Believe it or not, but I am halfway through revision 2 of the hubmotor. You ask, "what happened to the first version?"
Simple answer: I got lazy and the aesthetics bothered me. I mean, the motor was 1.625" wide, with only 1" of filleted tread. The 1/4" endcaps looked bulky and unattractive but I couldn't add an edge chamfer because the inner diameter features were already finished. Additionally, I neglected to add sufficient wiggle gap to the magnet ring rings, which made it extremely difficult to get the magnets in place. One formerly excited afternoon transformed into a painfully disappointing sanding feat. Once I had ONE magnet in the spacers, I knew that this was not worth the effort.
So with all these changes to be implemented, I elected to simply not finish version 1. Here is version 2: incredibly badass and sexy.
The wheel is now only 1.25" wide, with a 1.5" hubshaft (more wire space, finally!). I will still be using 1/4" endcaps, but I will turn down the edges and internal features so I can sink the endcaps further into the wheel. This also allows me to rid of the polycarbonate spacers, which served no purpose whatsoever. The mechanical lock nubs were replaced with precision eyeball machining aka I will be relying on a frictional fit from the endcaps and the OD of the magnet ring. This might seem like a bad idea, but It is better than trying to use 4-40's to lock the wheel and any slipping might act as a neat clutch feature. I also added .016" of space to the magnet gap so the magnets just drop in. No file work required.
To make the endcap features, I will be adopting a trick I learned from Shane Colton. First, machining will begin with a waterjet rough circle cut. A severely undersized internal bore and the seven through-bolt holes made. The bore will have a capscrew through it, accompanied with several nuts. These nuts will then be clamped in the chuck of the lathe, and all outer features will be finished. Thereafter, the bolts will be removed, and the bore will be opened with a boring bar. More work certainly, but I expect a much finer product.