The Ultimate Design & Drafting Checklist
In the world of engineering and design, the difference between a successful product launch and a manufacturing nightmare often comes down to the quality of the drawings. Whether you are a student at TAFE, a university engineering undergraduate, or a junior draftsperson in an Aussie workshop, understanding the standards of technical drawing is non-negotiable.
In Australia, we generally follow standards like AS 1100, which dictate that clarity and precision are paramount. "She’ll be right" is a great attitude for a BBQ, but a terrible one for engineering tolerances! To help you avoid costly rework, we’ve compiled a comprehensive checklist to review your designs before they hit the production floor.
1. The Golden Rules of Drafting
Before diving into specific parts or assemblies, you need to ensure your general drafting housekeeping is in order. These are the foundational elements that ensure your drawing is readable by any machinist or toolmaker from Perth to Parramatta.
Third Angle Projection: Ensure all drawings are in 3rd angle projection. This is the standard in Australia (and the US), whereas Europe often uses 1st angle. Getting this mixed up is a recipe for disaster.
Units: Unless specified otherwise, all units are assumed to be in millimetres (mm).
Scale: Check that the Correct Sheet Scale is displayed clearly in the title block.
Template Completeness: Ensure the drawing template is fully populated.
Title: Include product descriptions and project numbers.
Dates: Date drawn and date checked.
Authors: Latest updated details for "Drawn by" and "Designed by".
Material: Specify the correct material, including the specific "grade" or "alloy" (e.g., not just "Aluminium," but "Aluminium 6061-T6").
2. Part Drawing Checklist
When detailing individual components, the devil is in the detail. Use this checklist to ensure the part can be manufactured without a phone call to the design office.
Manufacturing & Moulding Details
Draft Angles: If you are designing for injection moulding or casting, have you checked the draft angles?
Tooling Info: Specify the location for the cavity number and the date stamp (if applicable).
Logos: Ensure the company logo appears on at least one visible part of the assembly. You must state if the detail is to be raised or sunken.
Dimensioning & Tolerances
Critical Dimensions: Are all dimensions specified by the engineer shown?
Holes: Are tapped holes clearly shown, including tapping detail (e.g., M6 x 1.0) and tapping depth?
Geometric Tolerances: Specify these on sheet metal and machined parts where fit and function are critical.
Revision Control
Revision Block: This is vital for traceability. State past and present information (e.g., "Dimension A was 10mm, now 12mm").
3. Assembly Drawing Checklist
The assembly drawing tells the story of how the parts fit together. It is the instruction manual for the production team.
BOM & Balloons: Check the Bill of Materials (BOM). Do the item numbers in the BOM match the Balloon Annotations on the drawing view?
Consumables:
Grease: Specify the grease grade, quantity, and surface application required.
Adhesives: Specify Loctite (or equivalent) grade, quantity, and location.
Kitting: If the product is supplied in a pack, include kitting information in the BOM.
Torque Settings: If a specific tightness is required, the Newton Metre (Nm) or torque requirement must be explicitly shown.
Packaging: Have packaging details been specified?
4. Dimensioning Do's and Don'ts
Clarity is king. A cluttered drawing leads to mistakes. Follow these rules to keep your drawings clean and professional.
| Do This | Avoid This |
|---|---|
| Datums: Create dimensions from a stable datum point (like a bearing hole, dowel hole, or centre line) rather than a curved surface. | Crossing Lines: Dimension lines should never cross other dimension lines. Avoid crossing extension lines where possible. |
| Spacing: Dimension lines should be spaced uniformly (approx. 10mm from the object, 6mm apart). | Duplication: Never give the same information in two different ways. It creates conflict if one is changed and the other isn't. |
| Views: Place dimensions in the view where the feature is shown in its true shape. | Hidden Lines: Avoid dimensioning to hidden lines. Use a section view instead. |
| Orientation: Notes should always be lettered horizontally. | Long Extensions: Avoid long extension lines; keep dimensions close to the feature. |
Pro Tip on Chains: Avoid a complete chain of detail dimensions; it is better to omit one to prevent tolerance accumulation. Alternatively, add (REF) or brackets to one dimension to indicate it is a reference dimension, allowing the tolerances to fall on the omitted dimension.
5. Final Polish: The "Sanity Check"
Before you hit print or export to PDF, run through these final tips to ensure your drawing is professional:
View Count: Keep the number of projections (views) to a minimum. Three views (Top, Front, Side) are normal; six views are extremely rare.
Clarity: No hidden detail unless absolutely necessary to explain the part.
Centring: Dimension figures should be approximately centred between the arrowheads.
Layout: Spreading out views on the sheet is cleaner than squeezing them in.
Annotations: Add centre lines and cross-hairs to all holes.
The Final Check: Make sure drawings are checked. A fresh pair of eyes will spot errors you have become blind to.
Next Step for You
Would you like me to create a printable one-page PDF summary of this checklist that you can pin up in your workshop or classroom?