Buy Shoulder Screws Online in Australia
Shoulder screws — also called shoulder bolts or stripper bolts — have a precision-ground cylindrical shoulder between the head and the thread, machined to a tighter, more consistent diameter than the thread itself. That shoulder is the working part of the fastener: it acts as a bearing surface, pivot pin, or precise mechanical stand-off, while the smaller-diameter thread simply does the job of clamping it in place. AIMS Industrial stocks the Hobson range of hex socket head shoulder screws, covering metric, UNC and BSW thread systems, for engineering, toolmaking and machinery work across Australia. For a deeper dive on the standards and selection criteria, see our Shoulder Bolt Guide: Sizes, Specifications and Applications.
Quick Reference
| Spec | Detail |
|---|---|
| Thread systems stocked | Metric (M5–M20), Imperial UNC (10-24 to 1/2"), Imperial BSW (3/8" x 1") |
| Shoulder diameters | Set by thread size per range — see product variants for exact shoulder Ø and length combinations |
| Material | Alloy steel — Grade 12.9 (metric range), high-grade alloy steel (UNC range) |
| Finish | Plain (uncoated) |
| Drive type | Hex socket (Allen key) |
| Governing standard | ISO 7379 — hexagon socket head shoulder screws |
| Shoulder tolerance | f9 per ISO 7379 (a controlled sliding fit, not a slip/press fit — check clearance against your mating bore) |
| Brand stocked | Hobson |
| Pack options | Singles (metric and UNC ranges); box of 25 (3/8" BSW line) |
How a shoulder screw is built
A shoulder screw has three sections from the head down: a hex socket head, a precision-ground shoulder (the longer, larger-diameter section), and a threaded end (shorter, smaller in diameter than the shoulder). Because the thread is undersized relative to the shoulder, the shoulder can bottom out against the mating face while the thread pulls the screw home into a tapped hole — the shoulder carries the working load and location, the thread just holds it there. Sizing is given as shoulder diameter × shoulder length × thread size (for example, an M8 thread on a 25 mm long shoulder).
Where shoulder screws earn their place
- Pivot and linkage joints — the ground shoulder gives a rotating lever or link a true, consistent bearing surface
- Pulley and roller axles — a fixed axle for a pulley, cam follower or roller to turn on
- Guide pins — precise, repeatable location between mating plates or components
- Press tool stripper plates — the original "stripper bolt" application, positioning a stripper plate relative to the die
- Spacers and stand-offs — a fixed, precise gap between two components in an assembly
- Custom machinery and jig work — anywhere you need a precision bearing surface on a shaft without machining a separate pin and retaining it with a circlip
The three ranges AIMS stocks
Metric — Grade 12.9 alloy steel, plain finish
Metric hex socket head shoulder screws from M5 through M20 thread, with shoulder lengths from 10 mm up to 100 mm depending on size. Manufactured from Grade 12.9 alloy steel with a plain (uncoated) finish — the standard high-tensile grade for shoulder screws carrying mechanical load in machinery and jig work.
UNC (imperial) — high-grade alloy steel, plain finish
Imperial UNC-thread shoulder screws from 10-24 through 1/2" thread, with shoulder lengths from 3/8" up to 2 1/2". Useful where you're maintaining or modifying older imperial-spec machinery, or matching existing imperial tooling and jigs.
BSW (imperial) — box of 25
A 3/8" shoulder × 1/2" thread × 1" length BSW shoulder screw, supplied in a box of 25 — a practical option where you're stocking up for a production run or maintaining older BSW-threaded equipment.
Specifying a shoulder screw correctly
Shoulder diameter and shoulder length are the dimensions that matter most — they set what the screw actually locates or bears against, not the thread size. Where the shoulder is running against a bushing or bearing bore, check the shoulder diameter against that bore's tolerance before you order; the ISO 7379 shoulder tolerance (f9) is a controlled sliding fit rather than a tight slip fit, so confirm it suits your application before specifying it as a running bearing surface. Shoulder length should match your grip requirement — the thickness of the components the shoulder passes through, plus enough length for the thread to engage a tapped hole without the shoulder bottoming out short.
Companion Collections
- Socket Head Cap Screws — the standard fully-threaded equivalent, same hex socket drive family
- Spacers — for stand-off applications not requiring a load-bearing shoulder
- Needle Roller Bearings — to pair with a shoulder screw used as a bearing pivot
- Shaft Collars — for axial location on a shoulder screw used as an axle or pivot pin
- Hobson — the full Hobson fastener range stocked at AIMS
- Fasteners — our full fastener range
Order from AIMS
Need help specifying a shoulder screw for a pivot, bearing mount or press tool, or checking a size we don't list here? Give our team a call on (02) 9773 0122, get in touch via our contact us page, or request a quote for a bulk or project order — we'll help you match shoulder diameter, length and thread to your job.
Frequently Asked Questions
What is a shoulder screw (shoulder bolt)?
A shoulder screw — also called a shoulder bolt or stripper bolt — is a fastener with a precision-ground cylindrical shoulder between the head and a smaller-diameter thread. The shoulder acts as a bearing surface, pivot, or precise spacer, while the thread simply secures the screw into a tapped hole.
What's the difference between a shoulder screw and a standard cap screw?
A standard socket head cap screw is threaded along most or all of its length and is designed purely to clamp. A shoulder screw has a smooth, precision-ground shoulder that's larger in diameter than its thread, so it can act as a bearing surface, pivot pin or fixed-length spacer — a job a fully-threaded cap screw can't do accurately.
What sizes does AIMS stock?
Metric hex socket head shoulder screws from M5 to M20 thread (10 mm to 100 mm shoulder lengths), UNC imperial shoulder screws from 10-24 to 1/2" thread (3/8" to 2 1/2" shoulder lengths), and a 3/8" x 1/2" x 1" BSW shoulder screw supplied in a box of 25.
What standard do these shoulder screws meet?
The metric range is manufactured to ISO 7379, the standard for hexagon socket head shoulder screws, which sets the shoulder diameter, shoulder length and thread relationship for each size.
What tolerance is the shoulder ground to?
Under ISO 7379 the shoulder diameter is held to an f9 tolerance — a controlled sliding fit. Check this against the tolerance of your mating bore or bushing before specifying a shoulder screw as a running bearing surface; f9 is not a tight slip fit.
What material and grade are AIMS's shoulder screws?
The metric range is Grade 12.9 alloy steel with a plain (uncoated) finish. The UNC range is high-grade alloy steel, also plain finish. Both are supplied by Hobson.
Do you stock stainless shoulder screws?
Not in this range currently — it's stocked in plain-finish alloy steel only. If you need corrosion resistance for an outdoor, washdown or food-contact application, contact our team and we'll check sourcing options for you.
What are shoulder screws typically used for?
Common uses include pivot and linkage joints, pulley or roller axles, guide pins for locating mating components, press tool stripper plates, and precision spacers or stand-offs in machinery and jig work.
Do you stock imperial as well as metric shoulder screws?
Yes — alongside the metric range, AIMS stocks UNC-thread shoulder screws (10-24 to 1/2") and a 3/8" BSW shoulder screw, for maintaining or building onto imperial-spec machinery and tooling.