Engineering Drawing in Australia: A Practical Guide to Australian Standards and Best Practice

Engineering drawing is the formal language of engineering — the set of conventions, symbols, and projection methods that allow a design to be communicated from an engineer’s mind to a fabricator’s workshop without ambiguity. In Australia, engineering drawings must comply with the AS 1100 Technical Drawing series, which is the nationally adopted standard for engineering drawing practice across mechanical, structural, architectural, and civil disciplines.

This guide covers the fundamentals of engineering drawing for Australian engineers and drafters: the relevant Australian Standards, the key conventions and drawing types, how to apply GD&T correctly, and practical guidance on producing drawings that pass quality review and get built accurately first time.

Australian Standards for Engineering Drawing — AS 1100 Series

The AS 1100 series is the primary Australian Standard for technical drawing, published by Standards Australia. It aligns closely with ISO 128 (general principles of presentation) but includes Australian-specific provisions. The key parts most relevant to engineering drafters are:

• AS 1100.101 — General principles: Line types (continuous thick, continuous thin, dashed, chain), sheet sizes (A0–A4), title block requirements, scale notation, and fold marks. Every engineering drawing produced in Australia should comply with this standard.
• AS 1100.201 — Mechanical engineering drawing: Orthographic projection (third-angle projection is the Australian standard — not first-angle, which is used in Europe), section views, detail views, auxiliary views, and surface texture symbols (Ra values in micrometres).
• AS 1100.301 — Architectural drawing: Symbol conventions, north point, grid notation, room naming, and the relationship between architectural, structural, and services drawings.
• AS 1100.401 — Technical illustration: Isometric, oblique and perspective drawing conventions for assembly illustrations and maintenance manuals.
• AS 1100.501 — Structural engineering drawing: Reinforcement notation, weld symbols (aligned with AS/NZS 1554), structural steel section callouts using Australian section designations (UB, UC, RHS, SHS, CHS, EA, UA).

One critical point for Australian drafters: third-angle projection is the default in AS 1100.201, and Australian manufacturers expect it. If you’re working with international clients or suppliers using first-angle (European) projection, the projection symbol must be clearly shown on every sheet to avoid costly misinterpretation of which face is which view.

The Core Elements of a Good Engineering Drawing

Title Block

AS 1100.101 requires every engineering drawing to include a title block containing, at minimum: drawing title, drawing number, revision number and date, scale, sheet size, projection symbol (first or third angle), drafter name and date, checker/approver name, and the name or logo of the originating company or organisation. In practice, Australian drawing title blocks used by fabricators and contractors also include the client name, project name or number, and a revision history table.

A drawing without a complete title block will be rejected by most Australian fabricators and building certifiers. In ASTCAD’s experience, the most common title block deficiencies on drawings received from clients for conversion are missing revision letters and missing scale callouts on detail views.

Line Types and Line Weights

AS 1100.101 defines the line types used in Australian engineering drawings. The most important distinction for fabrication drawings is between the visible outline (continuous thick — typically 0.5–0.7mm at A1 scale) and the hidden detail line (dashed thin — 0.25mm). Consistent line weights are essential: a drawing where all lines are the same weight is harder to read and interpret, particularly on prints at reduced sizes.

In CAD, line weights are controlled by layer or by object properties. The standard ASTCAD layer convention for AutoCAD drafting uses: layer 0.5 (outlines), layer 0.25 (dimensions, hatching, hidden lines), layer 0.7 (section cut lines), and layer 0.18 (annotation, centrelines). CAD files sent to CNC machines for drilling or cutting must have clean, closed geometry on the correct layers — open polylines and duplicate entities are a common cause of CNC errors on fabrication drawings.

Dimensioning to AS 1100

Correct dimensioning practice under AS 1100.201 requires:

• Dimension lines clear of the drawing outline (minimum 10mm from the nearest visible edge for the first dimension line, 7mm between subsequent parallel dimension lines)
• Arrowhead style: filled arrowheads (preferred in AS 1100) or open arrowheads — consistent throughout the drawing set
• Decimal notation: millimetres (mm) is the standard unit for Australian mechanical and structural drawings. Do not mix mm and metres on the same drawing. Dimensions below 1mm use 0.x notation (e.g. 0.5, not .5)
• Angular dimensions: degrees and decimal degrees (not degrees-minutes-seconds in most mechanical applications)
• Overall dimensions: always include the overall length, width, and height of a fabricated part on the main orthographic view, even when intermediate dimensions are also given
• Reference dimensions (non-controlled) are shown in parentheses: (150)

Orthographic Projection — Third-Angle Practice

Australian engineering drawing practice uses third-angle orthographic projection (the view is placed on the side where you would look from). In a standard three-view drawing:

• Front view: centre-left position
• Top view (plan): directly above the front view
• Right side view (end elevation): directly to the right of the front view

This is the opposite of first-angle (European) projection, where the right side view appears to the left of the front view. Mixing projections in a drawing set — or failing to mark the projection symbol — is one of the most dangerous errors in engineering drawing, as it can result in parts being fabricated mirrored or in the wrong orientation.

Geometric Dimensioning and Tolerancing (GD&T) in Australia

GD&T (Geometric Dimensioning and Tolerancing) is a system for precisely communicating the allowable variation in a part’s form, fit, and function. In Australia, GD&T follows AS 1100.201 and ISO 1101 (geometrical tolerancing). The US system (ASME Y14.5) uses slightly different conventions and should not be mixed with ISO/AS practice without explicit notation on the drawing.

The most commonly used GD&T symbols in Australian manufacturing drawings are:

• Flatness (⏥): Controls how flat a surface is — used on machined mating faces, base plates, and seal surfaces
• Straightness (—): Controls how straight a line element is — applied to shafts, rods, and linear features
• Circularity/Roundness (○): Cross-sectional roundness — common on turned components
• Cylindricity (⌭): Combines roundness, straightness, and taper in a single control for critical bore and shaft fits
• Perpendicularity (⊥): Controls squareness between features — important for bolt patterns, bearing housings, and structural connections
• Parallelism (∥): Controls the parallelism of a surface or axis relative to a datum — used on machined slideways and bearing surfaces
• True position (⊕): Controls the location of a feature (typically a hole centre) relative to a datum reference frame — used on bolt hole patterns
• Runout (↗) and Total Runout: Controls how much a surface varies during one full rotation — critical for rotating shafts and seal journals

A common error in Australian fabrication drawings is applying GD&T without datums. Every GD&T feature control frame that references a datum must have corresponding datum feature symbols (A, B, C) on the drawing with the correct datum reference letters in the feature control frame. Undatum’d GD&T is unenforceable and will be ignored by most Australian fabricators’ quality inspectors.

Weld Symbols on Australian Engineering Drawings

Weld symbols on Australian structural and mechanical drawings follow AS 2812 (welding, brazing and cutting vocabulary) and AS 1100.501, with weld quality requirements referenced to AS/NZS 1554.1 (structural steel welding) or AS/NZS 1554.5 (high-strength steels).

The most important weld symbol elements for Australian fabrication drawings are:

• Fillet weld size: shown as a number (in mm) to the left of the fillet weld symbol — e.g. “6▲” means a 6mm fillet weld
• Weld all around: circle at the elbow of the reference line indicates welding on all sides
• Field weld: flag at the elbow indicates a site weld (not a shop weld)
• Inspection category: SP (structural purpose) or GP (general purpose) per AS/NZS 1554.1 — must be stated in the drawing general notes or on the weld symbol for structural drawings
• NDT requirements: ultrasonic testing (UT), magnetic particle (MT), or dye penetrant (PT) notations should be added to critical welds on pressure vessel or lifting equipment drawings

CAD Drawing Production — Practical Tips for Australian Drafters

AutoCAD Setup for Australian Standards

• Set drawing units to millimetres and limits to match the intended output sheet size (A1 = 841 × 594mm at 1:1 in model space)
• Use the DIMSTYLE manager to create an AS 1100-compliant dimension style: text height 3.5mm at A1, arrowheads 3.5mm, decimal separator as a full stop (not comma)
• Use named layer standards (ISO or company standard) — never draw everything on Layer 0
• Set the LTSCALE global linetype scale to match your plot scale — hidden lines that look correct on screen may plot as continuous lines if LTSCALE is wrong
• Use attributed title blocks on layout tabs, not model space title blocks, to allow correct plotting at the sheet scale

SolidWorks Drawings for Australian Manufacturing

• Set the document properties to third-angle projection (Tools → Options → Document Properties → Detailing → Projection type: Third angle)
• Use DIN standard tolerances (ISO 286) for fits and clearances, not the ANSI standard defaults
• Set dimension standard to ISO in the document properties — this gives ISO-compliant GD&T symbols
• Use the “Cosmetic thread” feature for threaded holes and the correct thread callout standard (metric ISO — e.g. M12 × 1.75 — rather than UNC/UNF)
• Always include a full BOM (Bill of Materials) with part numbers, descriptions, material, quantity, and weight for fabrication shop drawings

Common Errors in Engineering Drawings and How to Avoid Them

Based on ASTCAD’s experience reviewing and converting engineering drawings for Australian fabricators, the most frequently encountered errors are:

1. Missing or inconsistent material callouts. Every part on a fabrication drawing must have its material specified — grade and specification (e.g. “AS/NZS 3678 Grade 350” for structural steel plate, “AS/NZS 1734 Alloy 5083-H321” for marine aluminium). A material note that just says “steel” or “aluminium” will cause the fabricator to substitute the cheapest available option.
2. Incorrect projection symbol. Drawing sent with no projection symbol and the views arranged in first-angle convention — the part gets built mirrored. Always show the projection symbol.
3. Undimensioned holes. Holes shown on one view but not dimensioned in the view that shows their true shape. Always dimension a hole in the view where it appears as a circle.
4. Over-constrained or conflicting dimensions. Reference dimensions without parentheses create ambiguity about which dimension controls the part. Close the dimension chain and use reference dimensions for overall dimensions that are the sum of toleranced intermediates.
5. Missing revision cloud on updated drawings. When a drawing is revised, the changed area should be clouded and the revision noted in the revision table. Drawings re-issued without revision marking cause confusion at the fabrication shop about what has changed.
6. Weld symbols without inspection category. Structural drawings should specify SP or GP weld category per AS/NZS 1554.1. Omitting this pushes the decision to the fabricator, who will default to GP.

Frequently Asked Questions

What is the Australian standard for engineering drawing?

The primary Australian standard for engineering drawing is the AS 1100 Technical Drawing series, published by Standards Australia. AS 1100.101 covers general principles (line types, sheet sizes, title blocks), AS 1100.201 covers mechanical engineering drawing (projection, dimensioning, GD&T, surface texture), and AS 1100.501 covers structural engineering drawing (reinforcement notation, weld symbols, structural section callouts). Australian engineering drawings also reference AS/NZS 1554 for weld symbols and ISO 1101 for geometric tolerancing symbols.

Does Australia use first-angle or third-angle projection?

Australia uses third-angle projection as the default, consistent with the US and Canada, and as specified in AS 1100.201. Europe (and much of Asia) uses first-angle projection. The projection type must always be shown via the standard projection symbol on engineering drawings, especially when drawings may be used internationally or when working with European suppliers and fabricators.

How many types of engineering drawings are there?

In Australian engineering practice, the main drawing types used in mechanical and structural work are: detail drawings (single parts with full dimensioning), assembly drawings (showing how parts fit together, with BOM), general arrangement drawings (showing overall layout and relationship of major components), fabrication drawings (optimised for shop-floor use — weld symbols, material callouts, CNC geometry), P&IDs (piping and instrumentation diagrams for process plants), wiring diagrams and single-line electrical diagrams, structural GA and shop drawings, and as-built drawings (produced after construction to record actual installed conditions). Each type follows specific conventions under the AS 1100 series.

What CAD software is used for engineering drawing in Australia?

The most widely used CAD software for engineering drawing in Australia is AutoCAD (2D and 3D, used across all disciplines), SolidWorks (mechanical design and fabrication drawings), Autodesk Inventor (mechanical, used heavily in mining and oil & gas), Revit (architectural and structural BIM), MicroStation (commonly specified by Pilbara iron ore operators and state road authorities), and Tekla Structures (structural steel detailing). The software choice is often client-driven — major infrastructure owners in Australia typically specify MicroStation or a particular Revit standard; manufacturing clients typically use SolidWorks or Inventor.

Related guides: CAD Drawing — A Complete Guide for Australian Engineers and Drafters | PDF to CAD Conversion Step-by-Step Guide | Fabrication Shop Drawing Checklist