Workshop Practice, Tools, and Equipment
What this domain tests
This domain tests safe selection, use and care of hand tools, power tools and measuring equipment. Level 3 candidates are expected to know when a tool is unsuitable, how to check calibration, and how to keep a bay organised so that the next job is not contaminated or delayed.
Core rules
- Use the tool for its designed purpose. A torque wrench is a setting instrument, not a breaker bar; impact sockets are used on impact guns, never chrome hand sockets.
- Check precision tools against their zero before use. A micrometer is checked with its ratchet on the anvil; a vernier caliper is closed and read for zero error.
- Store torque wrenches at the lowest scale setting, not at zero load or at the last setting, and recalibrate at the interval set by the workshop.
- Measure at room temperature where possible; a hot engine part will change the reading.
- Keep benches clear, return tools to shadow boards, and separate measuring tools from impact tools.
- Use jack stands and wheel chocks; do not rely on a trolley jack. Keep compressed-air nozzles below 2 bar for cleaning and never point them at skin.
Worked example
A vernier caliper with a least count of 0.02 mm is closed and the zero line of the vernier sits two divisions to the right of the main-scale zero, so the zero error is +0.04 mm. Measuring a piston skirt gives main scale 12 mm and vernier line 34 coincides: 12 + (34 × 0.02) = 12.68 mm. Because the zero error is positive, subtract it: true reading 12.68 − 0.04 = 12.64 mm. The reasoning is that the instrument already reads 0.04 mm too high before the part is measured.
Traps
Reading the wrong vernier scale, or forgetting to subtract a positive zero error, is common. Do not use a torque wrench that has been dropped or stored under load without checking it. Do not measure a brake disc with a caliper when a micrometer is specified. A chrome socket on an impact wrench can crack and throw fragments.