Sitka spruce split billets.
Luthiers talk of 'straight grain'. Pictured and explained below is what is meant by this term to a luthier. In the vise the spruce billet is posing for a picture. Looking closely, one can see the split line running across the butt of the billet.
Joining and Carving the Top
The picture above was taken this week (Dec 1, 2016). To get to this point, I first selected a suitable spruce billet from the Woody Strings 'warehouse'.
The story on the spruce billets in Woody's shop goes back to the early '80s when Woody lived in Alaska (1975 - 1985). The Sitka spruce soundboards for my mandolins come from SouthEast Alaska, Prince of Wales Island. In 1981, a friend, teaching music on the island at the time, invited me down from Fairbanks to help harvest some music-grade spruce.
Back in the days, when Alaska was still a territory of the U.S. (1950s), logging-road bridges were built with the best materials available_ Sitka spruce. Large, strong trees were selected to be used as bridge stringers (structural supports).
In the '80s (22 years into statehood), when I visited my friend, the spruce bridges of Prince of Wales Island were being replaced with concrete. In the process, the spruce stringers were cast aside into the forest. A few people, like my friend the teacher/violinist, knew how to mobilize the right men and machines to retrieve these 36-48" diameter spruce logs. My contribution to the 'harvesting' was to split mandolin/violin-size billets from the spruce rounds once they were under shelter back at the village where my friend was teaching. Pictured below are about 40 split billets from that adventure. This is music-grade spruce, now about 60 years since first harvested for bridge stringers. They have ~25 gpi and are the straightest spruce this luthier has ever seen. I can tell you for a fact that all of these billets came from the same Sitka spruce log. (see the split billet below)
The billet shown below had been taken to a chopping block where it was split down the center with a 10" blade and a sledge hammer. Notice how flat and straight the surfaces are on both sides of the split.
The result is two book-leafed pieces of spruce which will be joined in the center to create what we hope will be an acoustically symmetrical soundboard, that is, the spruce grain on one side of the centerline will be a mirror image of the other side (in grain separation and physical density). This soundboard, if carved properly, will transmit vibrations symmetrically from the bridge outward.
In the photo below, note that the quarter-split surfaces are flat, no twist... THIS is straight grain with no run out. A log can only split this straight if the tree grew tall, broad and straight, i.e. the growth rings are concentric with the axis of the tree and evenly distributed.