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This project is about creating a device that draws patterns in a dish of sand from under the dish, using stepper motors and magnets. Inspired by [[https://www.kickstarter.com/projects/edcano/sandsara|Sandsara]].

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This looks like it could be a fun project. It combines woodworking and electronics to make a cool little automatic ambient art thing.

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Broadly speaking it consists of a [[https://en.wikipedia.org/wiki/SCARA|SCARA]] robotic arm with two joints. One joint is at the centre, and one joint is at the midpoint of the arm. The arms are driven by a pair of stepper motors either side of the central axis. One axis is driven directly from one of the steppers. The other axis is driven via an idler pulley on the first axis to transmit the torque to the arm mounted on the second axis.

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Engineering. You can tell by the grid lines.

My intent is to drive it with an ESP8266 so I can send new patterns to it via wifi, and perhaps have it draw things automatically in response to goings on in the household, or world. I may have to use two microcontrollers: One in charge of driving the stepper motors and one in charge of the network communications. I don't want to have a pattern update interrupt the drawing.

It will be important to have it operate as quietly as possible, with no stepper whine or crunchy gear sounds. I intend to use pololu stepper drivers and steppers salvaged from an old reprap 3d printer.

If I use glass for the base, and a light-coloured sand, it should be possible to do the underlighting without too much effort.

Work logs:
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[[https://github.com/tjhowse/sand_drawing|Github]]
[[https://www.youtube.com/watch?v=4o7z1oJWaFY&list=PLT7ckgz8vcoY2YFqqQTA0kUofwehtqQul|Youtube playlist]]