hm - Aug13 - cover.indd - National Hardwood Lumber Association

RULES
CORNER
SIDE BEND, IT’S NOT A WORK-OUT MOVE
By Dana Spessert, NHLA Chief Inspector
As NHLA Chief Inspector I have been given many opportunities to
explain some of the more difficult to understand Rules. One of these
Rules or in this case “Defects” is the ever annoying Side Bend.
Side Bend is primarily caused by improper sawing practices with boards
that have off center growth rings which allow a much greater shrinkage
on one edge as opposed to the other. Another cause of Side Bend is an
edger that is ripping boards in the middle to create two boards prior to
drying and both pieces are subject to abnormal shrinkage patterns.
When inspecting lumber remember, the grades describe a board that is
to be processed in to another product and it is not intended to be used
in its entirety. In other words, the NHLA Rules are for raw material
inspection. Another thing to realize is that in the process of producing
another product a substantial amount of material can be removed and
the board may still yield the minimum required for the grade in which
it was sold or purchased.
When a board has Side Bend in FAS, F1F or Select and the surface measure is
less than 6, it is relatively easy to turn the arc of the bow up so that both ends
of the board are touching a flat surface. Measure up to the widest area between
the flat surface and the edge of the board, then subtract that number from
the full width of the board and that will give you the maximum width of a
straight edge cutting that may be available in that piece.
While this is a good measurement for narrow boards with small surface
measures for the full length this does leave a substantial amount of room
for interpretation in larger surface measures or lower grades where there
can be multiple cuttings taken.
Ideally, when faced with a board with Side Bend the inspector would
take a piece of string and use that to simulate the cutting of the saw and
then use that information to grade the board, but this approach would
be much too time consuming as well as impractical in a production
environment. I would recommend that the inspector use a string to
test a few boards and get a good understanding of how much Side
Bend is affecting the grade and use their best judgment in applying the
knowledge gained.
One of the most important things to remember when utilizing the
NHLA grades is that the useable portion of the board is measured to
establish the grade and not the defects.
Questions about the NHLA hardwood lumbering grading Rules should
be directed to Chief Inspector Dana Spessert. He can be reached by
phone at 901-399-7551 or by email at d.spessert@nhla.com.
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14 AUGUST 2013 HARDWOOD MATTERS WWW.NHLA.COM