Conversion of Timber

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Match the number and the pattern from the coded
table below with the letters from the table to
reveal the class topic. Example 3ltgtlt. 4-)
equals SO
-) ltgtlt -O
1 E O R
2 C V N
3 V S I
4 O N T
2-) 1ltgtlt 2-O 3-) 1-) 1-O 3ltgtlt 3-O 4-)
4ltgtlt
CONVERSION
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Conversion of Timber

• Grade 8

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The Conversion of timber process
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video clip of the conversion process
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What is conversion of timber

• The process of cutting logs into timber is called
  conversion.
• There are several methods of conversion, each of
  which has some special advantage. For some
  timbers conversion must take place before the log
  has time to dry out and shrink.

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What are some of the factors that determine the
type of cut?

• The way the cuts are made will depend on several
  factors ,some of which are
• The type of sawing machine
• The condition of the log
• Economy
• The size of log
• The wood species
• The end use of resulting timber

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What are the types of sawn Lumber?
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Methods of conversion of timber

• There are three main methods of conversion of
  timber. They are
• Plain sawn
• Quarter sawn
• Rift sawn

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Plain sawn

• Plain sawn which is sometimes called
  through-and-through or slash sawing. In plain
  sawing, the saw cut forms a tangent to one of the
  annual rings. There are several variations of
  plain sawing

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Picture of plain sawn
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Plain Sawn

• Advantages of plain sawn
• The log is easily-manipulated and frequent
  turning is not required.
• There is no waste of timber.
• It is a cheaper method
• Disadvantage of plain sawn
• It has the disadvantage that shrinkage may tend
  to warp and split the boards.
• They also tend to absorb more moisture from the
  air which can also lead to unwanted movement

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Quarter Sawn

• Quarter sawn lumber comes at a premium due to the
  labor it takes to mill each plank. To mill
  quarter sawn wood, each log is sawed at a radial
  angle into four quarters. Then each quarter is
  plain sawn. This method of quarter sawing does
  leave some waste, but much less than rift sawn
  lumber.

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Quarter sawn

• In quarter sawing , the saw cut is made at right
  angles to the annual rings. This method is used
  particularly to produce figured oak. A quarter
  sawn board will therefore expose the rays where
  as a plain sawn one would cut across them.

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Picture of Quarter sawn
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Quarter sawn

• Advantages of Quarter Sawn
• Smoother surface due to less distinct grain
• Decreased expansion and contraction on the
  planks width
• Twisting, cupping, and warping resistance
• Ages evenly over time
• Chances of surface checking are significantly
  reduced
• More resistant to moisture penetration
• Enhanced paint retention

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Quarter sawn

• Disadvantage of Quarter Sawn
• The cutting operation is much more complicated
  and involves more waste.
• The boards are rather narrow.
• It is an expensive method

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Rift sawn

• Milling rift sawn lumber takes more time and
  labor. It also has unique benefits over quarter
  and plain sawn lumber. Furniture makers depend on
  this cut of wood for the vertical grain that is
  shown from all sides. This linear grain pattern
  is achieved by milled perpendicular to log's
  growth rings. The log is milled carefully on an
  angle between 45 to 75.

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Rift sawn
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Rift sawn

• Advantages of Rift Sawn
• Ideal for custom furniture makers to use for
  table, chair and other straight pieces
• The most dimensionally stable cut of lumber
  available
• Unique, linear appearance on both sides of the
  lumber planks
• Rift sawn lumber is dimensionally superior to
  both plain sawn and quarter sawn lumber.

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Rift Sawn

• Disadvantage of Rift Sawn
• they also produce the most waste.
• rift sawn lumber will cost more per board foot
  than either quarter sawn and plain sawn lumber.

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Plain and Quarter
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Sawn lumber

                                                                                                                                                                
Plain Sawn vs Quarter Sawn vs Rift Sawn
Faster to produce More affordable Displays varied grain patterns the unique "cathedral" appearance Readily available   More stable than plain sawn lumber Increased moisture resistance Less likely to cup, twist warp Beautiful ribbon aka "fleck" patterns are prevalent in species like White Oak Red Oak Less expensive than rift sawn lumber   Ideal for custom furniture makers to use for table, chair and other straight pieces The most dimensionally stable cut of lumber available Unique, linear appearance on both sides of the lumber planks
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Plain sawn Vs Quarter sawn
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Why is it important to have allowance cut the
logs into timber?

• When sawing, an allowance is made for shrinkage
  and for planing the boards to the required
  finished sizes.

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summary
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classwork

• Write a letter to their best friend telling him
  or her how logs are converted into timber .