Buy Grub Screws Online in Australia
Common Questions about Grub Screws
What is a grub screw?
A grub screw is a small headless threaded fastener used to lock a component onto a shaft — pulleys, gears, collars and knobs. The screw sits flush inside a tapped hole and grips the shaft via the point. Also called set screws or socket set screws in catalogue terms.
What is the difference between a grub screw and a set screw?
In Australian usage the terms are used interchangeably. Set screw is the more formal term, grub screw is the common workshop name. Both describe a headless screw with internal hex or Allen drive used to clamp a hub or collar onto a shaft. AIMS lists them under both names.
What grub screw point types are available?
Cup point is the workshop standard — grips well on hardened shafts. Cone point bites into pre-drilled dimples for permanent locking. Flat point is gentle on the shaft for repositioning. Dog point seats into a milled flat. Knurled cup grips harder. AIMS stocks all common point types.
What size grub screw do I need?
Match the diameter and thread pitch to the tapped hole — common workshop sizes run M3, M4, M5, M6, M8, M10 and M12 metric, plus imperial quarter, five-sixteenths and three-eighths UNC. Length should be roughly equal to the screw diameter for full grip without protrusion.
Can grub screws be used at high temperature?
Standard alloy steel grub screws handle general workshop heat. For hot work, stainless or alloy variants are available — check the material listed on the product before ordering for high-temperature service. AIMS stocks alloy steel and stainless options in metric and imperial sizes across the common workshop range.
What DIN and ISO standards apply to grub screws?
Four DIN standards cover the common point styles: DIN 913 / ISO 4026 is flat point, DIN 914 / ISO 4027 is cone point, DIN 915 / ISO 4028 is dog point (cylindrical extension), and DIN 916 / ISO 4029 is cup point. All four share the same M-thread series and standard length range, so the choice of point is independent of the thread and length specification. Ordering by DIN or ISO number removes ambiguity when specifying to a supplier — the head style, drive and dimensional tolerances are all defined by the standard.
Should grub screws be used with Loctite?
For applications subject to vibration or shock loading, yes — a medium-strength threadlocker (Loctite 243 or equivalent) applied to the grub screw thread prevents loosening in service without preventing removal for maintenance. High-strength threadlocker (Loctite 271) suits permanent installations. Cup and knurled cup point grub screws already have good vibration resistance from the mechanical bite into the shaft; flat point grub screws in dynamic applications almost always need threadlocker. Never rely on the grub screw torque alone in vibrating drive applications.
What material grades are common for grub screws?
Three material classes cover most workshop needs. Class 14.9 (formerly 45H) alloy steel with black oxide finish is the workshop standard — high strength, magnetic, suits general use. A2 stainless (304 equivalent) handles indoor damp and mild outdoor exposure. A4 stainless (316 equivalent) handles marine and chemical exposure but at lower strength than alloy steel. Nylon-tipped grub screws combine an alloy steel body with a soft nylon insert at the point for non-marring hold. Check the material spec against the shaft material and service environment.
What drive types are available for grub screws?
Hex socket (Allen key) drive is the workshop standard — clean access on small screws, high torque without cam-out, low profile. Slotted drive is common on older machinery and imperial UNC/UNF grub screws in traditional workshops. Square socket (Robertson) and Torx drives appear on some specialist grub screws. For internal-hex sizes, the hex key size runs from 1.5 mm (M3 grub screw) up to 6 mm (M12 grub screw) — an Allen key set covering 1.5 to 8 mm handles the common range.
What is a nylon-tipped grub screw used for?
Nylon-tipped grub screws (also called plastic-tip or dog-point-with-nylon) have a soft nylon insert at the point, allowing them to clamp against a shaft without marking or damaging the surface. Common uses: polished or plated shafts where cup or cone point marking would be visible, soft materials (aluminium shafts, brass, copper) where a steel point would deform the shaft, and adjustable assemblies where the position needs to change without leaving witness marks. Trade-off: lower vibration resistance than a steel-on-steel cup point, so combine with threadlocker in dynamic applications.
Grub Screw Point Types — Quick Reference
Grub screws (set screws) are headless threaded fasteners specified by thread size, length, and point style. The point determines holding mechanism and removability. Manufactured to ISO 4026–4029 / DIN 913–916 standards in stainless steel and 14.9 high-tensile alloy. AIMS stocks standard metric M3 to M12 across all 4 point styles.
| Point Style | ISO / DIN | Holding Action | Best For |
|---|---|---|---|
| Cup Point | ISO 4029 / DIN 916 | Concave cup tip bites into shaft surface — high resistance to rotation + axial slip | Most general-purpose hold against rotation; default workshop pick |
| Flat Point | ISO 4026 / DIN 913 | Flat tip presses flat against mating surface — no marking | Frequent repositioning, soft shafts, flat key/keyway hold |
| Cone Point | ISO 4027 / DIN 914 | Sharp cone tip seats into a matching countersunk hole in shaft — strongest hold, permanent location | Permanent fix where exact position is critical |
| Dog Point | ISO 4028 / DIN 915 | Cylindrical extension at tip seats into a drilled receiving hole or groove | Pulleys/collars with pre-drilled holes for indexed location |
Grub screws are tightened with a hex (Allen) key. For Allen key sizes by screw size, see our socket head cap screw guide (same Allen key sizes apply across socket fasteners). For thread locking on grub screws subjected to vibration, see threadlockers.
Grub Screws (Set Screws)
Grub screws — also known as set screws — are headless threaded fasteners used to secure a component such as a pulley, gear, collar, encoder or knob to a shaft, or to fix one part against another surface. Without a protruding head, a grub screw can be recessed fully below the surface, making it suitable for rotating applications where a projecting fastener head would be a safety or interference hazard. Driven with an internal hex (Allen) key or slotted screwdriver, the screw generates clamping or indentation force at the point end against the mating surface.
AIMS Industrial supplies grub screws in standard metric sizes M3 to M12 across all four common point styles, in stainless steel and high-tensile alloy grades. Manufactured to ISO 4026 (flat), ISO 4027 (cone), ISO 4028 (dog) and ISO 4029 (cup) — equivalent to DIN 913, 914, 915 and 916 respectively.
Point styles
The point style determines how the grub screw bears against the mating surface and how repositionable the assembly is:
- Cup point (ISO 4029 / DIN 916) — the most common general-purpose point. A small concave cup at the tip bites into the shaft surface, providing good resistance to rotation and axial movement. The indentation left in the shaft allows the pulley or collar to be repositioned precisely if removed and refitted.
- Flat point (ISO 4026 / DIN 913) — a flat tip that bears on a flat surface or a flat ground into the shaft (machining a flat into the shaft is the correct practice for high-load applications). Distributes load over a wider area than a cup point, reducing shaft surface damage where multiple positioning adjustments are required.
- Dog point / half-dog (ISO 4028 / DIN 915) — a short cylindrical extension at the tip that locates into a drilled hole or slot in the shaft. Provides positive location and high resistance to axial movement. Used where accurate, repeatable positioning between the shaft and the hub is required — common in encoder mounts and indexing applications.
- Cone point (ISO 4027 / DIN 914) — a sharp conical tip that penetrates deeply into the shaft surface for maximum grip. Used in permanent or semi-permanent assemblies where maximum locking force matters more than shaft preservation.
Drive types & materials
Socket (hex/Allen) drive is the standard for metric grub screws in engineering applications — the internal hex allows high tightening torque in the recessed position. AIMS stocks grub screws in:
- Class 12.9 alloy steel (black oxide) — the standard high-tensile industrial grub screw. Suits most machinery and drivetrain applications.
- A2-70 stainless (304) — for indoor and lightly corrosive environments where rust would compromise the assembly.
- A4-80 stainless (316) — for marine, food processing and aggressive chemical environments.
Slotted grub screws are suited to light-duty applications and where an Allen key is not available — less common in modern engineering use.
Common applications
Grub screws are specified across pulley and sprocket hubs, gear-on-shaft fixing, shaft collars, encoder mounts, motor coupling hubs, hose-clamp adjustment, knob and lever retention, and bearing locking collars. For high-vibration applications, a grub screw is typically paired with a thread-locker (medium-strength threadlocker for service-disassembly assemblies, high-strength for permanent fixings).
Size selection & standards
Grub screws are specified by thread diameter and pitch (M3, M4, M5, M6, M8, M10, M12) and length. As a rule of thumb, choose a screw length 1.5–2× the thread diameter for adequate engagement in the hub or collar. Stocked metric sizes follow the ISO 4026–4029 / DIN 913–916 standards across both stainless and high-tensile grades.
Browse the wider fastener range
Grub screws sit within our broader fastener range. For the full set screw and machine screw family, see hex set screws, socket head cap screws and machine screws. For stainless options across all fastener types, see stainless fasteners. For background on socket-drive fasteners, torque values and grade selection, see our socket head cap screw guide.
For grub screw selection by thread, length and point style, call (02) 9773 0122 or contact our team.