I think you can get more-or-less parallel angle grinder grooves fairly easily by clamping the hub to a piece of angle-iron spaced up from the bench, and sliding the angle grinder along the benchtop, guided by another piece of angle iron. I do not recommend sliding the hub, because I think that would be dangerous. The most difficult bit is indexing the hub by an even amount after each groove is cut, then re-clamping it. All you are doing, is making a crude milling machine.
