INTRODUCTION
I’m sure many of you have seen this toy somewhere. Perhaps you had one as a child, or maybe you’ve printed the version I published on Thingivese / MakerWorld / Cults3D.
Whatever the case, you’ve surely wondered at some point how it works. As a toy that shouldn’t be able to balance, it apparently does so in the most unexpected way possible: on its beak.
In this post, I’ll try to explain as clearly as possible the science behind how this toy works, so that you can make your own. It’s the equivalent of revealing a magic trick, but without losing the magical aspect of it.
THE SCIENCE
If you’ve ever done any sport, or practised something like yoga, you’ll surely remember the stretching exercisecnt where you have to balance on just one leg. You’ll also remember how difficult it was. All that involuntary swaying your body did was aimed at finding what’s known as the centre of gravity.
The centre of gravity is the point at which every person, animal or object maintains their balance. This point also indicates that there is an equal distribution of weight on either side and between the front and back.
https://hikingwithyourhoney.com/hike-like-a-goat-part-2-center-of-gravity/
They say a picture is worth a thousand words.
In figure a, the stickman is static and symmetrical. The weight is evenly distributed on both sides.
In figure b, the stickman is leaning slightly, balancing the weight on the opposite side by stretching the leg out a little.
In figure c, the stickman is leaning significantly, balancing the weight on the opposite side by stretching out the arm and leg.
APPLYING THE SCIENCE TO TOY DESIGN
Now that we know how the centre of gravity works, designing a toy with these characteristics isn’t all that difficult. And even less so now, given how advanced technology is; almost any 3D modelling program includes a tool that calculates the centre of gravity.
In my case, I used Blender to design the general structure of my toy, as it is a free piece of software and quite intuitive once you know which buttons to press (like all programms).
In the image above, you can see where Blender has placed the centre of gravity for this model in relation to its geometry. You can see that the model’s design positions the centre of gravity just below the beak, which is where we want the bird to balance.
The rest is down to each person’s artistic skills.
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