Trammel of Archimedes, Snap, Ellipsograph, Ellipse, Math, Model

All children should have one of these for pondering over mathematics, I think.

The trammel of Archimedes is an interesting geometric structure for constructing ellipses or exploring simple and appealing mathematical relations. It is fairly easy to design in Fusion 360 or any other 3D design environment. It requires a bit of the Pythagorean Theorem if one wants to be accurate; it further allows students to play with elliptical curves. How do we know the curve so drawn is an ellipse?

In this design, I made the sliders (or shuttles) fairly loose for easy installation. There are two types of sliders here for smooth assembly. The sliders can be either snapped into the arm or fastened using caps (with a drop of glue if necessary).

I also designed the handle to accommodate a school pencil (up to a diameter 8.5mm) so that one can either turn the handle around for fun or insert a pencil and do some real drawing!

Of course, one can just use a handle-less bar and make a fidget toy--soothing and mind-entertaining.

References:

Trammel of Archimedes. https://en.wikipedia.org/wiki/Trammel_of_Archimedes
Ellipsographs: Do-nothing machines that do so much!
http://americanhistory.si.edu/blog/ellipsographs

Resolution:

.15 to .2mm

Infill:

20%

Notes:
A raft might be useful for printing the handle ring.

Post-Printing
Slide the sliders into the rails and snap the arm on and PLAY. Please note that once snapped into place, it can be hard to take them apart. Be patient and go slow.