Son of Sisyphus

I've been a longtime admirer of Bruce Shapiro's kinetic art and his marble-in-sand machines in particular.  It's now possible to buy his creations from sisyphus-industries but this is a DIY blog.  Plus I'm cheap.

Electronics to drive small stepper motors can be had for very little money thanks in large part to the 3D printer revolution.  This build uses an Arduino Uno with a cnc shield and A4988 drives.  The 3 steppers are Nema 17 and the power supply is an old computer psu.  The software is grbl using bCNC as a sender.  Grbl has the ability to slave 2 motors to 1 axis which allowed a  build with very little mechanical rigidity.

A view from below

2 motors slaved as 1 axis

The construction is very simple. Gt2 belts and pulleys, Oilite bushings on hardware store grade cold rolled steel shafts, a coil spring and a magnet.
The top side of the table has a layer of baking soda and a 3/4" steel ball. A strip of LED lights add colour and shadow effect.

Compared to the commercial offering this one is much noisier and noticeably less smooth in it's motion.  On the other hand it's much less expensive and has all the same capabilities.

first test run