Dan van der Vieren who uses our Parabola stretchers with his college Algebra classes wondered if we could design a frame to make a hyperbola like this one.

As it happens, we had a couple of ideas.  The best result was this gear design.  You can string the frame with elastic cord with the plate in the top position and then twist to make a variety of parabolas.  Here’s the Adobe Illustrator File           Here’s the  CorelDraw File         and here’s a short video to show how it works.

There are two levels so you can make different kinds of twists.  Have fun!

Here’s how the design looks in the computer and on the right you can see three sets in the laser cutter — an 18 x 24″ bed, 1/8″ thick baltic birch.  Assemble with Elmer’s glue and add stretch cord to finish!