wood design and manufacture. wood useful, natural material hard and fibrous in nature 3...
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Wood
Useful, natural material Hard and fibrous in nature 3 classifications to wood:
Hardwoods (slow growing 100 years from warmer climates)
Softwoods (quick growing 30 years) Manufactured boards (man made composites)
Each species of tree provides different timber that varies in colour, grain pattern, texture, strength, weight, stability, durability, cost and ease of working.
Hard woods
Hardwoods - broadleaf, deciduous trees shed their leaves in winter or evergreen trees that keep their leaves throughout the year.
Delicate with a shorter life span. Wood - stronger and in demand,
more expensive
Hard woodsName Origin/colour properties uses
Beech Europe/whitish pine to pale brown
Strong, straight grained, even texture
Furniture, turnery
Elm Europe/light, reddish brown
Tough, durable, difficult to work, cross-grained
Turnery, furniture, outdoor use
Oak Europe: light brownJapan: pinky-brown
Strong, durable, hard, tough, tannic acid that corrodes steel leaving blue stains
Furniture, flooring, boat building, veneers
Ash Europe: pale cream and light brown
Straight grained, coarse texture, good elasticity, works and finishes well
Sports equipment, tool handles, cabinet making, laminating
Mahogany
Central+South America, W.Indies, W.Africa/ pink reddish brown to deep brown
Fairly strong, medium weight, easy to work, durable, prone to warp
Furniture, panelling, veneers
Teak Burma, India/Golden Brown
Hard, strong, durable, natural oil – water resistant, works well but blunts too quickly
interior/exterior furniture, boat building
Walnut Europe, USA/ yellow, brown, bronze, dark lines
Attractive grain, cross grain makes finishing difficult
Veneers, furniture,
Soft woods
Softwoods - conifer trees that are cone bearing.
They have leaves all year round, known as evergreen,
Strong and withstand most weather conditions.
Cheaper to buy and readily available most of year.
softwoods
Name Origin/colour Properties/characteristics
uses
Scots pine Northern Europe, Russia/ Cream, pale brown
Straight grained but knotty, fairly strong, easy to work
Furniture, joinery, construction work
Red Cedar Canada, USA/dark, reddish colour
Light, soft, weak natural oils make it weather durable
Exterior shingles, cladding, sheds
Parana Pine South America/ pale yellow with red/brown streaks
Hard, straight, know-free, strong and durable, smooth finish, tends to warp, expensive
Quality interior joinery: staircases, built in furniture
Spruce (whitewood)
Northern Europe, America/creamy white
Fairly strong, small hard knots, resistant to splitting, resin pockets, not durable
Construction, general indoor work
Manufactured Boards
Strong, stable and economical Suited to mass produced furniture. Boards available in large sheets Beneficial to the environment – use up waste
products from the sawmill that are made into particles
Advantages: cheap, stable, thin veneers of expensive timers can be used to decorate, boards available in large sheets.
Disadvantages: edges require ‘facings’, repair and maintence can be difficult.
Manufactured BoardsName Composition Properties/
working characteristics
Uses
Plywood Thin veneers, cross laminated using odd number of layers
Stable, strong and easy to machine
Furniture, joinery, construction work
Block board 25mm strips glued together and faced with ply
Stiff, heavy, good load-bearing
Furniture, worktops, veneer groundwork
Hard board Highly compresses wood fibres
Cardboard like, weak and brittle
Low cost furniture parts – cabinet backs, drawer bottoms
MDF(Medium Density Fibreboard)
Compressed wood fibres
Easily machined, moulded and painted
General shell/painted work, veneer ground
Chipboard Compressed wood chips
Stiffness and strength vary with density(thick)
Furniture shell, good veneer ground
Adhesives
Used to bind two pieces of material together Selection of which adhesive depends on
purpose of product and material to be joined. Wood glue join timber products Some will allow for repositioning and
adjustment Others can bond straight away. Adhesives will not usually bond to greasy or
wet surfaces
Types of adhesives for woods PVA glue(polyvinyl acetate)
Mostly used wood glue. Sold ready mixed Strong and doesn’t stain Excess wipes off with damp cloth Light cramping required Seal edges of MDF before painting
Epoxy Resin Two part adhesive for unlike materials Bond glass, ceramics, wood, metal and
thermosetting plastics Mixing resin triggers chemical reaction that sets
adhesive Waterproof, good gap filler and electrical insulator Restricted to small scale applications as cost are
high Not suited to thermoplastics
Types of screws
COUNTERSUNK - SLOT HEAD: This can be used for general woodworking for example fitting hinges to doors. Because the screw is countersunk it can be tightened 'flush' to the surface of the material.
POZIDRIV HEAD: Used with special screw drivers which will not slip when pressure is applied. This is ideal when using screws in corners or confined spaces.
ROUND HEAD SCREW: These are used for fixing pieces of material together where countersunk holes are not being used. Round head screws can look quite decorative especially if they are made of brass.
Types of screws (contd)
RAISED HEAD SCREW: Used to fit door handle plates and decorative features that must look good.
CHIPBOARD SCREWS: The thread on this type of screw extends all the way along the length. It is best used with chipboard
SELF-TAPPING SCREWS: these are normally used to cut a thread in metal. A hole is drilled in the metal, a fraction smaller than the width of the screw. The self-tapping screw is then turned into the hole cutting a thread.
Types of nails ROUND WIRE NAIL - This is used for general work. It is not attractive
in shape and it can split wood when hammered in position
OVAL WIRE NAIL - This is a long nail and care must be taken when it is hammered into the wood. It is unlikely to split the wood.
LOST HEAD NAIL - This is ideal if it is necessary to hide the head of the nail as a punch can be used to hammer the head beneath the surface level.
PANEL PIN - A very popular way of joining woods although glue is usually included as part of the join.
TACK - Can be used for fixing textile materials to wood for example, fixing upholstery to furniture.
HARDBOARD PIN - The diamond shaped head is hidden when used in materials like hardboard
Knock down fitting
Can be put together easily, normally using only a screw driver, a drill, a mallet/hammer and other basic tools.
Temporary joints - many used to permanently join together items such as cabinets and other pieces of furniture that are purchased in a flat pack.
Knock down fittings PLASTIC CORNER BLOCK (FIXIT BLOCKS):
The corner block is pressed against the two pieces of material (normally wood based). Screws are used to fix the block into position. This type of joint is used to fit modern cabinets such as those found in a kitchen. It is a relatively strong joint although it has the advantage that it can be dismantled using a screwdriver.
NATURAL WOOD FITTING (SQUARE SECTION BATTEN): A piece of material such as pine can be drilled and
screws can be passed through these holes. This gives a cheap and effective knock-down joint. The screws are normally countersunk into the knock-down fitting.
RIGID JOINT: These are normally molded in plastic which makes
them strong. Screws pass through the four holes which hold the sides at each corner firmly together.
Knock down fittings TWO BLOCK FITTING (LOK-JOINTS):
These are made from plastic. A bolt passes through the first fitting into the thread of the second. As the bolt is tightened it draws the two fittings together. The pins help keep the fitting straight. This gives a very strong joint and it can be dismantled using a screwdriver.
CAM LOCKS: The disk fits into a recess in the first side of the
cabinet. It rotates by inserting a screwdriver into the slot in its side. The shaft is screwed into the second side of the cabinet. The collar of the shaft is passed through the hole in the second slot in the disk. When the disk rotates the shaft is locked in position. This keeps both sides of the cabinet locked together.
SCAN FITTINGS These are strong enough to be either permanent or
temporary joints. The cylinder is inserted into the first side of a cabinet in a pre-drilled hole. The screw is then pushed through the hole in the second side until it meets the cylinder. It can then be tightened with a screw driver until both sides of the cabinet pull together.