Standard Grade Craft & Design - PowerPoint PPT Presentation

Loading...

PPT – Standard Grade Craft & Design PowerPoint presentation | free to download - id: 3c23b1-NGI5N



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Standard Grade Craft & Design

Description:

Standard Grade Craft & Design Revision Materials Coping Saw Coping saws are used to remove complicated shapes and cut curves in wood and plastic. – PowerPoint PPT presentation

Number of Views:83
Avg rating:3.0/5.0
Slides: 33
Provided by: scottishsc
Learn more at: http://www.scottishschools.info
Category:
Tags: craft | design | grade | standard

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Standard Grade Craft & Design


1
Standard Grade Craft Design
Revision Materials
2
Coping Saw
  • Coping saws are used to remove complicated shapes
    and cut curves in wood and plastic.
  • The blade is held in a frame and may be easily
    replaced if broken.
  • The teeth of the blade point backwards towards
    the handle.
  • The saw cuts on the pull stroke and not on the
    forward stroke. This is because the blade is too
    flexible to be pushed.
  • The blade can be angled in the frame if the frame
    gets in the way when cutting larger sheet
    materials.

3
Tenon Saw
  • Tenon saws are used to make straight cuts in wood
    and
  • occasionally some plastics.
  • This type of saw has a stiff back and is suitable
    for detailed
  • cuts. The saws without this type of stiff back
    are more flexible
  • and are designed to cut large panels.
  • The tenon saw is generally used to cut woodwork
    joints.
  • The tenon saw is used in conjunction with the
    bench hook.
  • The bench hook is used to support the piece of
    wood while
  • it is being cut. It hooks onto the edge of a
    bench. The saw
  • has 12-14 teeth every 25mm.

4
Rip-Saw
  • Large panels or sheets of materials, for example
    plywood or MDF, require larger ripsaws in order
    to cut them by hand. Sheets that are small enough
    may be held in the vice, but larger sheets may
    need to be supported on special types of portable
    carpenter's supports called trestles.
  • Ripsaws are used to cut along the grain of large
    panels of real timber. Panel saws are shorter in
    length to ripsaws and have finer teeth, 10 teeth
    every 25mm. Ripsaws have 4-5 teeth every 25mm.
    Because of its finer teeth and shorter length,
    the panel saw is suited to thinner wood and
    sheets of manufactured boards.

5
Sawing An Introduction
  • Sawing is a way of separating the material that
    is not needed from the material that is. The cut
    or gap that is produced by the saw is called the
    kerf. The kerf is usually wider than the saw
    blade so that the blade does not get stuck when
    it is cutting through the material. Bending
    alternative teeth from left to right produces
    this gap. This bending of the teeth is called the
    set.
  • Hacksaw blades are normally in the shape of a
    wavy cutting edge. It is important when cutting
    to always cut to the outside of the marked line.
    This side of the line is called the waste side.
    You must also leave enough room for filing and
    sanding.
  • The choice of saw depends upon the type of
    material to be cut. Always use the correct saw.
    Wood saws like tenon and panel saws are not hard
    enough to cut through metal. Metal-working saws
    like hacksaws will cut through wood, but not very
    effectively. Plastics like acrylic and
    polystyrene may be cut with coping saws, but it
    is best to use a craft knife to slice the plastic
    along a straight line and snap it over a hard
    edge.

6
Sawing Metal - Hacksaws
  • Hacksaws and junior hacksaws produce straight
    cuts in metal. Both have replaceable blades held
    in tension in the saw frame. The teeth face away
    from the handle and cut on the forward stroke.
    This is the opposite effect to the coping saw,
    which cuts on the pull stroke.
  • The lengths of hacksaw blades are between 250mm
    and 300mm. The saw frames can be adjusted to
    cater for both sizes. Like the coping saw, the
    blades can be turned through 90 in the frame.
    This allows the hacksaw to cut larger sheets of
    metal.
  • Blades normally have 14, 18, 24 or 32 teeth every
    25mm. This is called the pitch of the blade.This
    is more teeth per blade than the coping saw,
    tenon saw, panel saw and rip saw. Soft materials
    require a coarse pitch, less teeth, hard
    materials, a fine pitch, more teeth. Three teeth
    should be in contact with the materials at all
    times. A fine-pitched blade needs to be used for
    tubes and thin gauge materials.
  • Sheet saws are like panel saws but with a hacksaw
    blade attached. These types of saws are used to
    cut sheet metals and plastics. They also cut
    corrugated sheet.

7
Abrafiles
  • The abrafile has a toothed, circular blade that
    fits into a frame. Abrafile blades can fit into a
    hacksaw frame using a pair of adaptors. Coarse,
    medium and fine grades are available. Abrafiles
    are used to cut out curves and rounded shapes
    from sheet metal. Abrafiles are very good at
    cutting wall tiles.
  • This image shows an abrafile blade in a junior
    hacksaw frame.

8
Sawing Wood By Machine
  • An electric fret saw has a reciprocating blade
    built into a frame. This means that the blade
    moves up and down and is pushed against the
    material. This type of machine is ideal for fine,
    detailed shapes and cuts small pieces of flat,
    sheet materials. It is very good for making
    jigsaw puzzles.
  • It does not cut thicker materials very well. It
    can be used to cut plastic a useful tip is to
    cover the part to be cut with masking tape to
    stop the plastic's waste sticking in the cut
    behind the blade.

9
Mitre Saws
  • Mitre saws have a blade that can be adjusted to
    any angle. The saw has cramps that allow the
    material to be fixed to the frame while cutting.
    The mitre saw may be used to cut 45 corners for
    picture frames and mitre joints.
  • The blade cuts on the backward stroke. It is
    possible to buy electrical mitre saws. These are
    called chopsaws.

10
Jigsaws
  • The image above is of a 'Dewalt' portable jigsaw.
    It is used to cut out complicated shapes from
    large sheet materials like plywood and MDF.
  • The blades can be changed to deal with such
    materials as metal and plastics. This type of
    saw, like the fretsaw, has a reciprocating blade
    that moves up and down.

11
Centre Lathe (Metals)
  • When turning materials in a centre lathe
  • the material to be turned is held in a rotating
    chuck
  • a cutting tool held in a tool post cuts the
    material
  • the shape of the cut depends upon the path taken
    by the tool
  • the material will either be cylindrical in shape
    or flat

12
Casting
  • Casting is a process where a metal is heated to
    such a high temperature, it turns to a liquid. We
    call this a molten state. The metal is poured
    into a mould, left to cool and removed (in a
    solid state).
  • When the metal (or plastic) is in this molten
    state, we say that it has reached its melting
    point.The temperature depends upon the type of
    materials used. This is an essential feature in
    casting and welding.
  • A company called Brambley Furniture produces
    aluminium cast furniture by traditional methods
    using sand-casting and hand-carved wooden
    patterns. Today, aluminium is used rather than
    iron and each piece is carefully finished in
    oven-hardened acrylic paint. The image above
    shows an example of a Brambley garden furniture
    set. The chairs have been sand-cast from
    aluminium and finished in an oven-hardened
    acrylic paint. Details are
  • Material aluminiumComposition it is a pure
    metalProperties light, soft and malleable. It
    conducts electricity and heat very easily and can
    be welded and soldered by a special process.
    Aluminium is a non-ferrous metal, meaning that it
    contains no iron and will not corrode and rust if
    left outside. This is very different from cast
    steel and iron, which rusts because they are both
    ferrous metals.Uses to make boats, aircrafts,
    railway coaches and foil for packaging and
    cooking. It may also be used to make engine
    cylinder heads, pistons, cranks, window frames,
    saucepans and electrical cables.

13
Manufactured (man Made) Boards
  • Manufactured boards are made from natural timber.
    Sandwiching thin sheets of wood together called
    veneers can make manufactured boards. The veneers
    are glued together and compressed. Taking
    particles of wood, mixing them with glue,
    compressing them and applying heat can also make
    manufactured boards.
  • Very wide boards of hardwoods or softwoods are
    expensive and in some case difficult to find.
    These sheets are also liable to warp. Joining
    narrow boards end-to-end is time-consuming to
    prepare and again liable to warp.
  • Advantages of using manufactured boards
    Manufactured boards are available in large
    sheets, much wider than is possible to cut from a
    tree. The boards are stable (do not warp). Unlike
    timber, they do not absorb moisture, dry out
    according to the weather, twist and split.
    Manufactured boards may be sold in standard
    sheets of 1,525 x 1,525mm or 1,220 x 2,240mm in a
    variety of thicknesses.

14
MDF Medium Density Fibreboard
  • MDF is a type of hardboard, which is made from
    wood fibres glued under heat and pressure.There
    are a number of reasons why MDF may be used
    instead of plywood or chipboard
  • It is dense, flat, stiff, has no knots and is
    easily machined.
  • It is made up of fine particles and does not have
    an easily recognisable surface grain.
  • It can be painted to produce a smooth quality
    surface.
  • Because MDF has no grain, it can be cut, drilled,
    machined and filed without damaging the surface.
  • However, it can be dangerous to use if the
    correct safety precautions are not taken. MDF
    contains a substance called urea formaldehyde,
    which may be released from the material through
    cutting and sanding. Urea formaldehyde may cause
    irritation to the eyes and lungs. Proper
    ventilation is required when using it and
    facemasks are needed when sanding or cutting MDF
    with machinery.
  • The dust produced when machining MDF is very
    dangerous. Masks and goggles should always
    beworn. Due to the fact that MDF contains a
    great deal of glue, the cutting edges of your
    tools will blunt very quickly.

15
MDF (Continued)
  • MDF can be fixed together with screws and nails
    but the material may split if care is not taken.
    If you are screwing, the screws should not be any
    further than 25mm in from the edge. When using
    screws, always use pilot holes. MDF may be
    dowelled together and traditional woodwork joints
    may even be cut. MDF may be glued together with
    PVA wood glue.
  • Oil, water-based paints and varnishes may be used
    on MDF. Urea formaldehyde is always being slowly
    released from the surface of MDF. When painting,
    it is good idea to coat the whole of the product
    in order to seal in the urea formaldehyde.
  • Veneers and laminates may also be used to finish
    MDF. Wax and oil finishes may be used as
    finishes, but they are less effective at sealing
    in the urea formaldehyde.
  • The image above is of an MDF unit. It has been
    screwed together and the heads of the screws have
    been covered with filler.

16
Plywood
  • Plywood consists of gluing together a number of
    thin veneers or plies of softwood or hardwood.
    There is always an odd number of veneers and each
    ply is at a right angle to the one below this
    gives the material its strength. The more veneers
    used, the stronger the plywood becomes.
  • Both the types of glue and veneers determine the
    suitability of a sheet for a particular
    application. The finish quality of plywood varies
    considerably some plywood has attractive grains
    while others can contain knots.
  • Plywood is graded for exterior or interior use,
    depending on the water resistance of the glue
    used to stick the plies together.
  • WBP - (weather and boil proof) plywood - exterior
    grade This type of plywood can be used outside.
    Water-resistant adhesives are used and can resist
    a certain amount of moisture. Sheds and cladding
    are made from this material. This plywood
    requires paint or varnish to protect the outer
    veneer from the elements.
  • Internal plywood Internal plywood does not
    contain water-resistant adhesive. The code used
    to represent this plywood is 'Int' - interior use
    only. It may be used for wall-panelling, flooring
    and furniture.
  • Shuttering boxes These are made from shuttering
    plywood. Shuttering boxes are used in the
    construction industry to contain concrete while
    it sets. The material is water-resistant to a
    certain extent. The surface of this material does
    not have a decorative veneer and is generally not
    suitable for use where an attractive quality
    finish is required.
  • Marine plywood This is made with waterproof
    adhesive so that it can be used underwater. The
    material should still be protected with paint or
    varnish.

17
Chipboard
  • Chipboard is made by gluing together wood
    particles with an
  • adhesive, under heat and pressure. This creates
    a rigid board
  • with a relatively smooth surface. It is
    available in a number of
  • densities normal, medium and high
  • Normal-density is fairly soft.
  • High-density is solid and hard. It is often used
    for kitchen tops (which are laminated with
    melamine) and fire doors.
  • Medium-density is somewhere between normal and
    high density.
  • There are exterior grades of chipboard available
    but most are only suitable for internal use. All
    grades of chipboard except the high-density
    variety tend to soak up water. Once it is
    waterlogged, chipboard tends to swell and break
    down.
  • Chipboard with a veneered surface is widely used
    for flat-pack furniture and work surfaces.
    High-density chipboard is often used as the
    carcass for kitchen units, worktops and flooring.
    This type of chipboard is hardwearing, rigid and
    heavy. Other grades of chipboard are standard,
    flame-retardant, flooring, and moisture-resistant.
    Ironing or gluing on strips of veneer may
    disguise the unattractive edge of veneered
    chipboard.
  • The vpicture above is a typical, flat-pack
    bookshelf. It is made from chipboard with a
    laminated outer surface.

18
Blockboard
  • Blockboard is made up of a core of softwood
    strips. These strips may be as wide as 25mm. The
    strips are placed edge-to-edge and sandwiched
    between veneers of hardwood. The sandwich is then
    glued under high pressure.
  • Blockboard is not suitable for outdoor use
    because the glues used are interior glues. When
    using blockboard to make such things as doors or
    tables, it is important to ensure that the core
    runs lengthways in order to achieve maximum
    strength.Blockboard may be used to make
    shelves, doors, panelling and partitions and is
    sold in sheets of 2,440 x 1,220mm and is normally
    30mm thick. Screws and nails may be used to
    attach blockboard, but you have to ensure that
    you make contact with the strips of softwood and
    not the gaps between the softwood strips.

19
Ergonomics
  • Ergonomics is the study of the relationship
    between people and their environment. The
    'environment' may be buildings, furniture,
    materials or tools. Everything made, to be used
    by humans, has been ergonomically designed.
    Designers may decide that their product is to be
    used by a person of a particular height or
    weight. When you buy a bike, there is room for
    adjustment, but it is very important that you
    choose the correct size frame for your height.
  • Bikes come in all shapes and sizes. The
    difference in the frame size depends on whether
    they are going to be used by children or adults.
    There is even a difference between bikes used by
    men and women. Designers may attempt to create
    products that are suitable for universal use.
    This is difficult, as the products have to be
    adjustable in order to suit the needs and sizes
    of a wide range of people.

20
Anthropometrics
  • Anthropometrics is the study of the average
    dimensions of human beings. The measurements of
    the people who will be using a product are taken
    and the maximum, minimum and average sizes can be
    calculated. The design can then be made suitable
    for a wide range of people. In order to design
    products that will be held or used by people, it
    is essential to have collected hand and body
    sizes. We call these sizes anthropometric data.
    This data is found in books available to
    designers, in which sizes, including details of
    human reach and ideal working surface height are
    listed. Kitchen designers use this type of
    information when designing new units.
  • Anthropometrics is really the study of the human
    form and human sizes. It involves finding out
    such things as
  • how far on average people can safely reach for
    objects
  • how much space they need
  • how much force they can apply to an object
  • Anthropometric data is found in charts and
    tables. It provides specific sizes such as finger
    lengths and hand spans, but also offers average
    group sizes for people of different age ranges.
    Other sizes to consider are height, reach, grip
    and sight lines. Game and toy designers need to
    use this information for product design.
    Understand that these sizes are constantly
    changing as the population grows.

21
Sensitive Design
  • Designing for the needs of the minority is
    referred to as sensitive design. Designing
    products for people with special needs,
    disabilities, the elderly and left-handed people
    can make their lives much easier.
  • Special aids fitted to handles and taps, cups and
    kettles can help these people manipulate objects
    that we find easy to manage and they may find
    difficult to manoeuvre. People suffering from
    arthritis find it difficult to operate round door
    handles with their fingers. It is much easier for
    them to move a lever with their wrists or arms.
  • For many companies, the decision to design
    products for the minority involves high financial
    risks and very low financial returns. If you
    think about it, the needs of minority groups are
    similar to the majority from time to time most
    of us have dirty, greasy hands and fingers due to
    working outside. We may not wish to hold the
    doorknob or tap handle. It would be a clear
    advantage to operate a lever with a wrist or
    forearm.
  • People with arthritis may find it difficult to
    operate taps. The ergonomically designed unit
    seen in the picture above sits on top of the tap
    and acts as a lever, which may be pushed by a
    forearm.

22
Sensitive Design (Continued)
  • Occasionally we all have difficulty removing
    plugs from electrical sockets. This plug with an
    integrated handle shown above would benefit us
    all. It is an example of how the needs of a
    minority group are the same as the majority.

23
Softwoods
  • The cone-bearing trees called conifers produce
    softwoods. They are generally evergreen and have
    easily recognisable needle-like leaves. They grow
    in cold or cool temperate climates in countries
    such as Canada, Scandinavia and northern Russia.
  • They grow much quicker than hardwoods. Softwoods
    take about 30 years to grow. They are cheaper,
    softer and easier to work than hardwoods. Their
    seeds are held in cones. Common examples are
    pine, fir, spruce, larch, cedar and the giant
    redwood.
  • The terms 'softwoods' and 'hardwoods' are used to
    describe the leaves, seeds and structure of the
    trees, not the type of wood produced. For
    example, balsa is light and very soft to use. It
    is used to make lightweight models, but is a
    hardwood. Yew is a coniferous tree (softwood) but
    is heavy and hard to use like some hardwoods.

24
Types Of Softwoods
  • MaterialScots pine
  • Sourcenorthern Europe, Scandinavia, Russia,
    Scotland
  • Colourcream to pale reddish brown heartwood,
    cream sapwood
  • Advantagesone of the cheapest and most readily
    available softwoods. It has a straight grain, is
    fairly strong and durable, easy to work and
    finishes well
  • Disadvantagesknotty and sometimes has a blue
    stain from a harmless fungus
  • Usesit is the most commonly used softwood in
    Britain, suitable for all inside work and if
    preserved properly, can be used outside

25
Hardboard
  • Hardboards are a cheaper option to plywood, where
    strength is not required. Hardboard is made from
    wood fibre, and is extracted from chips and
    pulped wood waste. In the production process, the
    pulp is exploded under pressure. Heat and steam
    are applied to leave fine, fluffy brown fibres.
    These fibres are transformed into mats, which are
    held together with lignum and other glues.
  • The mats are then pressed between steam-heated
    metal plates to give grainless sheets with one
    smooth, glossy surface and one textured surface.
    To prevent warping, moisture is added in a
    humidification chamber. Hardboard cannot be used
    outside because it absorbs water.
  • Three basic types of hardboard are available
    standard, medium and oil-tempered. Oil-tempered
    boards are impregnated with oil, making them
    stiffer, harder and more resistant to scratches
    and moisture. A number of speciality hardboards
    are available for specific purposes. These have
    embossed, perforated, plastic-faced or veneered
    surfaces.
  • The bases of the drawers above are made from
    hardboard with decorative veneers attached to
    them.

26
Plastics
  • These garden chairs have been made from
    polypropylene, a form of thermoplastic. They have
    been injection-moulded, are lightweight, easily
    stacked and can be wiped down and cleaned after
    use. These are very hygienic chairs because there
    are very few areas where particles of food may be
    lost and bacteria form. They are inexpensive to
    buy because they have been mass-produced and are
    sold in most garden centres.
  • Material polypropyleneChemical name
    polypropeneProperties lightweight and floats.
    It has very good chemical resistance. It is hard,
    can be sterilised and has a good resistance to
    wear and tear. It has good impact resistance even
    at low temperaturesUses to make garden chairs,
    crates, waste and chemical pipes, packaging film,
    battery cases, rope, sacks, carpets, car
    appliances, and medical syringesCommon forms
    powders, granules and rods

27
Density
  • Density is the amount of matter in an object
    (mass) per unit or space occupied by the matter
    (volume). Relative density is the ratio of the
    density of a substance with that of pure water at
    a temperature of four degrees centigrade.

28
Thermal Conductivity
  • This is the movement of heat through a material
    or substance. Space crafts have to endure extreme
    changes in temperature. In space, the temperature
    is very cold but on re-entry into the Earth's
    atmosphere, the craft has to endure extremely
    high temperatures. Fire resistant materials such
    as asbestos and silica tiles are used to prevent
    the spacecraft from vaporising on re-entry. The
    image above shows the space shuttle. Image
    courtesy of NASA.

29
Semi Conductors
  • These range between a conductor and an insulator.
    They allow an electrical current to flow only
    under certain conditions. They are used in
    electronic components. They are made from silicon
    and germanium. These two are poor conductors but
    when mixed with other impurities, their
    electrical resistance can be changed.
  • The moisture detector circuit shown above
    contains a transistor, which is a small
    electronic switch. Transistors process the
    information sensors. The transistor is made from
    semi-conducting materials and is affected by heat
    and light.

30
Thermal Insulators
  • These are normally non-metals and do not conduct
    electricity very well. Usually plastics, theymay
    be used for such things as kettle or pan handles.
    It is safe for the user to pick up the
    kettlewith the phenol formaldehyde handle
    because it is a poor conductor and does not gain
    heatvery quickly.
  • It would not be safe to pick up the kettle by the
    stainless steel body because this material is
    agood conductor and gains heat very quickly.
  • Thermal insulators do not gain heat quickly but
    also do not lose heat quickly. Air is a good
    thermal insulator. Birds' wings trap air between
    the feathers, which keeps them warm in winter.
  • Loft insulating and cavity wall insulation reduce
    the heat loss at home. Loft spaces and pipesare
    lagged with this material. The lagging traps the
    air between it and the copper pipes. Thisblanket
    of air prevents the pipes from losing too much
    heat and prevents them from cracking inthe
    winter.
  • THERMAL EXPANSION
  • Some materials expand when hot. The length of a
    steel bridge may increase in the summer. In order
    to allow for this change in length, expansion
    gaps are built into the bridge construction.

31
Electrical Conductivity
  • This refers to the movement of electricity
    through a material. All materials attempt to
    resist the flow of electricity to a certain
    extent some materials resist it more than
    others. Metals such as copper, gold, silver and
    some gases allow electricity to flow through them
    very easily. We say they are good conductors of
    electricity.Some materials resist the flow of
    electrical current and are called good
    insulators. These normally include the non-metal
    materials such as wood, glass and plastics.

32
Veneering
  • Veneering is the art of applying a thin sheet of
    decorative wood onto a piece of wood that may be
    plain or unattractive. It is a very old technique
    and was started in the 17th century. At the same
    time, people began to import more exotic woods
    into the country. Exotic woods are rare and
    expensive today. It would be too costly to make
    mass-produced furniture completely out of an
    exotic wood like African walnut. As a result,
    gluing veneers onto the surface of cheaper
    materials can produce manufactured boards. It
    forms the basis of mass-produced furniture today.
  • Decorative effects can be achieved by matching
    veneers and making patterns. This is called
    marquetry. The image above is of a cabinet that
    has been veneered using decorative hardwood
    veneers. Cutting shapes from the veneer and
    arranging them into geometric patterns has
    created the patterns on the surface.
About PowerShow.com