Resawing Spruce
Pictured here is a load of Sitka Spruce shipped direct from the forests of Alaska. We will show the process for converting it into top sets for Bear Meadow instruments.
The wood was furnished by Brent Cole, of Alaska Specialty Woods, in Craig, Alaska. Brent cuts tonewoods (instrument tops) for musical instruments. He normally sells top sets sized for guitars and violin-family instruments. By special arrangement, he agreed to supply Bear Meadow with Master Grade raw flitches of Sitka spruce. Since dulcimer tops are much longer than other instruments, and much narrower, he cut some four-foot long sections out of trees that seemed good candidates, and laid them aside for me until he had accumulated enough triangular segments, or flitches, for about 20 face-inches of Master Grade rectangular. He then ran them through his bandsaw mill to get them accurately quartersawn and into roughly 6"X4"X48" billets. As he went, he culled out obvious structural problems, stains, and odd colored areas that might signify deformities or odd chemistry.
Then he boxed them all up and mailed them to me. The two boxes of spruce billets arrived at the shop with about 15%-18% moisture content, so I let them stand a couple of days so it would come down to about 11% before doing any trimming. It's a lot easier to deal with dryer wood, but you don't want to give it a chance to check and split by letting the outside dry a lot faster than the inside. The best thing is to get it sliced into top sets as soon as possible, so it will all dry at the same rate.
So what is shown above are the billets after having been trued straight along one edge. You need one edge that is flat, so that when you put that edge against the bandsaw fence, you can saw another straight, flat edge on the other side of the billet. This gives a reference, from which the rest of the preparation can begin. It is very important to true up three faces (top, bottom, and one side) square and flat, so your sawing of the thin slices will be precise.
Here are the spruce billets after being trued up on three edges, and reduced to 4" height and 36" length. They are ready to be resawn into top sets. The ends have been varnished to retard drying. This is the place where the wood naturally gives up the greatest amount of moisture, and very quickly. If it is not sealed to retard the drying, the sudden shrinkage in such a local area will cause the wood to "check"--split into a network of small cracks. Notice the diagonal lines drawn on the end of each billet. These patterns are made unique to each block, and enable one to re-assemble the billet in its original order after it has been sawn into many narrow slices. This enables us to make sure that each pair of bookmatched top sets come from neighboring slices. You could scatter the sliced-up billet all over the floor, and still be able to re-assemble its slices in order!
Here is the spruce with three of the smaller boards already sliced. Each slice is about .150" Thick. Notice how the diagonal markings make it easy to keep all the slices in order. This will be crucial when we come to glue neighboring slices together along the edge to produce bookmatched tops.
Slices are next stickered so they will dry somewhat uniformly and freely. I use popsicle sticks, which are just the right size stickers for these pieces. It also helps to band the wood to discourage any warping (although accurately quartersawn wood should not twist, and rarely does). It also compacts it into a nice bundle, so it doesn't go tumbling off the shelf when a door gets slammed or something.
Here you can see the saw as set up for the resaw operation. The rip fence has a redwood extension attached (redwood was chosen because it is very stable), so the billet can be guided precisely throughout the whole sawing pass. It is very important to have the saw completely and newly tuned up for the resaw operation. And you should start the operation with a fresh bandsaw blade. The setup shown here is a Delta 14" bandsaw with a half-horsepower motor. Although I use a coarser blade for the truing up, the blade I use for the resawing itself is a Starrett 1/2" 4 TPI .025" blade. I find that this Starrett blade has the sharpness, precision of tooth set, steel quality and beam strength to do a good resaw job, yet thin enough not to waste wood on excessive kerf width. Kool Blocks do quite well for blade guides, so I haven't invested in fancy ballbearing blade guides. The motor is a little on the light side and it is easy to stall or overheat during resawing. But with a little care it does a very good job. Using this rig, I can consistently turn out 4" wide quartersawn boards at .150" thickness, holding +.015",-.00 tolerances, with good finish.
