Lesson Notes By Weeks and Term v3 - Senior Secondary 2
maintenance of hand tools
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maintenance of hand tools
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Subject: Wood-Work
Class: Senior Secondary 2
Term: 1st Term
Week: 5
Theme: Tools And Machine
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Keep the cutting edge of each hand to ol in good working condition. Oil blades of cutting to ols regularly. Safely store cutting to ols.
chisels, dedicated chisel racks hold them upright, preventing contact.
Drawer Dividers: In drawers, use dividers to separate tools and prevent them from jumbling together.
Environmental Factors: Dry Environment: Store tools in a dry area to minimize the risk of rust. Avoid storing them in damp basements or directly on concrete floors. In humid Nigerian climates, this is particularly important.
Cleanliness: Ensure tools are clean of sawdust, grime, and moisture before storage. * Security: Store tools out of reach of children and unauthorized personnel. Lockable toolboxes or workshop doors add security. 2.1 Introduction to Tool Maintenance Tool maintenance encompasses a set of practices designed to preserve the functionality, safety, and longevity of hand tools. For woodworking hand tools, this primarily involves sharpening, cleaning, oiling, and proper storage. Neglecting these practices leads to dull tools, increased effort, poor quality work, potential injuries, and premature replacement of tools, which can be a significant financial burden for Nigerian artisans. 2.2 Essential Hand Tool Maintenance Procedures 2.2.1 Sharpening Cutting Edges A sharp tool is safer and more efficient than a dull one. Dull tools require excessive force, increasing the risk of slips and accidents. Sharpening involves restoring the keen edge of a cutting tool. Grinding vs.
Honing (Sharpening): Grinding: This is the process of removing a significant amount of metal, usually with a coarse abrasive wheel (grinder), to establish the primary bevel angle or repair a severely damaged edge (e.g., nicks, chips). Grinding is done when the tool is very dull, the bevel angle needs correction, or the edge is damaged. It's a quick metal removal process.
Honing (Sharpening): This is the refinement of the edge using finer abrasive stones (sharpening stones) to achieve a razor-sharp finish. It follows grinding or is used for regular touch-ups when the edge is only slightly dull.
Sharpening Stones (Whetstones): Oilstones: These require a light oil (like kerosene or specialized honing oil) as a lubricant to float away metal particles and prevent clogging. Common types include Carborundum (silicon carbide) and India (aluminium oxide) stones, available in various grits (coarse, medium, fine).
Waterstones: These use water as a lubricant and are often preferred for their faster cutting action and ability to create a very fine edge. They require flattening periodically.
Diamond Stones: These are steel plates with industrial diamonds bonded to their surface. They are very durable, require minimal lubrication (water or dry), and come in various grits. They can sharpen carbide tools. Detailed Procedure for Sharpening a Jack-Plane Cutter (Iron): The jack plane is a common tool in Nigerian workshops. Its cutter (also called a plane iron or blade) needs frequent sharpening.
1. Disassembly: Remove the cap iron (also called the chip breaker) from the plane iron. The cap iron is typically held by a screw. Separate these two components completely.
2. Inspection: Examine the cutting edge for nicks, chips, or a rounded bevel. If severely damaged or if the bevel angle needs significant correction, start with grinding.
3. Grinding (if necessary): If a powered grinding wheel is used: Ensure the wheel is balanced, true, and dressed. Wear safety goggles. Hold the plane iron at its original bevel angle (typically 25-30 degrees for plane irons, though specific tools like chisels may vary). Maintain a consistent angle. Lightly touch the bevel to the wheel, moving it slowly from side to side to avoid creating a hollow or burning the edge. Dip the blade in water frequently to prevent overheating, which can temper (soften) the steel. Grind until all nicks are removed and a fine "wire edge" (burr) is formed along the back (flat side) of the blade.
4. Honing (Sharpening) the Bevel: Select a coarse sharpening stone (e.g., 600-1000 grit) lubricated with oil or water. Place the bevel of the plane iron flat on the stone, ensuring the established angle is maintained. Use a sharpening jig (honing guide) if available, common in modern workshops to maintain a consistent angle. Push the blade forward (away from you) with firm, even pressure, keeping the angle constant. Repeat several strokes. Move to a medium stone (e.g., 1000-3000 grit) and repeat the process, then to a fine stone (e.g., 4000-8000 grit or higher) for a razor-sharp edge. Continue until a consistent burr is felt along the entire length of the back edge.
5. Honing the Flat (Back)
Side: Lay the entire flat side of the plane iron perfectly flat on the finest sharpening stone. Make 5-10 light strokes, pushing the blade forward. This action removes the burr formed during bevel honing and polishes the back of the edge, which is crucial for cutting performance. (e.g., 1000-3000 grit) and repeat the process, then to a fine stone (e.g., 4000-8000 grit or higher) for a razor-sharp edge. Continue until a consistent burr is felt along the entire length of the back edge.
5. Honing the Flat (Back)
Side: Lay the entire flat side of the plane iron perfectly flat on the finest sharpening stone. Make 5-10 light strokes, pushing the blade forward. This action removes the burr formed during bevel honing and polishes the back of the edge, which is crucial for cutting performance. The goal is to achieve a perfectly flat and highly polished surface right up to the cutting edge on the back side.
6. Stropping (Optional): For an even finer edge, strop the blade on a leather strop loaded with honing compound.
7. Reassembly: Clean the plane iron thoroughly, then reattach the cap iron, ensuring it is positioned correctly (about 1.0 - 1.5mm from the cutting edge for general work on a jack plane). Precautions in Sharpening and Grinding Plane Cutters:
1. Eye Protection: Always wear safety goggles when grinding or sharpening to protect against flying metal particles or abrasive dust.
2. Maintain Angle: Consistently hold the tool at the correct grinding/honing angle to achieve a sharp and durable edge. Inconsistent angles lead to poor cutting performance.
3. Prevent Overheating: When using a grinding wheel, frequently dip the tool in water to prevent it from overheating and losing its temper (hardness). Burnt edges become soft and dull quickly.
4. Sharp Edges: Handle sharpened tools with extreme care to avoid accidental cuts. Use appropriate grips and always know where the edge is.
5. Stable Workpiece: Ensure the sharpening stone is stable and non-slipping, placed on a non-slip mat or held in a jig.
6. Clean Stones: Keep sharpening stones clean and lubricated. Clogged stones are ineffective. Flatten waterstones regularly to maintain their cutting efficiency. 2.2.2 Oiling Blades of Cutting Tools Purpose: Oiling metal parts, especially the blades of saws, chisels, and plane irons, is primarily to prevent rust (oxidation) and to a lesser extent, reduce friction during use. Rust can quickly pit and dull cutting edges, compromising tool performance and longevity.
What to oil: Exposed metal surfaces, especially cutting edges, saw blades, plane bodies (sole), and moving joints (e.g., pliers, saw tensioning mechanisms).
Type of oil: Light machine oil, 3-in-1 oil, or specialized tool protective oils are suitable. Kerosene is sometimes used for cleaning but is not ideal for long-term rust prevention.
Application: After cleaning a tool, apply a thin, even coat of oil using an oil rag or brush. Ensure complete coverage. For saw blades, wipe along the entire blade surface. For chisels and plane irons, focus on the bevel and flat surfaces, particularly the edge. 2.2.3 Safe Storage of Cutting Tools Proper storage is critical for protecting tools from damage, rust, and for preventing accidents.
Individual Protection: Sheaths/Guards: Always cover the cutting edges of chisels, gouges, and knives with individual plastic, leather, or wooden sheaths when not in use. This prevents accidental cuts and protects the edge from being blunted or chipped.
Saw Guards: Use a strip of wood with a kerf cut into it, or commercially available plastic guards, to protect saw teeth when stored.
Organized Storage Systems: Toolboxes: For smaller tools, a well-organized toolbox with compartments prevents tools from rattling against each other and damaging edges.
Tool Racks/Boards: Wall-mounted tool racks or pegboards are excellent for hanging tools individually. This keeps them visible, accessible, and prevents them from coming into contact with other tools. For chisels, dedicated chisel racks hold them upright, preventing contact.
Drawer Dividers: In drawers, use dividers to separate tools and prevent them from jumbling together.
Environmental Factors: Dry Environment: Store tools in a dry area to minimize the risk of rust. Avoid storing them in damp basements or directly on concrete floors. In humid Nigerian climates, this is particularly important.
Cleanliness: Ensure tools are clean of sawdust, grime, and moisture before storage.
Security: Store tools out of reach of children and unauthorized personnel. Lockable toolboxes or workshop doors 3.1 Teacher Activities Introduction (10 minutes): Begin by reviewing the previous lesson on types of hand tools.
Engage students with questions: "What happens if you use a dull knife to cut yam?" "Why do carpenters always keep their tools sharp?" Elicit responses related to efficiency, safety, and quality.
Introduce the topic: "Maintenance of Hand Tools," emphasizing its importance for safety, quality of work, and extending tool life in Nigerian woodworking. Explanation and Demonstration (30 minutes): Sharpening: Explain the concepts of grinding and honing. Demonstrate (live or using a video) the step-by-step process of sharpening a jack-plane cutter, highlighting the use of different grits of sharpening stones, maintaining the correct angle, and forming/removing the burr. Explicitly show precautions like eye protection and preventing overheating.
Oiling: Demonstrate how to clean and apply a thin layer of light machine oil to a saw blade and a chisel. Explain the purpose of oiling (rust prevention).
Storage: Display various safe storage methods (e.g., a simple chisel rack, a saw guard, a compartmentalized toolbox). Discuss the advantages of each method in a typical Nigerian workshop.
Interactive Session (15 minutes): Facilitate a question-and-answer session to clarify doubts. Ask students to identify tools that would require sharpening and oiling based on observed features. Prompt students to suggest appropriate storage solutions for specific tools. Supervised Practical Activity (35 minutes): Divide students into small groups. Provide each group with a dull plane iron, a sharpening stone (with appropriate lubricant), a piece of scrap wood, a hand saw, a rag, and light machine oil.
Activity 1 (Sharpening): Supervise students as they practice disassembling, inspecting, and sharpening the plane iron, focusing on maintaining the angle and feeling for the burr. Provide hands-on correction.
Activity 2 (Oiling): Guide students to clean and oil the saw blade and a chisel, ensuring thin, even application.
Activity 3 (Storage): Instruct students to demonstrate how they would safely store the sharpened plane iron and oiled saw/chisel using provided (or improvised) guards/racks. 3.2 Student Activities Participate in brainstorming and discussion sessions. Take detailed notes during the teacher's explanation and demonstration. Actively observe the teacher's demonstration of sharpening, oiling, and storage techniques. Ask clarifying questions during the interactive session. Engage in supervised group practical activities, applying sharpening, oiling, and safe storage techniques to real tools. Practice identifying tools needing maintenance and suggesting appropriate procedures. Clean up tools and the work area after practicals, reinforcing good workshop habits.
Empowering Local Artisans and Vocational Training: The skills learned in tool maintenance are directly applicable to the daily work of countless carpenters, furniture makers, and vocational trainees across Nigeria. By maintaining their tools, artisans in busy markets like Ladipo (Lagos) or those involved in traditional craft villages, ensure the quality of their products (e.g., smooth finishes on furniture, accurate joinery), which enhances their reputation and income. This lesson directly supports the development of competent vocational skills essential for self-employment and economic empowerment in Nigeria. Cost-Effectiveness and Resource Management: In an economy where importing quality tools can be expensive, and locally manufactured tools also represent a significant investment for a small business, proper tool maintenance becomes a critical cost-saving measure. A carpenter who regularly sharpens, oils, and safely stores his tools will replace them far less frequently than one who does not, thus preserving capital and improving profit margins. This concept of extending tool life through maintenance is a practical example of sustainable resource management within a Nigerian business context.
Workplace Safety in Nigerian Workshops: Many Nigerian workshops, particularly smaller ones, may have limited safety infrastructure. Teaching proper tool maintenance directly contributes to a safer working environment. A sharp tool requires less force, reducing the risk of slips, cuts, and muscle strain. Safe storage practices prevent accidental injuries from sharp edges left carelessly. This integration highlights the direct link between responsible tool care and the well-being of workers in local carpentry and fabrication workshops.