3D Printed Unicycle

I made this unicycle in 24 pieces and it’s all 3D printable: http://www.thingiverse.com/thing:941486

You just need to screw the pieces together, add a tire and tire tube, and some bearing balls.

If you have a few minutes please give it a like because it’s in a contest and I’m trying to win a 3D printer to print it out!

Also please let me know if you think you see any major design flaws because I’m a complete beginner at CAD and mechanical stuff.

Very nice, congrats on the design. It would be nice to see how it acts in the real world. My favorite part: the square seatpost and tube. I’ve often wondered why this isn’t a common thing on unicycles. It would completely eliminate the problem of the saddle going off-angle.
I would have “liked” it, but they wanted me to start an account, which I didn’t care to do. But good luck with it!

It’s a cool idea but unfortunately there’s no way that it will be strong enough to actually ride. I have a cheap 3D printer at home and do a reasonable amount of 3D printing myself as a hobby. The plastic that people print with isn’t any stronger than molded plastic, in fact it’s actually weaker because the layers don’t stick together perfectly. The first thing that would break would probably be the cranks as soon as you put any weight on them. Assuming they didn’t then the hub or pedals would probably come next. You might be able to make the wheel work but you would have to use metal for the hub, crankset and pedals. You could also possibly make the frame and seatpost work but where they come together it would require some metal to keep the seatpost in place. I think that there’s a good chance the saddle would be strong enough but man it would sure be painful, I tried doing a completely hard saddle once carved from wood and it was literally a huge pain in the butt.

There are some parts on a unicycle that would be great to make with a 3D printer. It’s just that plastic isn’t a strong enough material to take that much torque in the hub area.

Thanks for the insight. I wasn’t gonna try to do trials/MUni with it or anything–my goal with this was to win the contest and so my intention was for the unicycle to hold up just long enough to get some cool footage riding it. ABS plastic seems like it would do the trick, especially with very fine printer settings. I think Lance’s signature is also applicable to this.

Unfortunately I probably won’t print because it’s super expensive and too close to the contest deadline. But in the off chance that I win the printer I’ll definitely print it and see how it rides.

BTW, if you have a 3D printer definitely check out these pedals: http://www.thingiverse.com/thing:16736

Out of curiousity what kind of printer do you have?

Wow, I was just thinking about trying to print my own JCPC pedals before I saw that link even.

The printer I’ve got is this. These printers are sold cheaply because they have microchipped cartridges and proprietary software that forces you have to pay for expensive filament unless you are comfortable doing some hacking to put new firmware onto them. The biggest thing besides the price that I like about it is that the case it’s in is looks really sharp and does a nice job of containing mess.

The motivation to print a unicycle is aplaudable.

However I am not sure you have embraced the full power of printing because it looks too much like simply reproducing a traditional unicycle frame built that way because it is made of metal tubes.

With printing, the crown area could be engineered much more elaborately and make a smoother transition from the fork to the seat tube that would make the whole frame a lot stronger and stiffer.

More could probably be done designing with the strengths of printing techniques to distribute material in places producing internal labyrinths that are impossible with classical moulding. This cuts the cost of materials and reduces weight or more importantly in this case it, allows for wider stronger members on the same amount of material.

I would be looking for a lightweight rider with a very gentle touch to do the demo.

That’s a brilliant note. I’m completely OCD about my saddle alignement, it would be amazing to have a square seat post just for that matter!

If they can produce a working handgun that can handle the shock of firing a round, they must be on the way to making something strong enough for a unicycle.

The real question is: Could we sneak this plastic uni past the airport x-ray equipment :smiley:

It can fire a bullet a few times but that doesn’t mean that it can stand up to repeated firing. I suspect that the reason he designed it with a quick releasing barrel was because he was changing it out every few rounds. Why else would the video have shown him printing barrels in batches of six. Also, notice how in the video the reporter only says most of the parts are printed. At least the firing pin is made out of metal in that gun, possibly more than that.Anyway the two applications aren’t really comparable. Brief shock absorption is a completely different type of load than the torque and weight acting on a unicycle crankset. People break hardened chromoly hubs all the time, how will plastic fare in applications where processed metal doesn’t always suffice. I’m sure it’s possible to make an entirely 3D printed unicycle that could be ridden briefly by a lighter person but it would never go very far without completely redesigning the hub and crank system. There are actually already plastic unicycle wheels in existence but they use a metal insert for the hub because plastic just isn’t strong enough.

I have a unicycle with a square seatpost. Langenberg is the brand; it’s a company that makes artistic bicycles in Germany. It’s from 1982.

Drawbacks of the square seatpost:

  • Fit is not as snug over the frame as with round tubing. My Langenberg is fitting over two fork halves, like a Schwinn.
  • Mine uses a single pinch bolt at the back, like a traditional basic unicycle. This doesn't provide a very good grip. While it doesn't need nearly as much grip, this one tends to deform the frame in that area and might lead to cracking and breakage if I ever used the thing.

Both of those issues can be overcome. Cost (at least of labor) and weight would be relatively higher, compared to round tubing. Not sure if it’s worth all that just to have a seat that won’t twist. Also, extreme twisting forces (those bad hits/crashes) would be transmitted into your frame with greater force, possibly leading to bent frames.