Fitter Trade (ALP)

Fitter trade covers basic mechanical fitting work — tools, marking, measurement, hand operations.

Common Tools:

• Hammer: ball-peen, sledge, claw.
• Files: flat, half-round, round, triangular; cuts: single, double, rasp.
• Hacksaw: for cutting metal.
• Chisels: flat, cross-cut.
• Punches: center, prick, drift.
• Spanners and wrenches: open-end, ring, box, adjustable.
• Pliers: flat, round, side-cutting.

Measuring tools:

• Steel rule: least count 1 mm or 0.5 mm.
• Vernier caliper: least count 0.02 mm.
• Micrometer: least count 0.01 mm.
• Dial gauge: for surface flatness.
• Combination square: angle measurement.

Marking tools:

• Scriber: marks lines on metal.
• Center punch: marks centers for drilling.
• Surface plate: flat reference for marking.

Drilling:

• Twist drill: common for metal.
• Cutting speed: depends on material and drill diameter.
• Coolants: soluble oil, kerosene.

Threading:

• Tap: internal threads.
• Die: external threads.
• Thread types: metric, BSW, UNC, UNF.

Fits and Tolerances:

• Clearance fit: part moves freely.
• Interference fit: force-fit.
• Transition fit: between clearance and interference.
• Hole basis vs shaft basis systems.

Common operations:

• Filing, sawing, drilling, tapping, reaming, threading.
• Surface finish, deburring.

Safety:

• Always wear PPE: gloves, safety shoes, glasses.
• Don't leave tools on machines.
• Use right tool for the job.

RRB ALP focus: identify tools, basic measurements, common operations.