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a) State two timber conversion methods.
b) Sketch the method which would be most suitable for joinery purposes.
(a) Methods of Timber Conversion.
Through & Through
Through & Through Little thought is given to the use of the timber (Plain, Flat or Slab sawn) and consequently it is used mainly for softwoods. The method is cheap and some boards are wide, but outer boards tend to warp (or cup).
Tangential Sawn
Tangential sawn or round the log here each time a board is removed the log is rotated 90 degrees then another board is removed. These 'tangential' boards are generally stronger as the annual rings are longest on the face of the boards. Also this type of conversion creates attractive grain patterns on the face of the boards as shown here on this European Walnut sample.
Small Timber logs
Small Timber Logs As the average size of a softwood log which will be used in a Swedish or Finnish saw mill is in the order of 300mm then fancy sawing techniques are irrelevant. usual practice is to take two or three large (225-250mm) pieces out of the centre and narrower side or edge boards from round the sides.
Quarter Sawn
Quarter Sawn used predominantly for hardwoods where stability (and in some cases madullary figure is required as shown here on this Japanese Oak sample). Quarter sawing is expensive in production time and also in the waste produced but boards are more stable, shrink evenly and generally stay flat.
The sample shows the medullary figure, light sapwood to the right and darker heartwood to the left
b) Sketch the method which would be most suitable for joinery purposes.
Tangential Sawn
Tangential sawn or round the log is a suitable method of converting timber for both carpentry and joinery purposes.
For Carpentry it is relatively strong because of the long cross grain.
When correctly seasoned for Joinery it is reasonably stable (which means it twist warps and shrinks little and predictably). Also the boards cut from the centre of the log are predominately heartwood which is more durable and there are less knots.
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