Dui – good point – I’m not sure if the forces on the low rider are enough to cause any issues there…but it’s definitely something to keep an eye on. My only concern with softening that edge is how it would affect bed adhesion when printing the wheel hubs.
Here’s a view of the parts un-assembled:
First step is to stack the two hubs – you could glue them but I don’t think it’s necessary:
(Actually, you can install the bearings first – I did that on most of them but they can also be installed last.)
Next the hub is pressed into the tire – this takes some force but is possible due to the flexibility of the TPU:
Then the hub is rotated into position – this takes a LOT of force and is pretty tricky. The point in this photo is the hardest. Getting the tire over the ridge takes a lot of finesse and force, I found a blunt spatula type of tool helpful to get the lip over:
In fact, on most I needed some mechanical assistance – a long bolt or piece of allthread through the hub made it much easier to get the leverage needed to pull the tire on:
Like I said – once they’re on they don’t come off!
This was my first attempt with 3 perimeters – I had to cut it to get it off – the 6 perimeter versions are even harder to get off and are solid TPU from the crown to the PLA hub:
And…they work! I can’t upload the video until tonight but I was able to print enough parts to assemble a Y plate and test it on my table (which it turns out isn’t too thick after all)
It seems to track fairly well too. I even tried snugging the lower rollers to where it really pinches and the tires deform a little and it seemed fine. Actual cast urethane wheels are almost certainly a better option – but it does seem these are probably usable.
Oh – one thing I did learn. The inner spacer between the wheel bearings is not optional. I accidentally overtightened one of the bolts assembling my test setup. The PLA hubs stood up fine even with only 15% infill. However it created enough force to damage the bearings. Admittedly these were super cheap bearings (listed as “Free” on wish.com just pay $2 shipping for 10) that I only bought because I was curious how bad they’d be. They’re better than I expected for the price but still really lousy bearings. The two in the wheel I overtightened the inner race is now offset and super loose from being squished together. Oops. So…I’m going to modify the hub design one more time to make room for the proper spacers and will actually get some spacers to go in there (or maybe I’ll try printing some spacers just for giggles.)