BM WK 5 Timber

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WOOD

Strong & durable material

Lightweight, easy to work with

From trees and shrubs tough, fibrous, no two pieces exactly alike

PHYSICAL PROPERTIES

Growth rings - concentric circles

Grain appearance and textures of its pores, open orclosed(tight)

- creates a pattern and texture that is influenced bythe manner in which the wood is cut

Natural colors warm yellows, reds, browns

- modified by stain, change with light and airexposure

Different density and hardness, ability to take a finish


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Hardwoods
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Hardwoods

TEAKProperties:Teak is a hard hardwood, it is heavy and strong. It has a high durability and is strong in strength.Teak originated in India and Burma.Uses:

Teak is used to build boats, cabinets, other furniture, flooring and decorative veneers.Other:It is best to use an oil finish when using teak. It can also be difficult to glue and its dust has known tobe an irritant.

AMERICAN BIRCHProperties:American Birch is a hard hardwood, it is heavy and strong but has a low durability. It originated fromUSA and Canada. Birch also finishes well.

Uses:Making furniture, quality joinery, dowels and flooring. It is also used in the manufacture of plywood.

ENGLISH ELMProperties:English Elm is a hardwood with an intermediate hardness. It has an intermediate weight and

low durability. It finishes well but is not suitable for exterior work.Uses:Used for cabinet making, Windsor chairs, boat building, f looring and coffins
http://www.salvo.co.uk/images/userimgs/1578/37516_1.jpghttp://www.woodcomponents.ie/images/birch_american.jpghttp://www.fincaleola.com/images/teak.jpg


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Softwoods

DOUGLAS FIRProperties:Douglas- fir is a softwood, itUses:Douglas-fir is commonly used in the construction industry. It has also been used for home builtaircraft. They are also the most common Christmas tree in the USA

WESTERN RED CEDARProperties:Western Red Cedar is a lightweight softwood that has a high durability and finishes well. Itoriginated from Canada, UK and the USA. It is weak and is soft.Uses:Garden sheds, greenhouses, exterior boardings, fencing and posts.Notes:When nailing Western Red Cedar it is best to use galvanised or copper nails. This timber is nota true cedar

YELLOW PINE

Properties:Yellow pine is a softwood that has an intermediate weight and is also strong. It also has aintermediate durability and finishes well.Uses:Construction work, shipbuilding, flooring, joinery work, crates and pallets
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MANUFACTURING

PLAIN-SAWING

-Parallel cut of log into boards

-Varies in grain pattern-Tend to twist and wear unevenly

Effect Of WarpingThis is the most economical way of sawing logs, for it gives

the greatest possible amount of lumber with the least waste.There are, however, some disadvantages in this method ofsawing, particularly if the lumber is to be used for fine cabinetwork. Plain sawed lumber usually warps very badly. If you areto understand why this is true, you will need to knowsomething about the cause and effect of warping of lumber.In a living tree there is always considerable moisture in theform of sap. When the tree is cut down the sap, of course,ceases to circulate, and the moisture in the log begins toevaporate. As the log dries, all of the concentric rings,

representing the annual growths, become a little shorter andthus cause the log to crack. If it has been sawed into boards itwill, of course, dry even more rapidly, causing the portion ofthe rings in each board to shorten considerably, and thus bendor warp the board, as shown in the illustration. You willobserve that the edges of the board warp from the heart of thelog, and you can readily understand why this is true if you willstop to consider the cause of the warping. You will notice thatthe plank in the central portion of the log does not bend, but

the shortening of the rings causes it to become thinner oneach edge.

wood is quarter sawn a higher quality of plank is produced but less planks can be produced.

Seasoning woods:
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Seasoning is the controlled drying of timber. This can be achieved by natural seasoning or kilndrying. For both methods the moisture content must be lower than 20%. The ideal moisturecontent for a piece of wood is when the wood has the same moisture content as the airsurrounding it.For every 25mm of plank that you want to naturally season you will have to leave the wood for1 year.
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In order to overcome this tendency to warp, another method of sawinghas been devised. This method also adds great beauty to theappearance of the boards by exposing the medullary rays. This methodis called quarter sawing. It takes its name partly from the fact that, inthe process of sawing, the log is usually cut into quarters as the firstoperation. There are a number of different methods of quarter sawing,but they all have the same purpose in view, that of cutting the boardsas nearly as possible in a direct line from the bark to the heart. Thefollowing illustration shows four different methods of quarter sawing:

QUARTER SAWING

Methods Of Quarter SawingFigure A represents the method which makes each board perfectlyquartered. By studying this illustration you will observe that this is avery wasteful method, because there are so many wedge-shapedpieces that cannot be used. The method shown in Section B producesfairly good results, but is not so perfect as shown in Figure A. This isalso a wasteful method on account of the great number of small piecesleft. The method shown in Section C produces very good quarteredeffect, although you will observe there are a good many boards which

are not cut directly from the bark to the heart. This is one of the morecommon methods of producing quartered oak lumber. The irregularpieces left at the corners are usually cut into stock of some othercharacter.


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Rift sawn
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Rift-sawn boards are probably the least desirable of all the cuts. This is because these cuts can vary quite a bitdepending on where in the log they are cut. They also tend to "move" in two directions with makes them poor choicesfor flooring, table tops and decking. Rift cut is often left for building materials like 2x4, 2x6s, 4x4 and so on. This does

not mean that good quality hardwoods are not available in rift-sawn cuts, only that it is often not the ideal cut

RIFT SAWING

COMMON DEFECTS


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WoodDefect

Features Caused By Effect Solution

Blue Stain

A bluish graydiscoloration onthe woodssurface. Thisfeature is mostcommon inwoods like Holly,Pine, and

Sycamore.

Mold that grows inwarm and moistarea, usuallypoorly ventilated.

Discoloration of wood.

Can be cut off, placedout of sight, orconcealed with adark stain.

Bow

A curve along the faceof a board thatusually runs fromend to end.

Improper storage.Usually moistureevaporation fromone side and notthe other.

Stock is difficult to workwith and cut.

Cut in to smallerpieced, even outon a jointer, ornail (screws arebetter) in placewith bow bulgingout.

Checks or Splits

Breaks at the end of aboard that runalong the grain.Checks and splitsare usuallyrestricted to theend of a board.

Rapid Drying.Can effect the strength

and appearanceof the board.

Should be cut off orworked around.

COMMON DEFECTS

WoodFeatures Caused By Effect Solution
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DefectFeatures Caused By Effect Solution

Crook

Warping along theedge from one end tothe other. This is mostcommon in wood that

was cut from thecenter of the tree nearthe pith.

Can be caused byimproper drying andstorage or the

presence of reactionwood.

Can be difficult to workwith.

The higher spots canbe cut away on a tablesaw or jointer using aspecial jig.

Cup

Warping along the faceof a board from edgeto edge. This defect ismost common of plain-sawn lumber.

This defect can becaused when oneboard face dries at afaster rate than theother.

Stock can be difficult towork with. Trying to"force it flat" can causecracking along thegrain.

You can try allowingthe board to dry at thesame moisture contentunder pressure, rip it

into smaller pieces ona table saw, or use ajointer to remove thehigh spots.

Dead or Loose KnotA dark, usually looseknot.

This is caused by adead branch that wasnot fully integrated intothe tree before it wascut down.

Can mar theappearance of thewood, fall out, becomeloose, or weakenstock.

Should be cut out,around, or glued inplace and filled with awood putty.

Gum, Sap, or Pitch

Accumulations of a

resinous liquid on thesurface or in pockets Injury to the tree.

May cause difficultyShould either be cut offor scraped out and

Wood
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Machine Burn

Dark streaks along the

face of a board.

Usually caused byplaner blades that are

dull or spun on a part ofthe board for too long.

Discoloration to thesurface. Sometimes the

burn can penetrate intothe board.

Can be sanded off orcut down with a jointer.The depth of the board

often determines theamount of workneeded.

Ring CheckBreaks in the woodalong the annualgrowth rings.

Improper drying ordamage duringtransport.

Can effect strength orappearance.

Should be cut around,place out of sight, orglued down.

Tight KnotA know which is tightlyintegrated into thesurrounding wood.

This was once abranch that wasincorporated into thetree as its girthincreased.

Does not effect thelumber's strength.

May be removed forappearance purposes.Some lumber such asKnotty Pine, is highlyprized for this feature.

Twist

Warping in lumberwhere the ends twist inopposite directions.(Like twisting a towel)

Growing conditions,uneven drying or thepresence of reactionwood.

Can be difficult to workwith.

Can be cut into shorterboards or the highspots can be removedon a jointer.

WormholesSmall holes in thewood.

This is caused byinsects boring throughthe wood.

Can be used tosimulate old or wormywood.

Cut around worm holesor uses as is fordecorative purposes.Be sure the insects aredead.

WoodDefect

Features Caused By Effect Solution
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Blue Stain Checks or Splits

Worm holeCup
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BM WK 5 Timber