Building a Ganassi Viol

Veröffentlicht: 06.01.2014     Autor/in: Judith Kraft

Abstract

Comments and step by step description of the process and method of building a Renaissance viol after Silvestro Ganassi.

Forschungsprojekt

Transformationen instrumentaler Klanglichkeit

Zitierweise

Judith Kraft, "Building a Ganassi Viol". Forschungsportal Schola Cantorum Basiliensis, 2014.
https://www.forschung.schola-cantorum-basiliensis.ch/de/forschung/fruehe-streichinstrumente-1/kraft-building-a-ganassi-viol.html (Abgerufen am TT MM JJJJ)

Lizenz

The text of this article is provided under the terms of the Creative Commons License CC-BY-NC-ND 4.0

On my medieval fiddles, the top is flat on the outside, but thicker down the center along the entire length inside. This provides a way to reinforce the front in bending it onto the ribs, as we have done with the Ganassi.

With this approach to early viol-making, it was very interesting to take the process quite a few steps further along in building this Ganassi model. Here is a step-by-step description of that process.

Next, I transferred the thickness mapping to the inside of the front, using tracing paper and carbon paper. Where we were given leeway to change the thickness near the treble bridge foot, I made it thicker under that foot. Using a drill press, I marked the mapped-out thicknesses and then proceeded to gouge them out.

RIB AND BACK PREPARATION

On later viols, I build without a mold, gluing the ribs and blocks together upside down on a board to ensure that the front will match the original tracing. For the Ganassi, I chose to build the body from the back, without a mold. I reasoned that with ribs so thick, there was little chance of deformation between the front and the back. In addition, the curved back, the variable height of the ribs in the lower bouts, and the through-neck would have made it very difficult to control the neck angle (and bridge height) – a critical aspect of the instrument. I should point out here that when building my own viols I am not averse to trying different neck angles, but in this instance I wanted to limit the uncertainty and follow the drawing as closely as possible.

NECK PREPARATION

After hearing Stephan Schürch describe his problem with inserting the ribs into the neck block at the proper angle, I took the precaution of making a fake neck block for a trial run. It worked perfectly, so I was able to proceed with confidence, very thankful that I could benefit from another luthier’s experience.

Using my tracing paper neck outline, I drew the shape onto the neck block with carbon paper and cut it out. I used the same tracing paper/carbon paper technique for each side of the scroll. I could then carve the scroll using the same method as for a violin, except that I had to glue on ears to make the scroll wide enough. I used a double bass makers’ technique of cutting pieces from the part of the pegbox next to the scroll, which enabled me to match the wood.

Once the scroll was finished, I traced the rib slots and cut them with a large-set handsaw. The slots required supplementary filing in order to fully insert the thick ribs.

I then copied the curve of the heel foot from the drawing onto tracing paper and transferred it onto the neck block.

BACK

Once the back was jointed and thicknessed, I tried curving it by force, as we were asked to do. But I felt uncomfortable about applying that much pressure to the back and was afraid that I would lose control over the neck angle. So I decided instead to heat-shape the back.

However, after a few minutes on the bending iron, the back began to curve inward laterally. I was concerned that this would be a problem for the stability of the instrument, but when I tried to straighten it out, the center joint opened up. At this point, rather than force the joint closed with the risk of having it crack open again, I decided to unglue and redo the entire joint. (Fortunately, there was enough extra width to allow this.) The result was quite satisfactory: the back retained its lengthwise curve while remaining perfectly flat crosswise.
Just prior to gluing in the bracing, I heat-shrunk the back by placing it in front of a hot stove. This created a slight outward curve (on the outside), matched by a curve in the bracing. These curves had to be minimal in order to keep the ribs, once glued, from leaning in.

NECK GLUING

After adjusting the ribs in the neck slots, I was able to remove the surplus wood on the outside of the slot to shape the heel – this would have been very difficult to do after gluing in the ribs. In any case, the ribs adhered well to the neck block without the pressure of the outer part of the heel – it wouldn’t be necessary, as I might have feared, to clamp them.

Next, the neck was glued to the back, using the center line of the board for lateral alignment (at the bottom, the heel and the scroll) and a square to control it. I placed a wedge under the scroll to ensure the proper neck angle and controlled the neck projection at the bottom block.

The top ribs were inserted into the neck block and cut and adjusted to the back curve. They were then cut to length at right angles and beveled, as were the other ribs. The top ribs could then be glued into the neck block and onto the back.

The c-ribs were glued to the back and to the upper ribs. The corners were held together with adhesive tape while the linen corner reinforcements were glued in and until they dried. The lower ribs were glued to the c's, the bottom block and the back. I controlled the verticality with a square.

The contour was not perfect, so I wedged temporary braces against the inside of the ribs to correct this. I had attached strings to them for easy removal through the sound holes once the front was glued. One of the braces was collapsible. (I performed a trial run to make sure they could all be removed!) I made sure that atmospheric conditions were dry for gluing the front.

Normally, once the front was glued I should have put in all the purfling. However, knowing that I wouldn’t have time to finish the purfling and set up the viol (to say nothing of the varnish) before the conference in May 2013, I decided to inlay only the purfling that ran under the fingerboard – which would be impossible to do once the fingerboard was glued.

When that was completed, I was able to finish the fingerboard, checking once again for projection and bridge height.

The bridge came out 1mm higher than on the drawing. I thinned down the crown – under the strings – which improved the sound somewhat. Later I thinned out the middle all the way across, which gave more presence to the middle strings. The tailpiece was a bit too close to the bridge, but when I pulled it back, the sound became freer on the low strings. Finally, and most importantly, I decided to use a thicker gauge on the four lower strings. This gave much more presence to the middle and low registers. (Current stringing: d': 72, a: 92, e: 126, c: 160, G: 210, D: 290.) If the viol is played at a'=440 Hz, which is how I set it up, I would consider trying a thicker G string. At a'=465 Hz the current stringing would probably work.

It dried under similar conditions, but for four days. After sanding, a third, thicker coat was applied and left to dry for one week. Then came the final coat, of equal thickness, always with a brush. One week later, I sanded this coat with 1200 and then 1600 abrasive, without removing too much varnish. I wanted to end up with a surface that was smooth but not too shiny.

The two control samples – spruce and maple – that were provided to me, received the same treatment simultaneously. The viol dried in a sunlit room for several weeks before I set it up again. The initial sound of the varnished viol was a bit more subdued than it had been previously, but not markedly different.