I am currently in the Mechanical engineering program on the East Coast and a student in a mechanical engineering design course. We do some fun stuff with Creo parametric and drafting and such. I had heard tale of the final project being a unicycle in past years, but last semester it was switched to a tricycle. Luckily for me that was changed back this semester. I’m not sure what exactly to design yet, and my CAD skills aren’t anything super impressive, but I’m thinking something along the lines of 36er with inboard disc brake, touring handle and nightrider esque frame.
I remember reading about someone else who did something fairly similar a while back, but I decided that if there was enough interest it’s worth having my own thread. And by enough interest I mean I’d like a place to go WOOHOO after I finish a part at 5 AM like today.
I know at least a few of you on here are seasoned engineers, so if you have anything in particular to add or caution about I am more than willing to have a listen.
So far I have just designed a pair of ISIS standard cranks with French threaded pedals (M14x1.25 - I can’t stand English measurements yet). These are based off of the ISIS drawings online- with a few liberties added as the radius dimensions for one or two edges weren’t very specific. As I get more information on tolerancing and other important topics these will be incorporated into the design.
This is purely an exercise in fitment design-since I haven’t been through strength of materials or any of that jazz It’s all about the CAD and the fit.
Anyway, I hope some others find this interesting, and if so I’ll keep posting photos and tidbits of what I find interesting about the design aspect of building a unicycle. In the past I have been on the assembly side a lot and I’m hoping to see this transfer through well.
Should be a fun project. I did Wall-E for my final CAD project in college, then went on to be a TA for our basic CAD course.
Looks like you already probably know this from the mechanical side of things, but you want to avoid any sharp corners in your design, not only for stress purposes, but because it’s expensive and difficult to manufacture sharp edges. This is especially relevant in something slotted. In the real world, you want to fillet most edges, like the ones around the outside edge of the crank.
Good point! I had meant to round the edges of the first piece and it slipped my mind. Wouldn’t want anyone slicing their leg open on a knifelike aluminum crank! Do you mean Wall E as in the robot?
The next piece! I’m having some trouble with the interface between the cranks and the hub, it seems that the taper for the cranks starts too early. I’m basing the hub roughly off of the mad4one 1 piece CNC milled hubs, though I may widen the center a bit in the future.
Alrighty, Ive got preliminary parts for the bearings, hub, crank and Rim now. I went for a drilled out rim for theoretical weight savings and stuck with the ISIS drive cranks. I figured out where I was going wrong with the hub/crank mating, and it was just drawing error. By this point hopefully you can see where the concept is headed.
Ha, what a long way it’s been since those first parts. Looking back on them now they look ridiculously simple. Here is a link to the finished product for those who care to look! No guarantees on material thickness or accuracy of tolerancing, but hey I’m not licensed yet so it’s okay
if someone could explain how to insert a preview that would be great.
