By Bob Caletti and Jonathan Hoyt
The following example shows the procedure used to repair cracks in the sound board of a 15½-inch Regina table top music box.
Figure 1 shows an inside view of the Regina case. The largest crack in the soundboard is straight down the center, but there are smaller cracks to the left and right of the larger one.
Figure 2 shows the Regina case from the bottom. On the right side of the image is a board used to cover a slot cut into the soundboard by Regina. The slot provides clearance for the main gear of the mechanism.
Figure 3 shows the cover board removed in preparation for the sound board repair.
Figure 4 shows the long piece of wood that will be used to fill the crack. During repairs, the nails on both sides of the cracked soundboard were removed. Notice the small cracks on the right and left sides of the soundboard that are above the long crack. These will be epoxied and glued together. The longer and bigger crack will have a piece of wood custom fitted into it for a good tight fit.
Figure 5 illustrates how a tapered piece of wood is forced into the larger crack on the right to compress the smaller outer cracks together while it is being glued. The blue tape is used to contain the epoxy and keep it from running onto the inside surface of the soundboard.
Figure 6 shows how the wood strips were fitted into the crack with epoxy and the soundboard was clamped using cauls to keep it flat. The cracks were glued separately as the left and right cracks were not in exact alignment.
Figure 7 is a side view of the sound board being clamped to keep it flat while the epoxy cures. The sound board was then nailed around the perimeter per the original.
Figure 8 shows the process of chiseling the glued crack filler strips so that they become flat to the surface of the sound board.
Figure 9 shows the finished surface of the repaired Regina music box with bottom slot cover board back in place. The lighter wood of the cover board can be seen in the cutout as the original glue was sanded off to help it better adhere as it was glued back in place. Note the round witness mark in the center of the sound board. This is where the sound bridge goes. The sound bridge goes between the sound board and bedplate to transmit the vibrations from the combs/bedplate.
This should be a tight fit between the bedplate and sound board and should deflect the soundboard to create a slight concave shape when installed. When the music box was finished it sounded great. It was clear that the sound board repair helped bring out the full resonance of the music box.