This is my favorite 3D analogon to the famous 2D Yin-Yang symbol. This one is composed of pieces of spheres and cyclides. Two parts that are mirror images of one another join together to form a sphere. They will serve as a mathematical demonstration objects and will be the focus of a talk at the BRIDGES'99 Conference.
This design and fabrication effort is part of a research program sponsored by NSF to streamline the process of rapid prototyping of free form parts, by defining a clean separation and interface between designers and fabricators.
For a layered manufacturing process that needs support structure (e.g., SLA), they should be built in the +z direction so that the interesting cyclide surface on top is free of support stubs.
In the .STL file describing this part, the contours from different surfaces (e.g. around the equator) have not been merged -- but the cracks should be very small. Thus this requires software that does some polygon closing across small gaps automatically.
The compressed files can be downloaded from our anonymous FTP
site with:
ftp ftp.cs.berkeley.edu {login as "anonymous"; use your full
e-mail address as password.}
Then change directory: cd ucb/projects/unigrafix/STL99
Fetch desired file: get FILE.stl.gz
The FILE.stl.gz file can be uncompressed with gunzip.
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