Egg plotting:

My fascination with motion control began with this simple device-- a two axis egg plotter. I had just learned how to control two stepper motors, and needed some way of demonstrating just how interesting this capability is. The success of this experimental "eggbot" not only spurred me on to build bigger two-axis machines, but evolved into an educational tool-- I now teach kids to build their own eggbots, using a course I am continually expanding: "From Bits to Bytes... to Bots:"

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Eggbots, both the original and the educational versions, are relatively crude (only 400 steps per revolution), and have no pen up/dn facility. Even so, quite interesting patterns can be achieved:

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In order to achieve better detail (25,000 steps / rev.), I built two "Ovagraphs," using better motor drives (microstepping), and better mechanics:

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Video clips: (1M wmv, 30 sec.) / (1.7M avi, 7sec.)

more in eggs gallery.

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A more recent experiment, using an Engraving tool and an emu egg: