this fiddle is the second in a series exploring the sources of variety that we see in violins. A broader discussion of the ideas behind this series is laid out in an earlier post. where I suggest that there are four sources of variety in any violin, or man made object, that we encounter. These are:
- Design. The choice of and adjustments to the violin model.
- Materials
- Age. Everything in the universe changes over time. In violins we see the effects of interaction with the environment and the decay of materials.
- Execution. How closely the violinmaker was able to realize the ideal that they had in mind
As in the Turing Fiddle a computer generated pattern was designed to cover the surface of the violin. To make the Turing Fiddle, I carved the surface pattern by hand, thus introducing more variety during the execution of the design. This time I limited the variety due to execution by having the pattern carved into the violin surface by a machine. As with the Turing Fiddle I then finished and “antiqued” the surface of the violin, in order to mimic the effects of age.
Telescope Technology
The pattern on the violin surface was computer generated by Christy Reynolds, a telescope scientist who saw my Turing Fiddle on Instagram and commented on the similarity between the Turing patterns and the patterns that she had generated while working on the European Extremely Large Telescope. The patterns were an attractive by-product of solving a major technical problem, as Christy explains:
Telescopes operate by collecting light like gigantic funnels, enabling imaging of distant dim objects by dramatically increasing the number of light particles captured. The larger the primary mirror of the telescope, the more light can be gathered from these faint sources. The newest generation of telescope designs call for primary mirrors larger than can be currently manufactured. This means these mirrors must be broken up into segments form a single mirror as a mosaic. Telescope mirrors are curved bowls which bring light to a single focus, but these individual segment are not longer radially symmetric surfaces. This presents a complex manufacturing challenge solved by using precision robots. These robots follow a single path across the surface, slowing down where more material must be removed and speeding up in areas that require less removal. This process results in a surface curvature that can be exactly controlled, but causes the new problem of periodic surface texture. The easiest way to visit each point on the surface only once (to ensure we remove exactly what is required) is to raster back and forth across the mirror blank. This produces the exact curvature we specify, but leaves behind very periodic ripple in the surface. This ripple produces a diffraction effect, similar to the rainbow created by the regular grooves on a DVD. This highly undesirable in the images produced by a telescope, so a new algorithm was required that did not have a regular pattern like a raster but visited each point on the surface only once so that the correct amount of material is removed at each point. The random unicursal path algorithm was developed for this application and used to polish the prototype mirror segments for the European Extremely Large Telescope, a 30 meter optical telescope currently being built in Chile.
Pattern Design
Christy shows the process of generating a unicursal path
The density of the pattern is variable, we used the one on the right
Machine carving
The line generated by the computer became a path that a cutting tool would follow. For this I contacted Ben Pearse of Outlierworkshop. Ben provides Computer Numeric Controlled (CNC) machining services to the Lutherie world. In these days of digital scans of 3D objects CNC machines can carve very close copies of all of the parts of existing instruments. I’m not interested in making exact copies of old instruments, but for those who are this can save a lot of time and effort in the initial stages of making, allowing the maker more time to work on replicating the varnish and finished appearance of the original. Ben has a long client list many of whom he has Non Disclosure Agreements with. While Ben is throughly engaged in the technical side of his work he welcomed the chance to work on a project that would feature his work, rather than hiding it in the shadows.
CNC routed plates and ribs ready for assembly. The pattern carved into the surface of each part is formed by a single line that travels over the entire surface before returning to its origin (hence the” Unicursal Fiddle”)
The spruce top (seen prior to varnishing), showed “imperfections” in the quality of carving, caused by the difficulties of using a router on a soft wood like spruce. This supposed failure created a texture that did a lot to give the violin a more organic feel after it was antiqued.
This is an example of variety caused the interaction between the material and the tool and working methods.
The assembled violin with a “straight” finish
The pattern with its repeating parallel lines is eye catching and absorbing. It is reminiscent of some forms of primitive art, but its geometric style is rather mechanical looking. Not very organic.
Finishing
In My earlier post controlled-randomness-and-the-search-for-a-good-honest-violin-finish/ I talk about the dream of a violin finish that changes soon after application to give slightly unpredictable results. With that in mind I experimented using a combination of colored inks and pigments. The inks and pigments separated during the drying process to give somewhat random results.
At first I thought that unusual violin finish was too chaotic and garish, but over the next few days found it more compelling. I realised that it has some of the visual elements that I’ve been looking for. In particular the violin shows what I call “recursive variability” where the violin as a whole has a unifying visual theme, showing related but varied regions. Zoom into any of those regions and you will find the same effect repeated on a smaller scale. Every time you do this you will see more themes and more variations upon them. Zoom in on these gallery pictures to see for yourself
