l2 bench joinery unit 212 power point presentation 4
TRANSCRIPT
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Level 2 Diploma in Bench Joinery
PowerPoint presentation
Presentation 4
Unit 212: Produce setting out details for bench joinery products
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Level 2 Diploma in Bench Joinery
Aims of the sessionBy the end of this session you will be able to identify:
• different types of bench joinery materials
• the common defects found in joinery materials
• different sizes of materials used in bench joinery
• the tools used in bench joinery production.
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Joinery materialsTimber comes in many varieties:
• hardwoods• softwood• Canadian lumber sizes (CLS)• planed all round (PAR)• sawn• first-class joinery quality• plus many standards and types of man made board.
Most of these will be readily available and are in constant use within the construction industry. Some of the more valuable hardwoods may need to be ordered from your supplier.
Our main concern is with those materials used in the bench joinery section of industry.
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Types of timberOn the next slide you will find a list of timbers.
Using the internet, find out if they are hardwoods or softwoods.
Find a picture of each and produce a log book of species.
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Types of timber continuedPine Cedar Oak
Mahogany Cherry Greenheart
Fir Pruce Redwood
Teak Maple Walnut
Birch Hickory Hemlock
Ash Willow Beech
Redwood Iroko Utile
Merantti Weeping willow Tulip wood
Lignum vitae Western red cedar
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Joinery materials continuedIt used to be that softwood ‘sorted’ first-class joinery quality timber had to have no more than one knot every 300mm, but the modern major joinery companies now import timber that has had all blemishes, knots and natural defects removed and what is left is finger jointed together to give only top-quality timber.
There are many things to consider when choosing the type of timber to use:
• the client – he or she is paying, so it is their choice
• the architect – he or she interprets the client’s ideas and specifies the materials to be used
• how the log has been converted, eg through and through, tangential, quarter sawn, plain, rift. The type of end product will decide the type of log conversion to be used
• the buyer – can he or she source the correct timber for the job at the right price?
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Joinery materials continuedWe also need to consider:
• durability – how long will it last
• weight – how much will the finished product weigh; will it be too heavy?
• workability – how easy or difficult it is to use; will it produce the desired effect?
• ability to take preservatives and finishes.
And in the case of man-made boards:
• quality of finish
• interior
• moisture resistant (MR)
• weather and boil proof (WBP).
In most cases this will have been taken into consideration by the architect.
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Natural and seasoning defects• As with all naturally growing things, trees are subject to natural and
inflicted defects.
• Trees have natural defects – sloping grain, knots, shakes, upset, grain, waney edges, resin pockets, foreign bodies, decay, pith, blue stain, insect infestation.
• Seasoning defects, such as cupping, winding, twist, case hardening, bowing, springing, collapse, will all affect the selection of timber to be used in bench joinery production.
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Natural and seasoning defects
There are many other natural and seasoning defects. Look on the internet or use other sources to find two more examples and write a paragraph about each.
Cupping
Split end
Twisting
Cup shakeThunder shakeRing shake
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Sizes of timberHardwood is generally more expensive than softwood and as a result is used for decorative or aesthetic structural components where the ‘look’ of the finished timber is important.
There are a vast number of hardwoods available each having their own attraction. As a result, the timber is usually imported as boards of varying thicknesses which allows the end user to re-cut the board and finish it to the required dimension.
Hardwood is expensive. The price is subject to many factors but is related to its origin, which may be either temperate, sub-tropical or tropical. Because of this diversity, the sizes and sections will vary between region.
BS 5450:1977 gives the basic sizes of sawn hardwoods.
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Machines hardwood sizes12 x 50mm 9 x 47mm 32 x 38mm 27 x 35mm16 x 38mm 12 x 35mm 35 x 50mm 27 x 45mm
16 x 75mm 12 x 70mm 32 x 115mm 27 x 106mm
16 x 100mm 12 x 95mm 32 x 138mm 27 x 133mm
16 x 125mm 12 x 120mm 38 x 75mm 33 x 70mm
16 x 150mm 12 x 145mm 38 x 100mm 33 x 95mm
25 x 50mm 20 x 45mm 38 x 115mm 34 x 106mm
25 x 100mm 20 x 95mm 38 x 138mm 34 x 131mm
25 x 125mm 20 x 120mm 50 x 50mm 45 x 45mm
25 x 150mm 20 x 145mm 50 x 75mm 45 x 70mm
25 x 175mm 20 x 170mm 50 x 100mm 45 x 95mm
25 x 200mm 20 x 195mm 50 x 125mm 45 x 120mm
25 x 225mm 20 x 220mm 50 x 150mm 45 x 145mm
25 x 250mm 20 x 245mm 50 x 200mm 45 x 195mm
32 x 38mm 27 x 35mm 63 x 75mm 57 x 70mm
32 x 50mm 27 x 45mm 63 x 100mm 57 x 95mm
32 x 115mm 27 x 106mm 75 x 75mm 70 x 70mm
32 x 138mm 27 x 133mm 75 x 100mm 70 x 95mm
38 x 75mm 33 x 70mm 75 x 150mm 70 x 145mm
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Sizes of timber continuedSoftwood
The cross-sectional sizes of timber vary depending on whether supplies are from North America or Europe. If, for example, Canadian mills make no allowance for shrinkage when the wood is dried, a section 50mm x 100mm when sawn to that size would be reduced to say 46mm x 96mm when dried, whereas European mills cut their sections over size to allow for any shrinkage.
As timber hardly shrinks at all in length when dried it is not necessary to make any provision for this.
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Sizes of timber continuedWhere timber has to be re-sawn to produce smaller section sizes then allowances will have to be made for the sawn cut.
This is known as its ‘kerf’ and is usually about 2.5mm wide.
As an example, a 100mm x 50mm section is cut into four pieces 25mm x 50mm and would mean making three saw cuts at 2.5mm each. The result would be an undersized section approx 23mm x 50mm.
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Sizes of timber continuedIn machining any type of timber, the actual sizes available in the locality is all important. Waste must be avoided at all costs. The adoption of standard timber sizes will:
• reduce the overall cutting and machining waste
• reduce the time spent
• cut down on short lengths of timber building up in the workshop.
Basic hardwood sizes are shown as:
Depth x Thickness
mm x mm
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Structural timber sizesCommonly available target sizes of sawn softwood structural timber
Commonly available lengths of softwood structural timber
Source: BS EN 336:2003(E).
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Timber contentMoisture content and end user of timber
Moisture content (%) End user of timber
Air drying
28–30 Shrinkage begins
25 Pressure treated preservative or creosote
20–22 Sawn carcassing timber
17–18 External joinery timber and structural timber
14 Internal joinery for unheated buildings
10 Internal joinery for heated buildings
Kiln drying8–9 Internal joinery close to heating
source0–1 Oven dry
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Moisture
Image courtesy of David Walker. Reproduced with permission.
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Tools for setting and marking out
Combination squareCarpenter’s try square
Marking gaugeMortice gauge Cutting gauge
Set mitre
Combination gauge
Sliding bevel
Tape measure Range of steel rules
Squaring over box
American roofing square
Marking knife Dividers
Images courtesy of www.workshopheave.com; www.screwfix.com; www.shutterstock.com; David Walker. Reproduced with permission.
Framing square
Protractor, drawing set squares, compass, pencils
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Any questions?