Sand Table  photographs| sample animation

What is it?

The sand table is a functional piece of art. It is a complex electromechanical mechanism within a coffee table that draws patterns in sand.

A steel ball bearing sits on top of a pan filled with sand and is moved by a magnet hidden underneath. The magnet is driven along two axes by a gantry controlled by a computer with a web based interface.

My family and I stayed at Dean's house and had a wonderful time. Dean created the Segway and is a brilliant, prolific inventor with more patents than anyone alive. Each year the folks at DEKA, Dean’s world class invention and prototyping house, build him a one of kind holiday present. They create machines  that blend incredible craftsmanship with interesting scientific principles and/or something related to Dean or the company. When we arrived I helped him get his latest present working - a dynamic magnetic-suspension machine that could float a lit light bulb or a spinning helicopter. Throughout Dean's house there are other presents - a custom made pinball machine, a 100 ton Möbius coin press (one sided coins!), a chess playing robot, and more.

Soon after staying at Dean's house I contracted fifths disease in my shoulders. Normally a children's disease, in adults it causes severe joint and muscle pain. In my case it got my shoulders and made it difficult to do almost anything with my arms. I wanted a sophisticated machine with nice woodworking, just like Dean had, but I didn't have the staff to make one for me. The virus provided the downtime to think and draw plans for the sand table. I started machining parts as therapy to get my strength back.

Yes. If you know how to use a mill and a lathe it is relatively straight forward. All of the parts were machined by hand or obtained from parts suppliers. The parts were designed with Autodesk Inventor and the cad files are available. Instructions will be posted in the future. In the interim, contact me at mike at dubno dot com.

The table has a web based interface that allows a user to draw about 20 different types of patterns with lots of parameters.  Everything from spirals, snow flakes, text, clipart and mazes to fractals and strange attractors can be drawn. Simple Python modules make adding new patterns a daily activity.

I've hooked a camera up to the computer and written some software that lets me make stop-motion animated movies on the table. It is completely automated and uses a scripting language (xml) to interpolate and morph between images.  Check out the sample animation.

Color controllable LEDS have been added around the perimeter (courtesy of Color Kinetics) which I've just begun to play with.

What else may it do in the future?

There are a couple of ideas being tossed around with each clever person who has heard of the table. Some ideas that are being toyed with are –

• Switching out the permanent magnet for an electromagnet and using a tray filled with iron filings.
• Heat-activated binder in the sand to create permanent pieces.
• Attaching a simple fixed gate to the sand tray that would allow a fixed-magnet table to change balls.
• An eraser made with a ball bearing and saucer shaped piece of aluminum.

Bill Gurstelle did a lovely blog write-up for MAKE -

Read about the New York City Sand Table project

Special Note -