Combination Squares

Combination squares are the most versatile single layout and measurement tool in any Australian workshop. A combination square pairs a graduated steel rule (typically 150mm or 300mm) with sliding heads that lock anywhere along the rule with a knurled thumbscrew. One tool delivers four primary functions: 90° squareness check, 45° mitre marking, depth gauge, and — with the optional protractor and centre finder heads — any-angle setting and centre marking on round stock.

AIMS stocks combination squares from Dasqua (cast iron premium tier) and Maxigear (workshop default), in 150mm and 300mm sizes, as complete four-piece sets and individual replacement heads.

What is a combination square — the four components

A complete combination square set is a four-piece kit. Each component slides onto the same graduated rule and locks in any position:

• Square head — provides reference 90° and 45° faces for marking out, squareness checking, height transfer and step measurement. Includes a spirit level vial for levelling and a hardened scriber stored in the head for marking lines.
• Centre finder head (centre square) — V-block geometry locates the exact centre of a round bar, shaft or cylindrical workpiece. Critical for accurate centre punching before drilling concentric holes.
• Protractor head — graduated 0–180° (often with reverse scale) for setting and reading any angle. Used for mitre cuts, angled layout, dimensional checks against drawings.
• Graduated rule — 300mm (or 150mm) hardened tool steel or stainless steel, with metric and imperial graduations etched on both edges. Doubles as a steel rule when removed from the heads.

Combination square vs engineers square — which do you need?

An engineers square is a fixed 90° try square — single function, highest squareness accuracy (DIN 875 Grades 00, 0, 1, 2), and the reference tool against which other squares are checked. A combination square is variable and multi-function: 90°, 45°, any angle (with the protractor head), centre finding (with the centre head), depth gauge and rule. The trade-off is squareness accuracy — a precision engineers square holds tighter tolerance than the locked head of a combination square.

Use an engineers square when DIN 875 Grade 0 or Grade 1 squareness reference is required (inspection, setup work, milling vice alignment). Use a combination square for general layout, marking out, field work, mitre setting, centre finding and any-angle work. Most workshops want both.

For the full breakdown — DIN 875 accuracy grades, reversal method testing, sizes by trade, and selection by application — see the Engineers Square, Combination Square & Workshop Steel Rule Guide.

300mm vs 150mm combination squares

300mm (12") combination squares are the workshop default. They handle the full range of layout work on plate, bar and fabricated components, and the longer rule gives accurate angle reading with the protractor head. This is the size to buy first.

150mm (6") combination squares are the bench, toolbox and tight-space tool. Faster to handle for small component work, fits in a tradie's apron pocket, and lighter in the bag. Most fitters carry both sizes.

Cast iron heads vs zinc alloy — why it matters

The head material is the single biggest indicator of long-term accuracy and feel. Cast iron heads (premium tier — Dasqua, Starrett, Moore & Wright) hold their reference faces square over decades of workshop use, give the weighty solid feel that helps with consistent marking, and resist impact damage. Zinc alloy or aluminium heads (workshop tier — Maxigear, generic imports) are lighter and lower cost, fine for general marking out and field use, but the reference faces wear faster under daily fitting work.

The Dasqua 300mm Cast Iron Combination Set is the premium choice stocked at AIMS — full four-piece kit with replaceable individual components if a head is damaged.

Brands stocked at AIMS

Dasqua — the premium tier. Cast iron combination set with replaceable square head, centre finder head, protractor head and 300mm graduated rule. Each component sold separately so a worn head can be replaced without buying the complete set.

Maxigear — the AU industrial workshop default. Blade-only and complete combination square sets in 150mm and 300mm, plus the standalone Maxigear Centering Square for dedicated round-bar centre marking.

Other brands — Starrett, Mitutoyo and Moore & Wright premium combination squares are not regularly stocked but can be sourced on request through the supplier network. Bunnings consumer-tier combination squares are out of scope — we supply trade and industrial only.

Combination squares in the broader precision range

Combination squares sit alongside dedicated engineers squares, steel rules, straight edges, builder triangles and specialty rules. Browse the complete precision rules & squares collection for the full 36-product range, or go direct to engineers squares for dedicated 90° verification tools.

Buying guide — which combination square should you buy?

• Daily professional fitting and fabrication work — Dasqua 300mm Cast Iron Combination Set (full four-piece kit). The protractor and centre finder heads earn their keep on layout and centre-punch work; the cast iron heads last a working lifetime.
• General workshop and toolbox — Maxigear 300mm combination square. The workshop default at a sharper price point. Pair with a Maxigear engineers square for dedicated squareness verification.
• Bench work and tight spaces — Maxigear 150mm combination square. Toolbox-friendly size for small components, marking out, bench fitting.
• Lathe and centre-punch work — Maxigear Centering Square (standalone). Faster than fitting the centre finder head when round-bar centre marking is the primary task.

Care and accuracy maintenance

Combination squares are precision tools. Keep them away from impact damage (dropping kills accuracy), wipe down after use to prevent rust on the rule and heads, and store flat or hanging — never in a tool drawer where heavier tools land on them. Test squareness periodically with the reversal method (scribe a line against the head, flip the head, scribe a second line — any divergence is twice the error). For verification against a known reference, check against a calibrated engineers square.

Need help choosing?

Call AIMS Industrial on (02) 9773 0122, email sales@aimsindustrial.com.au, or use the contact form. We supply combination squares to Australian workshops, fabricators, fitting shops, machine shops and maintenance teams nationwide.