Upgrading our folding wagon to carry 100 pounds worth of kids
Our kids are starting to outgrow our double stroller, but will still want to ride from time to time. We've had this wagon for years, but it needed some upgrading. Rather than toss it and buy a new kid wagon, I decided to modify this one. Its biggest deficit was its wheels. They had metal sleeve bushings instead of real bearings and the wheels themselves were basically just an ABS doughnut with a narrow/thin rubber bands for tread. The treads had all cracked and fallen off. All this made the wagon hard to pull and loud.
I decided to make my own wheels to solve both problems. The new wheels consist of two halves and a TPU tread. The halves are keyed to mate with each other and are held together with m3 nuts/threadserts. Each half contains two skate bearings, resulting in four bearings per wheel. It's probably overkill, but I didn't want to leave the two halves unsupported in the center of the wheel at their interface.
Built in bridges for the somewhat weird shape to trick the slicer.
Now my 3 year old can pull me around in the wagon.
This is buried lower in the thread, so here it is again: the face you see facing you in the CAD was the first layer. Note the inset faces at 1:00, 3:00, 5:00, 7:00, 9:00 and 11:00. Due to their shape and the fact that they have a hole in the middle of them, a slicer would typically just try to print from the center out in mid air.
Orienting the print the other way around wouldn't have worked due to the way I decided the two halves to mesh - I would have been printing way more in mid air. This orientation also gives me a nice looking first layer facing out.
@alkheemist@aussie.zone was right on the money, here are a few closer visuals. They're only a layer thick. I've found that if I make them too wide the slicer will stop trying to turn them into a bridge.
CAD:
Here's one of the earlier ones before I got the spacing down. Without it my slicer would have tried to print the circular heatsert hole in midair.
We're way more utilitarian than that given our still pretty young kids, but maybe next year. For now it will remain "the wagon", lol. I'm really considering printing them a Hadley telescope for Christmas. They're both aware of planets and space, and know that space proves and rovers are a thing, but it's all a bit abstract to them right now.
I hear you-- Just saying, once you get a few kids in there, it's going to be four wheels carrying some very sophisticated sensor and communications equipment. Sounds like a rover to me. Still early in R&D though, I get it.
I would go with something like an old Meade ETX with autostar and just print some of the eyepieces you'll find that have lens kits you can buy. The eyepieces are nice and the prints are easy. An actual scope is a tricky project to dial in and the longer focal lengths are hard to use in practice. Something like an ETX60 is reasonably cheap and while you'll barely see more than dot with 3-4 tiny specs of Jupiter's moons or the haze of the Orion nebula, they are quite easy to find in practice. Doing initial alignment is also easy and forgiving. That's just my take. I also wouldn't mess with any of the phone camera adaptors. I ended up making my own that had 6 axis alignment, but the bubble lens and software compensation on most phones makes them mostly useless through and additional lens stack of an eyepiece.
What do you mean? The bearings are friction fit and ride pretty tightly on the 8mm bolt that runs through them. The screws that hold the two halves together screw into threadserts.