Types of Spanners Guide

Spanners are the backbone of any trade toolkit — and choosing the wrong type is one of the most reliable ways to round a nut, strip a fitting, or find yourself stuck halfway through a job. This guide covers every type of spanner used in Australian trades and workshops: what each one does, when to use it, and where it fails. Whether you are a maintenance fitter, tradie, mechanic, or setting up a home workshop, this is the complete reference.

Spanner or Wrench? The Australian Terminology

In Australia, the correct trade term is spanner. In the United States, the same tool is called a wrench. Both terms are understood in Australia, but spanner is the standard in trade settings. Some specific tools retain "wrench" in their name regardless — torque wrench, pipe wrench, and impact wrench are all normal Australian terminology.

One important AU-specific term: shifter refers specifically to an adjustable spanner, not to all spanners. If someone on site asks for "the shifter," they mean the adjustable. "A spanner" means the correctly-sized fixed spanner for the job.

The Main Types of Spanners Explained

There are more than a dozen distinct spanner types, each designed for specific access conditions, fastener types, and torque requirements. Understanding the limitations of each type is as important as knowing its intended use.

1. Open-End Spanner

The open-end spanner has two fixed U-shaped jaws at opposite ends, set at 15° to the handle axis. Most are double-ended with two different sizes (e.g. 10/11mm, 12/13mm, 16/17mm). The 15° offset allows the tool to be flipped end-for-end after each partial turn — effectively doubling the usable arc in confined spaces.

Best for: Quick access where a ring or socket cannot fit above the fastener; holding a nut while tightening from the opposite side; pipe fittings where a ring cannot thread over the tube end.

Limitation: The open jaw contacts only two faces of the fastener. Under high torque, this concentrates stress on two points and causes slipping and rounding. Open-end spanners are run-down and access tools — not break-out tools.

2. Ring Spanner (Box End Spanner)

A ring spanner has a fully enclosed circular head engaging all six faces of a hex fastener (twelve engagement points in a bi-hexagonal design). This full engagement makes it the strongest fixed spanner type and the correct choice for any high-torque or corroded fastener situation.

6-point vs 12-point (bi-hexagonal): Most Australian ring spanners are bi-hex (12-point). A 12-point ring repositions every 15° of swing; a 6-point requires 30°. In tight spaces with a limited swing arc, 12-point ring spanners complete a full rotation in half the repositioning lifts. Six-point rings distribute force more evenly per flat and are preferred for extreme torque or already-damaged fasteners.

Best for: High-torque applications, corroded or seized fasteners, repetitive tightening cycles where fastener rounding must be avoided.

3. Combination Spanner

The combination spanner is the most common spanner in Australian trade toolkits. It has an open-end jaw on one end and a ring on the other — both the same size. A 17mm combination spanner gives you a 17mm open end and a 17mm ring on one tool.

The open end runs the fastener down quickly; the ring end provides final high-torque drive or initial break-out grip. One tool, two functions, same size. A metric set from 6mm to 24mm covers the majority of fasteners in automotive, construction, and industrial maintenance work.

What to look for: Chrome-vanadium steel (Cr-V) construction, clearly stamped sizes, 12-point bi-hex ring profile, chrome-plate finish for corrosion resistance.

4. Adjustable Spanner (Shifter)

The shifter has one fixed jaw and one moveable jaw adjusted via a knurled worm gear. Common Australian sizes are 150mm, 200mm, 250mm, and 300mm — these refer to overall tool length, not jaw capacity.

Critical technique: Always position the shifter so the pulling force acts on the fixed (lower) jaw. When force acts toward the moveable jaw, it spreads under load and slips off the fastener. Close the jaw snugly to zero play before applying torque, and re-snug every few turns during sustained use.

Best for: Non-standard fastener sizes, large plumbing fittings, site work where carrying a full fixed spanner set is impractical. Not appropriate for critical or high-torque fasteners.

For a complete guide, see our Adjustable Spanner & Shifter Guide — types, sizes, jaw opening table, and correct use technique.

5. Socket Wrench and Ratchet Handle

A socket system separates the driving mechanism from the fastener engagement. Sockets clip onto a square-drive ratchet handle via a spring-loaded detent. Drive size determines both torque capacity and ratchet head bulk.

Six-point sockets are preferred for high-torque and damaged fasteners — better load distribution per flat. Twelve-point allows more entry angles and suits tight spaces at the expense of some contact area per flat. Use deep sockets for nuts on long studs or bolts in recessed holes. A breaker bar — not the torque wrench — is the correct handle for break-out.

For a complete size reference, see our Spanner & Socket Size Chart.

6. Ratchet Spanner

A ratchet spanner looks like a standard combination spanner but incorporates a ratchet mechanism in the ring end. The ring drives in one direction and free-spins on the return stroke — the tool never needs to be lifted and repositioned. Most have a reversing switch for direction change.

Best for: Confined spaces where a socket ratchet handle is too bulky but repeated short-stroke tightening is needed — engine bays, control panels, panel-mount assemblies. Fine-tooth ratchets (72-tooth and above) are preferred for very tight spaces where only a few degrees of swing are available.

Limitation: The ratchet mechanism reduces peak break-out torque compared to a solid ring. Use a conventional ring for break-out on seized fasteners, then switch to the ratchet spanner for run-down and tightening.

For a complete guide, see our Ratchet Spanner Guide — types, tooth count, flex head vs fixed head, and break-out tips.

7. Torque Wrench

A torque wrench is a precision measuring instrument that applies a specified, quantified torque to a fastener. It is not a general-purpose tool — it exists to ensure critical fasteners are tightened to the manufacturer's specification, preventing both loosening and overtightening damage.

Types in common Australian use:

• Click-type (micrometer): Set the desired torque; the wrench clicks and releases when reached. Most common in trade. Available in 1/4", 3/8", and 1/2" drive. Typical accuracy ±4% in the upper 80% of range.
• Beam-type: A needle deflects against a scale as torque is applied. Simple, accurate, durable — no calibration loss. Requires visual confirmation during use.
• Digital/electronic: Strain gauge with digital readout and programmable alerts. High accuracy (±1–2%). Used in production and calibration-critical environments.
• Torque-angle: Applies initial torque then rotates a specified additional angle. Required for torque-to-yield (TTY) stretch bolts — modern cylinder head and con-rod bolts.

For full torque wrench type comparison, drive selection, and calibration intervals, see our guides: Torque Wrench Selection Guide and Torque Wrench Calibration Guide.

8. Flare Nut Spanner (Line Spanner)

A flare nut spanner is a ring spanner with a slot cut in one side. The slot allows the tool to slide sideways over a pipe and seat around the fitting nut — providing near-full ring engagement on the nut without needing to thread the tool over the end of the tube.

Why it exists: Brake, fuel, hydraulic, and air conditioning lines have fitting nuts at the end of a rigid tube. A full ring cannot thread over the tube. An open-end spanner fits but provides only two-point contact — enough to round the soft fitting nuts these lines use. The flare nut spanner provides ring-level grip with open-end access.

Common AU applications: Brake line unions (M10×1.0, M12×1.0 in metric AU vehicles), fuel line fittings, A/C refrigerant line connections, hydraulic instrumentation tubing. A socket-drive crow foot version allows torque wrench use on these fittings.

9. Pipe Wrench (Stillson)

A pipe wrench — called a Stillson in Australia — has a spring-loaded jaw with serrated hardened teeth designed to grip round pipe. The jaw tightens its bite as torque is applied in the working direction. Pipe wrenches grip by biting into and slightly deforming the workpiece surface — they will mark any surface they contact.

Suitable materials only: Black steel pipe, galvanised steel pipe. Not suitable for chrome or decorative fittings, copper, aluminium, brass fixtures, or precision-machined surfaces. The teeth will scar these surfaces permanently.

10. Allen Key (Hex Key)

An Allen key — also called a hex key or hex wrench — is an L-shaped or T-shaped tool with a hexagonal cross-section, used to drive socket-head cap screws (SHCS), button heads, and grub screws.

Common forms:

• L-shape: Short arm for torque, long arm for reach. Most common form for trade use.
• T-handle: Fast for run-down. Not appropriate for final torque — overtightening strips the internal hex recess.
• Ball-end: Allows engagement up to ~25° off-axis. Use for run-down only — full flat-face engagement required for final torque.
• Hex bit sockets: Hex key inserts for standard drive ratchets or impact tools. Most efficient for production and maintenance work.

Metric vs imperial in Australia: Metric hex keys (1.5–12mm) are the primary standard. The 4mm, 5mm, and 6mm sizes are most commonly encountered. Imperial hex keys (3/32"–3/8") are needed for American-specification equipment and some imported power tools.

11. Impact Wrench (Rattle Gun)

In Australian trade vernacular, an impact wrench is universally called a rattle gun. It delivers high torque through rapid rotary hammer impacts (typically 1,000–3,200 impacts per minute) rather than continuous rotation. Each impact delivers a high-energy rotational jolt — the accumulative effect produces torques far beyond continuous motor output, with minimal reaction force felt by the operator.

Pneumatic vs battery-powered: Pneumatic tools are lighter for a given torque output and lower cost, but require a compressor and fixed air supply — best for workshops. Modern 18V/20V brushless battery tools match quality pneumatic output and go anywhere — best for site and field work.

Best for: Wheel nuts, structural bolting (M16+), high-volume fastener removal, and breaking seized fasteners where a breaker bar creates excessive reaction force.

12. Scaffold Spanner (Podger)

A scaffold spanner — called a podger or podger wrench — combines a fixed spanner head (typically 21mm for AU Kwikstage and Ringlock coupler nuts) with a tapered alignment spike (podger) on the opposite end. The spike aligns bolt holes in scaffolding components before the bolt is inserted; the spanner end tightens the coupler nut. One tool handles both alignment and fastening — critical when working at height where additional tools are dropped-object hazards.

13. Strap Wrench

A strap wrench uses a flexible loop of rubber, nylon webbing, or chain attached to a rigid handle. The loop grips through friction across the surface of the workpiece — no jaw contact, no edge loading.

Best for: Oil filter removal and installation (no canister piercing); chrome-plated plumbing fittings that must not be scratched; round pipe nipples and smooth cylindrical surfaces with no machined flats; PVC or thin-wall plastic components where jaw pressure would crack the material.

Limitation: Friction grip fails on wet or oily surfaces. Rubber or chain-type strap wrenches give better grip on oily filters than nylon webbing.

Spanner Types Comparison Table

Metric Spanner Sizes: What Fits What

In Australia, the overwhelming majority of fasteners are metric. The correct spanner for any hex fastener is determined by its AF (Across Flats) measurement — the distance between two parallel opposite faces of the hex head. This is the number stamped on every spanner. The approximate rule for standard metric hex fasteners is AF ≈ bolt diameter × 1.7.

For a printable metric, imperial, and BSP spanner reference, see our Spanner Size Chart — Metric, Imperial & BSP.

Metric vs Imperial Spanners in Australia

Australia completed its metric conversion progressively through the 1970s and 1980s. Metric is now the dominant standard across automotive, construction, manufacturing, and engineering. Imperial fasteners have not disappeared entirely — they appear in specific sectors and equipment types.

Where metric is the exclusive standard: All Japanese, Korean, European, and post-1980 Australian vehicles; all modern industrial machinery to ISO/DIN/AS standards; all Australian construction hardware (AS 1110, AS 1112).

Where imperial is still encountered:

• American agricultural equipment: Many US tractor and implement brands — John Deere, Case IH, Agco — maintain SAE imperial fasteners on chassis and drivetrain components through to recent models. Any AU farm workshop servicing US-brand machinery needs a complete imperial set.
• Pre-metric vehicles: Classic and vintage Australian vehicles built before the mid-1970s (pre-metric Holden, Ford, Chrysler AU) use imperial AF sizes throughout.
• Imported American industrial machinery: Compressors, pumps, conveyors from US manufacturers commonly use SAE fasteners throughout regardless of import date.

How to Read a Spanner Size

Every spanner is marked with its size. Understanding what the number means depends on the tool type:

• Open-end, ring, combination spanners: The stamped number (e.g. 17) is the AF in millimetres — the jaw width matching the across-flats measurement of the hex fastener head.
• Adjustable spanner (shifter): The number is the overall tool length in millimetres (150, 200, 250, 300), not the jaw opening capacity.
• Sockets: The socket size is the AF of the fastener it fits. The drive size (stamped on the square drive hole) indicates which ratchet it attaches to.
• Allen keys (hex keys): The number is the across-flats width of the hexagonal key shank — must match the fastener recess exactly.
• Pipe wrenches: The size refers to maximum recommended pipe diameter capacity, not the tool length.

How to Choose the Right Spanner

The right spanner depends on more than whether it fits the fastener head. Work through these five checks before picking up any tool:

1. Confirm metric or imperial. Measure the AF with a calliper if uncertain. A 19mm spanner on a 3/4" bolt (19.05mm AF) appears to seat — under break-out torque it will round the corners.

2. Assess the torque required. Run-down and light snug: open-end, Allen key, ratchet spanner. Standard assembly: combination ring end or socket ratchet. High torque — structural or mechanical joints: ring spanner or 1/2" drive socket with breaker bar. Manufacturer-specified torque: torque wrench — look up the spec, set the wrench, do not guess. Extreme torque or seized fastener: impact wrench with impact sockets.

3. Assess access constraints. Open access: choose by torque requirement. Restricted swing arc: ratchet spanner or flex-head socket ratchet. Limited overhead clearance: low-profile socket or offset ring spanner. Fastener on a pipe end: flare nut spanner or open-end. Round surface with no flats: pipe wrench (steel) or strap wrench (soft/polished).

4. Assess fastener condition. New, clean: any correctly-sized tool at the right torque level. Corroded or overtightened: ring spanner or socket only — maximum contact area. Partially rounded: use a socket or ring first; if still slipping, a damaged-bolt extractor socket. Completely rounded: nut splitter, vice-grips, or controlled cutting as a last resort.

5. Confirm precision requirements. Standard assembly: firm hand-tight-plus using ring end or socket. Manufacturer torque specification: torque wrench — non-negotiable for critical joints.

Common Spanner Mistakes to Avoid

Rounding fasteners with an open-end under high torque. Two-point contact concentrates force and rounds corners. Use a ring or socket for break-out and final torque. Switch to open-end only for run-down once the fastener is moving freely.

Using a shifter in the wrong direction. Force toward the moveable jaw causes it to spread and slip. Check the direction arrow before applying force.

Using a close-but-wrong size. 14mm open-end on a 9/16" bolt (14.3mm AF) appears to seat. Under torque, the 0.3mm difference rounds the corners. Measure with a calliper when uncertain.

Pushing instead of pulling. Where possible, pull a spanner toward the body. If the tool slips while pushing, knuckles impact the nearest sharp metal surface. Pulling provides more control and reduces injury risk.

Cheater bars on standard spanners. Extending a spanner handle with a pipe to gain more leverage is dangerous — the tool is not rated for the torque achievable. If more torque is needed, use a tool rated for the load: longer handle, breaker bar, or impact wrench.

Using a torque wrench as a breaker bar. Break-out force damages the internal spring mechanism and invalidates calibration permanently. Keep a dedicated breaker bar for break-out. The torque wrench enters the sequence only after the fastener is already moving.

Chrome sockets on impact tools. This is a safety requirement, not a preference. Chrome sockets can shatter under impact loads. Use black impact sockets with rattle guns exclusively.

Spanner Safety — Australian Standards

In Australian workplaces, hand tool use falls under general duty obligations in the Work Health and Safety Act 2011 and corresponding state legislation. The relevant manufacturing and quality standard for manually-operated spanners is AS/NZS 1700 — Hand Tools: Spanners and Wrenches, which covers dimensional, material, and marking requirements for tools sold in Australia and New Zealand.

Pre-use inspection: Check open-end jaw faces for rounding or spreading. Inspect ring internal profiles for wear (oval profile loses engagement). Look for cracks at the jaw root and ring-to-handle junction. Check adjustable spanner worm gear for grit or corrosion. Remove any damaged tool from service immediately.

Storage and maintenance: Chrome-vanadium spanners resist corrosion well but benefit from a light oil wipe after wet or marine environment use. Store in roll pouches, shadow boards, or foam-lined drawers — loose storage causes nicks and burrs on jaw faces. In scaffolding and elevated work, tool tethering is required under WHS regulations.

Frequently Asked Questions

What is the difference between a spanner and a wrench?

In Australian and British usage, the tool is called a spanner. In American usage, the same tool is called a wrench. They refer to the same thing — the names differ by region. In Australia, spanner is the correct trade term. Some specific tools retain "wrench" in their name — torque wrench, pipe wrench, and impact wrench are all standard Australian terminology. In casual conversation "wrench" is understood, but in trade settings "spanner" is correct.

What is the most versatile spanner for general trade work in Australia?

The combination spanner is the standard workhorse for Australian trade work. It combines an open-end jaw for fast run-down with a ring end for high-torque tightening on the same tool at the same size. A quality metric combination spanner set from 6mm to 24mm covers the majority of fasteners encountered in automotive, construction, and industrial maintenance. This is the correct starting point for any trade toolkit.

What does shifter mean in Australian trade terminology?

Shifter is the Australian colloquial term for an adjustable spanner — one with a fixed jaw and a moveable jaw adjusted via a worm gear to fit different fastener sizes. It is not a generic term for all spanners. Common sizes are 150mm, 200mm, 250mm, and 300mm, where the number is the overall tool length, not the jaw opening capacity.

How do I read the size marked on a spanner?

For open-end, ring, and combination spanners, the stamped number such as 17 is the AF (Across Flats) measurement in millimetres — the jaw width corresponding to the flat-to-flat dimension of the hex fastener head. A 17mm spanner fits a 17mm AF fastener, which is a standard M10 bolt. For adjustable spanners the number is the overall tool length. For Allen keys the number is the across-flats width of the hex key shank itself.

What is the difference between an open-end and a ring spanner?

An open-end spanner grips two opposite flats of a hex fastener using a U-shaped jaw. It is fast to position but contacts only two faces, making it prone to slipping and rounding the fastener under high torque. A ring spanner has a fully enclosed circular head engaging all six faces simultaneously, providing maximum grip and torque capacity. The ring is the correct choice for high torque or corroded fasteners. The open-end is correct for run-down speed and access in spaces where a ring cannot fit. Combination spanners carry both.

Can I use an adjustable spanner instead of a fixed spanner?

Yes, but it should not be the preferred choice. A shifter is most useful when the correct fixed spanner is unavailable, for non-standard fastener sizes, or for large plumbing fittings. The moveable jaw introduces flex that increases the risk of slipping and rounding the fastener, particularly under high torque. Load must always be applied toward the fixed jaw — not the moveable jaw. Whenever the correct fixed spanner is available, use it.

What spanner fits an M10 bolt?

An M10 bolt has a standard AF of 17mm under ISO 4014. A 17mm spanner or socket is the correct tool. The approximate rule for standard metric fasteners is AF equals bolt diameter multiplied by 1.7, giving 17mm for M10. When uncertain, measure the AF directly with a vernier calliper — some fastener types and grades use non-standard AF dimensions.

Why do most ring spanners have 12 points rather than 6?

A 12-point (bi-hexagonal) ring can be repositioned every 15 degrees of swing, compared to 30 degrees for a 6-point ring. In confined spaces with a limited swing arc, this halves the repositioning lifts needed per full fastener rotation. Six-point rings distribute force over more of each fastener face and are preferred for very high torque or damaged fasteners. In practice, 12-point is the standard for general use and 6-point is specified for maximum-torque situations.

What is a ratchet spanner and when is it the right tool?

A ratchet spanner has a ratchet mechanism in the ring end that drives the fastener in one direction and free-spins on the return stroke, eliminating the need to reposition the tool between strokes. It is correct in confined spaces where a socket ratchet handle is too bulky but repeated short-stroke tightening is needed. It is not the right tool for initial break-out on a seized fastener — the mechanism reduces peak torque. Use a conventional ring for break-out, then switch to the ratchet spanner for run-down.

How do I choose between 1/4 inch, 3/8 inch, and 1/2 inch drive socket sets?

Drive size determines torque capacity and ratchet head size. A 1/4 inch drive suits M4 to M8 fasteners and light precision work. A 3/8 inch drive is the most versatile and the recommended starting point, covering M6 to M16 and handling 80 to 120 Nm comfortably. A 1/2 inch drive is needed for M12 to M24 fasteners, wheel nuts, and heavy industrial work, handling 200 to 600 Nm manually. Most workshops carry all three, with the 3/8 inch set doing the majority of everyday work.

What is a flare nut spanner and when must I use one?

A flare nut spanner is a ring spanner with a slot cut in one side, allowing it to slide sideways over a pipe and engage the fitting nut at the tube end. It provides near-full ring engagement on the nut — far superior to an open-end spanner. It must be used on brake, fuel, hydraulic, and air conditioning line fittings where a full ring cannot thread over the tube. These fitting nuts are made from soft materials and round extremely easily with an open-end spanner. A rounded brake line fitting requires cutting the line and fitting a new end.

What type of spanner is correct for scaffolding work in Australia?

A scaffold spanner, also called a podger spanner, is the correct tool. It combines a fixed spanner head — typically 21mm for the Kwikstage and Ringlock coupler nuts used in the dominant Australian scaffolding systems — with a tapered alignment spike (podger) on the opposite end. The podger aligns bolt holes before the bolt is inserted; the spanner end tightens the coupler nut. A standard 21mm combination spanner does not include the alignment spike and is not a substitute.