Timbers

Question 1

What are the three timber classifications

Answer 1

Hardwood, Softwood, Manufactured board

Question 2

Hardwood (classifications)

Answer 2

slow growing, close grain, deciduous

Question 3

Softwood (classifications)

Answer 3

fast growing, wide grain, coniferous

Question 4

Manufactured Boards (classifications)

Answer 4

Man made timber using reconstituted wood and adhesives

Question 5

what are the stock forms of timber ( describe them)

Answer 5

Rough Saw: timber direct from seasoning, has nominal sizes instead of accurate finishes
Planed square edge: only has one accurate edge
Planed all round: all edges are planed, square and level
natural wood: timber direct from trees, maximum size is the size of the tree
Manufactured boards: man made timber in large sheets
Mouldings: pre-made shapes and profiles (e.g. skirting boards)

Question 6

Air seasoning

Answer 6

leave wood in a sheltered location as moisture slowly leaves the material. (cheap and easy but slow)

Question 7

kiln seasoning

Answer 7

stack planks in a kiln where temperature and humidity are controlled to quickly remove moisture (fast but expensive)

Question 8

Material properties of timber

Answer 8

strong along grain but weak across it
biodegradable
generally strong and widely available
generally good aesthetics
needs extensive finishing and seasoning to prevent decay and corrosion
generally easy to work with

Question 9

Seasoning (benifits)

Answer 9

removes 80-90% of moisture
prevents defects and deformation
gives better immunity to decay
prevents corrosion of metals
helps preservatives penetrate

Question 10

lamination

Answer 10

wood veneers are glued together over a bent former
clamps apply pressure forcing the timber to take the shape of the former
When the adhesive dries the veneers fuse into the shape of the former

Question 11

steam bending

Answer 11

heat and steam weakens lignin in the timber
the timber is more pliable and can be shaped around a former
when it cools and dries its strength is restored in the new shape

Question 12

Turning

Answer 12

a work piece is rotated at high speed and a cutting tool removes the surface material
used for shaping cylindrical or spherical objects

Question 13

Milling

Answer 13

a small rotating bit is used to cut complex shapes out of the timber. it can be manipulated by hand or with computers in CNC

Question 14

Routering

Answer 14

used to machine slots, holes or mouldings in timber
can be done by hand or with CNC

Question 15

Knock down fittings

Answer 15

removable joins often used in flatpack furniture
they are simple to install with limited skill and expertise while being strong and long lasting

Question 16

types of knock down fittings

Answer 16

modesty blocks
barrel and bolt nuts
Cam-lock connectors
wood screws
Coach bolts

Question 17

resins and laminations

Answer 17

used in manufactured boards to enhance the useable parts of a tree (sawdust, chips, fibres ect) to give multidirectional strength and no size limit

Question 18

Fire retardant resins

Answer 18

resins impregnated into the timber to limit flammability

Question 19

laminations

Answer 19

surface veneers which are added to other boards to improve their aesthetics

Question 20

preservatives

Answer 20

protect timber from fugal and bacterial attack
often timber is pretreated with a copper based chemical to kill fungi

Question 21

Pigmentation (timbers)

Answer 21

chemicals added to timber to change the aesthetics or make cheap softwood look like expensive hardwood

Question 22

polysaccharide

Answer 22

this chemical impregnated and cures inside wood cells to increase hardness, toughness and stability

Question 23

SCL (structural composite lumber)

Answer 23

strands of timber are layered and glued together with resins such as urea formaldehyde.

Question 24

LVL ( laminated veneer lumber)

Answer 24

veneers of timber are glued with urea formaldehyde with heat and pressure

Question 25

benefits and drawbacks of LVL and SCL

Answer 25

BENIFITS
unlimited length
high strength
less defects, splitting or shrinkage
better load bearing
DRAWBACKS
urea formaldehyde is a carcinogen