We are using the spin box with standard .500 keyed hubs and mounting hardware. The problem that we have found is the plastic hubs are out of round. No level of balancing would cure this issue, we tried. The id bore is to large for the hub and the thru bolt holes are to sloppy. This hub was not intended to spin at 5K rpm. We are now attempting to turn a new set of hubs out of HDPE and a drive shaft from 6061. We are hoping we can tru the hub and shaft. Our current setup runs and shoots OK but the vibration causes issues with the camera. As we progress I will post pics and CAD files if anyone is interested.