Package 9

Basic Workshop Tools

1. How to Use a Vernier Calliper

  • Definition: A hand-held slide-rule device used to accurately measure lengths, typically accurate to 0.02 mm (20 microns).

  • Measurements:

    • Types of measurements: Thickness, outside diameter, inside diameter, depth.

    • Primary pair of callipers: Used to measure outside dimensions.

    • Secondary pair of callipers: Used to measure inside dimensions.

  • How to Read the Vernier Calliper:

    • Reference the “0” graduation line on the bottom scale.

    • From the main scale (top), read off the whole number and first decimal place in cm (1mm = 0.1cm).

    • From the vernier scale (bottom), read off the second and third decimal places (0.02mm each).

    • Example measurement: 2.832cm (28.32mm).

2. Cutting, Drilling and Grinding

  • Cut-Off Saw:

    • Uses a silicon carbide cutting disk for ferrous metals.

    • Very dangerous if used on non-ferrous metals.

  • Reciprocating Cut-Off Saw:

    • Cuts large-section ferrous and non-ferrous metals.

    • Blade choice depends on material; lubricating coolant often used.

  • Vertical Band Saw:

    • Features a continuous blade driven in a closed-loop path.

    • Speed and tooth configuration should be adapted based on material.

    • Care must be taken to avoid injury when cutting small components by hand.

  • Drill Press:

    • Drills holes into various materials; speed varies (slow for metals, fast for woods/plastics).

    • Material should be clamped to avoid eccentric holes; coolant may be necessary for hard materials.

  • Bench-Top Grinder:

    • Used for grinding ferrous metals.

    • Risk of disk explosion if used on non-ferrous metals.

  • Bench-Top Vice:

    • Clamps materials securely while cutting, drilling, or filing.

3. Welding

  • Oxy-Acetylene Welding Torch:

    • Achieves temperatures of 3300°C with the correct gas ratio.

    • Different flame types based on the ratio of oxygen and acetylene:

      • Carburising flame (more acetylene) for alloy steels.

      • Neutral flame (equal parts) for low-carbon steels.

      • Oxidising flame (more oxygen) for non-ferrous metals.

    • Flash-back arrestors are necessary on gas lines.

    • Acetylene is switched ON first and OFF last while using the torch.

4. Machining

  • Lathe:

    • Used for making circular-profile parts (shafts, pulleys, etc.).

    • Material is clamped and rotated; cutting tool is maneuvered in X and R-planes.

    • Speed critical; hard materials typically turned at slower speeds.

    • CNC technology used in modern machines.

  • Milling Machine:

    • Manufactures three-dimensional parts by removing material from billets.

    • Speed depends on the material being machined; material is moved in X, Y, and Z dimensions.

    • Internal corners will have a radius equal to the cutting tool.

5. Sheet Metal

  • Guillotine:

    • Cuts sheet metal up to a few millimeters; suitable for ferrous and non-ferrous sheets.

    • Small units typically foot-operated while larger units are hydraulically driven; produces a clean cut.

  • Bending Brake:

    • Bends sheet metal (up to a few millimeters) from 0 to about 120 degrees.

    • Delivers neat bends; the radius of the bend depends on the fingers used.

    • Requires careful planning for the sequence of bends.