The holidays always remind us of our favorite toys from when we were kids. Johnny Astro, an Erector set, and — of course — a Spirograph. [CraftDiaries] has an Arduino machine that isn’t quite a Spirograph, but it sure reminds us of one. The Arduino drives two stepper motors that connect to a pen that can create some interesting patterns.
The build uses a few parts that were laser cut, but they don’t look like they’d be hard to fabricate using conventional means or even 3D printing. The author even mentions you could make them out of cardboard or foamboard if you wanted to.
The electronics are straightforward with two stepper drivers. We couldn’t help but think that some of the old 3D printer motherboards we have laying around here could handle this very easily. However, in this project, the CPU is an ordinary UNO with a CNC shield to drive the motors.
Of course, the real trick is the software. Apparently, the different patterns come from the relationship between the delay between steps of the right motor and that of the left motor. There’s got to be some math behind that, but the patterns are certainly pretty.
If you prefer something that looks more like an actual Spirograph, grab a bag of Lego. Or try the Art-O-Matic.
It’s built on the same principle as Spirograph which is why it looks like Spirograph: a mismatched number of steps per cycle for multi-axis system. The math describing this is surprisingly simple because the point is result of calculating the rotation of each circle, calculating the distance between them, and using it as the last side of a triangle with two fixed length sides.
Geee Sheldon Cooper…. you sure know how to drain the fun out a Spirograph… 😄
I’m not even a math guy, I just gave it a moment of thought because they wrote that there “has got to be some math behind it” as if it was some mystery. It doesn’t make the patterns less pretty… but it does mean it can be easily replicated using software now. :)
Seems to me you could do this with two motors running at a constant rate and different-sized wheels? Could have a suite of wheels to choose from. Would be amusing with 12hr clock motors, but might be jumpy.
Also author mentions the bolts holding arms together need to be re-tightened. Nylon washers would be wise.
Most Hackaday readers can distinguish between an SBC and a card game.
Just because “most” readers can figure it out is not a reason to be inaccurate.
No Arduino required to do that, you just need two dc motors and two pots.
Or just one dc motor and a variable link between the two wheels.
Or no motor at all, just a hand driven gear.
…or a plotter… https://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Hp_9862a.jpg/1024px-Hp_9862a.jpg
I use two cats. I call it a Hairy Plotter.
I use half a cat and call it scary plotter.
Moreover, a plotter, with the same number of electrical components, is much more versatile than this contraption, and probably not much less precise.
If you search for “Guilloche” you’ll find plenty of references to the mechanical versions of this for watch cases and jewlery – used in engraving banknotes etc. as well.