The month of November flew quickly by. Activity in the Woody Stings shop changed focus. The plan for this winter now includes producing two mandolins, one A-style and one F-style. I also have two guitars started but, realistically, I will be surprised if I finish the guitars before June. Carving mandolins is the priority at the moment.
Joining and Carving the Top
The picture above was taken this week (Dec 1). 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. The Sitka spruce soundboards for my mandolins comes 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 day when Alaska was still a territory of the U.S. (1950s), logging-road bridges were built with the only materials available_ Sitka spruce. Large, strong trees were selected to be used as bridge stringers (cross-wise structural supports).
In the '80s, 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 to retrieve 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. I still have about 40 split billets from that adventure. This is music-grade spruce, now about 60 years old with 15-30 gpi and very straight. (see below)
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. One can see the split line running across the butt of the billet.
Next, the billet is taken to a chopping block where it is split down the center with a 10" blade and a sledge hammer. 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 grain on the other side. Thus, the soundboard should transmit vibrations symmetrically from the bridge outward.
In the photo below, note that the split surfaces are flat, no twist... THIS is straight grain. A log can only split this straight if the tree grew tall, broad and straight, i.e. the growth rings are parallel to the axis of the tree and evenly distributed.
The billet should be split right down the center so that both of the resulting halves will be dimensionally the same. As one can see below, when I joined the two centers, the 'half' on the left was thicker than the 'half' on the right. No matter, the glued-up stock needs to be only 16-18 mm thick in the center. The 'half' on the left was about 30 mm at this point. After 24 hours of clamping, the spruce is ready for carving.
The next step to a symmetrical soundboard is to carve the inside and the outside of a turtle shell from the same piece of wood. That's where I am right now.
Detailed plans, sharp tools, modest expectations and great patience help in carving the soundboard. It first needs to have a flat underside. This can be accomplished on various types of table sanders or with a drum sander and some carefully placed, and glued support blocks at the four corners. The soundboard passes under the drum with the face down.
Having a true, flat surface on the bottom of the billet is very helpful in the carving and thickness process. In short, the carving begins with 'scooping' out the underside of the top to an approximate contour. Then, work the outside of the top down to 'fat' thickness dimensions. Keeping fat dimensions, alternate the work on both sides of the top until the contour of each side is acceptable. All that one wants to be thinking about up to this point is SHAPE.
Work down to the final thickness dimensions very slowly. Maintain a close check on the 8 or 10 spots that tell he thickness story...down the middle, across the mid-section and at the sound aperture (oval or f-hole). There are many sources on line with contour plans and/or thickness dimensions for both the top and back of the mandolin. I am using some very-well drawn and detailed plans of a Gibson A-3 from the early 1900s. They came from Georgia Luthier Supply. They're on line.
The key to carving: Be patient, don't expect to carve the entire top in one session (or even one day). There are many challenges to carving both sides of an turtle shell from the same wooden block. Go slowly and you will see the challenges coming before you have to deal with them.
Final word_ always support the work from the underside when carving, especially the points where the edges are clamped. Not seen in the picture above is a carved-from-styrofoam cradle under the soundboard. A styrofoam board is very easy to carve by raking it with a sharp sheetrock saw...(makes a mess).
Merry Christmas and Prosperous New Year !!!