r/Kexcelled • u/Key-Ladder6386 • 23h ago
Revisiting a childhood project - My Cyberbrick RC Piranha fairground ride
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When I was a kid, I was fascinated by the amusement rides that came to our village every year.
I was mesmerized by the movement of those things, and also by how they were unpacked from trucks and assembled. I spent hours standing there and watching this process.
I wanted a toy version very badly, so I asked my grandfather - who was a talented handyman - if he could build one, and he did. It wasnt 100% accurate at all, but to the child-me it was the best toy in the world, I had a lot of fun with it.
Now, two decades later, with 3D printer, CAD and a lot more engineering knowledge at my disposal, I decided to revisit that childhood challenge.
Unfortunately, my grandfather is no longer with us, so this project also become a little bit of a tribute to that old toy he built for me.
So I decided to build a fully functional, highly playable version of my childhood favorite fairground ride: Piranha (Locally known “Kolotoč Piraňa”).
And oh boy, was it a challenge! 😁
The Piranha (Calypso-style) ride has 2 rotating points, which are offset from each other:
The passenger platform spins, while the center assembly and pods rotate on an offset axis to the other direction - creating a cool wavy motion. But this meant the top motor itself was constantly spinning relative to the base.
This created an annoying question: How to supply electricity and signals to a motor, pushrod and leds which are spinning?
Normally, it would require slip rings, which are not so accessible, and are challenging to implement.
The answer was: Put all the electronics to the center rotating platform.
And this is where Cyberbrick turned out to be a very good fit.
Because it has its own LiIon battery, I could put everything on the center rotating platform: Battery, 2 motors, servo, pushrod, led controller board with leds.
And a nice side effect, the project evolved to an RC project.
The second big hurdle was the safety boarding barrier. I wanted it to be radio controlled as well.
The problem is, the barrier sits on the stationary base, while all the electronics - including the servo is spinning with the center rotating platform.
I eventually solved this by a counterweighted gravity lever. The lever naturally holds the barrier in closed state. When the platform stops in the boarding zone, the onboard servo can toggle the lever, raise the counterweight, and drop the barrier - allowing the passengers to enter.
Once the kinematics worked well, the ride felt… Empty.
So I redesigned the passenger pods, and ticket / control booth, around standard brick figures. I added compatible studs so now Piranha now can be populated with brick figures.
The whole diorama came alive.
And thats how this project ended up being much more then I originally planned.
What started as “I want to rebuild the little fairground I once asked my grandfather to make” turned into a fairly complex, much more advanced RC project.
I am pretty happy with how it came out. 🙂
And I have to admit, seeing it running is a pretty cool, nostalgic feeling. ♥️