MATSEC SEC Design and Technology common mistakes
MATSEC SEC Design and Technology · Understand the traps and how to avoid them.
Writing a design brief that names the product and its materials ("a pine bedside table with a drawer") instead of stating the problem and the user need, so the specification that follows has nothing to be judged against.
Candidates are asked to 'design a table' and treat the brief as a title for the project; they have not been taught to separate problem, brief and specification, and they want to start drawing as quickly as possible.
What to do instead
Write the brief as a problem statement with a user and a context: 'A student in a small shared bedroom needs somewhere to put a lamp, phone and books within reach of the bed, with floor space limited.' Then derive each specification point from a sentence in the brief and label it measurable (e.g. 'footprint no more than 400 x 400 mm').
Producing a specification of vague adjectives (strong, attractive, cheap, safe) with no numbers, then never referring to it again during evaluation.
Adjectives feel like requirements and are quick to write; candidates do not realise a specification is a measuring instrument and cannot be checked against 'attractive'.
What to do instead
Force every point into a testable form: a value, a range, or a yes/no check with the method named. 'Must support a 15 kg load without visible deflection, tested by loading with weights for 24 hours'; 'must cost under EUR 12 in materials, checked against a cutting list and price list'. Number each point so the evaluation can cite 'Spec 4: met/not met'.
Confusing hardness, toughness, strength and stiffness, and choosing materials on a single property - for example specifying glass for a school trophy base because it is 'strong and looks good', or mild steel for a handle that must not conduct heat.
Everyday language uses 'strong' for all four ideas, and candidates learn property tables as lists to memorise rather than as reasons for selection.
What to do instead
Practise a four-question drill for any material choice: will it be scratched or worn (hardness), will it be hit or bent without warning (toughness), will it carry the load (strength), will it deflect too far (stiffness)? Then add the non-mechanical constraints (cost, mass, thermal and electrical conductivity, corrosion, recyclability) and state the trade-off in one sentence.
Naming a tool without stating the process, the material it suits, or the safety precaution - e.g. answering 'use a drill' for making a 10 mm hole through acrylic, with no mention of bit type, support, speed or clamping.
Tool questions are revised as a list of names and pictures; candidates have often not handled the tool and cannot describe the sequence.
What to do instead
Answer tool questions in a fixed four-part pattern: operation (what is being done), tool and consumable (e.g. twist drill for wood/metal, lip-and-spur bit for acrylic), workholding (vice, G-clamp, backing board to prevent breakout), and control measure (speed, coolant, PPE, two-handed feed). Write the pattern out for the ten most common workshop operations before the exam.
Describing a manufacturing process in the wrong order or skipping the step that makes it work - for example vacuum forming without mentioning that the mould needs draft angles and air holes, or injection moulding without a sprue, runner and gate, or a jig being described as a tool that shapes the part rather than holds it.
Processes are learned from short videos that show the dramatic middle step; the preparation and release steps that determine success are invisible.
What to do instead
For each process, memorise a skeleton of five stages - prepare (pattern, mould, draft, release agent), set up (clamping, alignment, temperature), form, cool/cure, finish (trim, file, de-gate) - and be able to add one quality-control point ('cooling too fast causes warping; keep the mould warm').
Drawing third-angle orthographic views with hidden detail shown as solid lines, missing centre lines, or with the plan projected on the wrong side of the front view; and dimensioning with no units, duplicated dimensions, or dimensions on the drawing rather than between extension lines.
Candidates copy the look of a drawing without understanding projection: which view sits where, and what the line types mean.
What to do instead
Learn the rule 'the plan sits under the front view in third angle, above it in first angle' and always state which convention is used. Before submitting, run a line-type audit: visible outlines thick, hidden detail dashed, centre lines chain-dotted, construction lines thin and erased. Dimension each feature once, in millimetres, between extension lines with arrowheads touching them.
Analysing a lever or linkage by counting 'effort' and 'load' but ignoring distances, so a class 2 lever or a bell-crank is described as giving no advantage, or a four-bar linkage is said to 'move in a circle' with no mention of the fixed pivots and the coupler path.
The moment equation is memorised as a formula to plug numbers into rather than as a statement about distances from a pivot, and linkages are drawn as pictures rather than as constrained systems.
What to do instead
Always mark the fulcrum, then measure or state both distances before calculating: moment = force x perpendicular distance from pivot. For linkages, sketch and label the ground link, crank, coupler and rocker, and trace the path of one point through a full rotation to show what the mechanism actually produces.
Drawing a circuit with no return path to the supply, omitting the resistor in series with an LED, or treating current as something that is 'used up' by the first component in a series loop.
Circuit diagrams are copied as layouts of components rather than as closed loops, and the water analogy is misapplied so that current appears to be consumed.
What to do instead
Draw every circuit as a loop starting and ending at the supply terminals before adding components, and check with the two rules: current is the same at every point in a series loop, while voltage divides across components. Size an LED resistor explicitly from R = (Vsupply - Vled)/I, and state the values on the diagram.
Treating sustainability as a single sentence about recycling at the end of the evaluation, with no consideration of material source, energy in manufacture, product lifetime, disassembly or end-of-life route.
Sustainability is taught as a topic to mention rather than as a set of decisions made at each stage, and candidates lack a structure to apply it to their own product.
What to do instead
Use a life-cycle checklist against your own design and write one line for each: material source (recycled content, renewable), manufacturing energy and waste, expected lifetime and repairability (are fasteners removable?), number of materials and how they separate, and end-of-life route. Then name one change you made because of it and the trade-off it cost.
Ignoring the user's body and context in ergonomic decisions: giving a handle a diameter and length with no reference to grip, sizing a chair without seat height or popliteal clearance, or placing controls where the hand cannot reach without a stated reach envelope.
Ergonomics is reduced to 'make it comfortable', and candidates do not know that anthropometric data are ranges (5th to 95th percentile) rather than an average person.
What to do instead
Quote a number and a percentile for every ergonomic claim: grip diameter 25-40 mm for a power grip, seat height set so the 5th-percentile user's feet reach the floor, controls within the 5th-percentile reach envelope but clear of accidental contact. State which percentile you are designing for and why (adjustability covers the rest).