Polar plotters, AKA polargraphs, are devices that print on a vertical surface, based on the length of two strings holding a drawing instrument. Unlike a traditional CNC setup, where there are independent X and Y axes, polar plotters use a combination of the length of these lines and trigonometric relationships to determine a point on a whiteboard or other surface.
Thinking about this more, when I, and other students were in high school or middle school, it was hard to see why we needed to take algebra, or trigonometry. After graduating from engineering school and getting a job in the “real world” however, the need to know these concepts really well became obvious when designing certain parts and figuring out control schemes.
A polar plotter is a great way to show students that this kind of relatively complex math is actually quite useful in certain situations. I featured the Makelangelo plotter here in February, but another exciting solution, that almost seems specifically made for a classroom setting, is the gocupi, seen in the video below. It uses two suction cups to anchor the pulling motors, and attaches directly to a Raspberry Pi for control.
Now, if you’d like to illustrate to kids and/or college students why calculus is necessary, you might find that a little more challenging!