From DT Online
Revision as of 15:44, 5 February 2016 by DT Online (Created article)
Widening Joints are used to make wider boards by joining narrower ones edge to edge. Whichever jointing method is chosen, care should be taken to ensure the curve of the Annular Rings is reversed on adjacent boards as shown.
As timber dries out, its Annular Rings will tend to try and straighten. Reversing their direction in this way minimises the degree to which the widened board will cup or warp.
To avoid this problem almost completely, choose boards which have been sliced from across the centre of the tree and whose Annular Rings are therefore close to being at right angles to each face (these boards are known as Quarter Sawn - they are much sort-after and will be hard to find!)
It is important to ensure joining surfaces are straight and square and to arrange boards such that their grains go in the same direction - this so any subsequent planing and finishing is made easier. Check for Squareness by balancing one board one top of another and testing with a straight edge.