Side Bend or "Crook" and Sawing Methods

On wide boards, sawing too close to the pith can cause boards to bend sideways in drying. December 6, 2012

Question
Can someone help me with preventing the side bend in the pictures below? Our walnut is steamed, stickered, and then put in our air dried yard for anywhere from a week to two months. I donít know if this is happening there or not but our walnut kiln drying schedules havenít changed in past few years.


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Forum Responses
(Sawing and Drying Forum)
From contributor O:
This is Gene's area of expertise but since I came across this thread I'll offer the following. That form of warp is called crook. It is caused when one side of a board shrinks more than the other side. This can be caused when the short side was cut too close to the pith, I believe. Another cause is wood from a leaning tree. In short, I don't call crook a drying defect. Log selection and sawing can reduce crook.



From contributor Z:
Contributor O may be on to something here. Every time I have lumber quartersawn the boards with the pith on the edge crooks like a "(". I've always told myself that next time I'm going to trim off 1-1.5" behind the pith Ė maybe that would solve the problem as the pith wood (juvenile wood), during drying results in longitudinal shrinkage and will pull the wood fiber inward, resulting in the crook.


From Gene Wengert, forum technical advisor:

Contributor O is correct. See the Knowledge Base link below. Bottom line: drying does not affect crook (or side bend), but sawing pattern does.

Warp In Drying