I didn’t see a thread existing specifically about 3D-printed rims and making them, so I started this one.
So originally this got started by the need to get bigger backtires for my project drift trike, as I didn’t want to use original hard plastic wide ones meant for doing skids. I then discovered that the original bearings had the same OD as the ones in the superstar hubs (28mm), so I fit my extra hubs and wheels on the back of it. Trampa axles are 12mm dia. and the back axle on the trike is 15mm dia.
But to be honest, they look kinda dinky with their size. So I then started to look bigger wheels to get there. This lead me to wheelbarrow wheels, after finding a very nicely priced unit it was time to figure out how to get it on the axle, as the supplied bearing solution was for bigger sized axle and clearly made down to a price.
It took some wrestling moves to get that one-piece rim out of the tire. And turned out it didn’t need to be destroyed and could be removed without destructive violence from it’s prison, but I did mess up the first rim before I figured this out…
But the price was very right at 5,90€ for the complete wheel with inner tube, so I bought two for prototyping.
This then lead to the question: “why not 3D-print the rim?”. So I got prototyping, along this line I also thought why not try to fit the wheelbarrow tires to my board? I could at the same time optimize the bearing position/spacing to get more/better support for the wheel side drive gear. As the picture below demonstrates the un-ideal bearing setup for the drive wheels. This is a mock-up of my current setup with the Superstar hubs and trampa MTB trucks.
The problem with the original setup for the driven wheels is that the inner bearing gets most of the load and acts as a pivot point, so there is any imbalance on loading of the drive gear it can cause a slight wobble on the wheel.
I decided that buying some beefier bearings would be a good idea to help the 3D-printed rims take the forces more easily, as the 3D-printed mechanical part has more area to distribute the associated forces, also beefier bearings are likely to last longer and are able to handle the beating they get during esk8ing (bigger balls). Below is a picture with the original wheel bearings for the superstar hubs and trike wheels and the bigger replacements for them. The bigger bearings were either SKF or NSK around 1,7-2,8€ ea.
So I then prototyped some rims and figured out how beefy I needed to make them and below are some of the results. I tested a 3 spoke design, but decided to go with a 5 spoke design as it more evenly splits the load in the shorter spaces between the rim bolts.
Not shown is the very first prototype that bolted together, pumped the wheel to my ride pressure (4 bar) and then promptly exploded by ripping the tire lip off from the other side, shooting the lip off the high speeds and then the inner tube exploded after the tire was able to let it out from the side without lip. Needless to say, I beefed up the lip for the next versions.
Size comparison between the OG bearing and one that will be replacing it.
Simple 5 bolt (M4x40) pattern with the nuts embedded into the 3D-print afterwards.
The tires that I use on the superstar hubs are 200x50 and the wheelbarrow tire that I’ll try to get to fit is 260x85, so they are bigger and wider. Fitting them to the board is gonna be a tight fit.
“Don’t talk to me or my son again”
The wheelbarrow tire just about fits without wheelbite at full lean.
I’m planning on printing the rims with PETG once I have the final design figured out. I’m using PLA for these test parts.
