Grub Screws

A grub screw, also known as a set screw or socket set screw is used for securing sliding, moving or rotating components in place without the use of a conventional external head. Grub screws are commonly used to secure a pulley or a gear to a shaft or for attaching a handle or cam to a spindle.

These types of screws have a fully threaded body and work by passing through a threaded hole in the outer object and then tightened against the inner object to apply a clamping force and prevent it from moving. Allen keys or an internal wrenching drive are commonly used to tighten grub screws.

Types of Grub Screws and Socket Set Screws

The various types of grub screws are primarily differentiated by their point style, which dictates how the screw interacts with and secures the mating surface, ensuring the appropriate holding force for any application. The fasteners are then further categorised by their size measurement system: metric grub screws and imperial grub screws.

Hexagon Head

The hex head setscrew (or hex set screws) features a fully threaded body topped with a visible hexagon head, allowing it to be tightened using an external spanner or wrench. This style is used where a degree of head protrusion is acceptable and where a stronger external drive is required to achieve high torque and clamping force.

Socket Head

True socket set screws are defined by their headless design and internal drive (often a hexagon/Allen drive), meaning the entire fastener is fully recessed below the surface of the material once installed. This design is ideal for surfaces requiring a smooth finish and for mechanical systems where corrosion resistance and high tightening torque are critical.

Metric Grub Screws

Metric grub screws are fundamental to modern mechanical assemblies, machinery, and automotive applications requiring precise fastening. They are primarily available in diameters ranging from M1.2 up to M16 and beyond, with lengths extending from 1.5mm up to 190mm, providing expansive coverage for most industrial shaft securing requirements.

Imperial Grub Screws

Imperial grub screws are essential for maintaining and repairing older equipment and assemblies that utilise inch-based threads. These set screws typically range in size from 0 gauge to 3/4 inches in diameter, with standard lengths between 1/16 inch and 4 inches, ensuring perfect compatibility with existing imperial-threaded shafts and fittings.

How to Choose the Right Grub Screw for Your Needs

Selecting the correct set screw requires careful evaluation of the application environment, the required holding force, and the specific shaft geometry to ensure optimal performance and safety. Focusing on these key criteria will help you determine the most appropriate fastener for your machinery or assembly.

• Thread Standard and Size: Determine the precise diameter and thread pitch required to match the tapped receiving hole, choosing between metric grub screws (M sizes) or imperial grub screws (inch-based sizes) based on the equipment specifications.
• Length and Engagement: Select a length that ensures adequate thread engagement for maximum holding power without causing interference; the set screw must not protrude where it could contact moving parts.
• Drive Style and Head Form: Opt for the internal hex drive of a socket set screws/hex grub screw for compact, flush fastening; conversely, use a visible hex head setscrew/hex set screws where easier external wrenching is necessary and head protrusion is acceptable.
• Point Style: Choose the point based on the securing method needed: use cone points for positive shaft indentation, flat points for minimal marking, or dog points for location within a pre-machined feature.
• Material and Finish: Evaluate options such as high-tensile steel or stainless steel to meet strength requirements, and select the finish based on the environment to ensure necessary corrosion resistance (e.g., outdoor, marine, or food-grade applications).

Common Industrial Applications for Grub Screws

Grub screws are valued across manufacturing, maintenance, and assembly for their ability to provide secure, flush-fitting fastening that maintains precise component alignment. Their high reliability and versatility make them essential components in diverse machinery and industrial equipment across Australia.

• Power Transmission: Heavy-duty set screws are used to fix pulleys, gears, and collars firmly onto rotating shafts, preventing slippage under high torque loads in mechanical drives.
• Architectural Hardware: Recessed socket set screws are frequently utilised as grub screws for door handles, knobs, and fixtures, providing a clean, invisible method of securing the hardware to the spindle.
• Electrical and Electronics: Precision small grub screws are vital in electrical terminal blocks, sensors, and electronic housings where minute, flush, and tamper-resistant fastening is required.
• Tooling and Fixturing: In precision engineering, robust hex grub screws are used to lock stops, guides, and alignment pins into precise locations on machining jigs and fixtures.
• Fluid and Valve Control: Hex set screws are employed in high-pressure hydraulic and pneumatic valve blocks to securely seal access ports or hold internal adjusting components under reliable clamping force.

Your Trusted Grub Screw Supplier and Manufacturer in Australia

RS is Australia's leading grub screw supplier and distributor, offering an unparalleled selection of high-performance grub screws, set screws and socket set screws designed to meet the rigorous demands of manufacturing and maintenance across the nation.

Our extensive catalogue allows users to quickly filter and source the precise fastener they need according to critical specifications such as screw type, drive type, material finish, and thread standard. We guarantee quality by stocking products from renowned brands like Socomec, nVent SCHROFF, and our very own RS PRO. Besides grub screws, we also support your complete assembly needs with other types of screws and bolts like: self drilling screws, self tapping screws, as well as complete screw and bold kits.

For more information on delivery timelines and charges, please refer to our Delivery Information page.