Workshop Practice and Trade Skills
Workshop Practice and Trade Skills
This section tests hand tools, measurement, marking, cutting, drilling, tapping, soldering, crimping and conduit work, together with safe bench practice in an electrical workshop.
Core rules
- Measuring: steel rule, vernier calliper (least count usually 0.02 mm), micrometer (0.01 mm), try square and feeler gauge.
- Cutting: hacksaw teeth point forward and cut on the forward stroke; coarse teeth for soft thick metal, fine teeth for thin tube.
- Drilling: centre-punch first, use correct speed (slower for large bits and hard metal), clamp the work, withdraw to clear swarf.
- Tapping: drill size = tap size − pitch; lubricate and back off half a turn periodically.
- Conduit: cut square, ream the burr, bend with a spring or bender to a radius that does not collapse the tube.
- Soldering: clean and tin the bit, heat the joint, apply solder to the joint not the bit, avoid dry joints.
- Crimping: correct die and lug size, conductor fully inserted, tug-test after crimping.
- 5S: sort, set in order, shine, standardise, sustain.
Worked example
A vernier calliper has 50 divisions on the vernier scale, so least count = 1 mm/50 = 0.02 mm. The main scale reads 12 mm and the 23rd vernier division coincides with a main-scale line. Reading = 12 + 23 × 0.02 = 12 + 0.46 = 12.46 mm. Read the main scale at the vernier zero, then add the vernier fraction; do not count divisions from one.
Traps that cost marks
- Fitting the hacksaw blade with teeth pointing backwards.
- Using a drill too large for the tap, producing a stripped thread.
- Over-tightening terminal screws and crushing conductor strands.
- Leaving a dry or blobby solder joint that fails a continuity test.
- Measuring with a vernier that has not been zero-checked.