Craftsmanship analysis, interpreted through CAD and augmented

Computer Aided Design CAD was the virtual sketch-book to collate all the craftsmanship observations and virtually trial construction ideas created through a series of CAD software's Rhino, Flamingo, Tech Gems, and Matrix.

When rendered, it appeared as if it were a mere skeleton of the intended jewel. There were aspects that looked functional and visually lots of negative space between components. Piecing together our observation data a number of craftsmanship clues suggested possible manufacturing scenarios. 

Materials – material evidence of very flaky and water damaged pearls at the top of the wire structure, 

Wire structure – a number of different gauges of wire were used, with much finer wire wound around the circle structure of the body, indicated they were holding something in place, mechanically fixed rather than soldered suggested something sensitive to heat. 

Could these circles have held pearls would the size of the circles determined the size of the pearls? Could the large setting at the bottom may have contained a pearl or half pearl? A combination of craft observations with 17thC portraits festooned with meters of chain using pearl and wires presented clues to contemporary designs of the day and potentially what it looked like when it left the goldsmiths workshop 400 years ago. The final CAD augmentation and render presented a new perspective and interpretation on the original artefact, a compelling argument for tangibly realising the augmented virtual design. 

How can digital technologies and craftsmanship provide solutions for the heritage sector?

Museums have to negotiate a delicate and often conflicting set of issues. As custodians of our cultural heritage, they have a responsibility to preserve and protect the artefacts within their collections. As public institutions, they have to provide access to their collections for public engagement and scholarly research. How do these seemingly incompatible demands be simultaneously addressed? With advances in digital technologies and an understanding of craftsmanship, this paper will discuss how integrating traditional and digital technologies has provided opportunities to bridge these opposing demands.

The research was a collaboration between the Museum of London and the School of Jewellery at Birmingham City University and focused on one artefact, A14000 and for the purposes of this craft investigation more descriptively named the Pearl Dropper, an artefact from the Cheapside Hoard (An Elizabethan time capsule of craftsmanship, buried at some point before 1635 and then forgotten for 300 years). 

Data Collection – Craftsmanship observations

Getting up close: scoping the Pearl Dropper with the aid of a jewellers loupe, applying our experience as craftspeople to visually interrogate and deconstruct the artefact, surfaced many questions regarding its fabrication and construction techniques. Data was captured in photographs, sketch books and physical measurements. It was evident from the distorted wires, loose elements, fractured enamel and material loss that the artefact was extremely delicate and in a fragile condition. 

The Pearl Dropper’s condition presented issues of conservation, display, interpretation and access for the museum and therefore was an ideal candidate for the research investigation. 

It is one thing to look at an object for its aesthetic value it is a very different proposition to ask how did they make it originally and how would I make it now? 

Transforming virtual to tangible

Wax: Utilising the School of Jewellery's in-house 3D wax printer (Invision 3D system) provided a proof of concept build. This type of 3D printing is a proven method in the jewellery industry to create sacrificial wax patterns for metal casting.  However the complex structure presented issues for this manufacturing route - geometrically the structure had many undercuts, fine wires and voids to work around, and the amount of spruing (channels to allow the flow of molten metal to reach every section of the structure) required to reach all areas before it cooled deemed problematic.

Advances in 3D printing now enabled printing directly in metal, allowing for greater geometric flexibility and complex 3D structures. However I had no hands-on experience in integrating this technology within my own making methods as a craftsperson. Without the equipment in-house ES technologies agreed to share their printing expertise and the challenge of this build.

The initial direct laser melting (DLM) trial was met with a mixed reaction. Printed on a Concept laser Mlab on first appraisal there seemed more product support than build, had I misunderstood the technology? On closer inspection the fine wire cage structure of the Pearl Dropper had built, however the number of supports was excessive and required significant post processing to individually removal by hand. A phone call with ES Technologies resulted in a greater understanding of what we both require in term of CAD file and post print craftsmanship. With a realignment of the printing file to an upright position on the build platform, meaning that the CAD design acted as a self-support system, eliminating most of additional support structures.

CAD refinement, kit of parts, original construction

The first and second DLM prints were an exact recreation of the metal components of the pearl dropper but built as a single unit – the physical access between the wire arms of the cage structure was very limited making it impossible to accomplish the downstream techniques required. 

In order to incorporate the additional techniques, plating, pearls, enamel features and fabrication processes, greater access to the structure was required and therefor a rethink of the component structures and fabrication was required. The final design had to remain but an intermediary stage of manufacture was needed, to reconfigure the pearl dropper structure to accommodate the post processing additions. As such reverse engineering the build into component parts. 

The virtual CAD sketchbook allowed the visualisation of a kit of parts and potential methods of original construction.

The third DLM trial combined efficiency of platform build with access for craftsmanship post processing, a hybrid approach. The enamel arms form the cage structure of the body. The pearl arms are separate components to allow access for the attachment of pearls and then welding to the cage structure to complete the Pearl Dropper body.

CAD files laid out the nesting of the builds on the printing platform, illustrating the minimal CAD support in red. 

Layer by layer of metal powder was laid down each laser melted to the previous layer determined by the CAD file.

The video shows the excavation of the build, the build platform is raised allowing the loose powder to fall away to reveal the built components. Had it built successfully, could it be removed from the build platform without damage?

Our excitement and anticipation in seeing the components emerge gave us some insights into how those work men must have felt in 1912 when they discover the jewels for the first time. 

Post Processing 

What comes off the machine is a component which is only part of the craftsmanship journey, what comes of the bench after post processing is a product. Post processing required the removal of metal supports of the DLM process and filing back of the 3D printed components to provide a consistent surface for the downstream craft activities of plating, enamelling, pearl threading and fabrication. 

Until this point, the reconstruction had been virtual and mechanical, as a craftsperson there was an element of being detached from the making process. It was satisfying to get hands on and connect with the DLM material. Physically understand and learn through my hands how it responded to processes and become more attuned to the integration of DLM with my own craftsmanship. Hand finishing allowed me assess the strength of the structure give me confidence in applying the downstream activities of plating pearls and enamels.

The budget didn’t stretch to DLS in 18ct yellow gold so the bronze print was plated in18ct.

The enamelled surfaces on the original pearl dropper bulged beyond their metal rim settings, in recreating the same look, cold enamel had to be patiently applied and reapplied. The simple tool of a wooden cocktail stick proved incredibly useful in controlling the amount and thickness in applying  the enamel.

The attachment of pearls required several stages and a number of trials in copper wire to physically ‘figure out’ the ideal method of assembly. The most important aspect was the first twist, getting the tension right between wire and pearl, once the first pearl was attached the rest followed.

During this research there were moments of frustration, from, “oh that’s obvious”, to “this might actually work”, offset against the sheer satisfaction of making and realising the Pearl Dropper as it might have been when it first left the goldsmith workshop. On reflection there were many mistakes and there are things I would do differently if doing it again, however learning through integrating craftsmanship and digital technologies has revealed valuable insight on past practices of craftsmanship.

The recreated pearl droppers are now held by Hazel Forsyth Curator at MOL and are regularly used in public events. A jewel to be handled, touched and worn as it was intended to be by when it was first crafted. 

This projects success was a team effort and I’d like to thank Keith Adcock an incredible patient colleague who worked with me on the many refinements of the virtual CAD model, while being mind-full of the post processing and downstream craftsmanship required in the real world to realise the reconstruction. 

Acknowledgments:

Ann-Marie Carey – Fabrication, LSW, Scribe

Keith Adcock – CAD 

Frank Cooper  - Tech Hub

Karen Bartlett - Plating

Samantha Chilton – Enamel

Hazel Forsyth - Museum of London

Colin Cater - ES Technologies