Timbers Flashcards
What trees do hardwoods come from?
Deciduous trees
How long do hardwood trees take to grow?
60+ years
Where do the majority of hardwoods grow?
n tropical regions, such as Amazonian climates, while others grow in temperate climates such as Europe.
Why is the grain of hardwoods very close?
Because the growth rings are much smaller than softwoods
What are examples of hardwoods?
Beech, mahogany, oak, balsa, jelutong, birch and ash
What are the physical properties of beech?
Beech has a slight pink tint and a close grain
What are the working properties of beech?
Beech is tough, durable and is smooth to finish
What does mahogany look like
Mahogany has a dark-reddish colour and a very close grain
What are the working properties of mahogany?
durable, cuts and polishes easily, gives a fine finish, used for high-quality furniture
What are the physical properties of oak?
Oak is a moderate-brown colour with unique and attractive grain markings
What are the working properties of oak?
Oak is tough and durable, it polishes well, and is used for quality furniture
What does balsa look like
Pale and wide-spaced grain
What are the working properties of balsa?
Balsa is lightweight, very soft and easy to form, often used to make models
What is jelutong used for?
Model making and vacuum forming moulds
What is the grain of jelutong like?
Close and even
What are the working properties of jelutong?
easy to cut and shape, soft
Why is jelutong not used for structural uses?
Because it is so soft
What is birch used for?
Veneers in furniture
Why is birch selected?
Because of its even grain
Is birch easy to cut and shape?
Yes
Birch is unfortunately liable to…
rot and insect attacks
What is ash used for?
ladders, tool handles, walking sticks and sports equipment
What are the working properties of ash?
Strong, flexible, finishes well
Like birch, ash is liable to…
rot and insect attacks
What trees do softwoods come from?
Coniferous trees
What sort of leaves do coniferous trees have?
Needle-like
Do the leaves of coniferous trees stay on during the winter or not?
They stay on
What regions do softwoods usually grow in?
Colder regions, such as alpine climates
Why is larch a softwood exception?
Because it loses its leaves during the winter
How quickly do softwoods grow?
Very quickly, it can take between 20 and 30 years
Why are softwoods cheaper than hardwoods?
Because they grow quicker
Name 3 softwoods:
pine, cedar and larch
What are the physical properties of pine?
Pine is pale coloured with an aesthetically pleasing grain
What are the working properties of pine?
Lightweight, easy to form, used for construction and decking, in furniture
What are the physical properties of cedar?
Lightweight, pale colour with even texture
What are the working properties of cedar?
durable, strong, shock resistant, more expensive than pine but not as strong
What is larch used for?
-exterior cladding,
-floorboards,
-furniture,
-small boats
-fence posts
and is selected because it is durable and resistant to water. It is, however, more expensive than other softwoods.
What are manufactured timbers made from?
leftover wood such as sawdust and wood chippings.
What’s cheaper: manufactured boards, hardwoods or softwoods?
Manufactured boards because they are made from leftovers, and they can be made into large sheets (rather than being restricted to the size of a tree trunk).
What is a memory tip for manufactured boards?
S- Squashed
L- Layers
I- Industrial
M- Manmade
C- Chipboard H- Hardboard I- Inexpensive M- MDF P - Plywood
What is cedar used for?
furniture, veneers, model making, boat building
What are some examples of manufactured timbers?
MDF, plywood, chipboard
What is MDF used for?
general carpentry work ,flat-pack furniture ,as a veneer
Can MDF be painted?
Yes
What does MDF look like?
smooth, light brown
What are the working properties of MDF?
Smooth and easy to finish, absorbs moisture so not suitable for outdoor use
What is plywood used for?
furniture, shelving, construction and toys
How is plywood made?
Layers of veneer glued at 90 degree angles for strength, aesthetically pleasing outer layer
What forms is MDF available in?
water and fire resistant forms.
What are the working properties of plywood?
Easy to cut and finish, can be stained or painted
What is chipboard made from?
Chips of wood glued together
What is chipboard commonly covered with?
a real wood veneer or melamine sheet
Why does chipboard need a layer of veneer for protection?
Because if chipboard is exposed to moisture it will swell up and fall apart.
What is chipboard used for?
kitchen worktops, flat-pack furniture, diy work
Why is chipboard cheap?
Because it’s made from waste timber.
What is a knot?
A knot in timber marks where a branch grew out of the tree. In a plank of timber it appears as a circular part within the grain.
What is a veneer?
A thin decorative covering of fine wood applied to a coarser wood or other material.
How can the colour of a wood plank be altered?
using wax, varnishes, stains and paints.
What different types of paint can you get?
glossy, matt or silk.
What do wood stains do to timbers?
Enhance their appearance and provides protection. An additional coat of varnish after staining gives even further protection.
What are the advantages of oiling or waxing wood?
Oil and wax soak into timber and can be used to enhance the natural appearance of the timber. They also reduce a woods exposure to moisture
What appearance does a varnish give to wood?
It gives the wood a shiny finish
Why is varnish usually applied to wood in many layers?
so that the thickness of the varnish is more durable.
What is shellac?
A resin
How are layers built using shellac?
y rubbing the polish on to create a finish called French polish. It tends to be used on expensive furniture to give it a glossy shine but can be easily damaged by heat and water.
Do finishes need to be added on to a veneer?
Yes
What are growth rings?
A new layer of bark produced by softwoods and hardwoods each year
Are the growth rings close together for hardwoods?
yes
Are the growth rings close together for softwoods?
no
What 2 long vessels run through hardwoods?
fibres and pores
What are fibres?
A cell within the wood that can be extracted to make other products such as paper.
What do pores do?
They allow water to travel within the tree. When cut, these appear as tiny holes that often need to be filled with wood filler to create a smooth finish.
What environmental issues can occur as a result of de-forestation?
- soil erosion, that can lead to landslides
- an increase in global warming, as less tress are removing C02 from the atmosphere
Why are hardwoods planted in managed forests?
Because they take a long time to grow and so cutting hardwoods can lead to hardwood shortages
What is trend forecasting?
When manufacturers and retailers try to predict the trends or fashions over the following years so that they can design and make products that people will want in the future.
It is possible to minimise the environmental impact of cutting tress by…
…planting more trees than the trees that are cut
What boards are made from recycled timber?
plywood, MDF, chipboard and blockboard
What is blockboard?
Blockboard has a sandwich construction, where the core is made from strips of softwood and the 2 other outer surfaces are made from hardwood veneer to produce a relatively lightweight manufactured board that is strong and durable.
Can MDF be recycled?
No, because the gluing process makes it very difficult to recycle the timber a second time around
How does the supply and demand of timbers pollute the environment?
- Transportation often involves burning fossil fuels, which adds to the carbon footprint of timber.
- Wastage of small branches and leaves are often burned and this releases carbon dioxide.
- Processes such as kiln drying use energy, adding to the ecological footprint of timber.
What are the 6 r’s?
Refuse, rethink ,reuse, reduce, repair, recycle
What should you think of when choosing a timber?
aesthetics, environmental factors, genetic engineering, seasoning, availability, cost, social factors, trends & poularity
How can the way a timber looks be altered?
staining, varnishing, oiling, waxing, painting, laminating
What is a sustainable forest?
a forest that is carefully managed so that as trees are felled they are replaced with seedlings that eventually grow into mature trees.
What is seasoning?
Drying a tree to reduce the water content. (from 85% to 10%)
What are the advantages of seasoning timber?
Seasoning increases strength, stability and resistance to decay
What are the 2 types of seasoning?
air seasoning and kiln drying
What is air seasoning?
leaving the planks outside for a few years till they are 18% water
What is kiln drying?
pumping steam and warm dry air around the planks till they are 10% water
What do social factors include?
personal preferences age background finances interests
What is built-in product obsolescence?
When manufacturers or designers deliberately design products that stop working after a certain amount of time so that consumers are forced to buy new products
What is stock size?
The standard size a material is processed to , ready for a manufacturer to use
What is timber referred to once it’s been cut at a sawmill?
‘rough cut’
Hardwoods and softwoods are normally sold in lengths called:
regular sections, mouldings, dowels, sheets
What is a moulding?
A piece of timber that has a decorative pattern along its length
What is a dowel?
A cylindrical rod , usually made of wood, used to align and fasten pieces together
What is used to cut mouldings?
A spindle moulder
What is moulded timber used for?
Skirting boards and dado rails
What size are manufactured boards sold in?
2,440 mm × 1,220 mm. However, these are often too large for customers to transport, so part sheets can be sold, such as 1,220 mm × 6,10mm (half the size).
What is tension?
A pulling force
What is compression?
A pushing force
What is shear?
The forces acting across a material
Why does timber have a good tensile strength and a good compressive strenght?
Because of its fibrous structure
If untreated, timber…
does not have good bending qualities and often snaps when bent.
If timber is soaked in water or exposed to steam, what happens?
It can become more flexible
What is kerfing?
when slots are cut along the inside face of the timber to be bent, allowing for the inside face to cope with the compressive force
What is kerfing?
when slots are cut along the inside face of the timber to be bent, allowing for the inside face to cope with the compressive force
How can a rectangle of timber be strenghthened?
by putting a thick panel inside the frame, by adding a diagonal strut or triangle across each of the corners, by adding a strut from corner to corner.
What is a strut?
A beam that is used in structures to resist compressive forces - they either form the structure itself, eg a roof, or reinforce existing structures, eg diagonal beams in scaffolding.
What is a lamination?
At least 2 layers of material bonded together.
How is plywood strenghtened?
By having each layer of timber glued at right angles to each other. This makes the timber hard to bend in any direction.
What is a brace?
a bar that is added to strengthen a material or product. They usually go diagonally across a material to make triangle shapes.
Explain what a tie bar is and what it does?
A tie bar is used in a similar manner and holds the frame in shape. While a strut resists compression, a tie bar resists tension.
Where is a tie bar used in construction?
In construction, a tie bar sits across the structure where the roof meets the walls and acts to resist the weight of the roof.
What’s an advantage of embedding composite materials into a timber?
natural straighten, appearance and durability can be improved
What does a router do?
A router rotates a cutting bit at high speed.As the cutting tool passes over or along the edge of the timber, a cut or profiled shape is made. Routers can plunge into a material to cut holes. They can follow jigs or patterns
Which saws are most commonly used for cutting timber?
The circular saw and bandsaw
What does a mortiser do?
A mortiser makes a square hole for a mortise and tenon joint.
What is a bag press used to do?
to create curved shapes in laminated timber veneers. The bag is sealed and the air is sucked out while the glue dries between the veneers.
What are the 4 types of production?
prototype/one-off, batch, mass and continuous
What are examples of mass-produced timber products?
mouldings, doors and pencils.`
What are examples of continuously produced products?
stock sizes of timber and paper
What are marking-out methods?
Set square, jigs, fixtures, templates, patterns
What are jigs used for?
to guide a drill or saw to cut in exactly the same place each time on every piece of timber - reduces marking out time thus increasing the efficiency of the manufacturing process
What are fixtures used for?
Holding a piece of timber in place whilst it is being worked on
What are templates used for?
made out of paper, card, thin metal or wood, these are drawn around to mark out the same shape repetitively, with the aim of speeding up the marking-out process and decreasing the chance of an error occurring
What are patterns?
a collection of templates that go together to make a part, or all, of a product
What is sub-assembly?
a series of components that, when assembled, form a part of a product. For example, a wooden knob turned on a wood lathe may be bought pre-made to add to a piece of furniture or to a door. This saves manufacture and assembly time and means that additional machinery, such as a lathe, does not have to be bought and operated.
Why is it important to mark out shapes on timber as close as possible?
To minimise waste, and to save money
What digital device is used to measure timbers accurately?
A digital vernier caliper
