Liutaio Mottola Stringed Instrument Design

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Construction Details of the Libellula Electric Upright Bass - The Body and Neck Subassembly

The construction of Electric Upright Basses (EUB) probably varies more than for any other instrument family. Materials and construction techniques don't differ much from one violin to the next, and although different solid body electric guitars may not look alike they are all constructed pretty much the same. But there is tremendous variation in both materials used and construction of EUBs. Some are built a lot like solid body electric guitars and basses, others are more like semi-hollow electric guitars, and still others are constructed just like acoustic instruments. This wide range makes it impossible to show how a typical EUB is constructed, since in effect there is no typical EUB. These pages contain a pictorial presentation of how the Libellula EUB is constructed. As a solid body instrument most of its construction details are similar to those of other solid body EUBs. This page shows how the body/neck subassembly of the instrument is built.

Last updated: Saturday, August 15, 2015

The first step in the construction process is collecting the materials used for the instrument. The neck and body of the Libellula EUB are made of Honduras mahogany. The fingerboard of the instrument shown is made of Madagascar rosewood, and the fittings are made of Indian rosewood. The bridge is made of eastern hard maple. All of the major pieces are matched for color and grain and then cut to their initial sizes. At this point it doesn't look much like an instrument at all!

On this instrument the neck and the main part of the body are made from a solid piece of wood. The horizontal profile (the view from the side) of the instrument is marked on this core and then the profile of the neck is cut out on the band saw and then sanded smooth. A channel is routed on the fingerboard surface of the core for the adjustable trussrod.

Then the body end saddle is shaped and glued onto the end of the core.

The vertical profile (the view from the front of the finished instrument) is marked onto the core and sawed out. The sides are trimmed on the jointer.

Sometimes the body end is touched up by hand to ensure a perfect fit of the other body pieces.

The outline of the body side pieces are transferred to stock ...

... and then the body side pieces are sawed out and sanded smooth. The body side pieces are then glued to the core.

This instrument has a D neck. To make it easier to play further up the neck without using thumb position the sides of the body are chamfered. This also reduces overall weight. The chamfers are roughly cut out on the band saw and then sanded smooth using a spindle sander and a special jig.

Next, the top of the body below the end of the fingerboard is thinned down using a router.

Holes are drilled in the back of the body to accept the threaded inserts that are used to mount the “wing” assembly to the body of the finished instrument.

Holes for the volume control pot and the jack are also drilled at this time.

The body/neck core is now ready to have the fingerboard glued on. The fingerboard is roughly cut to shape on the band saw.

The trussrod is installed ...

... and then the fingerboard is glued on to the core. A lot of clamps are used!

An extension is glued on to the bottom of the nut end of the neck. This is where the volute will be in the finished instrument.

Now the sides of the fingerboard are trimmed flush to the sides of the body/neck core. This is done on the router table using a pattern router bit.

The end of the fingerboard is trimmed using a router and round-nosed router bit. Trimming is finished up by hand using a chisel and then a sanding block. Note that I'm not really chiseling into my hand.

The body is still not done. The bridge cavity and the control cavities still need to be routed, and the pegbox and scroll need to be built and attached. The neck needs to be carved, too. Still, it is starting to resemble an instrument at this point in the construction.

The pocket for the bridge is routed in the body using a template and pattern bit. When it is done it looks like this:

The template is put back on and the bridge blank is inserted in the pocket and then hollowed out using the template and a guide bushing on the router. Now it looks like an elongated cup. Then a very shallow ( approx. 0.031”) 0.125” wide trench is also routed in the center of the floor of the bridge cup. This trench will locate the piezo transducer on the floor of the bridge cup. Then the template is removed and the bridge cup is removed from the pocket. The trench in the bottom looks like this.

Finishing the bridge assembly will be done later, and is covered on a separate page.

A paper drilling template is put into the bottom of the bridge pocket to locate the holes that will be drilled there.

Five holes are drilled in the bottom of the bridge pocket right through the body. The three small holes are for the screws that attach the string anchor to the back. These will be countersunk next. The two large holes are for threaded inserts. In the finished instrument set screws in these inserts provide for bridge height adjustment from the back.

The control cavities, the cavity for the battery box, and the control cavity cover recesses are routed next, using templates and a pattern bit.

After passages are drilled between all of the cavities for the wiring, all the routing and drilling of the body will be done.

Now it's time for the scroll and pegbox. Complete instructions for carving a scroll are available on a separate page on this website.

Once the scroll is finished attention is returned to the body and neck. The fingerboard surface is shaped with a smooth radius. Facets are carved first with the belt sander and then touched up and rounded over with the hand plane. Then the entire fingerboard is shaped with a radius sanding block.

Then the neck is carved. The primary facets are also cut using the belt sander, but the tight places where the neck and volute join and where the neck and body join are done with a rasp.

The facets are touched up and then rounded over with a spokeshave and then the entire neck surface is rounded and smoothed with a file. Finally the entire neck surface is sanded smooth with a block.

After the neck is done the pegbox and scroll assembly is glued onto the neck.

When the glue is dry the extra length of the volute is trimmed and sanded to blend into the curve of the bottom of the pegbox.

Up to:                 Top of this page (Part 1: Constructing the body/neck assembly)
Continue with:  Part 2: Constructing the Wing