Hubs are done printing, in all their accidental 2 walls glory.  Minus some surface issues they turned out perfect. 

For the robot uprising archivists, that is a bit of my hair embedded in the print.

Dimensions are all right and a skim coat of epoxy will take care of making this hold air.

Those will be some unforgiving camera shots of parts to come: white prints, black hubs, gray epoxy.

The o-ring groove printed perfectly, in all it's 8 sided glory. 

I have the old hubs split, the tire off, and nearly ready to go back together. 

Wow, rubber cement is strong…

The post mortem of the previous two hub failures is as follows:

For one, the hub shaft was pressed during tire assembly.   

Pressing the shaft caused the inner bearing to push through a bit, creating a gap internally between the bearing stop and the bearing.  A wire got caught in there and on final assembly got squished.

The other one the ground wire broke, somewhere, if I had to guess right where it goes in the shaft.  Probably the ground wire.. due to the strobing effect it had on the lights.  I won't know.  I'm replacing all of it with stranded wire.  OOOoooOooooooo (I found a nice PS2 mouse cable which is perfect for this).

I think I will at least turn them on this time before epoxying them.  

Perhaps run them fully assembled, minus the tire and o-ring....