Timbers Flashcards
Shrinkage
Twists, warps, cups and/or bow timber when timber drying is uncontrolled
Splits
Occur at ends of timber if drying process is not controlled
Shakes
Cracks in timber due to uncontrolled drying OR if felled tree hits ground
Knots
When branch grows from tree trunk
Weaken timber, lead to decay, release resin which makes applying a finish difficult
Fungal attack
When timber is left unseasoned
Fungus cause disease and ruin wood
Types of defects
Shrinkage, Splits, Shakes, Knots, Fungal attack
Jelutong
Close grained, pail colour, medium hardness and toughness, easily worked
e.g. pattern making
Beech
Hard, strong, close-grained, light brown with flecks of brown, prone to warping and splitting, difficult to work
e.g. furniture, children’s toys, tool handles, bench tops
Mahogany
Strong, durable, deep reddish colour, available in wind planks, fairly easily worked but can have interlocking grain
e.g. good quality furniture, panelling, veneers
Oak
Hard, tough, durable, open-grained, can be finished to a high standard
e.g. high-quality furniture, flooring
Balsa
Lightweight, soft, easily worked, pale, weak, not very durable
e.g. model making, floats, rafts
Western Red Cedar
Resistant to weathering and decay, light reddish-brown colour, close straight grain, easily worked
e.g. fencing
Scots Pine
Straight grained, light yellow, soft, easy to work, can be knotty
e.g. interior joinery and furniture, window frames
Parana Pine
Distinctive open straight grain, contains few knots, strong, durable
e.g. internal joinery, staircases
Manufactured boards
Commercially produced timber sheets
Manufactured board advantages
- Available in much larger sheets
- Consistent properties throughout board
- More stable (less likely to warp, twist)
- Use lower grade timber so cheaper and more environmentally friendly
- Can be faced with veneer to improve appearance
- Well suited to CNC machining and volume production due to consistent properties
Medium Density Fibreboard
Made from compressed fine wood fibres bonded with resin, cheap, flat and smooth surface
e.g. cabinets, shelves
Plywood
Made from an odd number of wood veneers glued together with alternating grain, top and bottom veneers are same grain direction to improve strength, very strong, flat smooth surface
e.g. exterior wall sheathing, roofing
Chipboard
Made from wood chips bonded with resin, inexpensive, limited strength
e.g. kitchen worktops, flat pack furniture
Hardboard
Made from compressed fine wood fibres bonded with resin, one smooth side and one textured, very cheap
e.g. drawer bases, backs of wardrobes
Jigs Advantages
- Speed up process
- Reduce risk of human error
- Reduce unit cost of part
- Safer
- Increases accuracy
- Increase consistency
- Reduce wastage
Jigs Disadvantages
- Only cost effective for when many parts required
- Increase initial cost of part
- Requires high skill to produce
Marking out
- Ensure one face and one edge planed smooth (‘face side’ and ‘face edge’)
- Pencil, ruler, marking knife
- Try square for 90 degree angles
- Mitre square for 45 degree angles
- Sliding bevel for any angle
- Marking gauge for line parallel to edge
- Mortise gauge for double parallel line
- Template for irregular/identical parts
