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Reverse engineering a product

Design Project 2 weeks Medium build

Take a product apart down to its base components, knoll every part on a sheet, photograph it, and document what each part is, what it is made of, how it was made, and what it does.

The parts of a disassembled cordless drill laid out at right angles on a white sheet, grouped by type, photographed from directly above.

Overview

Everything manufactured was designed by someone who made decisions: what to mould, what to stamp, where the screws go, how the case snaps together, how the thing is meant to be assembled in a factory and never taken apart again. Reverse engineering is reading those decisions back out of the object.

You take a product apart until nothing can be separated further without breaking it. Every screw, spring, gear, board and moulding gets laid out on a sheet, at right angles, grouped, and photographed from above. That is knolling, and the discipline of it is the point: you cannot organise parts you have not looked at. Then you document each part and explain how the subsystems work together.

Good candidates: a cordless drill, an electric toothbrush, a computer mouse, a hard drive, an inkjet printer, a toaster, a mechanical toy, a bike derailleur, a stapler. Bring something you are curious about. It does not need to work.

Skills needed

  • Safe disassemblyresource comingBatteries out first, no mains power supplies, no CRTs, no sealed gas. Bagging and labelling fasteners as you go.
  • Knollingresource comingEvery part at right angles, grouped by function or type, with space between groups, shot from directly above.
  • Identifying materials and processesresource comingInjection moulding, die casting, stamping, machining, extrusion. Reading part lines, ejector marks and draft angles.
  • Measuring with calipersresource comingOutside, inside and depth measurements, and recording them in a table.
  • Modelling a part in FusionOptional. Recreate one part from your measurements.

Assessment

Criterion Developing Proficient Exemplary
Disassembly Stopped at sub-assemblies; parts broken Fully separated to base components, fasteners bagged Separated cleanly and could be reassembled from your documentation
Knolling photo Parts scattered or overlapping Right angles, grouped, evenly spaced, shot from above Grouping tells the story of the product; the photo could be published
Inventory Parts listed Every part with material, process and function Processes identified from physical evidence and explained
Function description Names what it does Explains each subsystem and how they connect Explains why it was designed that way and what it cost
Poster Elements present Clear, well organised, readable from a metre away Someone who has never seen the product understands it

Deliverables

  • The knolling photograph, shot from above with even light, parts labelled
  • A parts inventory table (part, quantity, material, manufacturing process, function)
  • A written description of how the product works, subsystem by subsystem
  • A one-page teardown poster combining the photo, the table and the description
  • Optional, a Fusion model of one part with a photo of the original beside it

Materials

  • One product per student or pair, dead or donated (see the safety list)
  • Screwdriver set including Torx and security bits, spudger, pliers, hex keys
  • Zip bags and a marker for fasteners
  • A white or grey sheet, tape, a tripod or a phone mount for the overhead photo
  • Calipers

Steps

Week 1: Take it apart

  1. Photograph the product whole, from several sides. Note anything on the labels: model, ratings, where it was made.
  2. Batteries out. Then find the fasteners. Some hide under labels and rubber feet. Bag and label the screws from each stage so you know what came from where.
  3. Work from the outside in. Snap-fit cases open with a spudger at the seam, not a screwdriver. If something will not come apart, look for a screw you missed before you force it.
  4. As each sub-assembly comes out, keep its parts together until you have understood it. Then separate it fully.
  5. Keep a running list: what you removed, in what order, and anything that surprised you.

Week 2: Organise, document, present

  1. Lay the sheet out. Sort parts into groups: structure, mechanism, electronics, fasteners, seals and springs. Within groups, sort by size.
  2. Knoll: every part parallel or perpendicular to the sheet edges, consistent gaps, nothing touching. Shoot from directly above in even light. Take several; pick the best.
  3. Fill in the inventory table. For material and process, look at the evidence: parting lines and ejector pin marks mean injection moulding; a rough textured side and smooth machined faces mean die casting; sheared edges mean stamping.
  4. Measure five parts with calipers and add the dimensions to the table.
  5. Write the function description, one paragraph per subsystem: what it does, what it connects to, what would fail if it were missing.
  6. Build the poster. Photo large, table and description around it. Label parts on the photo with numbers that match the table.
  7. Optional: model one part in Fusion from your measurements and put a render beside the photo.

Stretch options

  • Reassemble the product from your own documentation and see if it works.
  • Estimate the part count and the number of assembly operations, and guess at the factory cost.
  • Redesign one part so the product would be easier to repair.