Читать книгу The Uke Book Illustrated - John Weissenrieder - Страница 14

The bending iron is a 5-7.5cm (bigger is better) diameter iron pipe, 15cm long, that is closed on one end to trap heat and protect the luthier from scorching, and that has some kind of structure that permits it to be attached securely to the workbench or vise and be heated by a camp stove or torch. There are electrically heated professional versions available. Use extreme care.

Plain version

Fancy version

The shooting board is used to true the edge of a board, such as the edges of the top and back plates prior to joining them.

The shooting board consists of a flat board, approximately 15cm x 60cm x 1-2cm, which serves to raise the work off the benchtop, and a sanding board, 3cm x 3cm x 25-40cm, with a strip of 120 grit sandpaper on one side. The dimensions are approximate.

The important things are that two adjacent surfaces must be straight and true as well as at right angles to each other. One of these surfaces will be the underside and will ride on the benchtop; the other will have sandpaper attached to it and will be used to sand the joint straight. Choose a board with a base wide enough that it will be stable and not be prone to rocking when in use. Use of the shooting board is covered in depth in the chapter on the plates.

Light, or rather the thoughtful use of shadows, is one of the most important tools. Low-angle, oblique light makes surface detail much more visible, helping in the preparation of surfaces prior to gluing, leveling the purflings and bindings, or prepping for varnishing. Backlighting makes shape and form much more evident, useful in situations such as in checking the flatness of the neck or the scarf joint for the head, or in the preparation of the plate joints, or the evaluation of the symmetry and beauty of the curves of the head profile.

The solera is the workboard on which the ukulele is assembled. It ensures the proper orientation of the neck to the top and sides, and maintains this crucial relationship when the back is glued on. The solera can also double as a general workboard for thicknessing the top and back, layout of the bracing pattern, rosette installation, shaping the braces, etc. It also is a base for the go-bar deck.

The traditional Spanish solera is an “open” form, and the exactness of the final shape of the instrument assembled on it depends in large part on the precision with which the sides are bent.

The traditional Spanish method of assembly is relatively free with respect to methods using internal or external forms. The solera adapts easily to variations in plantilla (body profile) and doesn’t force the instrument into shape. The sides must be bent precisely to the desired shape, and the soundbox comes together with little inherent tension.

The solera will be an integral part of the work and can set the tone for the work to come, reflecting the luthier’s character and approach to the work. But in the end, it’s still just an aid to the (real) work of constructing a musical instrument.

The simplest solera consists of just a flat board, slightly larger than the instrument, and a couple of blocks to serve as reference points at the butt and waist of the instrument. A couple of coats of varnish protect it and keep glue from sticking to it. A slightly more sophisticated version (recommended) has slots to accommodate vertical supports that can be fixed to the solera with wing nuts as reference points for the sides, creating a light and versatile version of an external form.

The supports used at the waist and around the upper and lower lobes are simple blocks or large dowels (22-30mm diameter) with hanger bolts inserted. (A hanger bolt is a headless bolt with wood threads on one end and metal threads on the other.) Washers and wing nuts finish the job. A slot or oversized hole allows adjustment of the position of the vertical supports.

It is important that the vertical supports sit precisely vertical when bolted to the solera; the end where the hanger bolt is inserted must be cut squarely. Once installed, check them for square. Treat them with varnish so that stray glue won’t inadvertently glue the ukulele to the solera.

A thin, accurately cut pattern of the top that can be screwed in place on the solera aids in quick and precise positioning of the vertical supports.

A vertical block at the tail end of the solera, concave on one side to match the curvature of the butt of the instrument, clamps the sides and end block during assembly.

A reinforcement on the back stiffens and stabilizes the solera. A reinforced neck can be conveniently clamped in a vise or to a workbench. Threaded inserts allow the solera to be bolted to the workbench. Coupled with a small riser block, the solera-bolted-to-the-bench can be swiveled around, permitting optimum access to the instrument in all phases of construction.

Construct the solera so that the soundboard and neck, when placed on it for assembly, are in the same plane. Check them: a straightedge should touch at points A, B, and C.

The dimensional stability of the solera is important. It shouldn’t warp under normal fluctuations in humidity and temperature, nor deflect or flex excessively under the forces and pressures of clamping, etc. Use properly seasoned wood, and check the solera for flatness before critical phases of construction and assembly of the instrument.

The back bars are slightly curved on the side that is glued to the back of the instrument, giving it an arched or domed shape. Make a sanding board for shaping the bars. The sanding board will double as a counterform for gluing the bars to the back and for sanding the countour of the sides when fitting the back to the body just prior to closing the instrument.

The sanding board is a bit longer than the body of the instrument to permit back-and-forth sanding motion. This form consists of:

*A sturdy piece of wood 20-25mm thick x 5-7cm wide x 38cm long (the support)

*A slat of straight-grained, knot-free wood (high-quality plywood or masonite is good; it’s important that it flexes uniformly) 6mm thick and as wide and long as the support piece (the arch)

*Two strips of wood 8mm x 8mm thick and two strips 4mm x 4mm thick, all four as long as the support is wide

*Adhesive-backed 120 grit sandpaper

*Two 25mm (1”) wood screws

The radius of the arch is determined by the length of the sanding form coupled with the height of the strips of wood. The relationship is described by the following formula. (Kudos, Pythagoras.)

R=Radius of the back L=Length of the sanding form D=Height of the spacer block

Glue the external height strips to the arch-slate and assemble the form.

The internal height strips mustn’t deform the arch; position them with a light touch and a little glue to hold them in place.

Sight along the form to check the curves’ regularity.

Put it all together and put a strip of 120 grit sandpaper on it.