Tools and Maintenance Practices
Tools and Maintenance Practices
This domain tests selection, inspection, correct use, and care of hand tools, measuring instruments, and power tools. It also covers planned maintenance, fasteners, lubrication, and calibration awareness.
Core rules
- Use the right size: a spanner must fit the nut flats fully; never use an adjustable wrench as a hammer or a screwdriver as a chisel.
- Inspect before use: cracked handles, frayed cords, missing guards, and worn tips are rejection criteria.
- A vernier calliper's least count is usually 0.02 mm; a micrometer's is usually 0.01 mm. Check zero error before measuring.
- Follow torque values; over-tightening stretches threads and can crack castings. Use lubricant in the specified quantity.
- Keep maintenance records: date, machine, fault, action, spare used, and next due date.
Worked example
A vernier calliper has a main-scale reading of 12 mm and the 7th vernier division coincides with a main-scale line. Least count = 0.02 mm, so vernier reading = 7 × 0.02 = 0.14 mm. Total = 12.14 mm. If the calliper closes at 0.03 mm instead of zero, subtract that zero error from the measured value. The reasoning: main scale gives whole millimetres; the vernier division adds the fractional part.
Traps
Reading the wrong vernier line; ignoring zero error; measuring a hot or burred part; using a worn screwdriver that slips; and skipping the pre-use inspection.