Cycloid-O-Matic Draws Fun Shapes with Modded Steppers
Spirographs, which use a series of connected rotating gears to draw interesting curve patterns, have fascinated young and old alike for generations. Now, with the advent of cheap stepper motors and accessible design tools, InventorArtist Darcy Whyte has taken this toy into the 21st century with his Cycloid-O-Matic.

His project rotates paper using a lazy Susan arrangement, powered by a cheap-o 28BYJ-48 stepper motor. A pen is held in a clothespin overhead via a linkage system, attached to two stepper motors that vary its extension. This lets the pen move in and out/left and right according to the motion of the motors, while the paper itself spins to produce beautiful patterns.

Stepper motion is controlled by an Arduino Uno and GRBL shield. While it typically uses a computer interface, an Arduino-only version is in the works, though there’s a bit of an issue as of this writing in varying the motor speed.

One notable sub-hack here involves modifying the 28BYJ-48 motors for use with the GRBL shield, as the coils are normally center-tapped and would require a different type of driver. Conversion, however, is simply a matter of cutting a trace on the circuit board, and with proper measurement you can even do this through the housing without seeing the circuit board!
['Jeremy S. Cook']
['Arduino', 'Spirograph', 'Technology', 'Makers']