The Theorbo – Making lute forms

A lage part of the construction process of a lute is making the mould or form on which it is made. There are multiple ways to construct these, all with their own pros and cons.

Solid or skeleton

We don’t know how historical lute makers made their forms. Other than guitar and violin forms (Stradivari) none of them remain. Probably because they are rather bulky and take up quite a bit of space. When the lute went out of fashion, many of them probably got a new career as firewood.

Although one description survives, by Henri Arnaud de Zwolle (ca. 1440). In his works about music he made a drawing of a medieval lute and its mould. Very rudimentary, but clearly a form of the “skeleton”-type: a base plate on which multiple segments rest, dictating the form of the lute ribs.
The advantages of this type of mould are that it is fairly quick and cheap to make, lighter than solid models and you can reach within the instrument during construction. Main disadvantage is that you can’t see the complete inner shape directly and have to apply a vast amount of abstract thinking to visualize the shape.

Another form is the solid mould, described in Robert Lundberg’s lute making bible “Historical Lute Construction”. The core is formed by solid wooden blocks, shaped to the form of the lute. An advantage of this type is that you can adjust the inner shape of the lute bowl (the “air chamber”) directly. During the fiting of ribs you can rest a plane directly on the form, almost impossible on skeleton models. Disadvantages are weight, costs, the longer construction time and lack of possibility to reach inside of the lute during construction.

Making a mould

The construction always starts with drawing. I prefer to make a start on the computer and work it out by hand. At this moment it’s very convenient to know the system of measurement used by the original builder. It is a key that unlocks the underlying structure. A touchstone to find the original radii of the compass arcs and things like body and string dimensions. This is like making a puzzle without a draft, recreating
the design process of the initial builder, literally a re-construction.

With this found design I make a couple of templates. A hardboard (masonite) or plexiglass template of the body outline (inner mould, without the side thickness) to route the base plate.  And a paper model to lay out the rib structure. I like to make these simply with a  compass, scribe and ruler,
just like the old masters did. Why? Because it is less precise than something computer generated. In the virtual world you can get an almost infinite precision. But 17th century builders didn’t have that technology. By using these simple hand tools you get a sense of the scale, dimensions and proportions they had to work with.

The paper template is used to transfer the rib layout onto the segments. Both sides of the segment, because the facets are angled to follow the shape of the ribs. When you use a scribe to mark out the form, you have a clear line to work towards. Pencil lines fade or get wiped out during work, but when scratched in the surface it will stay no matter what.

Colleague guitar maker Joës van Went in my workshop. Working on his first lute form

Cutting and filing

The base plate is cut out and shaped with a router. A quick and easy way to make forms is to make a routing template for one half, put two screws along the centerline and move it over after you’ve shaped one side. This gives a smooth form that’s perfectly symmetrical.

The segments are cut out at an angle with an electric jigsaw or on the bandsaw. Then starts the rather laborious process of cleaning them up. Filing, filing, filing and… filing.

When the segments are ready they are fastened to the base plate and the spine of the form with a halving joint. This way the parts of the form keep each other secured.

The hardest segment to shape is the one on the lower end of the body. It’s rounded to the shape of the bow. Here the layers of the multiplex are an advantage, because they nicely show the shape of the segment.

There are multiple ways to fasten the form to your workbench while making the bowl. The simplest is just one piece of timber under the form to clamp it in the bench vise. But this way you can only move it one way. Another extreme is a system of lockable hinges, a bit like a stative. Pretty handy at first glance, but after working with it for some years I do think there are some disadvantages. So I have settled now for a simple wooden cross at the bottom. It can be clamped in your bench vise at any direction you like. And the best part, removed quickly to make room for another lute you are working on.

I have made these segmented forms in a variety of woods. And must say that I prefer (birch) multiplex for the segments and MDF for the base plate. It’s dimensionally the most stable and easy to work with. You can use MDF for the segments, but they are easily damaged because the material is quite soft on the sharp corners. But use whatever you like or have at hand, these forms are ideal to get rid of leftover pieces of wood and board.

If you want to get started with lute making I have plans available for a renaissance lute and its form. It’s a 7-course renaissance lute in G, based on the 1581 Georg Gerle example. You can also use this model to make a 6 course model (dimensions for the neck, head and bridge also on the plan). An ideal lute to start with!

It’s possible to follow a lute or guitar making course at my workshop (in the beautiful center of the Netherlands). Please send me a mail through the contact form at this site for details.

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