Tools and Equipment
Tools and Equipment
This domain tests selection, safe use, and maintenance of hand tools, measuring tools, power tools, welding machines, and gas apparatus. Exam questions often describe a task and ask for the correct tool or the reason a tool is unsafe.
Core rules
- Measuring: steel rule and tape for general dimensions; combination square for 90°/45°; try square for squareness; dividers and trammels for arcs; feeler gauges for gaps; fillet and undercut gauges for weld profile; calipers and micrometers for precision.
- Layout: chalk line, level, plumb bob, and centre punch. Check tools for wear; a damaged square cannot establish a true reference.
- Grinders: guard in place, wheel rated for the machine RPM, tool rest close to the wheel, no gloves near rotating parts, face shield over safety glasses. Ring-test bonded wheels before mounting where required; never exceed the wheel's maximum speed.
- Welding machines: match input voltage, cable size, duty cycle, and polarity. The ground clamp should be on clean metal close to the work.
- Gas apparatus: regulator/flowmeter, flashback arrestors at regulator and torch, approved hose, leak test with soap solution. Oxygen fittings must be oil-free.
- Maintenance: inspect before use; tag out defective equipment; do not field-repair damaged leads or regulators.
Worked example
A power source is rated 250 A at 60% duty cycle. What duty cycle is permitted at 300 A? Duty cycle varies with the square of current: D2 = D1 × (I1/I2)² = 60% × (250/300)² = 60% × 0.694 = 41.7%. At 300 A the machine may run about 42% of a 10-minute period, or 4.2 minutes, before cooling. The reasoning matters: duty cycle is based on a 10-minute test period and is not a simple linear ratio.
Traps
- Using a grinding disc above its RPM rating or without a guard.
- Confusing a regulator with a flowmeter; a flowmeter reads flow, not delivery pressure.
- Leaving a cylinder valve open or a torch leaking.
- Using the wrong polarity or undersized cable.
- Measuring from a damaged or worn reference edge.