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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 3<><. 4;-) equals “SO”
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:-O 1 E O R 2 C V N 3 S I 4 T
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CONVERSION

2. Conversion of Timber
Grade 8

3. The Conversion of timber process

4. video clip of the conversion process

5. 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.

6. 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

7. What are the types of sawn Lumber?

8. Methods of conversion of timber
There are three main methods of conversion of timber. They are :
Plain sawn
Quarter sawn
Rift sawn

9. 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

10. Picture of plain sawn

11. 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

12. 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.

13. 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.

14. Picture of Quarter sawn

15. Quarter sawn Advantages of Quarter Sawn
Smoother surface due to less distinct grain
Decreased expansion and contraction on the plank’s 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

16. 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

17. 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°.

18. Rift sawn

19. 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.

20. 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.

21. Plain and Quarter

22. Sawn lumber Plain Sawn Quarter Sawn Rift Sawn Faster to produce
                                                   
                                                    
Plain Sawn vs
Quarter Sawn
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

23. Plain sawn Vs Quarter sawn

24. 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.

25. summary

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