Start with the Standards You Will Be Asked About

Most CAD technician interviews in the UK involve a short technical conversation before anything else, and drawing standards are the usual opening subject. You do not need to recite clauses, but you should be able to talk comfortably about how a drawing is put together and why. In the UK, BS 8888 is the spine of technical product documentation. Be ready to explain the difference between first and third angle projection, and to note that first angle is the traditional default here, with third angle acceptable where the projection symbol clearly indicates it. Know your sheet sizes from BS EN ISO 5457, the standard scales, and the conventions for line types, section hatching and dimensioning. Be able to say why you would not dimension to a hidden line, and why over-dimensioning causes problems on the shop floor. Geometrical tolerancing is worth revising too. Datums, feature control frames, maximum material condition and surface texture symbols under ISO 1101 and ISO 1302 come up regularly for engineering roles. For architectural and BIM roles, expect questions about layer and naming conventions and about information management under ISO 19650. Practise saying this out loud. Reading it is easy; explaining it in your own words under mild pressure is the skill being tested.

Build a Small Portfolio That Shows Judgement

Take three to five drawings, not sixty. A panel learns more from a handful of well-chosen sheets than from a crowded folder. A strong set usually includes a general arrangement with sections and details, a manufacturing detail drawing with tolerances and surface finish, an assembly with a bill of materials and an exploded view, and a model that shows clean, fully defined sketches. Architectural candidates might show a plan, elevation and section set at 1:50 with a 1:5 detail. Add a short caption to each one explaining a decision: why that datum, why that tolerance, why the detail was called out at that scale. Only include your own work, and be honest about which parts you produced and which were collaborative. Interviewers notice honesty far more than they notice a missing sheet.

Rehearse a Timed Modelling Test

A common format is a 45 to 60 minute exercise: you are given a drawing, a photograph or a physical part, and asked to model it and produce a drawing. Practise this at home with a timer rather than a comfortable afternoon. Pick something with a few genuine features — a bracket with a slot, counterbored holes, a fillet and a chamfer is ideal. Then work through it properly:

• Set up your template first: millimetres, correct title block, materials and drawing sheet format.
• Model from fully constrained sketches, and name features sensibly so the tree reads clearly.
• Generate views from the model rather than tracing them, so associativity holds.
• Add a section view, a detail view and an isometric view.
• Dimension properly, including centre marks and hole callouts, then fill in the title block.

Aim to have a sound model and a readable drawing inside 40 minutes, leaving time to talk. If you spot an error halfway through, say so and correct it. Calm self-checking is exactly what the exercise is designed to reveal.

Have Teamwork and Communication Examples Ready

Technical ability gets you shortlisted; how you work with others gets you hired. Prepare three short examples using a situation, action and result structure. One might cover a coordination issue where your model clashed with another discipline's services. Another could describe a drawing returned with mark-ups and how you resolved each comment. A third might cover a late design change and how you managed the revision. Be specific about the mechanics. Mention revision clouds, transmittals, check-in and check-out on a document management system, naming conventions, model reviews and comment sheets. Say how you take feedback and how you raise a concern politely when you think a drawing is wrong.

Prepare for "Why Did You Do It That Way?"

Interviewers are often less interested in how fast you model than in whether you can justify your choices. Rehearse answers to questions such as:

• Why did you choose that datum, and what does it reflect in manufacture or assembly?
• Why that tolerance on a clearance hole, and what happens if it is too tight?
• Why model this as a single body rather than a weldment or an assembly?
• How would you revise this drawing for a second issue, and what would you change in the revision table?
• What would you do if the model and the drawing disagreed?

Also prepare for gaps. If you have not used a particular platform, say so and explain that the underlying concepts of constraints, feature trees and drawings transfer between them. Confidence comes from knowing your tools and being able to explain your reasoning, not from claiming familiarity you do not have.

On the Day Itself

Take a printed portfolio, a notebook, a pen and a copy of your CV. If the test is remote, check your screen sharing beforehand and have the drawing either printed or on a second screen so you are not flicking between windows. Narrate your thinking as you work, but describe decisions rather than every click. Ask practical questions about their templates, checking process, file management and who signs off drawings. It shows you are already thinking about how you would fit into their team. Arrive early, keep your explanations plain, and remember that a technician who can talk clearly about a drawing is worth more than one who simply draws quickly.