Part Description and Specifications for
"Saddle Trefoil"

This is a minimal, 3-fold symmetrical version of a 3-storey Scherk surface bent into a toroid.

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This part was generated with Carlo Séquin's sculpture generator, using the following settings:


This part will serve as a geometrical model in classes on modeling and math of minimal surfaces, and as a small scale model for artists, e.g., Brent Collins, who is doing similar sculptures in wood. It might get exhibited together with its corresponding wood sculpture.

This 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.

Fabrication Hints

The scale or strength of this model is not critical; it can be scaled so as to fit optimally a particular process or some remaining space in a run of a larger piece. The STL files describe a part with a diameter (in x) of 47,000 units and a thickness (in y) of 26,000 units. The surface walls are 1000 units thick. Ideally we would like a part scaled up to be 3-5 inches in diameter, i.e., interpret one unit to mean 0.1 mil.

Orientation is not critical either. However, for a layered manufacturing process (SLA, SLS, etc), it might be best to turn the object 90 degrees around the x-axis, thereby giving the part minimal height, and preserving its 3-fold symmetry ideally.

Part Description Files:

Compressed Berkeley UniGrafix description of Saddle Trefoil (

Compressed ASCII .STL file: saddletref.stl.gz (0.46MB)

Large compressed files can be downloaded from our anonymous FTP site with:
ftp {login as "anonymous"; use your full e-mail address as password.}
Then change directory: cd ucb/projects/unigrafix/STL
Fetch desired files: get saddletref.stl.gz
The saddletref.stl.gz file can be uncompressed with gunzip.

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