Thursday/ reviving my Spirograph memories

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This is the Spirograph set I recently bought at a Target store. It says ‘original’, but it’s really a modified version of the original sets that were developed by British engineer Denys Fisher and first sold in 1965.
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Happy Fourth of July! The Spirograph pattern is a ‘hypotrochoid’ with 15 petals, made by using the 56-toothed wheel inside the 105-toothed ring.
Here’s a cool animated illustration from Wikipedia’s ‘Hypotrochoid’ entry. The red curve is a hypotrochoid drawn as the smaller black circle rolls around inside the larger blue circle (parameters are R = 5, r = 3, d = 5).

I bought a Spirograph set last weekend and finally had some time to play with it today.  It brings back happy Spirograph memories!  I do have a few quibbles with this so-called ‘original’ Spirograph .. the original had 17 wheels (this one has 15) and two toothed racks (this one has one).  Yes, they threw in three additional geared shapes, but I don’t care too much for those. Finally, the felt-tip pens are terrible. I made the drawing below with a Parker Pen with a roller ball tip : much better.

One Reply to “Thursday/ reviving my Spirograph memories”

  1. I’m with you on the Spirograph….one of the best toys ever! And wow, you are really creative with your new one even though it is not as good as the old ones. And good for you for including some math on your blog as well!

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