Conversion of Timber Logs

 
   
   

 A tree should be converted into usable timber as soon as possible after felling.

 
   
   

The most common cuts are:

Quarter Sawn which produces Radial Boards.

Through and Through (Flat or Crown Sawn) which produces tangential boards and some quarter sawn.

 
   
   

The Quarter Sawn is far more labour intensive which results in a more expensive log. There is also more timber wastage. It is on the other hand more decorative and less prone to cup or twist. There are two ways of sawing timber on the quarter. 

 
   

 

Rift Sawn is the cut which falls between crown and true quarter sawn. It is straight grained and in oak, does not reveal any ‘silver ribbon’ grain features.  Annual growth rings form an angle between 30 and 60 degrees.

Quarter Sawn boards are radial cut from the centre of the tree. It produces the distinctive silver ribbon effect (in oak) across the whole board. Annual growth rings form an angle greater than 45 degrees. True quartered boards producing the best features will have the angle on or very much closer to 90 degrees.

Radial Boards (radial, figured or quarter sawn) are typically cut on ‘the quarter’ and produce a pattern of the medullary rays especially in quartered oak. Such timber is expensive due to the multiple cuts required to convert this board. The radial face of the board is slightly stronger and stiffer than the tangentially face but the cross section and condition of the timber has more effect on strength.  Annual growth rings form an angle greater than 45 degrees.

 
   

Through and Through (Flat or Crown sawn) produces predominantly tangentially sawn timber and some quarter sawn. Tangential timber is economically the best to produce because of the relatively less repetitive production methods. It is used comprehensively throughout the building industry.           

 
   

 

Crown Sawn is obtained by sawing tangentially to the annual rings. It is also referred to as ‘Plain Sawn’ or ‘through and through. There are other ways but they are all variations of tangential and radial cuts to obtain the best or most economical boards for the use it is to be put.  These basic cuts are not always able or need to be, on the exact tangent or radius of the trunk. The cuts, that fall between, crown and quarter are called ‘rift’.

Boxing the heart refers to eliminating the heartwood from the boards that would otherwise produce shakes.

 
   

Tangential Boards (crown, plain or flat sawn) are used extensively for beams and joists. They are stronger when placed correctly edge up with the load in the tangential axis. These types of boards suffer from ‘cupping’ if not carefully converted, seasoned, and stored properly. Annual growth rings form an angle less than 45 degrees.

 
   
   
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