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96 Cards in this Set
- Front
- Back
Two types of timber
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Hardwoods and Softwoods
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Hardwoods are from...
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Deciduous tress
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Softwoods are from...
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Coniferous trees
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Name four wood defects
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Warping, bowing, cupping, splitting or knots
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Properties of hardwoods
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More fibrous = greater mechanical strength and hardness
More expensive - because they take a longer time to grow |
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Properties of softwoods
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Made up of tube like cells - less dense, more prone to water damage
Can be resinous - Pine is VERY resinous |
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Growth and Production of woods
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Trees girth increases with height. Summer growth responsible for mechanical strength. Variation in look of cells = annual rings. Tree is felled then ready for seasoning. Once timber has dried out is cut into common shapes and sizes and can be sold.
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Everything about oak...
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Hardwood, tough, hard, durable
Used for furniture and veneers Finishes well Contains an acid that corrodes steel |
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Everything about mahogany...
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Hardwood, durable, medium density
Indoor furniture and woodwork Finishes well and is easy to work Prone to warping |
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Everything about beech...
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Hardwood, hard, tough
Toys and kitchen utensils Turns and finishes well Warping |
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Everything about ash...
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Hardwood, tough, flexible, good elasticity
Ladders, laminated furniture Flexible Can splinter |
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Everything about pine...
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Softwood, lightweight
Floorboards, toys Grows quickly, sustainable, nice colour and grain Warping and knots |
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Advantages of manufactured boards
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Available in large, flat sheets - not so much to join
Good dimensional stability Can be decorated - veneers, paint Flexible and easy to bend for laminating Wood wast can be used for chipboard and MDF |
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Disadvantages of manufactured boards
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Sharp tools needed as easily blunted
Thin sheets will bow if unsupported Difficult to join using traditional construction methods Sanding can produce hazardous dust particles Edges have to be treated |
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How is plywood made...
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Made of veneers, odd number of individual plies glued together at 90 degree angles to each other using synthetic resin and then compressed using a heat press.
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Everything about plywood...
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Very strong in all directions, resistant to splitting
Boat building Large sheets, tick sheets won't warp |
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Everything about chipboard...
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No grain patterns, made from waste products of wood bonded together using strong resins
Strong in all directions Not very water resistant, will chip on edges if unprotected |
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Everything about MDF...
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Good surface finish that can be veneered or painted
Dense, stable to changing conditions Will break down and absorb water if it gets very wet |
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Everything about hardboard...
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One side textured one side smooth
Made from compressed fibres soaked in resin before compressing Cheap Not strong as has no grain |
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What are ferrous metals...
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Contain iron, will rust, usually magnetic
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Everything about mild steel...
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Tough, malleable, magnetic
Structural girders Easy to join, cheap, recyclable Will oxidise if unprotected |
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Everything about stainless steel...
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Hard, tough, corrosion resistant
Cutlery, sinks Easy to clean, no surface finishing required, recyclable Difficult to join in school workshop, special welding equipment needed |
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Everything about carbon steel...
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Ductile
Nail, screws, nuts Recyclable Will rust if unprotected |
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What are non-ferrous materials...
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Don't contain iron, are not magnetic, good conductors of heat and electricity
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Everything about aluminium...
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Lightweight, soft, ductile, malleable, corrosion resistant
Kitchen foil, drink cans Recyclable, easily cast Expensive, difficult to weld |
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Everything about copper...
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Malleable, ductile, good heat and electrical conductor, Corrosion resistant
Electrical cables, pipes Recyclable, easily soldered Expensive, will tarnish |
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Everything about zinc...
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Corrosion resistant
Negative battery terminals, used for galvanising Recyclable Brittle |
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Everything about brass...
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Alloy of copper and zinc
Corrosion resistant, good fluidity, conductor of heat and electricity Plumbing fittings High lustre finish, tough, recyclable, casts well Expensive |
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Ductility
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Ability to be drawn into smaller, thinner sections
Copper Electrical wires |
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Malleability
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The ability to be deformed by compression without tearing
Mild steel Car body panels |
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Hardness
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The ability to withstand abrasive wear and indentation
Stainless steel Sinks |
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Toughness
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The ability to withstand sudden shock loading without
fracture Mild steel Nails |
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Elasticity
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The ability to return to original shape once deforming force is removed
High carbon steel Springs |
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Tensile strength
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The ability to withstand being pulled apart
Carbon steel Nails |
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Compressive strength
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The ability to withstand being squashed
Mild steel Car body panels |
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Shear strength
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The ability to withstand being slid apart
Stainless steel Security shear nuts |
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Plasticity
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The ability to change shape without breaking
Acrylic Garden chairs |
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Durability
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The ability to withstand weathering
All plastics Garden furniture |
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Polymers
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Made from molecules formed into long chains
Waterproof |
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Thermoplastics
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Thermoplastics can be heated reshaped and cooled to set many times
Made form long chains of molecules with few cross links Have plastic 'memory' - when reheated return to original shape unless damaged by overheating |
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Everything about acrylic...
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Good impact strength, lightweight, electrical insulator, durable
Fish tanks Recyclable, environmental stability, colours Scratches, soft, bad chemical resistance |
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Polyethene
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Tough, chemical resistance, soft, flexible, electrical insulator
Carrier bags, buckets Recyclable- but most ends in landfill sites |
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PVC
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Chemical resistance, lightweight, electrical insulator,
tough, durable Pipes, bottles Recyclable, cheap Dangerous fumes when burnt |
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HIPS
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Tough, high impact strength, electrical insulator
Toys, cutlery Colours, recyclable Expensive, non-biodegradable |
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ABS
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High impact strength, tough, durable, chemical resistant, electrical insulator, lightweight
Toys Colours Expensive |
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Thermosetting plastics
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Long chains of molecules that are cross linked = rigid molecular structure.
Soften when heated so can be shaped, but only once. Electrical insulators, hard, waterproof |
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Everything about polyester resin...
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Electrical insulator, hard, brittle, heat and chemical resistance
Casting, adhesives Colours, water resistance Contracts on curing, excess heat |
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Everything about urea formaldehyde...
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Stiff, hard, brittle, high tensile strength, scratch and stain resistant
Buttons, electrical castings Coloured, high surface hardness Toxic fumes when it cures |
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Carbon fibre
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Made of very thin fibres and carbon atoms
Skis, racket frames High strength to weight ratio, high tensile strength Expensive, weak when compressed |
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Glass reinforced plastic
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Plastic reinforced with glass fibres and epoxy resin matrix
Boats hulls, canoes Lightweight, good strength to weight ratio, durable Time consuming to make, cutting = dangerous to breath dust |
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Shape memory alloys
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They remember cold form shape when heated
Glasses - nitinol Anti-sclading valves Orthodontic wires - good elasticity, tensile strength, lightweight, expensive |
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Photochromic paint
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Changes colour when exposed to UV or sunlight - reversible
Used in textiles, vans Ability will decay over time |
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Reactive glass
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Because of added silver halide micro crystals in glasses
Smart glass in windows when voltage is applied Expensive to manufacture and install |
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Carbon nanotubes
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Cylindrical structure
Lighter but stronger than steel, flexible, conducts heat and electricity, inert, gives a hard tough finish to paint, high tensile strength, expensive, toxic |
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Marking out
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Take measurements from a datum - prevents cumulative errors
Timber from face side and edge |
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Steel rule
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For measuring up to 300mm in length
Rigid Ends can wear out |
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Measuring tape
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For making longer measurements
Can twist and break |
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Try square
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Marking out right angles on wood or plastic
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Engineer's square
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marking out right angles on metal or plastic
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Mitre square
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Marking out angles of 45 or 135 degrees
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Marking gauge
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Marking lines parallel to the face edge and side on wood
Set using steel rule. Consists of stock that slides up and down stem. Spur is pushed into wood |
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Cutting gauge
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Used for cutting across the grain
Blade instead of spur |
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Mortise gauge
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Marking two parallel lines fro a mortise and tenon joint
Two spurs |
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Scriber
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Scratch the surface of metal or plastic lightly
On metal use engineer's blue |
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Centre punch
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Used to make an indent for drilling in metals
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Dot punch
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marking the centres fro dividers
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Templates
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Used when a number of identical shapes need to be marked out
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Micrometers
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Used to take accurate measurements
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Saws
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Cut material not needed away from material that is
Teeth set in alternate directions to make a kerf. Must be wider than blade so saw doesn't get stuck. Cut to the waste side for finishing room |
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Coping saw
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Cuts curves in wood and plastic
Blade can be removed from frame and rotated but can break easily. Difficult to control on straight lines |
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Tenon saw
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General purpose woodworking saw
Depth of cut limited to blade length |
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Dovetail saw
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For small accurate work
Shorter than tenon saw Fine cut because of smaller teeth Not robust for general work |
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Adjustable hacksaw
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Used for fine or rough work in plastic and metal
Replaceable blade, can snap easily |
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Jack plane
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Smooths and flattens wood to size
Heavy and jams easily |
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Smoothing plane
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FInishing a surface and for on end grain
jams easily |
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Block plane
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Removes sharp edges
Can be used in one hand Jams easily and not good on large surfaces |
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Gouge
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Curved blade for carving
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Firmer chisel
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General purpose cutting or carving in wood
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Bevel-edged chisel
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used for cutting dovetails
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Mortise chisel
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Deeper balde for cutting mortise joints
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Cold chisels
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used to cut sheet metal by shearing across or chopping down
One end hardened and tempered other soft to absorb shock |
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Rasp
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Quick removal of waste wood
Clogs easily |
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Surform
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Fast removal of soft material
Blades break easily |
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Cross filing
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Removes waste rapidly
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Draw filing
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Removes marks left in wood from cross filing
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Files
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Made from high carbon steel, body is hardened and tempered tang is soft and fits in handle.
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Flat file
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Removes waste on large flat surfaces
Has a safe edge to prevent cutting into edge when filing a corner Brittle of dropped |
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Round file
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Creates curves and fillets
Small cross section = weak |
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Three square file
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Cuts into corners between 60 - 90 degrees
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Twist drill
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Used to create holes in materials
twist carries waste away in swarf Breakable |
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Flat bit
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Used to drill a hole all the way through
Will split underside of wood if not supported |
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Countersink bit
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Creates depression for head of countersunk screw
Chatters at high speeds |
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Hole saw
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Used on thin materials to create large drills
Burns at too high speed |
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One-off
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Highly skilled workers, constant discussion with clients, specialist area of work, unique products, made to measure, expensive, time consuming
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Batch
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production line set-up, workers semi skilled and flexible, quick response to customer demands, production line can be changed quickly , tools have to be reset for new production run
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Mass
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Semi-automated, much computer control, investment in machinery, low unit costs, 24/7, initial costs are high
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