Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Apply principles of basic measurement with various instruments.
• Explain and apply workshop safety concepts.
• Identify and describe various hand tools and their applications.
• Understand basic metal joining techniques like riveting.
• Describe the principles of simple machines.

Lesson summary

This week marks the start of our focused revision and examination preparation for Grade 10 Mechanical Technology. Mechanical Technology is not just about memorizing facts; it's about understanding how things work, how they're made, and how we can use this knowledge to improve our world. In South Africa, Mechanical Technology skills are crucial for infrastructure development, manufacturing, energy production, and various other industries that drive our economy and improve the lives of our citizens.

Lesson notes

2.1 Measurement and Measuring Instruments Accurate measurement is fundamental to Mechanical Technology. Incorrect measurements can lead to faulty components, inefficient systems, and even dangerous situations.

Steel Rule (Ruler): The simplest measuring tool. Steel rules are typically graduated in millimetres (mm) and sometimes inches. To read a steel rule accurately, align the zero mark with one end of the object being measured and read the graduation mark at the other end, ensuring your eye is perpendicular to the rule to avoid parallax error.

Example: Measuring the length of a bolt. Place the 0mm mark of the steel rule at the start of the bolt thread and read the length at the end of the bolt head. The resolution of a standard steel rule is usually 1mm.

Vernier Calliper: Offers more precise measurements than a steel rule. It consists of a main scale and a vernier scale. The vernier scale allows you to read fractions of a millimetre.

How to read a vernier calliper: Read the whole millimetre mark on the main scale just before the zero mark on the vernier scale. Find the mark on the vernier scale that perfectly aligns with a mark on the main scale. Multiply the vernier scale reading by the vernier's resolution (usually 0.02mm or 0.05mm). Add the two readings together.

Example: Main scale reading = 25mm; Vernier scale alignment at the 7th mark with 0.02mm resolution. Vernier reading = 7 * 0.02mm = 0.14mm. Total reading = 25mm + 0.14mm = 25.14mm.

Micrometer: Provides the highest precision among these instruments. It uses a screw thread to amplify small movements, allowing for readings to the nearest 0.01mm or even 0.001mm.

How to read a micrometer: Read the main scale on the sleeve. The sleeve has graduations of 0.5mm. Read the thimble scale. This indicates the fraction of a millimetre. Add the two readings together.

Example: Sleeve reading = 7.5mm; Thimble reading = 0.28mm. Total reading = 7.5mm + 0.28mm = 7.78mm. 2.2 Workshop Safety A safe workshop environment is paramount. Accidents can cause serious injury and damage to equipment. Understanding and adhering to safety rules is crucial.

Personal Protective Equipment (PPE): Safety Glasses: Protect eyes from flying debris.

Overalls/Apron: Protect clothing and skin from dirt, sparks, and chemicals.

Safety Shoes: Protect feet from dropped objects and sharp materials.

Gloves: Protect hands from cuts, burns, and chemicals (ensure correct glove type for the task).

Ear Protection (Earplugs/Earmuffs): Protect hearing from loud noises.

Dust Mask/Respirator: Protect the respiratory system from dust and fumes.

General Workshop Safety Rules: Keep the workshop clean and organized. Know the location of fire extinguishers and first aid kits. Use the right tool for the job. Inspect tools before use. Never operate machinery without proper training. Report any hazards or accidents immediately. No running or horseplay in the workshop. Ensure adequate ventilation.

Hazard identification: Examples include: Slippery floors, exposed electrical wires, unguarded machinery, improper storage of flammable materials. 2.3 Hand Tools Different hand tools serve specific purposes in a workshop. Knowing the correct tool for the job improves efficiency and safety.

Hammers: Used for striking. Different types include ball-peen, claw, and mallet. Use appropriate hammer weight for the task.

Screwdrivers: Used for driving screws. Different types (flat-head, Phillips, Torx) match different screw heads. Select the correct size and type to avoid damaging the screw head.

Pliers: Used for gripping, cutting, and bending. Types include combination pliers, long-nose pliers, and side-cutting pliers.

Wrenches: Used for tightening and loosening nuts and bolts. Types include open-end, box-end, and adjustable wrenches.

Files: Used for shaping and smoothing metal. Different types (flat, round, half-round) and grades (coarse, medium, fine) for different applications. Always use a handle for safety.

Saws: Used for cutting materials. Hacksaws are used for metal, while wood saws are used for wood. Secure the workpiece properly before sawing. 2.4 Basic Metal Joining Techniques Riveting: A permanent joining method using rivets (metal fasteners). A rivet is inserted through aligned holes in the materials to be joined, and the end is deformed (usually by hammering or using a riveting tool) to create a head that clamps the materials together.

Applications:* Joining sheet metal, aircraft structures, and other applications where welding is not suitable or practical.

Soldering: A joining process using a filler metal (solder) that melts at a relatively low temperature (below 450°C). The solder wets the base metals and forms a strong bond upon cooling. Flux is used to clean the surfaces and promote wetting.

Applications:* Joining electronic components, plumbing, and other applications where high strength is not required. Use lead-free solder where appropriate, especially for potable water applications.