Initially the Tasmanian Blackwood pieces for the ukulele back and sides were significantly thicker than required, so the first step in the construction process was to thickness sand these pieces down from approximately 6 mm to 3 mm. Following this, the bookmatched plates were edge sanded and joined.
Bookmatched Blackwood soundboard and back plates, prior to joining
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Once the bookmatched plates were joined, they were cut roughly to shape (leaving approximately 8 mm overhang), then further thickness sanded to get to a reasonable working thickness for installing the rosette. In this case the soundboard plate was thickness sanded to 2.1 mm, then the Tasmanian ‘Tiger’ Myrtle rosette was inlaid and levelled. The soundboard was then further thickness sanded to achieve the right long-grain stiffness and cross-grain flexibility, which in this case was at a thickness of 1.75 mm. The back plate was thinned to 2 mm.
Blackwood soundboard with "Tiger" Myrtle rosette, and Blackwood back
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The next step in the construction sequence was to add a cross grain bridge and soundhole patch to the soundboard, then to construct and fit the soundboard and back bracing. The patches are applied to reinforce the soundboard area directly under the bridge, and to compensate for the weakness generated by having a centre soundhole. All of the patches and bracing used in this ukulele are Engelmann Spruce. The braces were initially cut to size, then profiled into a triangular cross sectional shape, which provides good support to the soundboard but reduces the mass of the braces. The braces were then shaped to the 25 ft and 15 ft dome profile for the soundboard and back respectively, and fixed to the plates using the go-bar deck and the domed workboard. The centreline joint of the back plate was then reinforced using a domed cross grain Engelmann Spruce graft, that was specially shaped to have minimal mass, but provide maximum reinforcement for the joint between the two plates.
The cross braces on the back plate were then shaped by scalloping the ends near the perimeter of the ukulele, to further reduce mass and increase the flexibility if the plate, allowing the back to resonate more freely. The cross braces on the soundboard were shaped to have a parabolic top curve, which reduces the mass but maintains stiffness and strength. The ends of the braces near the ukulele perimeter were also scalloped to increase the ability of the soundboard to vibrate. The most important brace shaping was for the three fan braces that support the main soundboard around the bridge area. These tone bars are shaped so that they have maximum bending strength directly under the bridge saddle, and steadily decrease in stiffness toward the soundhole and the tail.
The cross braces on the back plate were then shaped by scalloping the ends near the perimeter of the ukulele, to further reduce mass and increase the flexibility if the plate, allowing the back to resonate more freely. The cross braces on the soundboard were shaped to have a parabolic top curve, which reduces the mass but maintains stiffness and strength. The ends of the braces near the ukulele perimeter were also scalloped to increase the ability of the soundboard to vibrate. The most important brace shaping was for the three fan braces that support the main soundboard around the bridge area. These tone bars are shaped so that they have maximum bending strength directly under the bridge saddle, and steadily decrease in stiffness toward the soundhole and the tail.
Blackwood soundboard and back plates, after bracing
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Internal soundboard and back bracing
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