Well... as to how I made it, most of the work was really design stuff. First, about 2 weeks of research. I would estimate I have about 50 hours just in reading and watching videos about bike and motorcycle wheels and hubs, including patent searches, finding photos of
cutaways usually shown at trade shows, and watching videos from the guy whose link you posted. If you go through the video description there's a link to a much more detailed video of how he made a different hub shell, which was very cool to see. Unfortunately, he only shows how the shell was made, so we don't get any detail on his axle design.
Once you have a good idea on how things are done, try and come up with a way to make it better. What I did, which you can see a little in the attached drawing on this post, was avoid a traditional axle, instead having the bearings rest on the end caps with the compression tube in the middle providing no support besides positioning the inner races and preventing them from twisting. I found out after I finished that this is already in use in a couple commercial designs so the "original ideas" part didn't really work out, but I have some new ideas for next time now :)
So now that you have a picture in your head, make a picture on paper. Get a rough sketch, then hammer out all the dimensions. Start with the standards (e.g. spoke holes are nearly always 2.4mm, or 3/32" because the bike industry has a thing for bastardized metric representations of english sizes), then the dimensions constrained by other parts (e.g. the hub flanges can only be so far apart or else they'll interfere with the fork), then you magically only have a few things left to decide for yourself. Like my dad always says, butter the outside of the toast first and the inside takes care of itself.
Once you have drawings, find a lathe and start cranking handles and there you go!
Cartridge bearings are a thing, but you probably didn't see them in the shop very often because they're not meant to be adjusted or rebuilt. Once they develop slop, they're toast and you replace them with new ones, although a set of cartridge bearings should last at least 10k miles if properly sealed so that's almost a nonissue. Loose ball (aka cup and cone) bearings last longer and are less expensive, but you are restricted to designing hubs around a threaded axle, cups are hard to find on their own, and if you fuck up the cup they are harder to replace.
Safety is an issue, I suppose. I did calculations on spoke tear-out, compression and buckling on both the compression tube and middle section of the hub shell, and shear and compression in the endcaps. The bearing seats in the hub shell are very much overbuilt, so I didn't bother running any analysis. Still though, I've been thinking of making another one for destructive testing :D
Questions are no problem, if you have any more please ask!
