Sawing Parallel to the Bark
When sawing tapered logs, the way you saw can affect the value of the boards you produce. September 17, 2008
Question
This may be a simplistic question but what exactly does "sawing parallel to the bark " mean, and why is it important?
Forum Responses
(Sawing and Drying Forum)
From contributor S:
Some logs are tapered, so sawing parallel to the bark means you don't throw away the high value wood on the outside of the log. The problem is you end up with odd shaped cants and tapered boards.
NHLA grading rules permit tapered boards, but if I remember the rules the
width is measured 1/3 from the smallest end? Anyway, some sawyers say sawing parallel to the bark is the way to go, others don't bother and just square up the log.
From Gene Wengert, forum technical advisor:
When you saw parallel to the bark, you will have the grain parallel to the lumber's length (unless the log has spiral grain) and will have a higher yield of upper grade lumber. For a tapered log, you can take the taper out of the outside wood (which is the clearest) and end up with short clear pieces. Or you can saw parallel to the bark and then take the taper out in the lower grade portion of the log. So long as upper grade is worth 4x of lower grade, it is worth the time it takes to saw parallel to the bark. Parallel to the bark is also called full taper. (Note that half-taper sawing, that is sawing between parallel to the bark and parallel to the center, is the worst choice of all).
From contributor S:
Increasing the cut dept will cause gullet overload leading to spillage and resulting in washboarding. There are a few factors involved in reducing the occurrence of this phenomenon. A single pitch saw has no chance of working as it should in these conditions no matter how much you square up the tips reduce the clearance angle and lengthen the hook (a radiated hook bottom will also cause spillage).
The vibration in the blade cause by the harmonics needs to be stabilized and the best way to achieve this is through a variable pitch. In theory every pitch on the saw should be different but that's not viable. Depending on the blade 3/5/7 variable pitch patterns are commonly used. People often talk about feed speeds being too slow. The essential component of any mill is the blade. It is completely dynamic, representing the machine it is on only.
