Lesson Notes By Weeks and Term v3 - Senior Secondary 1
Wood work machines
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Wood work machines
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Subject: Machine Woodworking
Class: Senior Secondary 1
Term: 3rd Term
Week: 8
Theme: Woodwork Machine And Machining
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Identify machine parts and accessories. Use machines and accessories correctly. Clean and lubricate machines and accessories.
The circular saw, specifically the table saw in a workshop context, is a power tool used primarily for cutting wood. It consists of a circular saw blade, mounted on an arbor, that protrudes through the top of a table. 2.1.
1. Main Parts of a Circular Saw (Table Saw): Saw Blade: The cutting tool, available in various tooth counts and types (e.g., rip blades, crosscut blades, combination blades) for different cutting tasks.
Motor: Provides power to rotate the saw blade. Typically electric.
Table (or Work Surface): A flat, stable surface on which the workpiece rests and slides during cutting. Usually made of cast iron or heavy steel.
Rip Fence: An adjustable guide, parallel to the saw blade, used to support the workpiece and guide it for ripping (cutting along the grain) to a specific width. It locks firmly in place.
Miter Gauge: A sliding guide that fits into slots (miter slots or T-slots) on the table, used to hold the workpiece at an angle for crosscutting or mitre cuts.
Blade Guard: A safety device that covers the exposed part of the saw blade above the table when not cutting, and often also covers the blade during cutting, to protect the operator.
Arbor: The shaft on which the saw blade is mounted.
Blade Tilt Handwheel: Used to adjust the angle of the saw blade for bevel cuts.
Blade Height Handwheel: Used to raise or lower the saw blade above the table for different cutting depths or operations.
On/Off Switch: Controls the power to the motor. Often includes an emergency stop feature.
Splitter/Riving Knife: A safety device located behind the blade, which helps prevent kickback by keeping the kerf (cut path) open and preventing the wood from pinching the blade.
Dust Port: An outlet for connecting a dust collection system, important for maintaining a clean workshop environment and reducing respiratory hazards. 2.1.
2. Accessories for a Circular Saw (Table Saw): Push Stick: A safety device used to push small workpieces or the trailing end of larger workpieces past the saw blade, keeping hands a safe distance away. Essential for narrow rips.
Featherboard: A safety accessory clamped to the table or fence, with fingers that apply constant pressure to the workpiece against the fence or table, ensuring consistent contact and preventing kickback.
Zero-Clearance Insert: A custom-made or bought table insert that fits snugly around the saw blade, reducing the gap between the blade and the table. This minimises tear-out, especially on crosscuts, and prevents small off-cuts from falling into the saw's mechanism.
Dado Set: A specialized set of blades (two outer blades and several chippers) used to cut wide grooves or dados into a workpiece for joinery. 2.1.
3. Operations Performed on a Circular Saw (Table Saw): Ripping: Cutting wood along the grain to reduce its width. The rip fence is essential for this operation.
Crosscutting: Cutting wood across the grain to reduce its length. The miter gauge is typically used.
Mitre Cutting: Cutting wood at an angle (usually 45 degrees) for corner joints. Performed with the miter gauge set at an angle.
Bevel Cutting: Cutting wood at an angle through its thickness. The blade tilt mechanism is used to angle the saw blade.
Dado Cutting: Cutting a flat-bottomed groove across the grain of a workpiece, often used for shelf supports or joinery, using a dado set. The surface planer is used to flatten one face of a board, square an edge, or reduce the thickness of lumber to a uniform dimension.
There are two main types: the jointer (for flattening faces and squaring edges) and the thickness planer (for achieving uniform thickness). In many small Nigerian workshops, a single machine might perform both functions or these roles are split between two distinct machines. This lesson will cover both aspects. 2.2.
1. Main Parts of a Surface Planer (Jointer/Thickness Planer): Infeed Table: The table on which the workpiece is placed before it passes through the cutter head. Its height is adjustable relative to the cutter head.
Outfeed Table: The table that supports the workpiece after it passes through the cutter head. Its height must be precisely aligned with the cutting circle of the blades for accurate planing.
Cutter Head: A rotating cylinder containing sharp knives (blades) that remove material from the wood surface.
Knives/Blades: The actual cutting tools, typically made of high-speed steel or carbide, which are mounted on the cutter head.
Fence (Jointer): An adjustable guide, usually mounted perpendicular to the table, that holds the workpiece at a specific angle (usually 90 degrees) to the cutter head for squaring edges. Depth Adjustment Handle/Crank (Thickness Planer): Used to raise or lower the entire cutter head assembly or the table to set the desired thickness of the workpiece.
Guards: Safety covers over the cutter head to protect the operator from the rotating blades.
Feed Rollers (Thickness Planer): Rubber or steel rollers that grip the workpiece and automatically feed it through the machine past the cutter head.
On/Off Switch: Controls the power to the motor. 2.2.
2. Accessories for a Surface Planer: Push Block: A safety device with a handle and sometimes rubber pads, used to push workpieces over the jointer table or through the thickness planer, keeping hands away from the cutter head. Essential for flattening faces and jointing edges.
Blade Setting Jig: A tool used to precisely align and set the planer knives in the cutter head after sharpening or replacement, ensuring consistent cutting depth. 2.2.
3. Operations Performed on a Surface Planer: Flattening a Face (Jointing): Creating one perfectly flat surface on a rough or warped board. This is typically the first step in preparing lumber.
Squaring an Edge (Jointing): Creating one perfectly straight and square edge, usually 90 degrees to the flattened face. This is crucial for joining boards or for subsequent ripping operations.
Planing to Thickness (Thicknessing): Reducing the thickness of a board to a uniform dimension, parallel to the flattened face. This ensures consistent material thickness for construction or furniture components. apply a light machine oil sparingly, working the handwheel to distribute it. This ensures smooth operation and prevents wear. * A student observes that the surface planer in their workshop has rust developing on the cast iron table after the rainy season. The teacher explains that this is due to humidity and lack of protection. The cleaning procedure involves using fine steel wool or an abrasive pad with mineral spirits to remove the rust, followed by a thorough cleaning and application of a thin layer of paste wax to protect against future corrosion. Proper maintenance is crucial for the longevity, safety, and performance of woodworking machines. 2.3.
1. Cleaning Machines and Accessories: Reasons for Cleaning: Safety: Accumulation of dust and sawdust can create fire hazards and obstruct moving parts, leading to unsafe operation.
Accuracy: Sawdust and resin build-up on tables, fences, and guides can affect the accuracy of cuts and planing.
Machine Longevity: Dust and wood sap (resin) can corrode metal parts and clog mechanisms, leading to premature wear and failure.
Efficiency: A clean machine operates more smoothly and efficiently.
Cleaning Procedures:
1. Disconnect Power: Always unplug the machine or turn off the main circuit breaker before any cleaning or maintenance. This is paramount for safety.
2. Remove Sawdust/Chips: Use a brush, shop vacuum, or compressed air (with caution and appropriate PPE like safety glasses) to remove sawdust and wood chips from all surfaces, especially around the motor, blade, cutter head, and adjustment mechanisms.
3. Clean Tables and Fences: Wipe down cast iron or steel tables and fences with a clean cloth. For sticky resin build-up, use a specialized resin remover or mineral spirits. After cleaning, apply a thin coat of paste wax (non-silicone) to tables to protect against rust and allow wood to slide smoothly.
4. Clean Blades/Knives: For circular saw blades, remove and clean off resin with blade cleaner. For planer knives, ensure they are free of debris; dull or chipped knives should be replaced or sharpened.
5. Check Ventilation/Dust Ports: Ensure dust ports are clear and not blocked. 2.3.
2. Lubricating Machines and Accessories: Reasons for Lubrication: Reduce Friction: Lubricants create a film between moving metal parts, reducing friction, heat, and wear.
Prevent Rust and Corrosion: Many lubricants also have rust-inhibiting properties, protecting exposed metal surfaces from moisture and oxidation, especially important in humid Nigerian environments.
Smooth Operation: Lubricated parts move freely, making adjustments (e.g., blade height, fence movement) easier and more precise.
Extend Machine Life: Regular lubrication prevents premature wear and tear, prolonging the operational life of the machine.
Lubrication Procedures:
1. Identify Lubrication Points: Consult the machine's manual for specific lubrication points.
Common areas include: Threaded Rods: For blade height and tilt adjustments on a circular saw, or table height adjustment on a planer.
Lead Screws/Gear Mechanisms: Used for fine adjustments.
Bearings: While many modern machines have sealed bearings, older models or certain components might require periodic grease application.
Fence Rails/Slides: For smooth movement of the rip fence.
2. Choose the Correct Lubricant: Dry Lubricants (e.g., graphite, silicone spray): Often suitable for surfaces where sawdust might stick to oil, like table slides or fence rails. Light Machine Oil (e.g., 3-in-1 oil): For threaded rods, pivots, and light mechanisms.
Grease: For heavier-duty bearings or specific grease fittings. Avoid excess grease which can attract sawdust.
3. Apply Sparingly: Apply lubricants as recommended. Excess oil or grease can attract sawdust, creating a sticky abrasive paste that can cause more harm than good.
4. Work Mechanisms: After applying lubricant, move the relevant parts (e.g., raise/lower blade, slide fence) to distribute the lubricant evenly.
5. Wipe Excess: Wipe away any excess lubricant to prevent it from attracting dust or staining workpieces.
Example Application in Nigerian Context: A furniture maker in Aba uses a circular saw daily to cut mahogany planks for chairs. After a week of operation, the blade height adjustment feels stiff. The teacher explains that sawdust and resin have likely accumulated on the threaded rod, hindering its movement. The teacher demonstrates how to unplug the saw, clean the rod with a brush and resin remover, and then apply a light machine oil sparingly, working the handwheel to distribute it. This ensures smooth operation and prevents wear. * A student observes that the surface planer in their workshop has rust developing on the cast iron table after the rainy season. The teacher explains that this is due to humidity and lack of protection. The cleaning procedure involves using fine steel wool or an abrasive pad with mineral spirits to remove the rust, followed by a thorough cleaning and application of a thin layer of paste wax to protect against future
Furniture Manufacturing Industry: In cities like Aba, Nnewi, and Lagos, where a vibrant furniture industry thrives, skilled workers use circular saws for dimensioning lumber and surface planers for achieving precision in furniture components (e.g., preparing table legs, cabinet panels, chair frames). Proper machine operation and maintenance directly translate to higher quality products, reduced waste, and increased profitability for businesses, supporting local employment and economic growth.
Building Construction and Carpentry: Nigerian builders and carpenters rely heavily on these machines for preparing timber for roofing, door frames, window frames, and structural components. For instance, jointing and thicknessing timber ensures that roof trusses are perfectly straight and uniform, leading to stable and durable structures resistant to extreme weather conditions. The ability to maintain these machines on a construction site or in a timber yard ensures continuous workflow and adherence to project deadlines. Entrepreneurship and Small Scale Businesses: Many Nigerian youths are seeking vocational skills to become self-employed. Understanding woodworking machines allows individuals to set up small workshops producing items like wooden doors, window frames, simple furniture, or even providing timber processing services (e.g., cutting planks to size, planing rough timber) for other businesses. The knowledge of cleaning and lubricating is critical for managing operating costs and ensuring that their limited capital equipment lasts longer, making their ventures sustainable and profitable.