Travis Fowler: Prosthetic Accessory

Concept:

I wanted to make a design that would be simple and elegant but still meet the design requirements and serve as a functional piece, not just a spectacle that someone might keep on display more than on their leg. The initial inspiration for the design came from the depiction of clouds in ancient Asian tapestry: loose spirals that create a form with depth. Each spiral holds a particular form or muscle group of the leg. The design shifted away from very tight spirals to more even spirals that twisted with the form of the leg. The actual model design was a big far off from what my drawings indicated but I didn't foresee the world of problems that I would encounter making such a long detailed single curve.

Technique:

I used almost every technique in my toolbox for this one. I began by importing some standard-sized leg references into Rhino and I began to create a loose leg-last for the spirals to be projected onto. I knew that great detail would be hard to capture with the spirals while keeping the flow of the curve smooth, so I used a loose fit loft to generate a fairly smooth last. From that point I wanted to just project the spirals onto the leg and get cracking but the spirals didn't cooperate very well so I only used the initial projections as a starting point. I used the rebuild command to make the curve more manageable and then proceeded to remove any major kinks in the curve. The curve was long and had many inflection points and turn so I needed to use many cross sections to guide the sweep extrusion. It took me upwards of 50 tries to finally sort out the curve and cross-sections into something I liked. I am now the Sweep1 master. Aligning seams of a cross-section in a sweep is a disaster when you have about 30 cross sections. I used a simple Boolean subtract to create the prongs that attach the spirals to the inner post. I added circular pads in the center of each spiral to add to the durability and to provide the hooks a solid place to connect to the spirals.

Materials:

I made it a point to keep the two spirals separate as solid pieces. The goal was to allow the prosthetic user to have a variety of different options for material but after I added the flex-clamp attachment system the materials that are viable in the design were drastically reduced. The material must be able to bend enough to slip onto the inner pole yet be rigid enough to retain its shape. Metals that bend but retain shape and flexible plastics are the best bet for materials that suit the attaching design. Matte copper or some other kind of textured metal is my preference but the huge variety of plastic colors and combinations of the two spirals leave the final choice for material up to the user.