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Blog: Unknown Miner Trophy Version Completed
Louis Wald
13/02/2014
The Unknown Miner Trophy was commissioned by the University of the Witwatersrand Engineering faculty following the acquisition of the Unknown Miner work erected on the steps of the entrance to the faculty building in 2012.
The work was originally made as a prototype for the Diamond Digger’s monument in Kimberley which was erected in 1960.
It was decided to make the trophy using 3D printing. The first step was to laser scan the original sculpture and produce a 3D model. This takes the form of an electronic file with x, y and z coordinates of many points on the surface of the work. Once you have the model it can be manipulated in a 3-D modelling package. You can rotate, zoom and pan as well as alter the model in multiple ways.
Drag mouse to rotate. Drag mouse with shift pressed to zoom
The sculpture model is now complete. At this stage the 3D print designer decides on how to approach the project. EnvisionTec uses a software product called "Magic" to configure and control the 3D printing machine. As the image shows, in this case it was decided to produce 2 figures, one as a backup.
The software generates thousands of bitmaps that are used in the 3D printing process, 20 per mm. A sample of 6 have been selected here to give an idea of the process.
After some unsuccessful attempts elsewhere EnvisionTec in Stoke on Trent in the UK agreed to do the print.
EnvisionTec use the Photopolymerization technique which produces a solid from a liquid. In digital light processing (DLP), a vat of liquid polymer is exposed to light from a DLP projector under safelight conditions. The exposed liquid polymer hardens. The build plate then moves down in small increments and the liquid polymer is again exposed to light. The process repeats until the model has been built. The liquid polymer is then drained from the vat, leaving the solid model.
The machine selected was the EnvisionTec Alpha shown below.
The process is far from instantaneous - it took around 25 hours - 300mm * 20 slides per mm = 6000 slides at approximately 15 seconds per slide. Because of previous unsuccessful attempts done elsewhere there was considerable anxiety about the results of this attempt. The following 4 images show the platform being raised to expose more and more of the print. Happily it looked to be of high quality from the outset.
A considerable amount or work remains to be done after the machine print is complete. Scaffolding elements need to be removed, and components need to be cleaned, sanded and assembled. This is a highly skilled process that requires a highly skilled craftsman. Gordon Brooks has decades of experience working in the ceramic industry in Stoke on Trent, specializing in the design and prototyping of ceramics using mainly Plaster of Paris.
Completed Resin - Printing Layers
The figure was then painted white to help expose faults. The printing layer pattern evident especially on the face and chest resulted in much discussion - should it be removed? does it add or detract? what detail will be lost of it is removed? A consensus quickly developed that it enhanced this particular work because in addition to
looking interesting it exposed the method that was used to fabricate it.
Alongside the Original
The Bronze Cast
3D Printing is currently is very topical. Media reports give the impression that this is a mature technology. Experience from this project however demonstrates that making a high quality small scale replica of a figurative sculpture using 3D Printing remains a significant challenge.
Considerable skill and effort are required from an experienced technician, all the way from deciding how to partition the item, how to support it using scaffolding all the way to assembling the parts and treating disruptions to the surface.
A strong consensus emerged amongst all involved that maintaining the printing layer pattern added to the aesthetic of the work in that it exposed the method used to fabricate it.