LUTHERIE

Step 1: Joining the top and back plates

My first task on my concert uke project was to rig a "shooting board" to true up the edges of my top and botton plate halves. I used William Cumpiano's example from his book Guitarmaking, Tradition and Technology as my guide. If you don't have this book, and are thinking of getting started in lutherie, it is a "must have." I first determined how the bookmatched plates should register to each other, and then stacked the plates for the back so that the edges to be joined were together. I then sandwiched the two between two nice flat boards with about 1/4" of the plates sticking out. I sharpened the blade on my old Stanley block plane and set it for just a whisper of a cut. I clamped the two boards together and ran the plane along the edge of the plates gently. After a couple of passes, I got a perfect, very thin double shaving. It looked like a DNA double helix! I unclamped the boards and, fitting the two plates together, held them up in front of a bright light. This is called "candleing." I could still see light in the middle of the seam, so I repeated the shooting, this time with emphasis on either end of the plates. The next inspection showed no light. I had done it! Cumpiano would be so proud. I repeated the process for the two top plate halves. The complete shooting process for the two plates took about an hour, but next time it should only take about half of that.

Joining the plates required another jig to clamp the halves together precisely. This time, I deviated from Cumpiano and designed my own system. I made three clamps, using lengths of 1/4" threaded rod, washers, wingnuts and blocks cut from pine 1x2's. I cut a piece of masonite to be about 1/2" shorter all around than my plates and lay it across the three clamps. I placed a sheet of wax paper on this and lay my back plates halves on the wax paper, put a bead of titebond wood glue on one half, rubbed the plate edges together to spread the glue evenly, and tightened the clamps gently. I put another piece of wax paper on top, and put a couple of C clamps on top to keep the plates from bowing upward. I left the plates in the jig for about 40 minutes, then removed them and stood them against the wall to allow air to circulate on both sides for another hour.

After allowing the glue to dry thoroughly, I needed to remove the excess glue and level the joint between the plates. For this, I needed a scaper. Rather than go out and buy one, I used an old plane blade and resharpened it on my whetstone. Ordinarily, after sharpening the beveled side of the blade, you flip it over and lay the blade flat on the stone and remove the fine burr that has developed along the edge. Instead, I rubbed the non-beveled edge across the shaft of a screwdriver to align and "turn" the burr. I now had a scaper, and I proceeded to use it on the back plate as shown, holding it at about a 50 degree angle and pulling it toward me in a smooth motion. The result, if your burr is formed correctly, is a cross between sawdust and plane shavings. The glue should disappear in a few passes, and then continue your scraping (rotating the plate every now and then) until the seam is all but undetectable

.