Project 1 - Parametric Object Design
Course: ATCM 6321 Digital Fabrication with Andrew Scott
This project is an exploration of growth processes that result in Voronoi partition structures, as well as an exploration of the process of digital parametric modeling to create real-world art objects.
Parametric modeling is a design approach that uses an algorithmic process for generating designed geometric forms. In this project, I was interested to develop an understanding of how to create patterned surfaces that have an organic structure.
I am documenting my learning process by creating an online eBook, using the gitbook platform. My gitbook has more detailed information about the functionality of grasshopper components used to create the grasshopper definition. Parametric Design With Grasshopper
Inspiration Natural Voronoi Patterns in Dragonfly Wings
The images below show that the upper edge of the dragonfly wing is rigid with many horizontal structural members, while the lower edge of the wing has a more delicate curving surface. The cell structures within each wing show patterning similar to Voronoi partitioning, so I'd like to explore the algorithmic nature of these structures.
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| Dragonfly Wings Show Voronoi Patterning |
The inspiration for this project is based on previous personal work, where I'd created a dragonfly necklace using silver metal clay, sapphires, and vitreous enamel for a necklace made in 2005, shown in the image below.
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| Silver Clay Dragonfly with Enameled Wings |
For this necklace, I explored creating transparent dragonfly wings using silver metal clay and enamel. I was inspired to use the plique-a-jour enamel technique by the exquisite art-nouveau jewelry designs of Rene Lalique.
In the fabrication process for the dragonfly necklace, I created metal-clay organic wing structures to resemble dragonfly wings, then filled in the metal voids with multi-layered vitreous glass enamel. To create the metal's wing pattern I used a photo-replication process. Black and white photographs of cicada wings were used to as a resist-pattern for exposed photopolymer print plates. This created a reversed-impression stamp which was used to imprint the wing structural form on metal clay material. Once the pattern was stamped on the metal clay, the voids were carved into the dried metal clay using micro diamond files and micro-drill bits as hand-carving tools. After the clay was fired, then multiple kiln firings were used to build up the transparent enamel structure. The necklace won an award from Japanese Association for Leisure & Culture.
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| Metal Clay - Fabrication Tools and Process |
Parametric Design Using Rhino3D and Grasshopper
For the current project, I wanted to use parametric modeling to create a similar wing inspired structure. I used Grasshopper3D and Rhino to create an organic surface that had voids / perforations at the voronoi site centers.
The image below shows the Rhino3D ghosted rendering in gray and the grasshopper version of the object in red. The object consists of 2 simple curves that were created in Rhino, along with the 3D Voronoi surface that is lofted between the curves through an algorithmic data-flow of transformation processes on geometric information.
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| Grasshopper Parametric Voronoi Object |
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| Rhino3D Baked Object (gray) and Grasshopper Parametric Object (red) |
In Grasshopper, an object-reference relationship is created between a grasshopper node and a Rhino nurbs-curve, so that the Rhino curve's geometry can be integrated with the grasshopper definition. Then an algorithmic, data-flow process is used to take geometric outputs from one Grasshopper node, pass each geometric structure, along with numeric sliders to control additional input parameters, and each Grasshopper node does some type of transformation to the algorithmic data. The image below shows the full Grasshopper Definition for this Voronoi dragonfly object. In the image, Grasshopper components are grouped in functional structures. The 4-components on the far-right are the finalized 3D surface objects which are baked to create the Rhino3D model.
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| Grasshopper Definition for Voronoi Dragonfly Wing |
The image below shows that voids are created by scaling the geometry of each Voronoi cell to a smaller size, where a surface is lofted between the original Voronoi cell border and this inset scaled version. In addition, a fillet is created on the inner corners of the void. This void structure is then extruded in the z-direction, these extruded walls with inner filleted corners will create a low-stress structure for inset enamel material.
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| Grasshopper 3D Voronoi Voids |
In order to create a 3D object that can be replicated using traditional mold-making techniques, I modified the perforated Voronoi surface by adding a membrane layer, which bisects each Voronoi extruded cell. This central membrane surface allows for the creation of a 1-part silicone mold. In future designs, I plan to create a 3D dragonfly wing with voids at the Voronoi site centers and then create a 2-part mold to allow the creation of a casting with voids that can be filled with enamel.
As my parametric modeling skills are not advanced, the objects that I created are quite simple. I have embraced the simplicity of the resulting simple forms, as they allow me to focus on exploring the material properties of the 3D print and subsequent cast resin objects. In addition, from a learning perspective, it's critical to develop a foundational understanding of creation of simple components in order to develop
In narrowing my focus on learning the material transformation processes, the first part of the process is having the digital file printed to create a 3D printed object.
3D Printed Object
One of the first lessons I learned is that digital fabrication workflow requires careful craftsmanship in the modeling and casting stages. My initial attempt at preparing my 3D print for mold-making was rushed, and the results were sub-optimal. When I coated my 3D print with XTC-3D, a brush-on coating for 3D printed parts that helps seal the object and smooth print striation details, I tried to rush the process. I tried to paint additional layers before the initial layers were fully dry, so the finish had brush marks and had accumulated dirt due to handling while the finish was drying. I created a mold using this poorly prepared print and the result was a mold that included these surface defects, which are transferred to any casted version. I have since sanded the surface and will be re-applying XTC-3D prior to creating a new mold.
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| 3D Printed Voronoi Object |
Mold Fabrication: Dragon Skin Platinum Silicone
A one-part mold of the 3D printed part was created using a premium quality silicone mold materials. For this project, I used Dragon Skin silicone product purchased from Reynolds Advanced Materials. Creating silicone molds requires careful execution of a series of steps, where attention to detail is focused on reducing air-bubbles throughout the mold-making process. Air bubbles may form adjacent to the molded object, which will result in surface defects for any subsequent cast objects. Since the mold material is relatively expensive, care in the 3D print preparation and in the mold making process is critical. My first mold was not a high-quality mold because I rushed in the 3D print preparation. Therefore, I will need to create a new mold, which is both a waste of time and expensive mold materials. I will reuse the material from the mold, I can cut the mold material into chunks and use as fill material when creating a new mold as long as both molds use the same material.
Casting Urethane Resin Objects
Similar to the mold fabrication process, creating a quality cast resin object requires focused attention to reduce air-bubbles throughout the casting process. A mold release spray is used to coat the mold, to minimize surface air-bubbles.
The urethane resin is a 2 part mixture that has a chemical reaction to create the resin, selecting a resin with a fast cure time allows for a faster fabrication process, however, it means that there is a short working-time for mixing the materials and filling the mold. For both mold-making and casting, the mixing process must be thorough, but should also be done carefully to reduce the introduction of air bubbles into the materials. The cast objects can be removed from the mold after about 10 minutes, and the resin remains quite flexible for the next 6 hours until the objects fully cure. During this 6 hour time, I decided to twist the wing objects, this created objects that resemble plant leaves. Since the objects have 2 outer curves, where one curve is straighter than the other, this configuration allows for natural spiraling around the straight edge as an axis.
The images below show the cast resin objects which were tinted transparant purple. Due to poor 3D print preparation, the cast objects had poor surface quality, so I used 3M sanding sponges to smooth the surface inperfections. The sanding sponges come in varying grits, so I used a series of 5 sanding stages: medium, fine, superfine, microfine, and ultrafine. The sanding sponges can also be used with water, this ensures that sanded particles can be washed away during the sanding process.
Finished Objects - Project 1
After sanding the objects to remove the surface defects caused by my rushed fabrication process, I was actually very happy with the resulting objects. The transparency of the resin, in conjunction with the matte finish due to sanding, and the organic structure of the object itself result in an object that feels good to hold and look at. I can envision creating quite a number of sculptures using these objects as the focal point. I plan to create a chandelier using these objects as hanging components, but I can also envision using these objects to create plant-like sculptures. The simplicity of the object's form will allow it to be used in multiples to create larger organic compositions.
Moving forward, I have recently created a new 3D object that has a more complex wing structure. It's currently being transformed from the digital format to a physical 3D printed object. Once I receive it, I'll continue the mold, casting fabrication workflow. There is something quite magical about creating an object in a digital world and then holding the 3D printed object and subsequent cast resin objects. It feels like a dream come true.
