On the slope...

Delwin D. Fandrich pianobuilders@olynet.com
Thu, 1 May 2003 10:06:59 -0700


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>From time to time the subject of gluing up soundboard panels in the =
small shop comes up. One of the difficulties encountered is that of =
machining the finished panel smooth and flat to some particular =
thickness. This process is exacerbated by a characteristic of spruce =
(well, all woods to some extent--it's just a bigger problem in spruce) =
called "slope."

When trees start to grow as seedlings they do so with a severe twist, as =
much as 45=BA in some trees. They do this for survival--their tiny =
little trunks do not yet have the strength to withstand the ravages of =
wind and storm. Or the occasional stomping of an otherwise friendly =
grizzly. This twist gives the little tree trunk the flexibility it needs =
to survive and grow. Over the years this twist straightens out and, =
ideally, the tree grows straight and true. Often, however, this twist =
will reverse itself just a bit giving rise to the characteristic of =
slope in lumber cut from the tree.=20

In most species commonly used by man for his various endeavors this is =
not a serious problem. It is, however, a serious problem for the =
woodworker attempting to hand-plane a glued-up spruce panel.

All of this introduction is to say that there is a good article on the =
subject in the current issue of WoodenBoat Magazing (#172--May/June =
2003). Written by an instructor at the Northwest School of Wooden Boat =
Building in Port Townsend, Washington, it deals mostly with white oak =
being prepared for steam bending but the principles apply to all woods

Del

Delwin D Fandrich
Piano Designer & Builder
Hoquiam, Washington 98550 USA
360.532-2563
360.532-6688
pianobuilders@olynet.com

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