A mechanical design with lots of gears


Creative Commons Attribution Share Alike

Commercial use is allowed, you must attribute the creator, you may remix this work and the remixed work should be made available under this license.

Learn more or download attribution tags


Inspired by a vintage egg beater and the Hot Wheels Super Charger


Thanks for inspiring me to actually build something from concept to a finished item.

When I first saw this contest, I knew that I wanted to make the time to try to build something mechanical, using as many printed parts as possible. My inspiration for this design was a combination of two things from my childhood … the Hot Wheels Super Charger, which used opposing rotating wheels to hurl cars along the track, and an egg beater which used bevel gears and a crank handle to spin the blades (yes, I am THAT old).

I started with some basic gear ratio calculations, and had a bad flashback to high school and college drafting classes, while I researched bevel gear designs. Online gear design tools are WAY better than doing them by hand back in the old days. After several failed attempts at modeling the bevel gears, I found a steel gear manufacturer online and used their basic design, then modified it to meet my needs and to help it print properly and quicker with less plastic.

From there I used Rhino 3D and Lightwave 3D to model all of the pieces that I needed to make this thing work. I went back to the proverbial drawing board many times, and went through a fair amount of filament running test parts, used a few bad words, but, the final design gives a nod to the inspirational items and it’s not far from what I originally envisioned.

It even works! You can see some short videos on my YouTube channel.
First Tests:

Unfortunately, the crank handle broke on the third launch, but, the first 2 were successful.
So, I designed a replacement handle to attach to the broken stub. An hour of so on the printer and I had 2 handles (yes, I made another spare). Super Glued it in place and then shot some more video and photos.
Second Tests:

Closeup View:

Showing how the gears all work and how the dart is propelled by the spinning grooved pulleys.

The only store bought parts are a few bolts and nuts, super glue and hot glue to hold things together, some grease to make the gears run smoother, and of course a Nerf dart for testing.

Overall, this has been a great experience, that has reminded me why I bought my first 3D printer, to take something from inside my brain and make it real.

Thanks for reviewing my contest entry and good luck to all entrants!

And remember ... Never Let The Machines Win

Please note:
Safety was not part of the original design parameters. This item includes moving parts which may cause harm to fingers, clothing, jewelry, hair, etc. Also, remember that it is designed to hurl a projectile through the air so, please be careful. The designer will not be held liable for injuries or damage caused by this device. You have been warned.

Materials and methods

The parts were all printed on my Sunhokey Prusa i3 clone (significantly modified), using various brands of PLA, and after a few minor jams, everything came together. I started out printing early parts with whatever filament happened to be in the printer, and, then decided that it looked like a patchwork project, so, I started using as many different colours as I had on hand. Hopefully this helps you see the different parts more clearly in the photos.

Tools used:

Computer: Macbook Pro
Sketching: Paper by 53 on an iPad
Modelling: Rhino 3D, Lightwave 3D and MeshMixer
Printer Controller: OctoPrint running on a Raspberry Pi 2
Slicer: Simplify 3D
Bed Surface: PRINTinZ

Filament Used:
Purple parts – MeltInk PLA
Orange parts - HobbyKing PLA
White parts – CoLiDo PLA
Black parts – AMZ3D PLA
Light Blue – Solutech PLA
Yellow parts – eSun PLA
Red parts – HobbyKing PLA
Gold parts – MG Chemicals PLA

Printer Settings:
Nozzle temperature: 230 degreesC (it is colder in my basement shop)
Bed temperature: 50 degreesC
Print Speed: generally around 40 to 50 mm/s
Infill: 15% to 50% depending on the part
Layer Height: 0.2mm
Supports: only as needed

Diet Pepsi
YouTube breaks - thanks to various 3D printing related channels that kept me going some late nights

During this project, I really appreciated some of the tweaking features of Simplify3D, and the ability to restart a print came in handy on one of the larger bevel gears. It also gave me a chance to try out my new PRINTinZ print surface which made most prints pop off easily.

Sorry that the assembly view isn’t done right. There are just too many parts (over 55 plastic parts) to get them all aligned properly. If you actually try to build this, and need help, please feel free to contact me and I will help.



Issues are used to track todos, bugs or requests. To get started, you could create an issue.


Mini il 570xn.1343682359 2jz9The 3D printing Guy commented ago

Well explored! I recognize the leap taken.

Cdd507605352fd816e8ceb06b7fdf3a2?default=blank&size=40Mike Fancy published this design ago