World Turtle Kinetic LEGO Sculpture


Hey everyone, Jason here. Today we are
going to take a look at Kristal’s latest model, which is the small sculpture of
the World Turtle, also referred to as the Cosmic Turtle. If you are unfamiliar with
the concept of the World Turtle, it’s an idea shared among several
mythologies about how the earth travels through the universe, being supported by
four elephants on the back a giant turtle. Terry Pratchett also used this concept as the backdrop for his Discworld series of
novels, so if you are a fan of fantasy novels you may be more familiar with it
from that source. One thing you might notice about this model is there is no
crank on it, which makes it a nice clean display piece, and that is because the
world itself acts as a crank. By spinning the world you can make the turtle appear
to swim. So, let’s take a closer look at how it works the earth sits on top of
the model and it has these mountains, a little forest here, a river to the
waterfall off the edge, and this little settlement. Definitive proof that the
world is indeed flat, right here folks. The earth is mounted on these 2 by 2
round bricks with an axle hole through them, and they just sit on this axle here
at the centre of the elephants to drive the swimming mechanism. So, we’ll take off these cute elephants and the back of the turtle to see what is going on inside.
It’s actually all quite simple, which it kind of needs to be to fit in this small
space. There is a black gear at the bottom of the drive axle which drives
this tan gear, and that tan gear is connected to a small crank and piston,
which drives the head of the turtle back and forth. The inside of each fin is
connected to the head assembly so that they also move back and forth with the
head, and the center of each fin is mounted to the base of the model so that
they act as simple levers. As the inside of the fin moves forward, the outside of
each fin moves backwards and vice-versa. As a result, you get this nice little
coordinated motion between head and the fins, which gives the
impression of the turtle swimming. As I was preparing to make this video I was wondering how I would do the introduction. Since there is no
externally exposed axle to drive the mechanism, there’s no easy way to connect
an external motor to power the turtle. But, I did notice that there was just
enough room in the back of the turtle to fit one of these old 9-volt micro motors.
Now one nice thing about these micro motors is that they don’t spin very fast
which means you don’t need to gear them down at all to drive a kinetic sculpture
like this. Of course there are some challenges with using these motors. Aside
from the fact that Lego hasn’t actually produced them in the last 20 years,
there’s no way to easily attach a gear to it. There’s no axle or axle hole in
the motor, it’s just a LEGO stud that rotates on the drive shaft. So, I had to get
a little bit creative, but I discovered I could use this relatively new part, this
1 by 1 round tile with a bar sticking out of it, and there’s actually enough
friction between that bar and a gear mounted on it to actually drive the gear.
Now, I actually ended up using the transparent version of that part because
it offers just a little bit more friction, and then we can just stick that
part on to the stud of the motor, and we’ll apply some power to it, and there
we go. I did have to modify the back of the
turtle a little bit to accommodate the 9 volt connector and the wire coming out
of the motor, but otherwise the motor nestles in there quite nicely. If you’d like to build your own copy of
this model there are building instructions available, you can head on
over to jkbrickworks.com to find those. And, that is about all there is to it.
Like and subscribe if you like this model and would like to see more. As always, thanks for watching, keep on building, and I’ll see you next time

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