2. CONVERSION OF TIMBER
๏ฑTrees are cut down during winter as there is
less growth, therefore less sap
๏ฑAfter felling trees are transported to sawmills
to be cut into boards
๏ฑThis process of converting logs to boards is
known as conversion
3. METHODS OF CONVERSION
3 methods of conversion
๏ฑThrough and through sawing
๏ฑTangential sawing
๏ฑQuarter sawing
4. Through and through sawing
This is one of the most popular methods of sawing.
The log is cut in parallel cuts in the direction of the
grain.
5. Through and Through
Sawing
Advantages
โข Low cost and fast
โข Maximum width of
planks obtained from
log.
โข Little wastage.
โข Reveals attractive
grain pattern,
especially in
softwoods.
6. Disadvantages
โข Not suitable for structural timber
โข With this method cupping caused by
tangential shrinkage is a problem (cupping
is the warping of the plank away from the
heart of the tree)
Through and Through Sawing
7. TANGENTIAL SAWING
โข The cut is made at a tangent to the annual rings of the
log.
โข Log must be turned 90ยบ after each cut.
โข Timber will display a flame figure
8. Tangential Sawing
Advantages
โข Produce board with flame figure
โข Tangential boards are strong boards, used for
beams and joists
โข Heartwood and sapwood are easily separated
โข These boards can take a nail without splitting
because of the position of their annual rings
9. Disadvantages
I) Prone to shrinkage (Cupping)
II) It is expensive as the log is turned
90ยบ for each cut
10. QUARTER SAWING
๏ฑThis method leaves the annual rings of the converted
timber meeting the face of the board at 45 ยบ or more.
๏ฑIt is important to note that the log must be rotated each
time a cut is taken.
๏ฑThis method can bring the best features in wood as it
produces silver grain which has clearly defined medullary
rays
11. Quarter Sawing
Advantages
โข An attractive grain
pattern is produced
โข Boards are more
stable and shrink
less
โข Boards wear more
evenly and
important for
flooring
12. Disadvantages
โขExpensive, as the log has to be first quartered
then turned for every cut.
โขBecause the log is quartered then cut again
narrower boards are produced
What are the methods are used in general to convert wood
into different shape and which method gives you a best wood
plank and reasons why?
