Zen rock garden table uses magnets and sand

[Nick] is working on a prototype of a coffee table sand plotter that draws patterns in sand a lot like a zen rock garden.

[Nick]’s zen rock garden uses a magnet to draw a ball bearing across the sand in interesting patterns. The build uses 3D printed gears and laser cut parts to rotate the table around and move the magnet along a radius of the circle. During the first test of the prototype, the ball bearing jerked around but this problem was solved by adding a piece of foam under the sand. Power is supplied through a slip ring in the base, and the table is controlled through Bluetooth.

Speaking of magnet-and-ball-bearing zen coffee tables, we ran across this video of a more professional-looking prototype that was the basis for a successful Kickstarter campaign. Like [Nick]’s prototype, the entire build relies on magnets and a ball bearing to move sand around in patterns. Because this zen table uses an XY axis instead of [Nick]’s polar setup, drawing logos is a lot easier math-wise, lthough it doesn’t look quite as cool as a circular rock garden.

After the break you can see these zen rock garden coffee tables in action.

14 thoughts on “Zen rock garden table uses magnets and sand”

1. majordump says:

Doing straight lines with Nick’s table is possible. It requires 2 motions rather than 1 but I think the logic and math for it would be easily done.

The etch-a-sketch idea is great too. Put the rotary encodes and bluetooth jive INSIDE an etch-a-sketch would be win too. Probably have to lose the drawing parts in place of the hardware but whatever.

1. arachnidster says:

The table does indeed support drawing straight lines. It interpolates in cartesian space, and converts to polar on each step, which is slow (especially in simulated floating point), but fast enough given the step rate I need.

2. Solenoid says:

Nice, but I’m worried about the motor noise that might make this a bit less zen.

1. arachnidster says:

The noise is noticeable at the speed I’m using in that video, but slow it down a bit and it’s very quiet, mostly due to the 16x microstepping I’m using.

3. charles says:

obligatory

Push those sand-rakers off our world!

4. hospadar says:

Cool!

Can it reset itself? as in flatten out the sand?

It would be cool to put glass over it and use it like a regular table, and have it slowly doodle patterns all the time and then shake itself flat to restart.

Maybe you could have it respond to things in the room when drawing patterns, like sound or light or temp.

1. arachnidster says:

To reset it, I draw a fine spiral pattern, just like Sisyphus does.

This is just a prototype – my intention has always been to use this to test the principle, and then scale it up to a coffee table just as you describe.

Regarding interactivity, I’ve had a few ideas, amongst them drawing a spiral with variations based on sound in the room, like a spiral version of an earthquake drum.

1. pRoFlT says:

What if you added a vibrate mode to make the sand flatten out?

And you could add a ball location to pick up and drop off different size balls :) You would need a third motor or linear actuator.

5. zuul says:

pretty cool

6. How does it jump to another section? MagLev?? The video keeps cutting off before it moves on to the next section…

1. ChalkBored says:

The square table starts off by making a series of rows. Then it hides it’s non-drawing movements by moving down the established rows to the bottom, then over to another row.

7. Steve says:

HI, I’m working on something similar and very interested in the “foam” approach mentioned. Can you describe the foam used? It clearly made a big difference!