Tools and Equipment
What this domain tests
Tools and Equipment covers selection, use, care and calibration of hand tools, measuring instruments, power tools and machine tools. COREN expects a craftsman to know the instrument's least count, the correct holding and reading method, and the maintenance that keeps a tool accurate and safe.
Core rules
- A steel rule is for rough work; a vernier caliper typically reads to 0.02 mm; an outside micrometer typically reads to 0.01 mm. Match the instrument to the tolerance.
- Check zero before use. A vernier that does not read zero when closed must be adjusted or rejected.
- Do not use a caliper as a C-clamp, scribe or hammer; do not store micrometers with the spindle closed.
- Machine tools: correct speed, feed and coolant; secure the workpiece; remove the chuck key before starting; never leave a lathe chuck key in place.
- Power tools: inspect the lead and plug, use the correct guard, and isolate before changing blades or bits.
- Calibration records should identify the instrument, date, result and next due date.
Worked example
A vernier caliper has 50 vernier divisions and a least count of 0.02 mm. The main scale reads 12 mm; the 34th vernier line coincides with a main-scale line. Vernier reading = 34 × 0.02 = 0.68 mm. Total = 12.68 mm. Record the result to the instrument's resolution, not as 12.7 mm.
Traps
Reading the wrong vernier line; forgetting to add the main-scale value; using a worn caliper; over-tightening a micrometer; and measuring with the instrument tilted. In machine-shop questions, the distractor is often a faster but unsafe method, such as removing a guard to reach a cut.