wood Flashcards
hardwoods
- come from deciduous trees
- close grain structure - harder and stronger
- can be sanded to a smoother, finer finish
- take 60-200 years to mature - generally more expensive than softwoods
- grown in central Europe, West Africa, Central and Southern America
softwoods
- come from coniferous trees
- open grain - less dense and strong
- take 10-30 years to mature - generally cheaper
- grown in cool Northern parts of Europe, Canada, and Russia
seasoning
- must be seasoned in order to reduce its moisture content
- air seasoning: air flows around stacked timber and dries out moisture, can take a couple years
- kiln seasoning: timber is housed in a kiln where steam is allowed to flow around the timber - much faster process
potential defects from drying in an uncontrolled way
- shrinkage - can twist, warp, cup or bow
- can also result in split ends
- can also result in cracks called shakes
knots
- form when a branch grows out of the tree trunk
- can cause several problems: weaken the timber and lead to decay
fungal attack
- occurs when timer is left unseasoned
- will cause disease and ruin the wood
jelutong
- hardwood
- pale colour, medium hardness and toughness, easily worked
- used for pattern making
beech
- hardwood
- hard, strong, light brown, prone to warping and splitting, difficult to work, does not splinter (safe)
- furniture, children’s toys
mahogany
- hardwood
- strong, durable, reddish colour, available in wide planks, rare, expensive, can be polished to a high gloss finish
- good quality furniture, panelling and veneers
oak
- hardwood
- hard, tough, durable, open-grained, can be finished to a high standard
- timber-framed buildings, high quality furniture, flooring
balsa
- hardwood
- lightweight, soft and easily worked, pale, weak and not very durable
- used for model-making, rafts
western red cedar
- softwood
- weather and decay resistant, reddish-brown, easily worked
- fencing, fence posts, cladding
scots pine
- softwood
- light yellow, soft and easy to work with, can be quite knotty
- interior joinery, furniture, window frames
parana pine
- softwood
- distinctive open, straight grain, a few knots but strong and durable, relatively inexpensive
advantages of manufactured boards
- available in much larger sheets
- consistent properties throughout the board
- make use of lower-grade timber, so more economic and environmental benefits
- less likely to shrink, warp or twist
two types of manufactured board
- laminated boards: gluing large sheets or veneers together
- compressed boards: gluing particles, chips, or flakes together under pressure
MDF
- manufactured board
- compressed fine woof fibers bonded with resin
- relatively inexpensive and smooth, flat surface
- used for furniture, flooring and cabinets
plywood
- manufactured board
- made from wood veneers glued together with alternating grain - each grain is layered at a 90 degree angle to the last and number of layers is always odd so two outside surfaces have the grain running in the same direction
- very strong, flat, smooth surface
- roofing and flooring
chipboard
- manufactured board
- wood chips bonded together with resin
- limited strength
- used for inexpensive construction material
hardboard
- manufactured board
- compressed fine wood fibres bonded together with resin
- one smooth side and one textured side
- inexpensive
- used for drawer bases and backs of wardrobes
veneers
thin sheets of natural timber
- construction veneers - typically used in the manufacture of plywood
- decorative veneers - applied to manufactured board to enhance their appearance
ecological footprint
- renewable and biodegradable
- recyclable
- generally good lifespan
- deforestation - destroys carbon sinks - destroys habitats and reduces biodiversity - contributes to global warming
- fossil fuels required to power machinery
(less compared to processing of other materials such as metals)
social footprint
- ethical issues with deforestation
- FSC ensures that forests are correctly managed
- employment opportunities
- endangered wildlife protected
- trees are replanted
life cycle of timber
1) planted
2) felled
3) transported
4) seasoned and shaped
5) transport and manufacture of product
6) use
7) landfill/compost/burned for fuel
PBS
planned both sides
PSE
planned square edge
PAR
planned all round
dowelling
cylindrical timber, useful for making wooden rails
one-off production
- used to manufacture bespoke timber products
- high quality timber often used by high skilled woodworkers
- generally very labour intensive and time-consuming, and therefore expensive
batch production
- a range of identical wood products made to a high consistency
- materials can be purchased in bulk, reducing the cost
- machinery is set up, more efficient, and less skilled labour is required
- unique appeal of “one-off” production is lost
jig
a device specially made to perform a specific part of the manufacturing process - can be used when cutting, drilling, sawing or gluing
- useful when process has to be carried out multiple times
- more efficient and reduce the risk of human error
- increase accuracy, consistency and reduce wastage
- increase initial cost and only cost effective if large number of similar parts are required
- high level of skill to produce
mass production
- manufactured in large quantities
- bulk buying significantly reduces cost
- specialist machinery used, and so unskilled workforce can be used
continuous flow production
- identical products made continuously 24/7 due to high demand
- requires highly specialised equipment and extensive use of CAM
- process can become fully automated
- requires large initial investment
disadvantages of high-volume production
- loss of employment
- high set-up costs
- products lose uniqueness
- more energy needed to power factories, contributing to carbon footprint
wastage
cutting, sawing or shaping timber to form a desired shape
addition
joining timber components together using wood joints and/or gluing
deforming and reforming
producing shapes by processes such as laminating and steam bending
marking out
1) face side and edge - one face and one edge smooth
2) pencil or marking knife (more accurate cut line)
3) ruler/ try square (T-square) or mitre square (45 degree angle) / sliding bevel (set to any angle)
4) marking gauge (parallel line) or mortise gauge (double parallel line)/ pre-drawn template
tenon saw
will cut straight lines, provided wood is held firmly in a vice of G-clamp
hand saw
used for cutting large pieces of wood
coping saw
used for cutting curves - difficult to use accurately, should always cut slightly away from the line
bandsaw/hegnersaw
mechanical saws that speed up process and improve accuracy
disc sander/belt sander/linisher
machines that use coarse glass paper to shape and smooth wood
planes/chisels
mechanical ways to shape wood - chisels can also be useful for cutting joints
hole saw vs forstner bit
- hole saw: large holes
- forstner bit: flat-bottom holes
joints
draw them and check in book
adhesives
- PVA (polyvinyl adhesive) is a strong glue but takes a long time to dry
- contact adhesive is a medium strength glue but provides a quick joint
- epoxy resins can be used to join wood to other materials such as metals and polymers
woodscrews
- quick and convenient method to join two components together
- made from steel with protective coating to prevent rusting
- designed for use with power tools such as cordless drill
KD fittings
- knock down fittings often used with flat pack furniture
- enable furniture to be sold unassembled, taken home in carboard box and assembled using simple tools
- flat pack furniture has greatly reduced the cost of buying furniture
lamination
gluing veneers of natural timber in between two halves of a mould to create complex shapes
steam bending
steaming a section of natural timber to make it pliable, clamped to a mould then held for several hours until cooled
surface preparation
- should be sanded using a variety of different grades of sandpaper to remove any marks and smooth the surface
- should be free from dust, oil and dirt
wood stain
will change the colour of the timber but offers little protection
wood preservative
soaks into the timber and protects it from moisture and insect attack - can also include a stain
- generally used on garden sheds and fencing
- tanalising - pressure applying a preservative
varnishes
offer good protection, often used clear but can come in a variety of colours
oils
easy to apply and reasonable protection
- not particularly long lasting and need a recoating each year
- e.g. danish oil and teak oil
wax polishes
low level of protection and recommended on top of a varnished surface
paints
high level of protection and available in a wide range of colours
- most require an extra level of preparation/undercoat
