Most of us have probably seen a video of a sand drawing table at work, in which a steel ball — magnetically-coupled to a gantry under a layer of sand — lazily draws geometric patterns with utter precision and zen-like calmness. That’s all well and good, but [Mark Rehorst] thinks it can also be interesting to crank up the speed and watch the ball plow through sand just as physics intended. There’s a deeper reason [Mark] is working at this, however. Faster drawing leads to less crisp results, but by how much, exactly? To answer this, [Mark] simply ran his table (which is named The Spice Must Flow) at both fast and slow speeds and documented the results.
These two images show the difference between running the table at 100 mm/s versus 500 mm/s. The slower speed is noticeably crisper, but on the other hand the faster speed completed the pattern in about a fifth of the time. [Mark] says that as the ball aggressively accelerates to reach target speeds, more sand is thrown around over existing lines, which leads to a loss of detail.
Crisper detail, or a faster draw? Which is “better” depends on many things, but it’s pretty clear that [Mark]’s cat finds the fast version more exciting. You can see [Mark]’s table at high speed and the cat’s reaction in the video, embedded below.
If you were lucky at the 2015 World Maker Faire you may have stumbled upon strange writings of poetry on the ground — written in sand. While at first confusing, if you followed the poetry along you also caught a glimpse of Skryf, a draw bot by [Gijs van Bon].
The creator was asked to perform poems for a festival about transition and letting go. Naturally, building a robot to write poetry in sand was the downright obvious answer to the question.
I was asked to perform 40 poems during a 10 day festival, and the poems were about transition and letting go. And then I thought the obvious thing to do as an artist is to make a machine that writes those poems with sand. I started writing them, and when the third poem was written, the first one was completely gone, and it was such a beautiful thing.
The robot uses a laptop for input, which is connected to the bicycle carriage. One servo controls the left-to-right movement, and another releases the sand. Forward and back is controlled by the main drive train, which must have been fun to account for (they aren’t servos!)