Workshop Technology and Manufacturing
Core concepts
Understand measuring instruments: vernier callipers, micrometers, dial gauges, and feeler gauges, including least count. Know hand tools and their correct use, marking out, sawing, filing, drilling, tapping, reaming, and grinding. Study machine tools: lathe, milling machine, drilling machine, and shaping machine, including operations and safety. Learn welding processes, brazing, soldering, and their applications. Understand fits and tolerances, limits, surface finish, and the difference between interchangeable manufacture and fitting. Know the principles of casting, forging, and rolling.
Common traps
Questions often confuse least count with accuracy, or clearance fit with interference fit. Watch for tapping drill size being confused with the nominal bolt size. Welding defects such as porosity, slag inclusion, and lack of fusion are frequently mixed up. Never assume a vernier calliper reads to 0.01 mm unless the scale confirms it.
Worked example
For an M10 × 1.5 thread, the tapping drill diameter ≈ nominal diameter − pitch = 10 − 1.5 = 8.5 mm. Rule of thumb: tapping drill size = major diameter − pitch for metric coarse threads.
Study approach
Practise reading vernier and micrometer scales. Link fits and tolerances to assembly requirements, and always state the safety precautions for each machine tool.