, slot, or recess in the underlying surface, working much like a dowel for positive location.

Knurled Cup Point

Knurled cup point set screws behave like plain cup point screws but add serrations or teeth around the outer edge of the cup. The knurling bites into the mating surface and improves resistance to loosening in vibration-prone applications, although it can mark the part and is best suited to permanent or semi-permanent installations.

How Grub Screws Work

Grub screws secure components by applying pressure through a threaded hole to prevent movement between mating parts.

• Force Transmission: Grub screws are tightened into a threaded hole until their tip presses firmly against a shaft, spindle, or mating surface. This creates a holding force through thread tension and direct contact at the screw point.
• Movement Prevention: The pressure at the contact point prevents relative movement between components. Depending on the application, it can restrict rotation, axial movement, or both, keeping parts securely fixed.
• Point Interaction and Grip Mechanism: The screw tip plays a key role in performance. Different point styles (e.g. flat, cup, cone) influence how the screw grips the surface, from frictional contact to slight indentation or positive location for improved holding strength.
• Load and Vibration Resistance: Properly tightened grub screws can maintain retention under vibration and cyclic loads. The combination of friction, contact pressure, and point engagement helps resist loosening during operation.
• Installation and Performance Factors: Reliable performance depends on correct tightening torque, sufficient thread engagement, and the appropriate point style. Over-tightening can damage the mating surface or strip threads, while under-tightening may cause slippage or loss of holding force.

Grub Screw Selection Guide

Select a grub screw based on the application, holding requirements, material compatibility, and installation needs.

• Point Type Selection: Choose the point style based on the application. Cup points provide strong holding power for general retention. Flat points minimise surface damage and suit soft materials or frequent adjustment. Cone points offer maximum holding strength for permanent fixing while dog points provide accurate alignment in holes or slots.
• Load and Holding Requirements: Select a screw size and point style that meets the required torque, load, and operating conditions. Higher load or vibration may require stronger grip or more aggressive point types.
• Material Compatibility: Ensure the screw material is compatible with the mating surface to reduce galling, wear, or corrosion. Material and finish selection is especially important in harsh or corrosive environments.
• Vibration and Retention Needs: For applications subject to vibration or cyclic loading, choose point styles such as cup or knurled designs to improve resistance to loosening.
• Installation Access and Drive Type: Consider the available space and tools when choosing the drive type (e.g. hex socket, slotted). Limited access areas may require compact tools or specific drive configurations.
• Maintenance and Adjustability: For assemblies requiring frequent adjustment or repositioning, flat point screws minimise surface damage and allow easier reuse.

Applications of Hex Socket Set Screws

The headless, flush design of a hex socket set screw lets it lock rotating and sliding parts onto a shaft without a protruding head, which is why these fasteners are used across machinery, equipment, and precision assemblies.

• Electric Motor Manufacturing: In machinery and power transmission, pulleys, gears, and shaft collars rely on set screws to stay locked onto motor shafts under load. Without the right fastener in the correct position, components shift, causing alignment failures in the drive.
• Automotive: The headless design of grub screws is useful in drivetrain components and engine controls, where a bolt head would physically interfere with rotating parts. Set screws hold these assemblies together while leaving the rotating path unobstructed.
• Consumer Electronics: In electronics and audio equipment, set screws secure potentiometer knobs and motor couplings within precision enclosures. Flat point or soft-tip variants may be preferred, where surface marking must be avoided.
• Plumbing: In plumbing fixtures, as in HVAC systems, set screws secure critical components so the assembly operates reliably. They are used to fix handles, knobs, and fittings to a spindle or shaft, preventing movement during operation.
• Robotics: In robotics, grub screws secure couplings and components to drive shafts in joints and actuators, while newer magnetic-drive designs allow tool-free adjustment in hard-to-reach joints. Their flush installation keeps moving joints free of protrusions in confined spaces.

Trusted Grub Screws Supplier & Manufacturer in Singapore

Whether you are maintaining existing equipment or building new machinery, RS offers a wide range of grub screws for industrial applications as a trusted manufacturer and supplier in Singapore. The range includes products from leading brands such as RS PRO, Ganter, and Socomec, providing options to suit various installation and engineering requirements.

Use the website to filter products by size, point type, material, and price. You can also save parts lists and reorder items quickly. In addition to grub screws, our fasteners and fixings range includes related products such as spring pins and threaded inserts.

Eligible in-stock orders may be available for next-working-day delivery, subject to availability, order value, and cut-off times. Delivery charges and order cut-off times are available on our delivery page.