Why don't we try building this time machine?

Well, I tend to agree with the others here. But if this were possible, I think the dense metal would have to be extremely large and therefore spinning 1000 times per sec would equate to HUGE speeds at the outer perimeter of the spin, thus creating warped space-time. This seems to be physically impossible due to the engineering feats needed to employ such a technique. Maybe many centuries in the future, but if time travel is possible, there should be more feasible ways, uming this way even works.