Oliver 2019, Owner'S Manual

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2019 Lathe OLIVERMACHINERY.NET 25 | Page
Wood 101
Why do we have this section?
Before going through the operation of woodturning and the list of quality issues, it is important to
understand the structure of wood and possible wood defects so woodturning can be done safely.
Structure of Wood
The growth rate of trees changes in different seasons and creates tree rings and wood grain that we can
see. The tree rings and wood grains represent wood fibers with varying levels of strength and hardness.
A woodturner needs to read the wood grain and cut the wood properly to create a fine finish.
Think of wood as a bunch of straws bundled together. The “straws” are the strong wood fiber that runs
along the trunk and branches of a tree. While the wood fibers are strong, the bonding between fibers is
not as strong. This makes the wood easier to break up along the grain.
Different Types of Wood Grain
End Grain – This is the face of the wood that we can
see the tree ring. When cutting into the end grain with
dull tools or if too much pressure is applied, the wood
fibers can split and create a tear-out.
Edge Grain - Represents the radial plane of a log and
typically has a straight and uniform pattern like a
quarter-sawn board.
Face Grain – Represents the tangential plane of the
wood with a variable pattern of wood grain.
Wood Defects
Check and Shake
Check is the splitting of wood that happens along the
wood grain. Check happens when the wood is drying
unevenly, and there is no way to relieve the stress
caused by wood shrinkage. Blanks with checks are
structurally compromised and can cause a catch. Using
proper drying techniques and removing the pith in a
blank can prevent checks from developing as wood
stabilizes.
Cup shake or ring shake is the kind of wood splitting
that occurs along the wood ring. Wood with ring/cup
shake is structurally compromised. This type of wood
splitting is often hidden from the surface. As more
wood is removed from turning, a chunk of wood can
suddenly dislodge without warning. Therefore, it is
important to inspect the wood for defects before and
during the operation and avoid standing in the line of
fire.
( Ring Shake Photo Credit: Tanya J. Laird - https://youtu.be/Mr-dN0QEYi4 )